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Sample records for discrete choice transport

  1. Protective Behaviour of Citizens to Transport Accidents Involving Hazardous Materials: A Discrete Choice Experiment Applied to Populated Areas nearby Waterways.

    PubMed

    de Bekker-Grob, Esther W; Bergstra, Arnold D; Bliemer, Michiel C J; Trijssenaar-Buhre, Inge J M; Burdorf, Alex

    2015-01-01

    To improve the information for and preparation of citizens at risk to hazardous material transport accidents, a first important step is to determine how different characteristics of hazardous material transport accidents will influence citizens' protective behaviour. However, quantitative studies investigating citizens' protective behaviour in case of hazardous material transport accidents are scarce. A discrete choice experiment was conducted among subjects (19-64 years) living in the direct vicinity of a large waterway. Scenarios were described by three transport accident characteristics: odour perception, smoke/vapour perception, and the proportion of people in the environment that were leaving at their own discretion. Subjects were asked to consider each scenario as realistic and to choose the alternative that was most appealing to them: staying, seeking shelter, or escaping. A panel error component model was used to quantify how different transport accident characteristics influenced subjects' protective behaviour. The response was 44% (881/1,994). The predicted probability that a subject would stay ranged from 1% in case of a severe looking accident till 62% in case of a mild looking accident. All three transport accident characteristics proved to influence protective behaviour. Particularly a perception of strong ammonia or mercaptan odours and visible smoke/vapour close to citizens had the strongest positive influence on escaping. In general, 'escaping' was more preferred than 'seeking shelter', although stated preference heterogeneity among subjects for these protective behaviour options was substantial. Males were less willing to seek shelter than females, whereas elderly people were more willing to escape than younger people. Various characteristics of transport accident involving hazardous materials influence subjects' protective behaviour. The preference heterogeneity shows that information needs to be targeted differently depending on gender and age

  2. Protective Behaviour of Citizens to Transport Accidents Involving Hazardous Materials: A Discrete Choice Experiment Applied to Populated Areas nearby Waterways

    PubMed Central

    de Bekker-Grob, Esther W.; Bergstra, Arnold D.; Bliemer, Michiel C. J.; Trijssenaar-Buhre, Inge J. M.; Burdorf, Alex

    2015-01-01

    Background To improve the information for and preparation of citizens at risk to hazardous material transport accidents, a first important step is to determine how different characteristics of hazardous material transport accidents will influence citizens’ protective behaviour. However, quantitative studies investigating citizens’ protective behaviour in case of hazardous material transport accidents are scarce. Methods A discrete choice experiment was conducted among subjects (19–64 years) living in the direct vicinity of a large waterway. Scenarios were described by three transport accident characteristics: odour perception, smoke/vapour perception, and the proportion of people in the environment that were leaving at their own discretion. Subjects were asked to consider each scenario as realistic and to choose the alternative that was most appealing to them: staying, seeking shelter, or escaping. A panel error component model was used to quantify how different transport accident characteristics influenced subjects’ protective behaviour. Results The response was 44% (881/1,994). The predicted probability that a subject would stay ranged from 1% in case of a severe looking accident till 62% in case of a mild looking accident. All three transport accident characteristics proved to influence protective behaviour. Particularly a perception of strong ammonia or mercaptan odours and visible smoke/vapour close to citizens had the strongest positive influence on escaping. In general, ‘escaping’ was more preferred than ‘seeking shelter’, although stated preference heterogeneity among subjects for these protective behaviour options was substantial. Males were less willing to seek shelter than females, whereas elderly people were more willing to escape than younger people. Conclusion Various characteristics of transport accident involving hazardous materials influence subjects’ protective behaviour. The preference heterogeneity shows that information needs

  3. Choice-Based Conjoint Analysis: Classification vs. Discrete Choice Models

    NASA Astrophysics Data System (ADS)

    Giesen, Joachim; Mueller, Klaus; Taneva, Bilyana; Zolliker, Peter

    Conjoint analysis is a family of techniques that originated in psychology and later became popular in market research. The main objective of conjoint analysis is to measure an individual's or a population's preferences on a class of options that can be described by parameters and their levels. We consider preference data obtained in choice-based conjoint analysis studies, where one observes test persons' choices on small subsets of the options. There are many ways to analyze choice-based conjoint analysis data. Here we discuss the intuition behind a classification based approach, and compare this approach to one based on statistical assumptions (discrete choice models) and to a regression approach. Our comparison on real and synthetic data indicates that the classification approach outperforms the discrete choice models.

  4. Discrete choice experiments of pharmacy services: a systematic review.

    PubMed

    Vass, Caroline; Gray, Ewan; Payne, Katherine

    2016-06-01

    Background Two previous systematic reviews have summarised the application of discrete choice experiments to value preferences for pharmacy services. These reviews identified a total of twelve studies and described how discrete choice experiments have been used to value pharmacy services but did not describe or discuss the application of methods used in the design or analysis. Aims (1) To update the most recent systematic review and critically appraise current discrete choice experiments of pharmacy services in line with published reporting criteria and; (2) To provide an overview of key methodological developments in the design and analysis of discrete choice experiments. Methods The review used a comprehensive strategy to identify eligible studies (published between 1990 and 2015) by searching electronic databases for key terms related to discrete choice and best-worst scaling (BWS) experiments. All healthcare choice experiments were then hand-searched for key terms relating to pharmacy. Data were extracted using a published checklist. Results A total of 17 discrete choice experiments eliciting preferences for pharmacy services were identified for inclusion in the review. No BWS studies were identified. The studies elicited preferences from a variety of populations (pharmacists, patients, students) for a range of pharmacy services. Most studies were from a United Kingdom setting, although examples from Europe, Australia and North America were also identified. Discrete choice experiments for pharmacy services tended to include more attributes than non-pharmacy choice experiments. Few studies reported the use of qualitative research methods in the design and interpretation of the experiments (n = 9) or use of new methods of analysis to identify and quantify preference and scale heterogeneity (n = 4). No studies reported the use of Bayesian methods in their experimental design. Conclusion Incorporating more sophisticated methods in the design of pharmacy

  5. Discrete Elements Method of Neutral Particle Transport

    DTIC Science & Technology

    1983-10-01

    0 ,,S" . K A t - "’.* DISCRETE ELEMENTS METHOD NEUTRAL PARTICLE TRANSPORT ..- DISSERTATION AF. IT/DS/PH/83-5 Kirk A. Mathews LCDR USN D~ Approved for...DISCRETE ELEMENTS METHOD OF NEUTRAL PARTICLE TRANSPORT DISSERTATION Presented to the Faculty of the School of Engineering of the Air Force Institute...o .°. .• . r •.- - DS/PH/83-5 DISCRETE ELEMENTS METHOD OF NEUTRAL PARTICLE TRANSPORT 4 "by Kirk A. Mathews LCDR USN Approved: , Charles J

  6. Modeling Village Water Demand Behavior: A Discrete Choice Approach

    NASA Astrophysics Data System (ADS)

    Mu, Xinming; Whittington, Dale; Briscoe, John

    1990-04-01

    This study presents a discrete choice model of households' water source choice decisions in developing countries. This model is estimated with data collected by in-depth personal interviews with 69 households in Ukunda, Kenya, a small town south of Mombasa. The results suggest that households' source choice decisions are influenced by the time it takes to collect water from different sources, the price of water, and the number of women in a household. Household income, however, did not have a statistically significant effect. Essentially the same data were used to estimate a traditional water demand model which attempts to explain the quantity of water demanded by a household as a function of collection time, income, and other socioeconomic variables. The results of the discrete choice and traditional water demand models are compared in this paper.

  7. A deterministic discrete ordinates transport proxy application

    SciTech Connect

    2014-06-03

    Kripke is a simple 3D deterministic discrete ordinates (Sn) particle transport code that maintains the computational load and communications pattern of a real transport code. It is intended to be a research tool to explore different data layouts, new programming paradigms and computer architectures.

  8. Reconceptualising the external validity of discrete choice experiments.

    PubMed

    Lancsar, Emily; Swait, Joffre

    2014-10-01

    External validity is a crucial but under-researched topic when considering using discrete choice experiment (DCE) results to inform decision making in clinical, commercial or policy contexts. We present the theory and tests traditionally used to explore external validity that focus on a comparison of final outcomes and review how this traditional definition has been empirically tested in health economics and other sectors (such as transport, environment and marketing) in which DCE methods are applied. While an important component, we argue that the investigation of external validity should be much broader than a comparison of final outcomes. In doing so, we introduce a new and more comprehensive conceptualisation of external validity, closely linked to process validity, that moves us from the simple characterisation of a model as being or not being externally valid on the basis of predictive performance, to the concept that external validity should be an objective pursued from the initial conceptualisation and design of any DCE. We discuss how such a broader definition of external validity can be fruitfully used and suggest innovative ways in which it can be explored in practice.

  9. Air Cargo Transportation Route Choice Analysis

    NASA Technical Reports Server (NTRS)

    Obashi, Hiroshi; Kim, Tae-Seung; Oum, Tae Hoon

    2003-01-01

    Using a unique feature of air cargo transshipment data in the Northeast Asian region, this paper identifies the critical factors that determine the transshipment route choice. Taking advantage of the variations in the transport characteristics in each origin-destination airports pair, the paper uses a discrete choice model to describe the transshipping route choice decision made by an agent (i.e., freight forwarder, consolidator, and large shipper). The analysis incorporates two major factors, monetary cost (such as line-haul cost and landing fee) and time cost (i.e., aircraft turnaround time, including loading and unloading time, custom clearance time, and expected scheduled delay), along with other controls. The estimation method considers the presence of unobserved attributes, and corrects for resulting endogeneity by use of appropriate instrumental variables. Estimation results find that transshipment volumes are more sensitive to time cost, and that the reduction in aircraft turnaround time by 1 hour would be worth the increase in airport charges by more than $1000. Simulation exercises measures the impacts of alternative policy scenarios for a Korean airport, which has recently declared their intention to be a future regional hub in the Northeast Asian region. The results suggest that reducing aircraft turnaround time at the airport be an effective strategy, rather than subsidizing to reduce airport charges.

  10. Using discrete choice experiments to understand preferences in health care.

    PubMed

    Pfarr, Christian; Schmid, Andreas; Schneider, Udo

    2014-01-01

    Whenever processes are reconfigured or new products are designed the needs and preferences of patients and consumers have to be considered. Although at times neglected, this becomes more and more relevant in health care settings: Which modes of health care delivery will be accepted? What are the patients' priorities and what is the willingness to pay? To which degree are patients mobile and for which kind of services are they willing to travel? Preferences, however, are difficult to measure, as they are latent constructs. This becomes even more difficult, when no past choices can be analyzed either as the service or the product is yet to be developed or as in the past there has not been free choice for patients. In such cases, preferences cannot be surveyed directly. Asking individuals openly for their attitudes towards certain services and products, the results are likely biased as individuals are not confronted with budget constraints and trade-offs. For this reason, discrete choice experiments (DCEs) are frequently used to elicit patient preferences. This approach confronts patients with hypothetical scenarios of which only one can be chosen. Over the past few years, this tool to reveal patients' preferences for health care has become very popular in health economics. This contribution aims at introducing the principles of DCEs, highlighting the underlying theory and giving practical guidance for conducting a discrete choice experiment in health economics. Thereby we focus on three major fields of patient demand: designing health insurance, assessing patient utility of new pharmaceuticals and analyzing provider choice. By having a closer look at selected international studies, we discuss the application of this technique for the analysis of the supply and the demand of health care as well as the implications for assessing patient mobility across different health care systems.

  11. A review of the application and contribution of discrete choice experiments to inform human resources policy interventions.

    PubMed

    Lagarde, Mylene; Blaauw, Duane

    2009-07-24

    Although the factors influencing the shortage and maldistribution of health workers have been well-documented by cross-sectional surveys, there is less evidence on the relative determinants of health workers' job choices, or on the effects of policies designed to address these human resources problems. Recently, a few studies have adopted an innovative approach to studying the determinants of health workers' job preferences. In the absence of longitudinal datasets to analyse the decisions that health workers have actually made, authors have drawn on methods from marketing research and transport economics and used Discrete Choice Experiments to analyse stated preferences of health care providers for different job characteristics. We carried out a literature review of studies using discrete choice experiments to investigate human resources issues related to health workers, both in developed and developing countries. Several economic and health systems bibliographic databases were used, and contacts were made with practitioners in the field to identify published and grey literature. Ten studies were found that used discrete choice experiments to investigate the job preferences of health care providers. The use of discrete choice experiments techniques enabled researchers to determine the relative importance of different factors influencing health workers' choices. The studies showed that non-pecuniary incentives are significant determinants, sometimes more powerful than financial ones. The identified studies also emphasized the importance of investigating the preferences of different subgroups of health workers. Discrete choice experiments are a valuable tool for informing decision-makers on how to design strategies to address human resources problems. As they are relatively quick and cheap survey instruments, discrete choice experiments present various advantages for informing policies in developing countries, where longitudinal labour market data are seldom

  12. A review of the application and contribution of discrete choice experiments to inform human resources policy interventions

    PubMed Central

    Lagarde, Mylene; Blaauw, Duane

    2009-01-01

    Although the factors influencing the shortage and maldistribution of health workers have been well-documented by cross-sectional surveys, there is less evidence on the relative determinants of health workers' job choices, or on the effects of policies designed to address these human resources problems. Recently, a few studies have adopted an innovative approach to studying the determinants of health workers' job preferences. In the absence of longitudinal datasets to analyse the decisions that health workers have actually made, authors have drawn on methods from marketing research and transport economics and used Discrete Choice Experiments to analyse stated preferences of health care providers for different job characteristics. We carried out a literature review of studies using discrete choice experiments to investigate human resources issues related to health workers, both in developed and developing countries. Several economic and health systems bibliographic databases were used, and contacts were made with practitioners in the field to identify published and grey literature. Ten studies were found that used discrete choice experiments to investigate the job preferences of health care providers. The use of discrete choice experiments techniques enabled researchers to determine the relative importance of different factors influencing health workers' choices. The studies showed that non-pecuniary incentives are significant determinants, sometimes more powerful than financial ones. The identified studies also emphasized the importance of investigating the preferences of different subgroups of health workers. Discrete choice experiments are a valuable tool for informing decision-makers on how to design strategies to address human resources problems. As they are relatively quick and cheap survey instruments, discrete choice experiments present various advantages for informing policies in developing countries, where longitudinal labour market data are seldom

  13. Personal Traits Underlying Environmental Preferences: A Discrete Choice Experiment

    PubMed Central

    Soliño, Mario; Farizo, Begoña A.

    2014-01-01

    Personality plays a role in human behavior, and thus can influence consumer decisions on environmental goods and services. This paper analyses the influence of the big five personality dimensions (extraversion, agreeableness, conscientiousness, neuroticism and openness) in a discrete choice experiment dealing with preferences for the development of an environmental program for forest management in Spain. For this purpose, a reduced version of the Big Five Inventory survey (the BFI-10) is implemented. Results show a positive effect of openness and extraversion and a negative effect of agreeableness and neuroticism in consumers' preferences for this environmental program. Moreover, results from a latent class model show that personal traits help to explain preference heterogeneity. PMID:24586905

  14. Evaluating reproductive decisions as discrete choices under social influence.

    PubMed

    Bentley, R Alexander; Brock, William A; Caiado, Camila C S; O'Brien, Michael J

    2016-04-19

    Discrete choice, coupled with social influence, plays a significant role in evolutionary studies of human fertility, as investigators explore how and why reproductive decisions are made. We have previously proposed that the relative magnitude of social influence can be compared against the transparency of pay-off, also known as the transparency of a decision, through a heuristic diagram that maps decision-making along two axes. The horizontal axis represents the degree to which an agent makes a decision individually versus one that is socially influenced, and the vertical axis represents the degree to which there is transparency in the pay-offs and risks associated with the decision the agent makes. Having previously parametrized the functions that underlie the diagram, we detail here how our estimation methods can be applied to real-world datasets concerning sexual health and contraception. © 2016 The Author(s).

  15. Preferred choice of work setting among nurses in Thailand: A discrete choice experiment.

    PubMed

    Kunaviktikul, Wipada; Chitpakdee, Bunpitcha; Srisuphan, Wichit; Bossert, Thomas

    2014-05-08

    The shortage of health personnel and nurses is an important issue in many developed and developing countries. Understanding preferred choice of work setting is an important strategy for retaining nurses in their work. The purpose of this study was to determine choices made by nurses in Thailand relative to their preferences for a work setting. A discrete choice experiment was conducted to elicit attributes and levels of job characteristics expected to contribute to work-place preferences. The sample included 921 nurses and was selected using stratified random sampling. A random effects probit model was used to identify factors contributing to work-setting preferences. The results showed that nurses' first work-place preference was a high level of work setting. The second preference was to work in a hospital in the same province as their families. The results provide information for hospital and nurse administrators and policymakers seeking to address the nursing shortage.

  16. Energy-pointwise discrete ordinates transport methods

    SciTech Connect

    Williams, M.L.; Asgari, M.; Tashakorri, R.

    1997-06-01

    A very brief description is given of a one-dimensional code, CENTRM, which computes a detailed, space-dependent flux spectrum in a pointwise-energy representation within the resolved resonance range. The code will become a component in the SCALE system to improve computation of self-shielded cross sections, thereby enhancing the accuracy of codes such as KENO. CENTRM uses discrete-ordinates transport theory with an arbitrary angular quadrature order and a Legendre expansion of scattering anisotropy for moderator materials and heavy nuclides. The CENTRM program provides capability to deterministically compute full energy range, space-dependent angular flux spectra, rigorously accounting for resonance fine-structure and scattering anisotropy effects.

  17. Drivers of choice of resuscitation fluid in the intensive care unit: a discrete choice experiment.

    PubMed

    Taylor, Colman B; Hammond, Naomi E; Laba, Tracey-Lea; Watts, Nicola; Thompson, Kelly; Saxena, Manoj; Micallef, Sharon; Finfer, Simon; Myburgh, John

    2017-06-01

    To understand the fundamental drivers, and their relative importance, of doctors' and nurses' choice of resuscitation fluid in critically ill patients in Australia and New Zealand. A discrete choice experiment (DCE) administered via an online survey. Respondents were presented with one of four randomly selected DCE choice sets, each including five patient scenarios. The respondent chose between two types of hypothetical resuscitation fluid. The fluid type was characterised by several attributes and each attribute had pre-specified levels. Convenience sample of 367 Australian and New Zealand intensive care unit doctors and nurses. The dependent variable was fluid choice, and a regression equation was used to estimate the effect of each fluid attribute on the probability of observing the sequence of choices made over the five patient scenarios. The relative importance of each of the respective fluid attributes was calculated based on the percentage contribution to overall utility (ie, fluid preference). For doctors, safety concerns, patient type and fluid type were collectively responsible for almost three-quarters of decision-making utility (71%). The volume of intravenous fluid administered was the only clinical parameter not reaching statistical significance as a driver of fluid choice (P = 0.06). For nurses, decision making was influenced to a greater extent by the same three attributes (90%), although other unmeasured attributes may have been driving choice. Doctors and nurses rely on different information when choosing resuscitation fluids, although both cohorts are heavily influenced by safety concerns, patient type and fluid type. This information can be used to modify prescribing behaviour.

  18. Patient preferences regarding prophylactic cranial irradiation: A discrete choice experiment.

    PubMed

    Lehman, Margot; Gorayski, Peter; Watson, Susanne; Edeling, Desiree; Jackson, James; Whitty, Jennifer

    2016-11-01

    In patients with non-small cell lung cancer (NSCLC) treated with chemoradiotherapy (CRT), prophylactic cranial irradiation (PCI) is not standard practice. This study determined patient preferences for PCI with respect to survival benefit, reduction in brain metastases (BM) and acceptable toxicity. A Discrete Choice Experiment was completed pre- and post-treatment. Patients made 15 hypothetical choices between two alternative PCI treatments described by four attributes: amount of life gained, chance of BM, ability to care for oneself, and loss of memory. Participants also chose between PCI and no PCI. 54 and 46 surveys were completed pre- and post-treatment. The most important attributes pre-treatment were: a survival benefit >6months, of 3-6months, avoiding severe problems with memory and self-care, avoiding quite a bit of difficulty with memory and maximally reducing BM recurrence. Post-treatment, BM reduction became more important. 90% of patients would accept PCI for a survival benefit >6months, with a maximal reduction in BM even if severe memory/self-care problems occurred. With a 10% reduction in BM and mild problems with memory and self-care 70% of patients pre- (90% post-treatment) would accept PCI for a survival benefit of 1-3months, and 52% pre- (78% post-treatment) for no survival benefit. Improvement in survival is the most important attribute of PCI with patients willing to accept significant toxicity for maximum survival and less toxicity for less survival benefit. BM reduction became more important after treatment. The majority of patients would accept PCI for no survival benefit and a reduction in BM. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Discrete choice experiment of smoking cessation behaviour in Japan.

    PubMed

    Goto, Rei; Nishimura, Shuzo; Ida, Takanori

    2007-10-01

    In spite of gradual increases in tobacco price and the introduction of laws supporting various anti-tobacco measures, the proportion of smokers in Japan's population is still higher than in other developed nations. To understand what information and individual characteristics drive smokers to attempt to quit smoking. These determinants will help to realise effective tobacco control policy as a base for understanding of cessation behaviour. Discrete choice experiments on a total of 616 respondents registered at a consumer monitoring investigative company. The effect of price is greater on smokers with lower nicotine dependence. For smokers of moderate and low dependency, short term health risks and health risks caused by passive smoking have a strong impact, though the existence of penalties and long term health risks have little influence on smokers' decisions to quit. For highly dependent smokers, non-price attributes have little impact. Furthermore, the effects of age, sex and knowledge are also not uniform in accounting for smoking cessation. Determinants of smoking cessation vary among levels of nicotine dependency. Therefore, how and what information is provided needs to be carefully considered when counselling smokers to help them to quit.

  20. Best-worst scaling vs. discrete choice experiments: an empirical comparison using social care data.

    PubMed

    Potoglou, Dimitris; Burge, Peter; Flynn, Terry; Netten, Ann; Malley, Juliette; Forder, Julien; Brazier, John E

    2011-05-01

    This paper presents empirical findings from the comparison between two principal preference elicitation techniques: discrete choice experiments and profile-based best-worst scaling. Best-worst scaling involves less cognitive burden for respondents and provides more information than traditional "pick-one" tasks asked in discrete choice experiments. However, there is lack of empirical evidence on how best-worst scaling compares to discrete choice experiments. This empirical comparison between discrete choice experiments and best-worst scaling was undertaken as part of the Outcomes of Social Care for Adults project, England, which aims to develop a weighted measure of social care outcomes. The findings show that preference weights from best-worst scaling and discrete choice experiments do reveal similar patterns in preferences and in the majority of cases preference weights--when normalised/rescaled--are not significantly different.

  1. Measuring the loss of consumer choice in mandatory health programmes using discrete choice experiments.

    PubMed

    Parkinson, Bonny; Goodall, Stephen; Norman, Richard

    2013-04-01

    Economic evaluation of mandatory health programmes generally do not consider the utility impact of a loss of consumer choice upon implementation, despite evidence suggesting that consumers do value having the ability to choose. The primary aim of this study was to explore whether the utility impact of a loss of consumer choice from implementing mandatory health programmes can be measured using discrete choice experiments (DCEs). Three case studies were used to test the methodology: fortification of bread-making flour with folate, mandatory influenza vaccination of children, and the banning of trans-fats. Attributes and levels were developed from a review of the literature. An orthogonal, fractional factorial design was used to select the profiles presented to respondents to allow estimation of main effects. Overall, each DCE consisted of 64 profiles which were allocated to four versions of 16 profiles. Each choice task compared two profiles, one being voluntary and the other being mandatory, plus a 'no policy' option, thus each respondent was presented with eight choice tasks. For each choice task, respondents were asked which health policy they most preferred and least preferred. Data was analysed using a mixed logit model with correlated coefficients (200 Halton draws). The compensating variation required for introducing a programme on a mandatory basis (versus achieving the same health impacts with a voluntary programme) that holds utility constant was estimated. Responses were provided by 535 participants (a response rate of 83 %). For the influenza vaccination and folate fortification programmes, the results suggested that some level of compensation may be required for introducing the programme on a mandatory basis. Introducing a mandatory influenza vaccination programme required the highest compensation (Australian dollars [A$] 112.75, 95 % CI -60.89 to 286.39) compared with folate fortification (A$18.05, 95 % CI -3.71 to 39.80). No compensation was

  2. Preferences for colorectal cancer screening strategies: a discrete choice experiment

    PubMed Central

    Hol, L; de Bekker-Grob, E W; van Dam, L; Donkers, B; Kuipers, E J; Habbema, J D F; Steyerberg, E W; van Leerdam, M E; Essink-Bot, M L

    2010-01-01

    Background: Guidelines underline the role of individual preferences in the selection of a screening test, as insufficient evidence is available to recommend one screening test over another. We conducted a study to determine the preferences of individuals and to predict uptake for colorectal cancer (CRC) screening programmes using various screening tests. Methods: A discrete choice experiment (DCE) questionnaire was distributed among naive subjects, yet to be screened, and previously screened subjects, aged 50–75 years. Subjects were asked to choose between scenarios on the basis of faecal occult blood test (FOBT), flexible sigmoidoscopy (FS), total colonoscopy (TC) with various test-specific screening intervals and mortality reductions, and no screening (opt-out). Results: In total, 489 out of 1498 (33%) screening-naïve subjects (52% male; mean age±s.d. 61±7 years) and 545 out of 769 (71%) previously screened subjects (52% male; mean age±s.d. 61±6 years) returned the questionnaire. The type of screening test, screening interval, and risk reduction of CRC-related mortality influenced subjects' preferences (all P<0.05). Screening-naive and previously screened subjects equally preferred 5-yearly FS and 10-yearly TC (P=0.24; P=0.11), but favoured both strategies to annual FOBT screening (all P-values <0.001) if, based on the literature, realistic risk reduction of CRC-related mortality was applied. Screening-naive and previously screened subjects were willing to undergo a 10-yearly TC instead of a 5-yearly FS to obtain an additional risk reduction of CRC-related mortality of 45% (P<0.001). Conclusion: These data provide insight into the extent by which interval and risk reduction of CRC-related mortality affect preferences for CRC screening tests. Assuming realistic test characteristics, subjects in the target population preferred endoscopic screening over FOBT screening, partly, due to the more favourable risk reduction of CRC-related mortality by endoscopy

  3. Acceptance of vaccinations in pandemic outbreaks: a discrete choice experiment.

    PubMed

    Determann, Domino; Korfage, Ida J; Lambooij, Mattijs S; Bliemer, Michiel; Richardus, Jan Hendrik; Steyerberg, Ewout W; de Bekker-Grob, Esther W

    2014-01-01

    Preventive measures are essential to limit the spread of new viruses; their uptake is key to their success. However, the vaccination uptake in pandemic outbreaks is often low. We aim to elicit how disease and vaccination characteristics determine preferences of the general public for new pandemic vaccinations. In an internet-based discrete choice experiment (DCE) a representative sample of 536 participants (49% participation rate) from the Dutch population was asked for their preference for vaccination programs in hypothetical communicable disease outbreaks. We used scenarios based on two disease characteristics (susceptibility to and severity of the disease) and five vaccination program characteristics (effectiveness, safety, advice regarding vaccination, media attention, and out-of-pocket costs). The DCE design was based on a literature review, expert interviews and focus group discussions. A panel latent class logit model was used to estimate which trade-offs individuals were willing to make. All above mentioned characteristics proved to influence respondents' preferences for vaccination. Preference heterogeneity was substantial. Females who stated that they were never in favor of vaccination made different trade-offs than males who stated that they were (possibly) willing to get vaccinated. As expected, respondents preferred and were willing to pay more for more effective vaccines, especially if the outbreak was more serious (€6-€39 for a 10% more effective vaccine). Changes in effectiveness, out-of-pocket costs and in the body that advises the vaccine all substantially influenced the predicted uptake. We conclude that various disease and vaccination program characteristics influence respondents' preferences for pandemic vaccination programs. Agencies responsible for preventive measures during pandemics can use the knowledge that out-of-pocket costs and the way advice is given affect vaccination uptake to improve their plans for future pandemic outbreaks

  4. Acceptance of Vaccinations in Pandemic Outbreaks: A Discrete Choice Experiment

    PubMed Central

    Determann, Domino; Korfage, Ida J.; Lambooij, Mattijs S.; Bliemer, Michiel; Richardus, Jan Hendrik; Steyerberg, Ewout W.; de Bekker-Grob, Esther W.

    2014-01-01

    Background Preventive measures are essential to limit the spread of new viruses; their uptake is key to their success. However, the vaccination uptake in pandemic outbreaks is often low. We aim to elicit how disease and vaccination characteristics determine preferences of the general public for new pandemic vaccinations. Methods In an internet-based discrete choice experiment (DCE) a representative sample of 536 participants (49% participation rate) from the Dutch population was asked for their preference for vaccination programs in hypothetical communicable disease outbreaks. We used scenarios based on two disease characteristics (susceptibility to and severity of the disease) and five vaccination program characteristics (effectiveness, safety, advice regarding vaccination, media attention, and out-of-pocket costs). The DCE design was based on a literature review, expert interviews and focus group discussions. A panel latent class logit model was used to estimate which trade-offs individuals were willing to make. Results All above mentioned characteristics proved to influence respondents’ preferences for vaccination. Preference heterogeneity was substantial. Females who stated that they were never in favor of vaccination made different trade-offs than males who stated that they were (possibly) willing to get vaccinated. As expected, respondents preferred and were willing to pay more for more effective vaccines, especially if the outbreak was more serious (€6–€39 for a 10% more effective vaccine). Changes in effectiveness, out-of-pocket costs and in the body that advises the vaccine all substantially influenced the predicted uptake. Conclusions We conclude that various disease and vaccination program characteristics influence respondents’ preferences for pandemic vaccination programs. Agencies responsible for preventive measures during pandemics can use the knowledge that out-of-pocket costs and the way advice is given affect vaccination uptake to improve

  5. The Role of Qualitative Research Methods in Discrete Choice Experiments

    PubMed Central

    Vass, Caroline; Rigby, Dan; Payne, Katherine

    2017-01-01

    Background. The use of qualitative research (QR) methods is recommended as good practice in discrete choice experiments (DCEs). This study investigated the use and reporting of QR to inform the design and/or interpretation of healthcare-related DCEs and explored the perceived usefulness of such methods. Methods. DCEs were identified from a systematic search of the MEDLINE database. Studies were classified by the quantity of QR reported (none, basic, or extensive). Authors (n = 91) of papers reporting the use of QR were invited to complete an online survey eliciting their views about using the methods. Results. A total of 254 healthcare DCEs were included in the review; of these, 111 (44%) did not report using any qualitative methods; 114 (45%) reported “basic” information; and 29 (11%) reported or cited “extensive” use of qualitative methods. Studies reporting the use of qualitative methods used them to select attributes and/or levels (n = 95; 66%) and/or pilot the DCE survey (n = 26; 18%). Popular qualitative methods included focus groups (n = 63; 44%) and interviews (n = 109; 76%). Forty-four studies (31%) reported the analytical approach, with content (n = 10; 7%) and framework analysis (n = 5; 4%) most commonly reported. The survey identified that all responding authors (n = 50; 100%) found that qualitative methods added value to their DCE study, but many (n = 22; 44%) reported that journals were uninterested in the reporting of QR results. Conclusions. Despite recommendations that QR methods be used alongside DCEs, the use of QR methods is not consistently reported. The lack of reporting risks the inference that QR methods are of little use in DCE research, contradicting practitioners’ assessments. Explicit guidelines would enable more clarity and consistency in reporting, and journals should facilitate such reporting via online supplementary materials. PMID:28061040

  6. Discrete choice experiments in pharmacy: a review of the literature.

    PubMed

    Naik-Panvelkar, Pradnya; Armour, Carol; Saini, Bandana

    2013-02-01

    Discrete choice experiments (DCEs) have been widely used to elicit patient preferences for various healthcare services and interventions. The aim of our study was to conduct an in-depth scoping review of the literature and provide a current overview of the progressive application of DCEs within the field of pharmacy. Electronic databases (MEDLINE, EMBASE, SCOPUS, ECONLIT) were searched (January 1990-August 2011) to identify published English language studies using DCEs within the pharmacy context. Data were abstracted with respect to DCE methodology and application to pharmacy. Our search identified 12 studies. The DCE methodology was utilised to elicit preferences for different aspects of pharmacy products, therapy or services. Preferences were elicited from either patients or pharmacists, with just two studies incorporating the views of both. Most reviewed studies examined preferences for process-related or provider-related aspects with a lesser focus on health outcomes. Monetary attributes were considered to be important by most patients and pharmacists in the studies reviewed. Logit, probit or multinomial logit models were most commonly employed for estimation. Our study showed that the pharmacy profession has adopted the DCE methodology consistent with the general health DCEs although the number of studies is quite limited. Future studies need to examine preferences of both patients and providers for particular products or disease-state management services. Incorporation of health outcome attributes in the design, testing for external validity and the incorporation of DCE results in economic evaluation framework to inform pharmacy policy remain important areas for future research. © 2012 The Authors. IJPP © 2012 Royal Pharmaceutical Society.

  7. Men's preferences for prostate cancer screening: a discrete choice experiment

    PubMed Central

    de Bekker-Grob, E W; Rose, J M; Donkers, B; Essink-Bot, M-L; Bangma, C H; Steyerberg, E W

    2013-01-01

    Background: Screening for prostate cancer (PC) may save lives, but overdiagnosis and overtreatment are serious drawbacks. We aimed to determine men's preferences for PC screening, and to elicit the trade-offs they make. Methods: A discrete choice experiment (DCE) was conducted among a population-based random sample of 1000 elderly men (55–75-years-old). Trade-offs were quantified with a panel latent class model between five PC screening aspects: risk reduction of PC-related death, screening interval, risk of unnecessary biopsies, risk of unnecessary treatments, and out-of-pocket costs. Results: The response rate was 46% (459/1000). Men were willing to trade-off 2.0% (CI: 1.6%–2.4%) or 1.8% (CI: 1.3%–2.3%) risk reduction of PC-related death to decrease their risk of unnecessary treatment or biopsy with 10%, respectively. They were willing to pay €188 per year (CI: €141–€258) to reduce their relative risk of PC-related death with 10%. Preference heterogeneity was substantial, with men with higher educational levels having a lower probability to opt for PC screening than men with lower educational levels. Conclusion: Men were willing to trade-off some risk reduction of PC-related death to be relieved of the burden of biopsies or unnecessary treatments. Increasing knowledge on overdiagnosis and overtreatment, especially for men with lower educational levels, is warranted to prevent unrealistic expectations from PC screening. PMID:23361056

  8. Adolescent girls' preferences for HPV vaccines: a discrete choice experiment.

    PubMed

    Brown, Derek S; Poulos, Christine; Johnson, F Reed; Chamiec-Case, Linda; Messonnier, Mark L

    2014-01-01

    To measure adolescent girls' preferences over features of human papillomavirus (HPV) vaccines in order to provide quantitative estimates of the perceived benefits of vaccination and potential vaccine uptake. A discrete choice experiment (DCE) survey was developed to measure adolescent girls' preferences over features of HPV vaccines. The survey was fielded to a U.S. sample of 307 girls aged 13-17 years who had not yet received an HPV vaccine in June 2008. In a latent class logit model, two distinct groups were identified--one with strong preferences against vaccination which largely did not differentiate between vaccine features, and another that was receptive to vaccination and had well-defined preferences over vaccine features. Based on the mean estimates over the entire sample, we estimate that girls' valuation of bivalent and quadrivalent HPV vaccines ranged between $400 and $460 in 2008, measured as willingness-to-pay (WTP). The additional value of genital warts protection was $145, although cervical cancer efficacy was the most preferred feature. We estimate maximum uptake of 54-65%, close to the 53% reported for one dose in 2011 surveillance data, but higher than the 35% for three doses in surveillance data. We conclude that adolescent girls do form clear opinions and some place significant value on HPV vaccination, making research on their preferences vital to understanding the determinants of HPV vaccine demand. DCE studies may be used to design more effective vaccine-promotion programs and for reassessing public health recommendations and guidelines as new vaccines are made available.

  9. The Role of Qualitative Research Methods in Discrete Choice Experiments.

    PubMed

    Vass, Caroline; Rigby, Dan; Payne, Katherine

    2017-04-01

    The use of qualitative research (QR) methods is recommended as good practice in discrete choice experiments (DCEs). This study investigated the use and reporting of QR to inform the design and/or interpretation of healthcare-related DCEs and explored the perceived usefulness of such methods. DCEs were identified from a systematic search of the MEDLINE database. Studies were classified by the quantity of QR reported (none, basic, or extensive). Authors ( n = 91) of papers reporting the use of QR were invited to complete an online survey eliciting their views about using the methods. A total of 254 healthcare DCEs were included in the review; of these, 111 (44%) did not report using any qualitative methods; 114 (45%) reported "basic" information; and 29 (11%) reported or cited "extensive" use of qualitative methods. Studies reporting the use of qualitative methods used them to select attributes and/or levels ( n = 95; 66%) and/or pilot the DCE survey ( n = 26; 18%). Popular qualitative methods included focus groups ( n = 63; 44%) and interviews ( n = 109; 76%). Forty-four studies (31%) reported the analytical approach, with content ( n = 10; 7%) and framework analysis ( n = 5; 4%) most commonly reported. The survey identified that all responding authors ( n = 50; 100%) found that qualitative methods added value to their DCE study, but many ( n = 22; 44%) reported that journals were uninterested in the reporting of QR results. Despite recommendations that QR methods be used alongside DCEs, the use of QR methods is not consistently reported. The lack of reporting risks the inference that QR methods are of little use in DCE research, contradicting practitioners' assessments. Explicit guidelines would enable more clarity and consistency in reporting, and journals should facilitate such reporting via online supplementary materials.

  10. Multiple Choice Knapsack Problem: example of planning choice in transportation.

    PubMed

    Zhong, Tao; Young, Rhonda

    2010-05-01

    Transportation programming, a process of selecting projects for funding given budget and other constraints, is becoming more complex as a result of new federal laws, local planning regulations, and increased public involvement. This article describes the use of an integer programming tool, Multiple Choice Knapsack Problem (MCKP), to provide optimal solutions to transportation programming problems in cases where alternative versions of projects are under consideration. In this paper, optimization methods for use in the transportation programming process are compared and then the process of building and solving the optimization problems is discussed. The concepts about the use of MCKP are presented and a real-world transportation programming example at various budget levels is provided. This article illustrates how the use of MCKP addresses the modern complexities and provides timely solutions in transportation programming practice. While the article uses transportation programming as a case study, MCKP can be useful in other fields where a similar decision among a subset of the alternatives is required. Copyright 2009 Elsevier Ltd. All rights reserved.

  11. Discrete Choice Modeling (DCM): An Exciting Marketing Research Survey Method for Educational Researchers.

    ERIC Educational Resources Information Center

    Berdie, Doug R.

    Discrete Choice Marketing (DCM), a research technique that has become more popular in recent marketing research, is described. DCM is a method that forces people to look at the combination of relevant variables within each choice domain and, with each option fully defined in terms of the values for those variables, make a choice of options. DCM…

  12. Determinants of the choice of GP practice registration in England: evidence from a discrete choice experiment.

    PubMed

    Lagarde, Mylene; Erens, Bob; Mays, Nicholas

    2015-04-01

    There have been growing concerns that general practitioner (GP) services in England, which are based on registration with a single practice located near the patient's home, are not sufficiently convenient for patients. To inform the decision as to whether to change registration rules allowing patients to register 'out-of-area' and to estimate the demand for this wider choice, we undertook a discrete choice experiment with 1706 respondents. Latent class models were used to analyse preferences for GP practice registration comparing preferences for neighbourhood and non-neighbourhood practices. We find that there is some appetite for registering outside the neighbourhood, but this preference is not uniformly shared across the population. Specifically individuals who are less mobile (e.g. older people and those with caring responsibilities), or satisfied with their local practice are less likely to be interested in registering at a practice outside their neighbourhood. Overall, people feel most strongly about obtaining an appointment with a GP as quickly as possible. Respondents regarded weekend opening as less important than other factors, and particularly less important than extended practice opening hours from Monday to Friday. Assuming a constant demand for GP services, a policy encouraging GP practices to extend their opening hours during the week is likely to decrease the average patient waiting time for an appointment and is likely to be preferred by patients. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  13. Segmenting patients and physicians using preferences from discrete choice experiments.

    PubMed

    Deal, Ken

    2014-01-01

    People often form groups or segments that have similar interests and needs and seek similar benefits from health providers. Health organizations need to understand whether the same health treatments, prevention programs, services, and products should be applied to everyone in the relevant population or whether different treatments need to be provided to each of several segments that are relatively homogeneous internally but heterogeneous among segments. Our objective was to explain the purposes, benefits, and methods of segmentation for health organizations, and to illustrate the process of segmenting health populations based on preference coefficients from a discrete choice conjoint experiment (DCE) using an example study of prevention of cyberbullying among university students. We followed a two-level procedure for investigating segmentation incorporating several methods for forming segments in Level 1 using DCE preference coefficients and testing their quality, reproducibility, and usability by health decision makers. Covariates (demographic, behavioral, lifestyle, and health state variables) were included in Level 2 to further evaluate quality and to support the scoring of large databases and developing typing tools for assigning those in the relevant population, but not in the sample, to the segments. Several segmentation solution candidates were found during the Level 1 analysis, and the relationship of the preference coefficients to the segments was investigated using predictive methods. Those segmentations were tested for their quality and reproducibility and three were found to be very close in quality. While one seemed better than others in the Level 1 analysis, another was very similar in quality and proved ultimately better in predicting segment membership using covariates in Level 2. The two segments in the final solution were profiled for attributes that would support the development and acceptance of cyberbullying prevention programs among university

  14. Age and choice in health insurance: evidence from a discrete choice experiment.

    PubMed

    Becker, Karolin; Zweifel, Peter

    2008-01-01

    A uniform package of benefits and uniform cost sharing are elements of regulation inherent in most social health insurance systems. Both elements risk burdening the population with a welfare loss if preferences for risk and insurance attributes differ. This suggests the introduction of more choice in social health insurance packages may be advantageous; however, it is widely believed that this would not benefit the elderly.A representative telephone survey of 1000 people aged >24 years living in the German- and French-speaking parts of Switzerland was conducted. Participants were asked to compare the status quo (i.e. their current insurance contract) with ten hypothetical alternatives. In addition, participants were asked questions concerning utilization of healthcare services; overall satisfaction with the healthcare system, insurer and insurance policy; and a general preference for new elements in the insurance package. Socioeconomic variables surveyed were age, sex, total household income, education (seven categories ranging from primary school to university degree), place of residence, occupation, and marital status. To examine the relationship between age and willingness to pay (WTP) for additional options in Swiss social health insurance.A representative telephone survey of 1000 people aged >24 years living in the German- and French-speaking parts of Switzerland was conducted. Participants were asked to compare the status quo (i.e. their current insurance contract) with ten hypothetical alternatives. In addition, participants were asked questions concerning utilization of healthcare services; overall satisfaction with the healthcare system, insurer and insurance policy; and a general preference for new elements in the insurance package. Socioeconomic variables surveyed were age, sex, total household income, education (seven categories ranging from primary school to university degree), place of residence, occupation, and marital status. A discrete choice

  15. Eliciting community preferences for complementary micro health insurance: a discrete choice experiment in rural Malawi.

    PubMed

    Abiiro, Gilbert Abotisem; Torbica, Aleksandra; Kwalamasa, Kassim; De Allegri, Manuela

    2014-11-01

    There is a limited understanding of preferences for micro health insurance (MHI) as a strategy for moving towards universal health coverage. Using a discrete choice experiment (DCE), we explored community preferences for the attributes and attribute-levels of a prospective MHI scheme, aimed at filling health coverage gaps in Malawi. Through a qualitative study informed by a literature review, we identified six MHI attributes (and attribute-levels): unit of enrollment, management structure, health service benefit package, copayment levels, transportation coverage, and monthly premium per person. Qualitative data was collected from 12 focus group discussions and 8 interviews in August-September, 2012. We constructed a D-efficient design of eighteen choice-sets, each comprising two MHI choice alternatives and an opt-out. Using pictorial images, trained interviewers administered the DCE in March-May, 2013, to 814 household heads and/or their spouse(s) in two rural districts. We estimated preferences for attribute-levels and relative importance of attributes using conditional and nested logit models. The results showed that all attribute-levels except management by external NGO significantly influenced respondents' choice behavior (P<0.05). These included: enrollment as core nuclear family (odds ratio (OR)=1.1574), extended family (OR=1.1132), compared to individual; management by community committee (OR=0.9494) compared to local micro finance institution; comprehensive health service package (OR=1.4621), medium service package (OR=1.2761), compared to basic service package; no copayment (OR=1.1347), 25% copayment (OR=1.1090), compared to 50% copayment; coverage of all transport (OR=1.5841), referral and emergency transport (OR=1.2610), compared to no transport; and premium (OR=0.9994). The relative importance of attributes is ordered as: transport, health services benefits, enrollment unit, premium, copayment, and management. To maximize consumer utility and encourage

  16. Women's Preferences for Place of Delivery in Rural Tanzania: A Population-Based Discrete Choice Experiment

    PubMed Central

    Paczkowski, Magdalena; Mbaruku, Godfrey; de Pinho, Helen; Galea, Sandro

    2009-01-01

    Objectives. We fielded a population-based discrete choice experiment (DCE) in rural western Tanzania, where only one third of women deliver children in a health facility, to evaluate health-system factors that influence women's delivery decisions. Methods. Women were shown choice cards that described 2 hypothetical health centers by means of 6 attributes (distance, cost, type of provider, attitude of provider, drugs and equipment, free transport). The women were then asked to indicate which of the 2 facilities they would prefer to use for a future delivery. We used a hierarchical Bayes procedure to estimate individual and mean utility parameters. Results. A total of 1203 women completed the DCE. The model showed good predictive validity for actual facility choice. The most important facility attributes were a respectful provider attitude and availability of drugs and medical equipment. Policy simulations suggested that if these attributes were improved at existing facilities, the proportion of women preferring facility delivery would rise from 43% to 88%. Conclusions. In regions in which attended delivery rates are low despite availability of primary care facilities, policy experiments should test the effect of targeted quality improvements on facility use. PMID:19608959

  17. Women's preferences for place of delivery in rural Tanzania: a population-based discrete choice experiment.

    PubMed

    Kruk, Margaret E; Paczkowski, Magdalena; Mbaruku, Godfrey; de Pinho, Helen; Galea, Sandro

    2009-09-01

    We fielded a population-based discrete choice experiment (DCE) in rural western Tanzania, where only one third of women deliver children in a health facility, to evaluate health-system factors that influence women's delivery decisions. Women were shown choice cards that described 2 hypothetical health centers by means of 6 attributes (distance, cost, type of provider, attitude of provider, drugs and equipment, free transport). The women were then asked to indicate which of the 2 facilities they would prefer to use for a future delivery. We used a hierarchical Bayes procedure to estimate individual and mean utility parameters. A total of 1203 women completed the DCE. The model showed good predictive validity for actual facility choice. The most important facility attributes were a respectful provider attitude and availability of drugs and medical equipment. Policy simulations suggested that if these attributes were improved at existing facilities, the proportion of women preferring facility delivery would rise from 43% to 88%. In regions in which attended delivery rates are low despite availability of primary care facilities, policy experiments should test the effect of targeted quality improvements on facility use.

  18. Chronic pain patients' treatment preferences: a discrete-choice experiment.

    PubMed

    Mühlbacher, Axel C; Junker, Uwe; Juhnke, Christin; Stemmler, Edgar; Kohlmann, Thomas; Leverkus, Friedhelm; Nübling, Matthias

    2015-07-01

    The objective of this study was to identify, document, and weight attributes of a pain medication that are relevant from the perspective of patients with chronic pain. Within the sub-population of patients suffering from "chronic neuropathic pain", three groups were analyzed in depth: patients with neuropathic back pain, patients with painful diabetic polyneuropathy, and patients suffering from pain due to post-herpetic neuralgia. The central question was: "On which features do patients base their assessment of pain medications and which features are most useful in the process of evaluating and selecting possible therapies?" A detailed literature review, focus groups with patients, and face-to-face interviews with widely recognized experts for pain treatment were conducted to identify relevant treatment attributes of a pain medication. A pre-test was conducted to verify the structure of relevant and dominant attributes using factor analyses by evaluating the most frequently mentioned representatives of each factor. The Discrete-Choice Experiment (DCE) used a survey based on self-reported patient data including socio-demographics and specific parameters concerning pain treatment. Furthermore, the neuropathic pain component was determined in all patients based on their scoring in the painDETECT(®) questionnaire. For statistical data analysis of the DCE, a random effect logit model was used and coefficients were presented. A total of 1,324 German patients participated in the survey, of whom 44 % suffered from neuropathic back pain (including mixed pain syndrome), 10 % complained about diabetic polyneuropathy, and 4 % reported pain due to post-herpetic neuralgia. A total of 36 single quality aspects of pain treatment, detected in the qualitative survey, were grouped in 7 dimensions by factor analysis. These 7 dimensions were used as attributes for the DCE. The DCE model resulted in the following ranking of relevant attributes for treatment decision: "no character

  19. Modeling the Bullying Prevention Program Preferences of Educators: A Discrete Choice Conjoint Experiment

    ERIC Educational Resources Information Center

    Cunningham, Charles E.; Vaillancourt, Tracy; Rimas, Heather; Deal, Ken; Cunningham, Lesley; Short, Kathy; Chen, Yvonne

    2009-01-01

    We used discrete choice conjoint analysis to model the bullying prevention program preferences of educators. Using themes from computerized decision support lab focus groups (n = 45 educators), we composed 20 three-level bullying prevention program design attributes. Each of 1,176 educators completed 25 choice tasks presenting experimentally…

  20. Environmental Factors in the Choice of EGMs: A Discrete Choice Experiment.

    PubMed

    Rockloff, Matthew J; Moskovsky, Neda; Thorne, Hannah; Browne, Matthew; Bryden, Gabrielle M

    2016-06-09

    EGMs are a form of entertainment, and the gambling environment is an important contributor to the overall experience. Logically, to select a play-environment, EGM gamblers must choose the platform through which to access the EGM (e.g., internet, mobile application or land-based venue), a particular provider (e.g., specific website, app vendor or branded casino), and the game itself (e.g., based on graphical theme or bonus features; Thorne et al. in J Gambl Stud, 2016. doi: 10.1007/s10899-016-9601-2 ). A discrete choice experiment was conducted to identify the features of the platform, provider and game that are most strongly preferred by EGM gamblers. Participants were 245 EGM gamblers from clubs in Victoria, Australia and 7516 EGM gamblers from an Australian online panel. Results indicate that the ideal environment for the average gambler consists of: gambling at a club that is close to home; with a group of friends; in a relatively quiet place that has air conditioning, cheap food and a large space to play in; on a classic game with quality animations and small bet sizes; where you feel safe and secure; and where there is a wide variety of other games to play when you are done. Segmenting these results by problem-gambler status highlights important differences in preferences between problem and non-problem gamblers. Problem gamblers are less likely to give weight to the company they share and have a preference for larger venues. Using a powerful paradigm from marketing research, the present study was able to determine the relative value of different features of the EGM gambling environment, and also contributes important insight towards what constitutes a safer environment for recreational play.

  1. Discrete energy transport in collagen molecules

    NASA Astrophysics Data System (ADS)

    Alain, Mvogo; Germain, H. Ben-Bolie; Timoléon, C. Kofané

    2014-09-01

    The modulational instability in the three coupled α-polypeptide chains of a collagen molecule is investigated. Choosing symmetric and asymmetric solutions, and applying the so-called rotating-wave approximation, we describe the dynamics of the system by the discrete nonlinear Schrödinger (DNLS) equation. The linear stability analysis of the continuous wave solution is performed. The numerical simulations show the generation of trains of solitonic structures in the lattice with increasing amplitude as time progresses. The effect of damping and noise forces of the physiological temperature (T = 300 K) introduces an erratic behavior to the formed patterns, reinforcing the idea that the energy used in metabolic processes is confined to specific regions for efficiency.

  2. Health system choice: a pilot discrete-choice experiment eliciting the preferences of British and Australian citizens.

    PubMed

    Scuffham, Paul A; Whitty, Jennifer A; Taylor, Matthew; Saxby, Ruth C

    2010-01-01

    Citizen preferences surrounding desirable health system characteristics should be considered when undertaking health system reform. The objective of this study was to pilot test a discrete-choice instrument designed to elicit preference weights surrounding health system attributes. A discrete-choice experiment was designed and administered to two convenience samples (n=50 each) recruited from the UK and Australia. The impact of eight health system attributes representing level of health, equity, responsiveness and healthcare financing on the choice between hypothetical health systems was analysed utilizing mixed logit analysis. All characteristics affected the likelihood a health system would be preferred, with the exception of the additional tax contribution levels required to finance the system. There were very few missing or inconsistent responses. The direction of preferences was consistent with expectations for both samples; that is, an improvement in attributes describing level of health, equity or responsiveness increased the likelihood that a health system would be preferred. A number of potential improvements to the preference instrument are suggested. The discrete-choice technique used in this study offers a feasible method for eliciting health system preferences, and its use in a larger-scale study to elicit and compare the preferences of representative population samples is supported.

  3. Do patients always prefer quicker treatment? : a discrete choice analysis of patients' stated preferences in the London Patient Choice Project.

    PubMed

    Burge, Peter; Devlin, Nancy; Appleby, John; Rohr, Charlene; Grant, Jonathan

    2004-01-01

    The London Patient Choice Project (LPCP) was established to offer NHS patients more choice over where and when they receive treatment, and to reduce waiting times. The LPCP offered those patients waiting around 6 months for elective procedures a choice of treatment at an alternative NHS or private hospital, or treatment at an overseas hospital.The aim of this article is to investigate the following questions regarding patients' response to choice: (a) What are the factors that patients consider when deciding whether to accept the alternatives they are offered? (b) What is the relative importance to patients of each factor when making their choices, i.e. what trade-offs are patients prepared to make between time waited and other factors? (c) Are there any systematic differences between subgroups of patients (in terms of their personal, health and sociodemographic characteristics) in their response to choice?Patients' preferences were elicited using a discrete choice experiment. Patients eligible to participate in the LPCP were recruited prior to being offered their choice between hospitals and each presented with seven hypothetical choices via a self-completed questionnaire. Data were received from 2114 patients. Thirty percent of respondents consistently chose their 'current' over the 'alternative' hospital. All the attributes and levels examined in the experiment were found to exhibit a significant influence on patients' likelihood of opting for an alternative provider, in the expected direction. Age, education and income had an important effect on the 'uptake' of choice. Our results suggest several important implications for policy. First, there may be equity concerns arising from some patient subgroups being more predisposed to accept choice. Second, although reduced waiting time is important to most patients, it is not all that matters. For example, the reputation of the proffered alternatives is of key importance, suggesting careful thought is required about

  4. Developing a discrete choice experiment in Malawi: eliciting preferences for breast cancer early detection services.

    PubMed

    Kohler, Racquel E; Lee, Clara N; Gopal, Satish; Reeve, Bryce B; Weiner, Bryan J; Wheeler, Stephanie B

    2015-01-01

    In Malawi, routine breast cancer screening is not available and little is known about women's preferences regarding early detection services. Discrete choice experiments are increasingly used to reveal preferences about new health services; however, selecting appropriate attributes that describe a new health service is imperative to ensure validity of the choice experiment. To identify important factors that are relevant to Malawian women's preferences for breast cancer detection services and to select attributes and levels for a discrete choice experiment in a setting where both breast cancer early detection and choice experiments are rare. We reviewed the literature to establish an initial list of potential attributes and levels for a discrete choice experiment and conducted qualitative interviews with health workers and community women to explore relevant local factors affecting decisions to use cancer detection services. We tested the design through cognitive interviews and refined the levels, descriptions, and designs. Themes that emerged from interviews provided critical information about breast cancer detection services, specifically, that breast cancer interventions should be integrated into other health services because asymptomatic screening may not be practical as an individual service. Based on participants' responses, the final attributes of the choice experiment included travel time, health encounter, health worker type and sex, and breast cancer early detection strategy. Cognitive testing confirmed the acceptability of the final attributes, comprehension of choice tasks, and women's abilities to make trade-offs. Applying a discrete choice experiment for breast cancer early detection was feasible with appropriate tailoring for a low-income, low-literacy African setting.

  5. Modelling the Preferences of Students for Alternative Assignment Designs Using the Discrete Choice Experiment Methodology

    ERIC Educational Resources Information Center

    Kennelly, Brendan; Flannery, Darragh; Considine, John; Doherty, Edel; Hynes, Stephen

    2014-01-01

    This paper outlines how a discrete choice experiment (DCE) can be used to learn more about how students are willing to trade off various features of assignments such as the nature and timing of feedback and the method used to submit assignments. A DCE identifies plausible levels of the key attributes of a good or service and then presents the…

  6. Modelling the Preferences of Students for Alternative Assignment Designs Using the Discrete Choice Experiment Methodology

    ERIC Educational Resources Information Center

    Kennelly, Brendan; Flannery, Darragh; Considine, John; Doherty, Edel; Hynes, Stephen

    2014-01-01

    This paper outlines how a discrete choice experiment (DCE) can be used to learn more about how students are willing to trade off various features of assignments such as the nature and timing of feedback and the method used to submit assignments. A DCE identifies plausible levels of the key attributes of a good or service and then presents the…

  7. Hospital sector choice and support for public hospital care in New Zealand: Results from a labeled discrete choice survey.

    PubMed

    Brown, Paul; Panattoni, Laura; Cameron, Linda; Knox, Stephanie; Ashton, Toni; Tenbensel, Tim; Windsor, John

    2015-09-01

    This study uses a discrete choice experiment (DCE) to measure patients' preferences for public and private hospital care in New Zealand. A labeled DCE was administered to 583 members of the general public, with the choice between a public and private hospital for a non-urgent surgery. The results suggest that cost of surgery, waiting times for surgery, option to select a surgeon, convenience, and conditions of the hospital ward are important considerations for patients. The most important determinant of hospital choice was whether it was a public or private hospital, with respondents far more likely to choose a public hospital than a private hospital. The results have implications for government policy toward using private hospitals to clear waiting lists in public hospitals, with these results suggesting the public might not be indifferent to policies that treat private hospitals as substitutes for public hospitals.

  8. Factors affecting food choices of older adults from high and low socioeconomic groups: a discrete choice experiment.

    PubMed

    Kamphuis, Carlijn B M; de Bekker-Grob, Esther W; van Lenthe, Frank J

    2015-04-01

    Healthiness, price, and convenience are typically indicated as important motives for food choices; however, it is largely unknown to what extent older adults from high and low socioeconomic groups differ in these underlying motives. A discrete choice experiment (DCE) is an innovative way to elicit implicit motives for food choices. The aim was to investigate differences in food motives between socioeconomic groups by means of a DCE. A DCE was carried out during a face-to-face interview among older adults as part of the Health and Living Conditions in Eindhoven and surrounding cities (GLOBE) cohort study, The Netherlands. Participants (n = 399; mean age: 63.3 y) were offered a series of choice sets about a usual dinner at home and were asked to choose in each choice set between 2 meals and an opt-out choice, with different combinations of attribute levels. We included 5 meal attributes (taste, healthiness, preparation time, travel time to shops, and price) and 3 or 4 levels for each attribute. Data were analyzed by multinomial logit models. Healthiness, taste, price, and travel time to the grocery store proved to significantly influence older adults' meal decisions; preparation time was not significant. Healthiness was the most important attribute for all of the participants. More highly educated participants rated a healthy and less expensive meal to be more important than did less educated participants. Those with a high income rated a meal that was healthy and very tasteful to be more important than did those with a lower income. Healthiness, taste, price, and travel time to grocery shops influenced older adults' meal decisions. Higher socioeconomic groups valued health more than did lower socioeconomic groups. DCEs represent a promising method to gain insight into the relative importance of motives for food choices. This trial was registered at www.isrctn.com as ISRCTN60293770. © 2015 American Society for Nutrition.

  9. What factors influence older people in the decision to relinquish their driver's licence? A discrete choice experiment.

    PubMed

    McNamara, Annabel; Chen, Gang; George, Stacey; Walker, Ruth; Ratcliffe, Julie

    2013-06-01

    To investigate the relative importance of a number of key factors that influence older people in the decision to relinquish their driver's licence. A discrete choice experiment (DCE) was administered as an online survey to Australian adults, 65 years plus (N=114) who drive, recruited from an online panel. The survey was composed of three main sections. (A) The Adelaide Driving Self Efficacy Scale to assess confidence in driving. The scale is generated from individual's responses about confidence in their driving ability in various situations. (B) The DCE in which respondents were presented with a series of hypothetical binary choice situations and asked to indicate in which situation they would be more likely to relinquish their driving licence. (C) Socio-demographic and health status questions. A conditional logit regression model was adopted to analyse the DCE data. Older people would be more likely to relinquish their driver's licence due to advanced age, low confidence in driving ability and in situations where their local doctor advises them to cease driving. Other transport options availability and the cost of public transport were not found to be influential to this decision. Factors pertaining to the individual themselves including advanced old age and low confidence in driving ability may be more influential than environmental factors such as availability of other transport options and the cost of public transport in an older person's decision to relinquish their driving licence. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  10. Ordering effect and price sensitivity in discrete choice experiments: need we worry?

    PubMed

    Kjaer, Trine; Bech, Mickael; Gyrd-Hansen, Dorte; Hart-Hansen, Kristian

    2006-11-01

    The objective of this paper is to analyse the impact that attribute ordering has on the relative importance of the price attribute. A discrete choice experiment was performed in order to elicit psoriasis patients' preferences for treatment. We tested for ordering effect with respect to the price attribute, and disclosed noticeable higher price sensitivity when the price attribute was placed at the end of the program description. Our results indicate that preferences are context dependent and that heuristics may be used in the choice process. Our result does not, however, suggest that ordering effect is a symptom of lexicographic ordering. Copyright (c) 2006 John Wiley & Sons, Ltd.

  11. Estimation of Dynamic Discrete Choice Models by Maximum Likelihood and the Simulated Method of Moments

    PubMed Central

    Eisenhauer, Philipp; Heckman, James J.; Mosso, Stefano

    2015-01-01

    We compare the performance of maximum likelihood (ML) and simulated method of moments (SMM) estimation for dynamic discrete choice models. We construct and estimate a simplified dynamic structural model of education that captures some basic features of educational choices in the United States in the 1980s and early 1990s. We use estimates from our model to simulate a synthetic dataset and assess the ability of ML and SMM to recover the model parameters on this sample. We investigate the performance of alternative tuning parameters for SMM. PMID:26494926

  12. A discrete-continuous choice model of climate change impacts on energy

    SciTech Connect

    Morrison, W.N.; Mendelsohn, R.

    1998-09-01

    This paper estimates a discrete-continuous fuel choice model in order to explore climate impacts on the energy sector. The model is estimated on a national data set of firms and households. The results reveal that actors switch from oil in cold climates to electricity and natural gas in warm climates and that fuel-specific expenditures follow a U-shaped relationship with respect to temperature. The model implies that warming will increase American energy expenditures, reflecting a sizable welfare damage.

  13. Prediction of discretization error using the error transport equation

    NASA Astrophysics Data System (ADS)

    Celik, Ismail B.; Parsons, Don Roscoe

    2017-06-01

    This study focuses on an approach to quantify the discretization error associated with numerical solutions of partial differential equations by solving an error transport equation (ETE). The goal is to develop a method that can be used to adequately predict the discretization error using the numerical solution on only one grid/mesh. The primary problem associated with solving the ETE is the formulation of the error source term which is required for accurately predicting the transport of the error. In this study, a novel approach is considered which involves fitting the numerical solution with a series of locally smooth curves and then blending them together with a weighted spline approach. The result is a continuously differentiable analytic expression that can be used to determine the error source term. Once the source term has been developed, the ETE can easily be solved using the same solver that is used to obtain the original numerical solution. The new methodology is applied to the two-dimensional Navier-Stokes equations in the laminar flow regime. A simple unsteady flow case is also considered. The discretization error predictions based on the methodology presented in this study are in good agreement with the 'true error'. While in most cases the error predictions are not quite as accurate as those from Richardson extrapolation, the results are reasonable and only require one numerical grid. The current results indicate that there is much promise going forward with the newly developed error source term evaluation technique and the ETE.

  14. Benefit-risk assessment of HMG-CoA reductase inhibitors (statins): a discrete choice experiment.

    PubMed

    Wanishayakorn, Tanatape; Sornlertlumvanich, Korn; Ngorsuraches, Surachat

    2016-02-25

    To conduct the benefit-risk assessment of 3-hydroxy-3-methyl-glutaryl (HMG) coenzyme A reductase inhibitors (statins) using a discrete choice experiment, based on 3 major stakeholders' perspectives including patients, experts and policymakers in Thailand. A discrete choice experiment questionnaire survey in three stakeholders' perspectives. Public hospitals in Thailand. A total of 353 policymakers, experts and patients. Stakeholders' preferences for assessment criteria (stroke reduction, myocardial infarction reduction, myalgia and hepatotoxicity). Statins' ranking and maximum acceptable risk in all perspectives were also calculated. For any perspective, the most and least important criteria were the risk of hepatotoxicity and the benefit of myocardial infarction reduction, respectively. Patients and experts agreed on the order of importance for myalgia and stroke reduction, but policymakers had different order of importance in these criteria. Overall, results showed that the highest and lowest chances of being chosen were atorvastatin and rosuvastatin, respectively. Only patients' ranking order was different from others. Maximum acceptable risk of hepatotoxicity was lower than that of myalgia, reflecting the greater concern of all perspectives to statin consequence on liver. The results of benefit-risk assessment from every perspective were somewhat consistent. This study demonstrated the feasibility of applying a discrete choice experiment in the benefit-risk assessment of drugs and encouraged the engagement of multiple stakeholders in the decision-making process. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  15. Benefit–risk assessment of HMG-CoA reductase inhibitors (statins): a discrete choice experiment

    PubMed Central

    Sornlertlumvanich, Korn; Ngorsuraches, Surachat

    2016-01-01

    Objectives To conduct the benefit–risk assessment of 3-hydroxy-3-methyl-glutaryl (HMG) coenzyme A reductase inhibitors (statins) using a discrete choice experiment, based on 3 major stakeholders’ perspectives including patients, experts and policymakers in Thailand. Design A discrete choice experiment questionnaire survey in three stakeholders’ perspectives. Setting Public hospitals in Thailand. Participants A total of 353 policymakers, experts and patients. Outcomes Stakeholders’ preferences for assessment criteria (stroke reduction, myocardial infarction reduction, myalgia and hepatotoxicity). Statins’ ranking and maximum acceptable risk in all perspectives were also calculated. Results For any perspective, the most and least important criteria were the risk of hepatotoxicity and the benefit of myocardial infarction reduction, respectively. Patients and experts agreed on the order of importance for myalgia and stroke reduction, but policymakers had different order of importance in these criteria. Overall, results showed that the highest and lowest chances of being chosen were atorvastatin and rosuvastatin, respectively. Only patients’ ranking order was different from others. Maximum acceptable risk of hepatotoxicity was lower than that of myalgia, reflecting the greater concern of all perspectives to statin consequence on liver. Conclusions The results of benefit–risk assessment from every perspective were somewhat consistent. This study demonstrated the feasibility of applying a discrete choice experiment in the benefit–risk assessment of drugs and encouraged the engagement of multiple stakeholders in the decision-making process. PMID:26916689

  16. Patient preferences for managing asthma: results from a discrete choice experiment.

    PubMed

    King, Madeleine T; Hall, Jane; Lancsar, Emily; Fiebig, Denzil; Hossain, Ishrat; Louviere, Jordan; Reddel, Helen K; Jenkins, Christine R

    2007-07-01

    Effective control of asthma requires regular preventive medication. Poor medication adherence suggests that patient preferences for medications may differ from the concerns of the prescribing clinicians. This study investigated patient preferences for preventive medications across symptom control, daily activities, medication side-effects, convenience and costs, using a discrete choice experiment embedded in a randomized clinical trial involving patients with mild-moderate persistent asthma. The present data were collected after patients had received 6 weeks' treatment with one of two drugs. Three choice options were presented, to continue with the current drug, to change to an alternative, hypothetical drug, or to take no preventive medication. Analysis used random parameter multinomial logit. Most respondents chose to continue with their current drug in most choice situations but this tendency differed depending on which medication they had been allocated. Respondents valued their ability to participate in usual daily activities and sport, preferred minimal symptoms, and were less likely to choose drugs with side-effects. Cost was also significant, but other convenience attributes were not. Demographic characteristics did not improve the model fit. This study illustrates how discrete choice experiments may be embedded in a clinical trial to provide insights into patient preferences.

  17. Urban transportation: Perspectives on mobility and choice

    NASA Technical Reports Server (NTRS)

    Sincoff, M. Z. (Editor); Dajani, J. S. (Editor); Arnold, G. R.; Bird, J. W.; Brooks, C. M. (Editor); Cobb, W. E.; Cross, J. E.; Darby, L. F.; Erb, N. H.; Ficht, J. C.

    1974-01-01

    A study of urban transportation systems are presented characterized by intensive scrutiny of many ideas, philosophies, and academic perspectives. This report is intended to communicate some dimensions of the urban transportation problem to the general public.

  18. Percolation assisted excitation transport in discrete-time quantum walks

    NASA Astrophysics Data System (ADS)

    Štefaňák, M.; Novotný, J.; Jex, I.

    2016-02-01

    Coherent transport of excitations along chains of coupled quantum systems represents an interesting problem with a number of applications ranging from quantum optics to solar cell technology. A convenient tool for studying such processes are quantum walks. They allow us to determine all the process features in a quantitative way. We study the survival probability and the transport efficiency on a simple, highly symmetric graph represented by a ring. The propagation of excitation is modeled by a discrete-time (coined) quantum walk. For a two-state quantum walk, where the excitation (walker) has to leave its actual position to the neighboring sites, the survival probability decays exponentially and the transport efficiency is unity. The decay rate of the survival probability can be estimated using the leading eigenvalue of the evolution operator. However, if the excitation is allowed to stay at its present position, i.e. the propagation is modeled by a lazy quantum walk, then part of the wave-packet can be trapped in the vicinity of the origin and never reaches the sink. In such a case, the survival probability does not vanish and the excitation transport is not efficient. The dependency of the transport efficiency on the initial state is determined. Nevertheless, we show that for some lazy quantum walks dynamical, percolations of the ring eliminate the trapping effect and efficient excitation transport can be achieved.

  19. A concurrent, multigroup, discrete ordinates model of neutron transport

    SciTech Connect

    Dorr, M.R.; Still, C.H.

    1993-10-22

    The authors present an algorithm for the concurrent solution of the linear system arising from a multigroup, discrete ordinates model of neutron transport. The target architectures consist of distributed memory computers ranging from workstation clusters to massively parallel computers. Based on an analysis of the memory requirement and floating point complexity of matrix-vector multiplication in the iterative solution of the linear system, the authors propose a data layout and communication strategy designed to achieve scalability with respect to all phase space variables. Numerical results are presented to demonstrate the performance of the algorithm on the nCUBE/2.

  20. Using Discrete Choice Experiments to Inform the Benefit-Risk Assessment of Medicines: Are We Ready Yet?

    PubMed

    Vass, Caroline M; Payne, Katherine

    2017-05-23

    There is emerging interest in the use of discrete choice experiments as a means of quantifying the perceived balance between benefits and risks (quantitative benefit-risk assessment) of new healthcare interventions, such as medicines, under assessment by regulatory agencies. For stated preference data on benefit-risk assessment to be used in regulatory decision making, the methods to generate these data must be valid, reliable and capable of producing meaningful estimates understood by decision makers. Some reporting guidelines exist for discrete choice experiments, and for related methods such as conjoint analysis. However, existing guidelines focus on reporting standards, are general in focus and do not consider the requirements for using discrete choice experiments specifically for quantifying benefit-risk assessments in the context of regulatory decision making. This opinion piece outlines the current state of play in using discrete choice experiments for benefit-risk assessment and proposes key areas needing to be addressed to demonstrate that discrete choice experiments are an appropriate and valid stated preference elicitation method in this context. Methodological research is required to establish: how robust the results of discrete choice experiments are to formats and methods of risk communication; how information in the discrete choice experiment can be presented effectually to respondents; whose preferences should be elicited; the correct underlying utility function and analytical model; the impact of heterogeneity in preferences; and the generalisability of the results. We believe these methodological issues should be addressed, alongside developing a 'reference case', before agencies can safely and confidently use discrete choice experiments for quantitative benefit-risk assessment in the context of regulatory decision making for new medicines and healthcare products.

  1. Personal health records in the Netherlands: potential user preferences quantified by a discrete choice experiment.

    PubMed

    Determann, Domino; Lambooij, Mattijs S; Gyrd-Hansen, Dorte; de Bekker-Grob, Esther W; Steyerberg, Ewout W; Heldoorn, Marcel; Pedersen, Line Bjørnskov; de Wit, G Ardine

    2017-05-01

    To identify groups of potential users based on their preferences for characteristics of personal health records (PHRs) and to estimate potential PHR uptake. We performed a discrete choice experiment, which consisted of 12 choice scenarios, each comprising 2 hypothetical PHR alternatives and an opt-out. The alternatives differed based on 5 characteristics. The survey was administered to Internet panel members of the Dutch Federation of Patients and Consumer Organizations. We used latent class models to analyze the data. A total of 1,443 potential PHR users completed the discrete choice experiment. We identified 3 latent classes: "refusers" (class probability 43%), "eager adopters" (37%), and "reluctant adopters" (20%). The predicted uptake for the reluctant adopters ranged from 4% in the case of a PHR with the worst attribute levels to 68% in the best case. Those with 1 or more chronic diseases were significantly more likely to belong to the eager adopter class. The data storage provider was the most decisive aspect for the eager and reluctant adopters, while cost was most decisive for the refusers. Across all classes, health care providers and independent organizations were the most preferred data storage providers. We identified 3 groups, of which 1 group (more than one-third of potential PHR users) indicated great interest in a PHR irrespective of PHR characteristics. Policymakers who aim to expand the use of PHRs will be most successful when health care providers and health facilities or independent organizations store PHR data while refraining from including market parties.

  2. Supporting driver headway choice: the effects of discrete headway feedback when following headway instructions.

    PubMed

    Risto, Malte; Martens, Marieke H

    2014-07-01

    With specific headway instructions drivers are not able to attain the exact headways as instructed. In this study, the effects of discrete headway feedback (and the direction of headway adjustment) on headway accuracy for drivers carrying out time headway instructions were assessed experimentally. Two groups of each 10 participants (one receiving headway feedback; one control) carried out headway instructions in a driving simulator; increasing and decreasing their headway to a target headway of 2 s at speeds of 50, 80, and 100 km/h. The difference between the instructed and chosen headway was a measure for headway accuracy. The feedback group heard a sound signal at the moment that they crossed the distance of the instructed headway. Unsupported participants showed no significant difference in headway accuracy when increasing or decreasing headways. Discrete headway feedback had varying effects on headway choice accuracy. When participants decreased their headway, feedback led to higher accuracy. When increasing their headway, feedback led to a lower accuracy, compared to no headway feedback. Support did not affect driver's performance in maintaining the chosen headway. The present results suggest that (a) in its current form discrete headway feedback is not sufficient to improve the overall accuracy of chosen headways when carrying out headway instructions; (b) the effect of discrete headway feedback depends on the direction of headway adjustment. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  3. Patients' valuation of the prescribing nurse in primary care: a discrete choice experiment.

    PubMed

    Gerard, Karen; Tinelli, Michela; Latter, Sue; Smith, Alesha; Blenkinsopp, Alison

    2015-12-01

    Recently, primary care in the United Kingdom has undergone substantial changes in skill mix. Non-medical prescribing was introduced to improve patient access to medicines, make better use of different health practitioners' skills and increase patient choice. There is little evidence about value-based patient preferences for 'prescribing nurse' in a general practice setting. To quantify value-based patient preferences for the profession of prescriber and other factors that influence choice of consultation for managing a minor illness. Discrete choice experiment patient survey. Five general practices in England with non-medical prescribing services, questionnaires completed by 451 patients. Stated choice of consultation. There was a strong general preference for consulting 'own doctor' for minor illness. However, a consultation with a nurse prescriber with positive patient-focused attributes can be more acceptable to patients than a consultation provided by a doctor. Attributes 'professional's attention to Patients' views' and extent of 'help offered' were pivotal. Past experience influenced preference. Respondents demonstrated valid preferences. Preferences for consulting a doctor remained strong, but many were happy to consult with a nurse if other aspects of the consultation were improved. Findings show who to consult is not the only valued factor in choice of consultation for minor illness. The 'prescribing nurse' role has potential to offer consultation styles that patients value. Within the study's limitations, these findings can inform delivery of primary care to enhance patient experience and substitute appropriate nurse prescribing consultations for medical prescribing consultations. © 2014 John Wiley & Sons Ltd.

  4. Exactly solvable potentials with finitely many discrete eigenvalues of arbitrary choice

    NASA Astrophysics Data System (ADS)

    Sasaki, Ryu

    2014-06-01

    We address the problem of possible deformations of exactly solvable potentials having finitely many discrete eigenvalues of arbitrary choice. As Kay and Moses showed in 1956, reflectionless potentials in one dimensional quantum mechanics are exactly solvable. With an additional time dependence these potentials are identified as the soliton solutions of the Korteweg de Vries (KdV) hierarchy. An N-soliton potential has the time t and 2N positive parameters, k1 < ⋯ < kN and {cj}, j = 1, …, N, corresponding to N discrete eigenvalues lbrace -k_j^2rbrace. The eigenfunctions are elementary functions expressed by the ratio of determinants. The Darboux-Crum-Krein-Adler transformations or the Abraham-Moses transformations based on eigenfunction deletions produce lower soliton number potentials with modified parameters lbrace c^' }_jrbrace. We explore various identities satisfied by the eigenfunctions of the soliton potentials, which reflect the uniqueness theorem of Gel'fand-Levitan-Marchenko equations for separable (degenerate) kernels.

  5. Patients' preferences for primary health care - a systematic literature review of discrete choice experiments.

    PubMed

    Kleij, Kim-Sarah; Tangermann, Ulla; Amelung, Volker E; Krauth, Christian

    2017-07-11

    Primary care is a key element of health care systems and addresses the main health problems of the population. Due to the demographic change, primary care even gains in importance. The knowledge of the patients' preferences can help policy makers as well as physicians to set priorities in their effort to make health care delivery more responsive to patients' needs. Our objective was to describe which aspects of primary care were included in preference studies and which of them were the most preferred aspects. In order to elicit the preferences for primary care, a systematic literature search was conducted. Two researchers searched three electronic databases (PubMed, Scopus, and PsycINFO) and conducted a narrative synthesis. Inclusion criteria were: focus on primary health care delivery, discrete choice experiment as elicitation method, and studies published between 2006 and 2015 in English language. We identified 18 studies that elicited either the patients' or the population's preferences for primary care based on a discrete choice experiment. Altogether the studies used 16 structure attributes, ten process attributes and four outcome attributes. The most commonly applied structure attribute was "Waiting time till appointment", the most frequently used process attribute was "Shared decision making / professional's attention paid to your views". "Receiving the 'best' treatment" was the most commonly applied outcome attribute. Process attributes were most often the ones of highest importance for patients or the population. The attributes and attribute levels used in the discrete choice experiments were identified by literature research, qualitative research, expert interviews, or the analysis of policy documents. The results of the DCE studies show different preferences for primary health care. The diversity of the results may have several reasons, such as the method of analysis, the selection procedure of the attributes and their levels or the specific research

  6. Discrete-time dynamic user-optimal departure time/route choice model

    SciTech Connect

    Chen, H.K.; Hsueh, C.F.

    1998-05-01

    This paper concerns a discrete-time, link-based, dynamic user-optimal departure time/route choice model using the variational inequality approach. The model complies with a dynamic user-optimal equilibrium condition in which for each origin-destination pair, the actual route travel times experienced by travelers, regardless the departure time, is equal and minimal. A nested diagonalization procedure is proposed to solve the model. Numerical examples are then provided for demonstration and detailed elaboration for multiple solutions and Braess`s paradox.

  7. Preferences for treatment of Attention-Deficit/Hyperactivity Disorder (ADHD): a discrete choice experiment.

    PubMed

    Mühlbacher, Axel C; Rudolph, Ina; Lincke, Hans-Joachim; Nübling, Matthias

    2009-08-13

    While there is an increasing emphasis on patient empowerment and shared decision-making, subjective values for attributes associated with their treatment still need to be measured and considered. This contribution seeks to define properties of an ideal drug treatment of individuals concerned with Attention-Deficit/Hyperactivity Disorder (ADHD). Because of the lack of information on patient needs in the decision-makers assessment of health services, the individuals' preferences often play a subordinate role at present. Discrete Choice Experiments offer strategies for eliciting subjective values and making them accessible for physicians and other health care professionals. The evidence comes from a Discrete Choice Experiments (DCE) performed in 2007. After reviewing the literature about preferences of ADHS we conducted a qualitative study with four focus groups consisting of five to eleven ADHS-patients each. In order to achieve content validity, we aimed at collecting all relevant factors for an ideal ADHS treatment. In a subsequent quantitative study phase (n = 219), data was collected in an online or paper-pencil self-completed questionnaire. It included sociodemographic data, health status and patients' preferences of therapy characteristics using direct measurement (23 items on a five-point Likert-scale) as well as a Discrete-Choice-Experiment (DCE, six factors in a fold-over design). Those concerned were capable of clearly defining success criteria and expectations. In the direct assessment and the DCE, respondents attached special significance to the improvement of their social situation and emotional state (relative importance 40%). Another essential factor was the desire for drugs with a long-lasting effect over the day (relative importance 18%). Other criteria, such as flexibility and discretion, were less important to the respondents (6% and 9%, respectively). Results point out that ADHD patients and their family members have clear ideas of their needs

  8. Modelling Discrete Choice Variables in Assessment of Teaching Staff Work Satisfaction

    PubMed Central

    2015-01-01

    Levels of self-reported job satisfaction and motivation were measured by survey in a sample of 286 teachers. Using the discrete choice framework, the paper tries to assess the relevance of the considered indicators (demographic, social, motivational) in overall teaching work satisfaction. The findings provide evidence that job satisfaction is correlated significantly with level of university degree held by the teacher, type of secondary school where the teacher is enrolled, revenues, and salary-tasks adequacy. This is important for the Romanian economy, since the education system is expected to provide future human resources with enhanced skills and abilities. PMID:25849295

  9. Using Blocked Fractional Factorial Designs to Construct Discrete Choice Experiments for Health Care Studies

    PubMed Central

    Jaynes, Jessica; Wong, Weng Kee; Xu, Hongquan

    2016-01-01

    Discrete choice experiments (DCEs) are increasingly used for studying and quantifying subjects preferences in a wide variety of health care applications. They provide a rich source of data to assess real-life decision making processes, which involve trade-offs between desirable characteristics pertaining to health and health care, and identification of key attributes affecting health care. The choice of the design for a DCE is critical because it determines which attributes’ effects and their interactions are identifiable. We apply blocked fractional factorial designs to construct DCEs and address some identification issues by utilizing the known structure of blocked fractional factorial designs. Our design techniques can be applied to several situations including DCEs where attributes have different number of levels. We demonstrate our design methodology using two health care studies to evaluate (1) asthma patients’ preferences for symptom-based outcome measures, and (2) patient preference for breast screening services. PMID:26823156

  10. Discrete-choice experiments versus rating scale exercises to evaluate the importance of attributes.

    PubMed

    Wijnen, Ben Fm; van der Putten, Inge M; Groothuis, Siebren; de Kinderen, Reina Ja; Noben, Cindy Yg; Paulus, Aggie Tg; Ramaekers, Bram Lt; Vogel, Gaston Cwm; Hiligsmann, Mickael

    2015-01-01

    To examine the difference between discrete-choice experiments (DCE) and rating scale exercises (RSE) in determining the most important attributes using a case study. Undergraduate health sciences students were asked to complete a DCE and a RSE. Six potentially important attributes were identified in focus groups. Fourteen unlabelled choice tasks were constructed using a statistically efficient design. Mixed multinomial logistic regression analysis was used for DCE data analysis. In total, 254 undergraduate students filled out the questionnaire. In the DCE, only four attributes were statistically significant, whereas in the RSE, all attributes except one were rated four or higher. Attribute importance differs between DCE and RSE. The DCE had a differentiating effect on the relative importance of the attributes; however, determining relative importance using DCE should be done with caution as a lack of statistically significant difference between levels does not necessarily imply that the attribute is not important.

  11. Testing Ecological Theories of Offender Spatial Decision Making Using a Discrete Choice Model

    PubMed Central

    Summers, Lucia

    2015-01-01

    Research demonstrates that crime is spatially concentrated. However, most research relies on information about where crimes occur, without reference to where offenders reside. This study examines how the characteristics of neighborhoods and their proximity to offender home locations affect offender spatial decision making. Using a discrete choice model and data for detected incidents of theft from vehicles (TFV), we test predictions from two theoretical perspectives—crime pattern and social disorganization theories. We demonstrate that offenders favor areas that are low in social cohesion and closer to their home, or other age-related activity nodes. For adult offenders, choices also appear to be influenced by how accessible a neighborhood is via the street network. The implications for criminological theory and crime prevention are discussed. PMID:25866412

  12. Providing Information to Parents of Children with Mental Health Problems: A Discrete Choice Conjoint Analysis of Professional Preferences

    ERIC Educational Resources Information Center

    Cunningham, Charles E.; Deal, Ken; Rimas, Heather; Chen, Yvonne; Buchanan, Don H.; Sdao-Jarvie, Kathie

    2009-01-01

    We used discrete choice conjoint analysis to model the ways 645 children's mental health (CMH) professionals preferred to provide information to parents seeking CMH services. Participants completed 20 choice tasks presenting experimentally varied combinations of the study's 14 4-level CMH information transfer attributes. Latent class analysis…

  13. A Discrete Choice Conjoint Experiment to Evaluate Parent Preferences for Treatment of Young, Medication Naive Children with ADHD

    ERIC Educational Resources Information Center

    Waschbusch, Daniel A.; Cunningham, Charles E.; Pelham, William E., Jr.; Rimas, Heather L.; Greiner, Andrew R.; Gnagy, Elizabeth M.; Waxmonsky, James; Fabiano, Gregory A.; Robb, Jessica A.; Burrows-MacLean, Lisa; Scime, Mindy; Hoffman, Martin T.

    2011-01-01

    The current study examined treatment preferences of 183 parents of young (average age = 5.8 years, SD = 0.6), medication naive children with ADHD. Preferences were evaluated using a discrete choice experiment in which parents made choices between different combinations of treatment characteristics, outcomes, and costs. Latent class analysis…

  14. Providing Information to Parents of Children with Mental Health Problems: A Discrete Choice Conjoint Analysis of Professional Preferences

    ERIC Educational Resources Information Center

    Cunningham, Charles E.; Deal, Ken; Rimas, Heather; Chen, Yvonne; Buchanan, Don H.; Sdao-Jarvie, Kathie

    2009-01-01

    We used discrete choice conjoint analysis to model the ways 645 children's mental health (CMH) professionals preferred to provide information to parents seeking CMH services. Participants completed 20 choice tasks presenting experimentally varied combinations of the study's 14 4-level CMH information transfer attributes. Latent class analysis…

  15. A Discrete Choice Conjoint Experiment to Evaluate Parent Preferences for Treatment of Young, Medication Naive Children with ADHD

    ERIC Educational Resources Information Center

    Waschbusch, Daniel A.; Cunningham, Charles E.; Pelham, William E., Jr.; Rimas, Heather L.; Greiner, Andrew R.; Gnagy, Elizabeth M.; Waxmonsky, James; Fabiano, Gregory A.; Robb, Jessica A.; Burrows-MacLean, Lisa; Scime, Mindy; Hoffman, Martin T.

    2011-01-01

    The current study examined treatment preferences of 183 parents of young (average age = 5.8 years, SD = 0.6), medication naive children with ADHD. Preferences were evaluated using a discrete choice experiment in which parents made choices between different combinations of treatment characteristics, outcomes, and costs. Latent class analysis…

  16. Consumer Behavior in the Choice of Mode of Transport: A Case Study in the Toledo-Madrid Corridor

    PubMed Central

    Muro-Rodríguez, Ana I.; Perez-Jiménez, Israel R.; Gutiérrez-Broncano, Santiago

    2017-01-01

    Within the context of the consumption of goods or services the decisions made by individuals involve the choice between a set of discrete alternatives, such as the choice of mode of transport. The methodology for analyzing the consumer behavior are the models of discrete choice based on the Theory of Random Utility. These models are based on the definition of preferences through a utility function that is maximized. These models also denominated of disaggregated demand derived from the decision of a set of individuals, who are formalized by the application of probabilistic models. The objective of this study is to determine the behavior of the consumer in the choice of a service, namely of transport services and in a short-distance corridor, such as Toledo-Madrid. The Toledo-Madrid corridor is characterized by being short distance, with high speed train available within the choice options to get the airport, along with the bus and the car. And where offers of HST and aircraft services can be proposed as complementary modes. By applying disaggregated transport models with revealed preference survey data and declared preferences, one can determine the most important variables involved in the choice and determine the arrangements for payment of individuals. These payment provisions may condition the use of certain transport policies to promote the use of efficient transportation. PMID:28676776

  17. Consumer Behavior in the Choice of Mode of Transport: A Case Study in the Toledo-Madrid Corridor.

    PubMed

    Muro-Rodríguez, Ana I; Perez-Jiménez, Israel R; Gutiérrez-Broncano, Santiago

    2017-01-01

    Within the context of the consumption of goods or services the decisions made by individuals involve the choice between a set of discrete alternatives, such as the choice of mode of transport. The methodology for analyzing the consumer behavior are the models of discrete choice based on the Theory of Random Utility. These models are based on the definition of preferences through a utility function that is maximized. These models also denominated of disaggregated demand derived from the decision of a set of individuals, who are formalized by the application of probabilistic models. The objective of this study is to determine the behavior of the consumer in the choice of a service, namely of transport services and in a short-distance corridor, such as Toledo-Madrid. The Toledo-Madrid corridor is characterized by being short distance, with high speed train available within the choice options to get the airport, along with the bus and the car. And where offers of HST and aircraft services can be proposed as complementary modes. By applying disaggregated transport models with revealed preference survey data and declared preferences, one can determine the most important variables involved in the choice and determine the arrangements for payment of individuals. These payment provisions may condition the use of certain transport policies to promote the use of efficient transportation.

  18. Eliciting preferences for medical devices in South Korea: A discrete choice experiment.

    PubMed

    Lee, Hye-Jae; Bae, Eun-Young

    2017-03-01

    This study aims to identify the attributes that contribute to the value of medical devices and quantify the relative importance of them using a discrete choice experiment. Based on a literature review and expert consultation, seven attributes and their levels were identified-severity of disease (2), availability of substitutes (2), improvement in procedure (3), improvement in clinical outcomes (2), increase in survival (2), improvement in quality of life (3), and cost (4). Among 576 hypothetical profiles, optimal choice sets with 20 choices were developed and experts experienced in health technology assessment and reimbursement decision making in South Korea were surveyed. A total of 102 respondents participated in the survey. The results of the random-effect probit model showed that among the seven attributes, six, except for improvement in procedure, had a significant impact on respondents' choices on medical devices. Respondents were willing to pay the highest amount for devices that provided substantial improvements in quality of life, followed by increased survival, improved clinical outcome, treatment without substitutes, and technology for treating severe diseases. The findings of this experiment will inform decision-makers of the relative importance of the criteria and help them in reimbursement decision making of medical devices. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Human group choice: discrete-trial and free-operant tests of the ideal free distribution.

    PubMed

    Madden, Gregory J; Peden, Blaine F; Yamaguchi, Tetsuo

    2002-07-01

    Ideal free distribution theory predicts that foragers will form groups proportional in number to the resources available in alternative resource sites or patches, a phenomenon termed habitat matching. Three experiments tested this prediction with college students in discrete-trial simulations and a free-operant simulation. Sensitivity to differences in programmed reinforcement rates was quantified by using the sensitivity parameter of the generalized matching law (s). The first experiment, replicating prior published experiments, produced a greater degree of undermatching for the initial choice (s = 0.59) compared to final choices (s = 0.86). The second experiment, which extended prior findings by allowing only one choice per trial, produced comparable undermatching (s = 0.82). The third experiment used free-operant procedures more typical of laboratory studies of habitat matching with other species and produced the most undermatching (s = 0.71). The results of these experiments replicated previous results with human groups, supported predictions of the ideal free distribution, and suggested that undermatching represents a systematic deviation from the ideal free distribution. These results are consistent with a melioration account of individual behavior as the basis for group choice.

  20. Modeling improvements in booster seat use: a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Bruce, Beth S; Snowdon, Anne W; Chen, Yvonne; Kolga, Carol; Piotrowski, Caroline; Warda, Lynne; Correale, Heather; Clark, Erica; Barwick, Melanie

    2011-11-01

    Automobile crashes are the leading cause of death in children aged 1-14 years. Many children, however, are not properly restrained in safety seats that reduce serious injury and death. This study used a discrete choice conjoint experiment to study factors influencing the decision to use booster seats. Parents of 1714 children aged 4-9 years from nine Canadian provinces completed choice tasks presenting experimentally varied combinations of 15 4-level booster seat promotion attributes. Latent class analysis yielded three segments of parents. The choices of the Benefit Sensitive segment (50%) were most sensitive to the injury prevention benefits of booster seats. The choices of parents in the Context Sensitive segment (33.5%) were more likely to be influenced by installation complexity, oppositional behavior, and the prospect that their child may be teased for riding in booster seats. Parents in the High Risk segment (16.5%) were younger, less educated, and less knowledgeable about vehicle safety legislation. They anticipated fewer benefits, expected more barriers and were less likely to use booster seats. Simulations suggest that consistent enforcement coupled with advertising focusing on injury prevention and the use of booster seats by other parents would increase adoption. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Energy Transport in Quantum Systems with Discrete Spectrum

    NASA Astrophysics Data System (ADS)

    Levin, George; Jones, Wesley; Walczak, Kamil; Yerkes, Kirk

    2012-02-01

    Energy transport in quantum system driven by stochastic perturbations is examined. One of the goals of this study is to determine how the Landauer channels can be defined in a system with discrete energy spectrum. A model describes a particle trapped in a confining potential and subjected to a stochastic perturbation localized off-center of the potential well. The perturbation pumps energy into the system which results in non-zero average energy flux between different regions of the confining potential. The energy flux can be defined in terms of quantum advection modes, where each mode is associated with an off-diagonal element of the density matrix and carries a finite, quantized amount of energy per unit of the probability flux. Statistical correlations between different modes and the net energy flux will be discussed.

  2. Discrete strategies to reduce intake of discretionary food choices: a scoping review.

    PubMed

    Grieger, Jessica A; Wycherley, Thomas P; Johnson, Brittany J; Golley, Rebecca K

    2016-05-06

    On a population level, dietary improvement strategies have had limited success in preventing the surge in overweight and obesity or reducing risk factors for chronic disease. While numerous multi-component studies have examined whole-of-diet strategies, and single component (i.e. discrete) dietary intervention strategies have targeted an increase in core foods (e.g. fruits, vegetables, dairy), there is a paucity of evidence on the effectiveness of dietary intervention strategies targeting a decrease in discretionary choices. The aim of this review was to identify dietary intervention strategies that are potentially relevant to reducing intake of discretionary choices in 2-65 year olds. A scoping review was carried out to map the literature on key discrete dietary intervention strategies that are potentially applicable to reducing discretionary choices, and to identify the targeted health/nutrition effects (e.g. improve nutrient intake, decrease sugar intake, and reduce body weight) of these strategies. Studies conducted in participants aged 2-65 years and published in English by July 20, 2015, were located through electronic searches including the Cochrane Library, Medline, Embase, CINAHL, and Scopus. Three thousand two hundred and eighty three studies were identified from the search, of which 44 met the selection criteria. The dietary intervention strategies included reformulation (n = 13), substitution (n = 5), restriction/elimination (n = 9), supplementation (n = 13), and nutrition education/messages (n = 4). The key findings of the review were: restricting portion size was consistently beneficial for reducing energy intake in the acute setting; reformulating foods from higher fat to lower fat could be useful to reduce saturated fat intake; substituting discretionary choices for high fibre snacks, fruit, or low/no-calorie beverages may be an effective strategy for reducing energy intake; supplementing nutrient dense foods such as nuts and

  3. Preferences for policy options for cannabis in an Australian general population: A discrete choice experiment.

    PubMed

    Shanahan, Marian; Gerard, Karen; Ritter, Alison

    2014-07-01

    Policy choices for illicit drugs such as cannabis entail consideration of competing factors such as individual health, societal views about pleasure, and criminal justice impacts. Society must weigh up these factors in determining the preferred cannabis policy; although often cast as a contest between legalisation of cannabis or full prohibition the actual policy choices are not so black and white. This study assessed societal preferences for different cannabis policies and multiple consequences. A discrete choice experiment (DCE) quantified value-based preferences for alternative cannabis policies described by the five key attributes legal status, health harms, criminal justice service costs, rates of cannabis use and purchase location. An online survey was conducted on a population sample of 1020 Australians. The analytical model was based on stated choices for Policy A, B or Current Policy. The results revealed a strong general preference for either civil penalties or legalisation compared to cannabis cautioning (Current Policy) and a strong dislike of criminalising possession and use of cannabis. Results also demonstrate difference in preferences among those with different demographics and beliefs. Understanding these nuances help to quantify the range of preferences held within the population and can be used to inform policy. This is the first known DCE survey applied to the area of illicit drugs policy. It demonstrates the public hold disparate views on the most appropriate status for cannabis offences and they are able to make trade-offs between policy choices and outcomes in complex areas of social policy. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Wettability-gradient-driven micropump for transporting discrete liquid drops

    NASA Astrophysics Data System (ADS)

    Bardaweel, Hamzeh K.; Zamuruyev, Konstantin; Delplanque, Jean-Pierre; Davis, Cristina E.

    2013-03-01

    In this paper, we report our efforts toward building a microelectromechanical system-based micropump. The micropump is driven by a wettability gradient and used to transport discrete drops. The gradient in wettability is distributed axisymmetrically, with hydrophobicity of the micropump surface decreasing radially toward the center. Both physical and chemical properties of the surface are altered to obtain the wettability gradient needed for driving the drops. The surface of the micropump is, first, patterned with pre-designed micro-features that define the roughness of the surface and, then, coated with a low-energy interface film. Results show that drops deposited on the surface of the micropump move, in a directional way, along the wettability gradient. The average velocity of the deposited drops is 5 mm s-1. Measured contact angles decrease gradually from 157.0° to 124.2° toward the center of the micropump surface. Maximum driving force exerted by the solid surface on the drops is 12.82 µN. The average size of the drops transported on the surface of the micropump is 2 µL.

  5. The theory of planned behaviour and discrete food choices: a systematic review and meta-analysis.

    PubMed

    McDermott, Máirtín S; Oliver, Madalyn; Svenson, Alexander; Simnadis, Thomas; Beck, Eleanor J; Coltman, Tim; Iverson, Don; Caputi, Peter; Sharma, Rajeev

    2015-12-30

    The combination of economic and social costs associated with non-communicable diseases provide a compelling argument for developing strategies that can influence modifiable risk factors, such as discrete food choices. Models of behaviour, such as the Theory of Planned Behaviour (TPB) provide conceptual order that allows program designers and policy makers to identify the substantive elements that drive behaviour and design effective interventions. The primary aim of the current review was to examine the association between TPB variables and discrete food choice behaviours. A systematic literature search was conducted to identify relevant studies. Calculation of the pooled mean effect size (r(+)) was conducted using inverse-variance weighted, random effects meta-analysis. Heterogeneity across studies was assessed using the Q- and I(2)-statistics. Meta-regression was used to test the impact of moderator variables: type of food choice behaviour; participants' age and gender. A total of 42 journal articles and four unpublished dissertations met the inclusion criteria. TPB variables were found to have medium to large associations with both intention and behaviour. Attitudes had the strongest association with intention (r(+)  = 0.54) followed by perceived behavioural control (PBC, r(+)  = 0.42) and subjective norm (SN, r(+)  = 0.37). The association between intention and behaviour was r(+)  = 0.45 and between PBC and behaviour was r(+)  = 0.27. Moderator analyses revealed the complex nature of dietary behaviour and the factors that underpin individual food choices. Significantly higher PBC-behaviour associations were found for choosing health compromising compared to health promoting foods. Significantly higher intention-behaviour and PBC-behaviour associations were found for choosing health promoting foods compared to avoiding health compromising foods. Participant characteristics were also found to moderate associations within the model. Higher

  6. Patient Preferences for Features of Health Care Delivery Systems: A Discrete Choice Experiment.

    PubMed

    Mühlbacher, Axel C; Bethge, Susanne; Reed, Shelby D; Schulman, Kevin A

    2016-04-01

    To estimate the relative importance of organizational-, procedural-, and interpersonal-level features of health care delivery systems from the patient perspective. We designed four discrete choice experiments (DCEs) to measure patient preferences for 21 health system attributes. Participants were recruited through the online patient portal of a large health system. We analyzed the DCE data using random effects logit models. DCEs were performed in which respondents were provided with descriptions of alternative scenarios and asked to indicate which scenario they prefer. Respondents were randomly assigned to one of the three possible health scenarios (current health, new lung cancer diagnosis, or diabetes) and asked to complete 15 choice tasks. Each choice task included an annual out-of-pocket cost attribute. A total of 3,900 respondents completed the survey. The out-of-pocket cost attribute was considered the most important across the four different DCEs. Following the cost attribute, trust and respect, multidisciplinary care, and shared decision making were judged as most important. The relative importance of out-of-pocket cost was consistently lower in the hypothetical context of a new lung cancer diagnosis compared with diabetes or the patient's current health. This study demonstrates the complexity of patient decision making processes regarding features of health care delivery systems. Our findings suggest the importance of these features may change as a function of an individual's medical conditions. © Health Research and Educational Trust.

  7. Projected discrete ordinates methods for numerical transport problems

    SciTech Connect

    Larsen, E.W.

    1985-01-01

    A class of Projected Discrete-Ordinates (PDO) methods is described for obtaining iterative solutions of discrete-ordinates problems with convergence rates comparable to those observed using Diffusion Synthetic Acceleration (DSA). The spatially discretized PDO solutions are generally not equal to the DSA solutions, but unlike DSA, which requires great care in the use of spatial discretizations to preserve stability, the PDO solutions remain stable and rapidly convergent with essentially arbitrary spatial discretizations. Numerical results are presented which illustrate the rapid convergence and the accuracy of solutions obtained using PDO methods with commonplace differencing methods.

  8. Hospital preferences of nursing students in Korea: a discrete choice experiment approach.

    PubMed

    Park, Bo-Hyun; Ko, YuKyung

    2016-09-29

    DCE was applied to investigate nursing students' preferred hospital choice criteria and to investigate the trends in the trade-offs by calculating the marginal rate of substitution between these criteria. This study identified the properties of the hospitals primarily selected by nursing students, and aims to estimate the monetary value of each attribute. Based on discussions and in-depth interviews with nursing students' focus groups and a literature review, we created a discrete choice experiment (DCE) that assessed how students' stated preference for a certain hospital choice was influenced by various job attributes: higher salary, location, hospital type, salary per year, provision of a dormitory, etc. We applied this DCE to nursing students in South Korea using a brief structured questionnaire, and we used conditional logit models to estimate the utility of each job's attributes. Willingness to pay (WTP) was estimated as the ratio of the value of the coefficient of interest to the negative of the cost attribute. Complete data for the DCE analysis were available for 702 nursing students. In the main effect mixed logit model, the welfare system and organizational culture were most strongly associated with job preference. Location, hospital type, and opportunity to upgrade qualifications had a negative influence on hospital choice. The WTP threshold was 7,043,000 KRW for the welfare system and 9,928,000 KRW for the organizational culture (relation-oriented). Better nursing working conditions, such as a positive organizational culture and the provision of a welfare system, can improve the motivation and applications for hospitals in rural areas.

  9. A discrete choice experiment to determine patient preferences for injection devices in multiple sclerosis.

    PubMed

    Shingler, S L; Swinburn, P; Ali, S; Perard, R; Lloyd, A J

    2013-08-01

    Relapsing-remitting multiple sclerosis (MS) is usually managed with disease modifying drugs (DMDs), most commonly administered via self-injection. The aim of this study was to estimate the influence that different treatment-related attributes have for MS patients on their choice of MS DMD device. By establishing the relative importance of these characteristics for patients it should be possible to better understand the acceptability of a given device and to optimize the development of future devices. A discrete choice experiment (DCE) survey was developed on the basis of a review of published literature. Attributes identified for inclusion in the survey were: ease of use; comfort of use; presence of additional functions, needle visibility; practicality and efficacy. Choice sets were presented as pairs of hypothetical treatments based upon a fractional factorial design. One-hundred device-using MS patients completed the survey online. Analysis was conducted using a mixed-logit approach. Analysis of the DCE data revealed that all attributes significantly predicted treatment choice. Efficacy exhibited the largest effect on treatment selection and this provided context for understanding the magnitude of impact for the other attributes. Reducing the discomfort associated with device use and eliminating the necessity for assembly or drug reconstitution were highly valued. The addition of reminder and time-stamping functions, improved needlestick injury prevention, and reduction in device size were secondary concerns but still deemed desirable. Efficacy is of primary importance to MS patients, but characteristics of drug delivery devices can play an important role in treatment decision-making. Not all device characteristics could be included, and results are based upon 100 participants only. Findings suggest there is significant potential value in developing self-injection devices that are not only efficacious but also convenient and comfortable to use. Reducing barriers

  10. Order of Presentation of Dimensions Does Not Systematically Bias Utility Weights from a Discrete Choice Experiment.

    PubMed

    Norman, Richard; Kemmler, Georg; Viney, Rosalie; Pickard, A Simon; Gamper, Eva; Holzner, Bernhard; Nerich, Virginie; King, Madeleine

    2016-12-01

    Discrete choice experiments (DCEs) are increasingly used to value aspects of health. An issue with their adoption is that results may be sensitive to the order in which dimensions of health are presented in the valuation task. Findings in the literature regarding order effects are discordant at present. To quantify the magnitude of order effect of quality-of-life (QOL) dimensions within the context of a DCE designed to produce country-specific value sets for the EORTC Quality of Life Utility Measure-Core 10 dimensions (QLU-C10D), a new utility instrument derived from the widely used cancer-specific QOL questionnaire, the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30. The DCE comprised 960 choice sets, divided into 60 versions of 16 choice sets, with each respondent assigned to a version. Within each version, the order of QLU-C10D QOL dimensions was randomized, followed by life duration in the last position. The DCE was completed online by 2053 individuals in France and Germany. We analyzed the data with a series of conditional logit models, adjusted for repeated choices within respondent. We used F tests to assess order effects, correcting for multiple hypothesis testing. Each F test failed to reject the null hypothesis of no position effect: 1) all QOL order positions considered jointly; 2) last QOL position only; 3) first QOL position only. Furthermore, the order coefficients were small relative to those of the QLU-C10D QOL dimension levels. The order of presentation of QOL dimensions within a DCE designed to provide utility weights for the QLU-C10D had little effect on level coefficients of those QOL dimensions. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  11. Consumer preferences for electronic cigarettes: results from a discrete choice experiment.

    PubMed

    Czoli, Christine D; Goniewicz, Maciej; Islam, Towhidul; Kotnowski, Kathy; Hammond, David

    2016-04-01

    E-cigarettes present a formidable challenge to regulators given their variety and the rapidly evolving nicotine market. The current study sought to examine the influence of e-cigarette product characteristics on consumer perceptions and trial intentions among Canadians. An online discrete choice experiment was conducted with 915 Canadians aged 16 years and older in November 2013. An online commercial panel was used to sample 3 distinct subpopulations: (1) non-smoking youth and young adults (n=279); (2) smoking youth and young adults (n=264) and (3) smoking adults (n=372). Participants completed a series of stated-preference tasks, in which they viewed choice sets with e-cigarette product images that featured different combinations of attributes: flavour, nicotine content, health warnings and price. For each choice set, participants were asked to select one of the products or indicate 'none of the above' with respect to the following outcomes: interest in trying, less harm and usefulness in quitting smoking. The attributes' impact on consumer choice for each outcome was analysed using multinomial logit regression. Health warning was the most important attribute influencing participants' intentions to try e-cigarettes (42%) and perceived efficacy as a quit aid (39%). Both flavour (36%) and health warnings (35%) significantly predicted perceptions of product harm. The findings indicate that consumers make trade-offs with respect to e-cigarette product characteristics, and that these trade-offs vary across different subpopulations. Given that health warnings and flavour were weighted most important by consumers in this study, these may represent good targets for e-cigarette regulatory frameworks. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  12. Investigating consumers' and informal carers' views and preferences for consumer directed care: A discrete choice experiment.

    PubMed

    Kaambwa, Billingsley; Lancsar, Emily; McCaffrey, Nicola; Chen, Gang; Gill, Liz; Cameron, Ian D; Crotty, Maria; Ratcliffe, Julie

    2015-09-01

    Consumer directed care (CDC) is currently being embraced internationally as a means to promote autonomy and choice for consumers (people aged 65 and over) receiving community aged care services (CACSs). CDC involves giving CACS clients (consumers and informal carers of consumers) control over how CACSs are administered. However, CDC models have largely developed in the absence of evidence on clients' views and preferences. We explored CACS clients' preferences for a variety of CDC attributes and identified factors that may influence these preferences and potentially inform improved design of future CDC models. Study participants were clients of CACSs delivered by five Australian providers. Using a discrete choice experiment (DCE) approach undertaken in a group setting between June and December 2013, we investigated the relative importance to CACS consumers and informal (family) carers of gradations relating to six salient features of CDC (choice of service provider(s), budget management, saving unused/unspent funds, choice of support/care worker(s), support-worker flexibility and level of contact with service coordinator). The DCE data were analysed using conditional, mixed and generalised logit regression models, accounting for preference and scale heterogeneity. Mean ages for 117 study participants were 80 years (87 consumers) and 74 years (30 informal carers). All participants preferred a CDC approach that allowed them to: save unused funds from a CACS package for future use; have support workers that were flexible in terms of changing activities within their CACS care plan and; choose the support workers that provide their day-to-day CACSs. The CDC attributes found to be important to both consumers and informal carers receiving CACSs will inform the design of future CDC models of service delivery. The DCE approach used in this study has the potential for wide applicability and facilitates the assessment of preferences for elements of potential future aged care

  13. The use of alternative preference elicitation methods in complex discrete choice experiments.

    PubMed

    Yoo, Hong Il; Doiron, Denise

    2013-12-01

    We analyse stated preference data over nursing jobs collected from two different discrete choice experiments: a multi-profile case best-worst scaling experiment (BWS) prompting selection of the best and worst among alternative jobs, and a profile case BWS wherein the respondents choose the best and worst job attributes. The latter allows identification of additional utility parameters and is believed to be cognitively easier. Results suggest that respondents place greater value on pecuniary over non-pecuniary gains in the multi-profile case. There is little evidence that this discrepancy is induced by the extra cognitive burden of processing several profiles at once in the multi-profile case. We offer thoughts on other likely mechanisms.

  14. Estimating health state utility values from discrete choice experiments--a QALY space model approach.

    PubMed

    Gu, Yuanyuan; Norman, Richard; Viney, Rosalie

    2014-09-01

    Using discrete choice experiments (DCEs) to estimate health state utility values has become an important alternative to the conventional methods of Time Trade-Off and Standard Gamble. Studies using DCEs have typically used the conditional logit to estimate the underlying utility function. The conditional logit is known for several limitations. In this paper, we propose two types of models based on the mixed logit: one using preference space and the other using quality-adjusted life year (QALY) space, a concept adapted from the willingness-to-pay literature. These methods are applied to a dataset collected using the EQ-5D. The results showcase the advantages of using QALY space and demonstrate that the preferred QALY space model provides lower estimates of the utility values than the conditional logit, with the divergence increasing with worsening health states. Copyright © 2014 John Wiley & Sons, Ltd.

  15. Modeling the mental health service utilization decisions of university undergraduates: A discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Zipursky, Robert B; Christensen, Bruce K; Bieling, Peter J; Madsen, Victoria; Rimas, Heather; Mielko, Stephanie; Wilson, Fiona; Furimsky, Ivana; Jeffs, Lisa; Munn, Catharine

    2017-05-16

    We modeled design factors influencing the intent to use a university mental health service. Between November 2012 and October 2014, 909 undergraduates participated. Using a discrete choice experiment, participants chose between hypothetical campus mental health services. Latent class analysis identified three segments. A Psychological/Psychiatric Service segment (45.5%) was most likely to contact campus health services delivered by psychologists or psychiatrists. An Alternative Service segment (39.3%) preferred to talk to peer-counselors who had experienced mental health problems. A Hesitant segment (15.2%) reported greater distress but seemed less intent on seeking help. They preferred services delivered by psychologists or psychiatrists. Simulations predicted that, rather than waiting for standard counseling, the Alternative Service segment would prefer immediate access to E-Mental health. The Usual Care and Hesitant segments would wait 6 months for standard counseling. E-Mental Health options could engage students who may not wait for standard services.

  16. Qualitative Development of a Discrete Choice Experiment for Physical Activity Interventions to Improve Knee Osteoarthritis.

    PubMed

    Pinto, Daniel; Danilovich, Margaret K; Hansen, Paul; Finn, Daniel J; Chang, Rowland W; Holl, Jane L; Heinemann, Allen W; Bockenholt, Ulf

    2017-06-01

    To describe the qualitative process used to develop attributes and attribute levels for inclusion in a discrete choice experiments (DCE) for older adult physical activity interventions. Five focus groups (n=41) were conducted, grounded in the Health Action Process Approach framework. Discussion emphasized identification and prioritization attributes for a DCE on physical activity. Semi-structured interviews (n=6) investigated attribute levels and lay-language for the DCE. A focus group with physical activity researchers and health care providers was the final stakeholder group used to establish a comprehensive approach for the generation of attributes and levels. A DCE pilot test (n=8) was then conducted with individuals of the target patient population. All transcripts were analyzed using a constant comparative approach. General community and university-based research setting. Volunteers (N=55) aged >45 years with knee pain, aches, or stiffness for at least 1 month over the previous 12 months. Not applicable. Interview guides, attributes, attribute levels, and discrete choice experiment. The most influential identified attributes for physical activity were time, effort, cost, convenience, enjoyment, and health benefits. Each attribute had 3 levels that were understandable in the pilot test of the DCE. The identification of 6 physical activity attributes that are most salient to adults with knee osteoarthritis resulted from a systematic qualitative process, including attribute-ranking exercises. A DCE will provide insight into the relative importance of these attributes for participating in physical activity, which can guide intervention development. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  17. Societal preferences for rheumatoid arthritis treatments: evidence from a discrete choice experiment.

    PubMed

    Harrison, Mark; Marra, Carlo; Shojania, Kam; Bansback, Nick

    2015-10-01

    There is a concern that cost-effectiveness analysis using quality-adjusted life years does not capture all valuable benefits of treatments. The objective of this study was to determine the value society places on aspects of RA treatment to inform policymaking. A discrete choice experiment was administered to a representative sample of the Canadian general population. The discrete choice experiment, developed using focus groups, had seven attributes (route and frequency of administration, chance of benefit, chance of serious and minor side effects, confidence in evidence and life expectancy). A conditional logit regression model was used to estimate the significance and relative importance of attributes in influencing preferences on the quality-adjusted life years scale. Responses from 733 respondents who provided rational responses were analysed. Six attribute levels within four attributes significantly influenced preferences for treatments: a willingness to trade a year of life expectancy over a 10-year period to increase the probability of benefiting from treatment, or two-thirds of a year to reduce minor or serious side effects to the lowest level or improve the confidence in benefit/side-effect estimates. There was also some evidence of a preference for oral drug delivery, though a subgroup analysis suggested this preference was restricted to injection-naive respondents. Our results suggest society values the degree of confidence in the estimates of risks and benefits of RA treatments and the route of administration, as well as benefits and side effects. This study provides important evidence to policymakers determining the cost-effectiveness of treatments in arthritis. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. A discrete-choice experiment to determine patient preferences for injectable multiple sclerosis treatments in Germany

    PubMed Central

    Poulos, Christine; Kinter, Elizabeth; Yang, Jui-Chen; Bridges, John F. P.; Posner, Joshua; Gleißner, Erika; Mühlbacher, Axel; Kieseier, Bernd

    2016-01-01

    Objectives: The aim of this study was to assess the relative importance of features of a hypothetical injectable disease-modifying treatment for patients with multiple sclerosis using a discrete-choice experiment. Methods: German residents at least 18 years of age with a self-reported physician diagnosis of multiple sclerosis completed a 25–30 minute online discrete-choice experiment. Patients were asked to choose one of two hypothetical injectable treatments for multiple sclerosis, defined by different levels of six attributes (disability progression, the number of relapses in the next 4 years, injection time, frequency of injections, presence of flu-like symptoms, and presence of injection-site reactions). The data were analyzed using a random-parameters logit model. Results: Of 202 adults who completed the survey, results from 189 were used in the analysis. Approximately 50% of all patients reported a diagnosis of relapsing–remitting multiple sclerosis, and 31% reported secondary progressive multiple sclerosis. Approximately 71% of patients had current or prior experience with injectable multiple sclerosis medication. Approximately 53% had experienced flu-like symptoms caused by their medication, and 47% had experienced mild injection-site reactions. At least one significant difference was seen between levels in all attributes, except injection time. The greatest change in relative importance between levels of an attribute was years until symptoms get worse from 1 to 4 years. The magnitude of this difference was about twice that of relapses in the next 4 years, frequency of injections, and flu-like symptoms. Conclusions: Most attributes examined in this experiment had an influence on patient preference. Patients placed a significant value on improvements in the frequency of dosing and disability progression. Results suggest that changes in injection frequency can be as important as changes in efficacy and safety attributes. Understanding which attributes of

  19. Perceived Risks Contra Benefits of Using Biosimilar Drugs in Ulcerative Colitis: Discrete Choice Experiment among Gastroenterologists.

    PubMed

    Baji, Petra; Gulácsi, László; Golovics, Petra A; Lovász, Barbara D; Péntek, Márta; Brodszky, Valentin; Rencz, Fanni; Lakatos, Péter L

    2016-09-01

    In middle-income countries, access to biological therapy is limited in ulcerative colitis in terms of the number of patients and the length of therapy. Because of their cost advantages, biosimilars have the potential to improve access to therapy, but physicians have concerns toward their use because of the lack of evidence from randomized clinical trials. To explore the preferences of gastroenterologists for biosimilar drugs in ulcerative colitis as well as to compare our results with results of previous studies on gastroenterologists' preferences toward biosimilars. A discrete choice experiment was carried out involving 51 Hungarian gastroenterologists treating patients with inflammatory bowel disease in May 2014 with the following attributes: type of treatment (biosimilar/originator), severity of disease, availability of continuous medicine supply, and the stopping rule (whether the treatment is covered after 12 months). A conditional logit model was used to estimate the probabilities of choosing a given profile. According to the results, the stopping rule was the most important attribute. The type of treatment mattered only for patients already on biologicals. The probabilities of choosing the biosimilar option with all the benefits offered in the discrete choice experiment over the originator option under the present reimbursement conditions are 85% for new patients and 63% for patients already treated. Most gastroenterologists have concerns about using biosimilars. They, however, are willing to consider the use of biosimilars if they could reallocate the potential savings to provide their patients better access to biological treatment. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  20. Preferences for managing symptoms of differing severity: a discrete choice experiment.

    PubMed

    Rennie, Lisa; Porteous, Terry; Ryan, Mandy

    2012-12-01

    To design cost-effective health services it is important to understand why people adopt particular symptom management strategies. To establish the relative importance of factors that influence decision making when managing symptoms of differing severity, to establish how people trade between these factors, and to estimate the monetary value placed on different management types. Discrete choice experiment. UK online research panel. Successive members of an online panel were invited to participate until 480 discrete choice experiment questionnaires were completed. Relative preferences for managing three symptom scenarios of varying severity were measured. Symptom management was described by three characteristics (management type, availability, and cost). Preferences for ways of managing symptoms were measured by using conditional logit analysis. A total of 98.5% of the completed questionnaires were valid (473 of 480 respondents). People preferred to manage minor symptoms by self-care or by visiting a pharmacy and were willing to pay £21.58 and £19.06, respectively, to do so. For managing moderately severe symptoms, people preferred to consult a general practitioner and were willing to pay £34.86 for this option. People preferred to manage potentially very severe symptoms by consulting a general practitioner and were willing to pay £73.08 to do so. Respondents were willing to trade between management types; options less preferred became more attractive when waiting time and cost were reduced. People value self-care, supported self-care, and general practitioner consultation differently depending on the type of symptoms. Manipulating costs to users and waiting times for different services could allow policymakers to influence the services people choose when managing symptoms. Copyright © 2012 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  1. A discrete-choice experiment to determine patient preferences for injectable multiple sclerosis treatments in Germany.

    PubMed

    Poulos, Christine; Kinter, Elizabeth; Yang, Jui-Chen; Bridges, John F P; Posner, Joshua; Gleißner, Erika; Mühlbacher, Axel; Kieseier, Bernd

    2016-03-01

    The aim of this study was to assess the relative importance of features of a hypothetical injectable disease-modifying treatment for patients with multiple sclerosis using a discrete-choice experiment. German residents at least 18 years of age with a self-reported physician diagnosis of multiple sclerosis completed a 25-30 minute online discrete-choice experiment. Patients were asked to choose one of two hypothetical injectable treatments for multiple sclerosis, defined by different levels of six attributes (disability progression, the number of relapses in the next 4 years, injection time, frequency of injections, presence of flu-like symptoms, and presence of injection-site reactions). The data were analyzed using a random-parameters logit model. Of 202 adults who completed the survey, results from 189 were used in the analysis. Approximately 50% of all patients reported a diagnosis of relapsing-remitting multiple sclerosis, and 31% reported secondary progressive multiple sclerosis. Approximately 71% of patients had current or prior experience with injectable multiple sclerosis medication. Approximately 53% had experienced flu-like symptoms caused by their medication, and 47% had experienced mild injection-site reactions. At least one significant difference was seen between levels in all attributes, except injection time. The greatest change in relative importance between levels of an attribute was years until symptoms get worse from 1 to 4 years. The magnitude of this difference was about twice that of relapses in the next 4 years, frequency of injections, and flu-like symptoms. Most attributes examined in this experiment had an influence on patient preference. Patients placed a significant value on improvements in the frequency of dosing and disability progression. Results suggest that changes in injection frequency can be as important as changes in efficacy and safety attributes. Understanding which attributes of injectable therapies influence patient

  2. Prioritising health service innovation investments using public preferences: a discrete choice experiment.

    PubMed

    Erdem, Seda; Thompson, Carl

    2014-08-28

    Prioritising scarce resources for investment in innovation by publically funded health systems is unavoidable. Many healthcare systems wish to foster transparency and accountability in the decisions they make by incorporating the public in decision-making processes. This paper presents a unique conceptual approach exploring the public's preferences for health service innovations by viewing healthcare innovations as 'bundles' of characteristics. This decompositional approach allows policy-makers to compare numerous competing health service innovations without repeatedly administering surveys for specific innovation choices. A Discrete Choice Experiment (DCE) was used to elicit preferences. Individuals chose from presented innovation options that they believe the UK National Health Service (NHS) should invest the most in. Innovations differed according to: (i) target population; (ii) target age; (iii) implementation time; (iv) uncertainty associated with their likely effects; (v) potential health benefits; and, (vi) cost to a taxpayer. This approach fosters multidimensional decision-making, rather than imposing a single decision criterion (e.g., cost, target age) in prioritisation. Choice data was then analysed using scale-adjusted Latent Class models to investigate variability in preferences and scale and valuations amongst respondents. Three latent classes with considerable heterogeneity in the preferences were present. Each latent class is composed of two consumer subgroups varying in the level of certainty in their choices. All groups preferred scientifically proven innovations, those with potential health benefits that cost less. There were, however, some important differences in their preferences for innovation investment choices: Class-1 (54%) prefers innovations benefitting adults and young people and does not prefer innovations targeting people with 'drug addiction' and 'obesity'. Class- 2 (34%) prefers innovations targeting 'cancer' patients only and has

  3. Energetically stable discretizations for charge transport and electrokinetic models

    NASA Astrophysics Data System (ADS)

    Metti, Maximilian S.; Xu, Jinchao; Liu, Chun

    2016-02-01

    A finite element discretization using a method of lines approached is proposed for approximately solving the Poisson-Nernst-Planck (PNP) equations. This discretization scheme enforces positivity of the computed solutions, corresponding to particle density functions, and a discrete energy estimate is established that takes the same form as the energy law for the continuous PNP system. This energy estimate is extended to finite element solutions to an electrokinetic model, which couples the PNP system with the incompressible Navier-Stokes equations. Numerical experiments are conducted to validate convergence of the computed solution and verify the discrete energy estimate.

  4. Using stated preference discrete choice modelling to evaluate the introduction of varicella vaccination.

    PubMed

    Hall, Jane; Kenny, Patricia; King, Madeleine; Louviere, Jordan; Viney, Rosalie; Yeoh, Angela

    2002-07-01

    Applications of stated preference discrete choice modelling (SPDCM) in health economics have been used to estimate consumer willingness to pay and to broaden the range of consequences considered in economic evaluation. This paper demonstrates how SPDCM can be used to predict participation rates, using the case of varicella (chickenpox) vaccination. Varicella vaccination may be cost effective compared to other public health programs, but this conclusion is sensitive to the proportion of the target population immunised. A choice experiment was conducted on a sample of Australian parents to predict uptake across a range of hypothetical programs. Immunisation rates would be increased by providing immunisation at no cost, by requiring it for school entry, by increasing immunisation rates in the community and decreasing the incidence of mild and severe side effects. There were two significant interactions; price modified the effect of both support from authorities and severe side effects. Country of birth was the only significant demographic characteristic. Depending on aspects of the immunisation program, the immunisation rates of children with Australian-born parents varied from 9% to 99% while for the children with parents born outside Australia they varied from 40% to 99%. This demonstrates how SPDCM can be used to understand the levels of attributes that will induce a change in the decision to immunise, the modification of the effect of one attribute by another, and subgroups in the population. Such insights can contribute to the optimal design and targeting of health programs.

  5. Modeling the bullying prevention program preferences of educators: a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Vaillancourt, Tracy; Rimas, Heather; Deal, Ken; Cunningham, Lesley; Short, Kathy; Chen, Yvonne

    2009-10-01

    We used discrete choice conjoint analysis to model the bullying prevention program preferences of educators. Using themes from computerized decision support lab focus groups (n = 45 educators), we composed 20 three-level bullying prevention program design attributes. Each of 1,176 educators completed 25 choice tasks presenting experimentally varied combinations of the study's attribute levels. Latent class analysis yielded three segments with different preferences. Decision Sensitive educators (31%) preferred that individual schools select bullying prevention programs. In contrast, Support Sensitive educators (51%) preferred that local school boards chose bullying prevention programs. This segment preferred more logistical and social support at every stage of the adoption, training, implementation, and long term maintenance processes. Cost Sensitive educators (16%) showed a stronger preference for programs minimizing costs, training, and implementation time demands. They felt prevention programs were less effective and that the time and space in the curriculum for bullying prevention was less adequate. They were less likely to believe that bullying prevention was their responsibility and more likely to agree that prevention was the responsibility of parents. All segments preferred programs supported by the anecdotal reports of colleagues from other schools rather than those based on scientific evidence. To ensure that the bullying prevention options available reflect the complex combination of attributes influencing real world adoption decisions, program developers need to accommodate the differing views of the Decision, Support, and Cost Sensitive segments while maximizing the support of parents and students.

  6. Improving Chinese primary care providers' recruitment and retention: a discrete choice experiment.

    PubMed

    Song, Kuimeng; Scott, Anthony; Sivey, Peter; Meng, Qingyue

    2015-02-01

    Local primary care facilities in China struggle to recruit and retain doctors and nurses. Implementing policies to address this issue requires detailed knowledge of the preferences of primary care workers. The aim of this study is to find out which job attributes affect Chinese primary care providers' choice of job and whether there are any differences in these job preferences between doctors and nurses. A discrete choice experiment was used to analyse the job preferences of 517 primary care providers, including 282 doctors and 235 nurses. Chinese primary care providers in Community Health Organizations (CHOs) considered monetary factors and non-monetary factors when choosing a job. Doctors' and nurses' preferences over job attributes were similar. Though income was important, Chinese primary care providers had strongest preferences for sufficient welfare benefits, sufficient essential equipment and respect from the community. Younger primary care providers were more likely to value training and career development opportunities. In order to retain skilled primary care providers to work in CHOs, policymakers in China need to improve primary care providers' income, benefits and working conditions to fulfil their basic needs. Policymakers also need to invest in CHOs' infrastructure and strengthen training programmes for primary care providers in order to raise the community's confidence in the services provided by CHOs. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2013; all rights reserved.

  7. Women's Preferences for Treatment of Perinatal Depression and Anxiety: A Discrete Choice Experiment.

    PubMed

    Ride, Jemimah; Lancsar, Emily

    2016-01-01

    Perinatal depression and anxiety (PNDA) are an international healthcare priority, associated with significant short- and long-term problems for women, their children and families. Effective treatment is available but uptake is suboptimal: some women go untreated whilst others choose treatments without strong evidence of efficacy. Better understanding of women's preferences for treatment is needed to facilitate uptake of effective treatment. To address this issue, a discrete choice experiment (DCE) was administered to 217 pregnant or postnatal women in Australia, who were recruited through an online research company and had similar sociodemographic characteristics to Australian data for perinatal women. The DCE investigated preferences regarding cost, treatment type, availability of childcare, modality and efficacy. Data were analysed using logit-based models accounting for preference and scale heterogeneity. Predicted probability analysis was used to explore relative attribute importance and policy change scenarios, including how these differed by women's sociodemographic characteristics. Cost and treatment type had the greatest impact on choice, such that a policy of subsidising effective treatments was predicted to double their uptake compared with the base case. There were differences in predicted uptake associated with certain sociodemographic characteristics: for example, women with higher educational attainment were more likely to choose effective treatment. The findings suggest policy directions for decision makers whose goal is to reduce the burden of PNDA on women, their children and families.

  8. Women’s Preferences for Treatment of Perinatal Depression and Anxiety: A Discrete Choice Experiment

    PubMed Central

    Ride, Jemimah; Lancsar, Emily

    2016-01-01

    Perinatal depression and anxiety (PNDA) are an international healthcare priority, associated with significant short- and long-term problems for women, their children and families. Effective treatment is available but uptake is suboptimal: some women go untreated whilst others choose treatments without strong evidence of efficacy. Better understanding of women’s preferences for treatment is needed to facilitate uptake of effective treatment. To address this issue, a discrete choice experiment (DCE) was administered to 217 pregnant or postnatal women in Australia, who were recruited through an online research company and had similar sociodemographic characteristics to Australian data for perinatal women. The DCE investigated preferences regarding cost, treatment type, availability of childcare, modality and efficacy. Data were analysed using logit-based models accounting for preference and scale heterogeneity. Predicted probability analysis was used to explore relative attribute importance and policy change scenarios, including how these differed by women’s sociodemographic characteristics. Cost and treatment type had the greatest impact on choice, such that a policy of subsidising effective treatments was predicted to double their uptake compared with the base case. There were differences in predicted uptake associated with certain sociodemographic characteristics: for example, women with higher educational attainment were more likely to choose effective treatment. The findings suggest policy directions for decision makers whose goal is to reduce the burden of PNDA on women, their children and families. PMID:27258096

  9. Deleting 'irrational' responses from discrete choice experiments: a case of investigating or imposing preferences?

    PubMed

    Lancsar, Emily; Louviere, Jordan

    2006-08-01

    Investigation of the 'rationality' of responses to discrete choice experiments (DCEs) has been a theme of research in health economics. Responses have been deleted from DCEs where they have been deemed by researchers to (a) be 'irrational', defined by such studies as failing tests for non-satiation, or (b) represent lexicographic preferences. This paper outlines a number of reasons why deleting responses from DCEs may be inappropriate after first reviewing the theory underpinning rationality, highlighting that the importance placed on rationality depends on the approach to consumer theory to which one ascribes. The aim of this paper is not to suggest that all preferences elicited via DCEs are rational. Instead, it is to suggest a number of reasons why it may not be the case that all preferences labelled as 'irrational' are indeed so. Hence, deleting responses may result in the removal of valid preferences; induce sample selection bias; and reduce the statistical efficiency and power of the estimated choice models. Further, evidence suggests random utility theory may be able to cope with such preferences. Finally, we discuss a number of implications for the design, implementation and interpretation of DCEs and recommend caution regarding the deletion of preferences from stated preference experiments. Copyright 2006 John Wiley & Sons, Ltd.

  10. Exploring the social value of health-care interventions: a stated preference discrete choice experiment.

    PubMed

    Green, Colin; Gerard, Karen

    2009-08-01

    Much of the literature on distributive preferences covers specific considerations in isolation, and recent reviews have suggested that research is required to inform on the relative importance of various key considerations. Responding to this research recommendation, we explore the distributive preferences of the general public using a set of generic social value judgments. We report on a discrete choice experiment (DCE) survey, using face-to-face interviews, in a sample of the general population (n=259). The context for the survey was resource allocation decisions in the UK National Health Service, using the process of health technology appraisal as an example. The attributes used covered health improvement, value for money, severity of health, and availability of other treatments, and it is the first such survey to use cost-effectiveness in scenarios described to the general public. Results support the feasibility and acceptability of the DCE approach for the elicitation of public preferences. Choice data are used to consider the relative importance of changes across attribute levels, and to model utility scores and relative probabilities for the full set of combinations of attributes and levels in the experimental design used (n=64). Results allow the relative social value of health technology scenarios to be explored. Findings add to a sparse literature on 'social' preferences, and show that DCE data can be used to consider the strength of preference over alternative scenarios in a priority-setting context.

  11. The Effect of Perceived Risks on the Demand for Vaccination: Results from a Discrete Choice Experiment

    PubMed Central

    Sadique, Md Z.; Devlin, Nancy; Edmunds, William J.; Parkin, David

    2013-01-01

    The demand for vaccination against infectious diseases involves a choice between vaccinating and not vaccinating, in which there is a trade-off between the benefits and costs of each option. The aim of this paper is to investigate these trade-offs and to estimate how the perceived prevalence and severity of both the disease against which the vaccine is given and any vaccine associated adverse events (VAAE) might affect demand. A Discrete Choice Experiment (DCE) was used to elicit stated preferences from a representative sample of 369 UK mothers of children below 5 years of age, for three hypothetical vaccines. Cost was included as an attribute, which enabled estimation of the willingness to pay for different vaccines having differing levels of the probability of occurrence and severity of both the infection and VAAE. The results suggest that the severity of the health effects associated with both the diseases and VAAEs exert an important influence on the demand for vaccination, whereas the probability of these events occurring was not a significant predictor. This has important implications for public health policy, which has tended to focus on the probability of these health effects as the main influence on decision making. Our results also suggest that anticipated regrets about the consequences of making the wrong decision also exert an influence on demand. PMID:23408936

  12. Conducting discrete choice experiments to inform healthcare decision making: a user's guide.

    PubMed

    Lancsar, Emily; Louviere, Jordan

    2008-01-01

    Discrete choice experiments (DCEs) are regularly used in health economics to elicit preferences for healthcare products and programmes. There is growing recognition that DCEs can provide more than information on preferences and, in particular, they have the potential to contribute more directly to outcome measurement for use in economic evaluation. Almost uniquely, DCEs could potentially contribute to outcome measurement for use in both cost-benefit and cost-utility analysis. Within this expanding remit, our intention is to provide a resource for current practitioners as well as those considering undertaking a DCE, using DCE results in a policy/commercial context, or reviewing a DCE. We present the fundamental principles and theory underlying DCEs. To aid in undertaking and assessing the quality of DCEs, we discuss the process of carrying out a choice study and have developed a checklist covering conceptualizing the choice process, selecting attributes and levels, experimental design, questionnaire design, pilot testing, sampling and sample size, data collection, coding of data, econometric analysis, validity, interpretation and welfare and policy analysis. In this fast-moving area, a number of issues remain on the research frontier. We therefore outline potentially fruitful areas for future research associated both with DCEs in general, and with health applications specifically, paying attention to how the results of DCEs can be used in economic evaluation. We also discuss emerging research trends. We conclude that if appropriately designed, implemented, analysed and interpreted, DCEs offer several advantages in the health sector, the most important of which is that they provide rich data sources for economic evaluation and decision making, allowing investigation of many types of questions, some of which otherwise would be intractable analytically. Thus, they offer viable alternatives and complements to existing methods of valuation and preference elicitation.

  13. Rural clinician scarcity and job preferences of doctors and nurses in India: a discrete choice experiment.

    PubMed

    Rao, Krishna D; Ryan, Mandy; Shroff, Zubin; Vujicic, Marko; Ramani, Sudha; Berman, Peter

    2013-01-01

    The scarcity of rural doctors has undermined the ability of health systems in low and middle-income countries like India to provide quality services to rural populations. This study examines job preferences of doctors and nurses to inform what works in terms of rural recruitment strategies. Job acceptance of different strategies was compared to identify policy options for increasing the availability of clinical providers in rural areas. In 2010 a Discrete Choice Experiment was conducted in India. The study sample included final year medical and nursing students, and in-service doctors and nurses serving at Primary Health Centers. Eight job attributes were identified and a D-efficient fractional factorial design was used to construct pairs of job choices. Respondent acceptance of job choices was analyzed using multi-level logistic regression. Location mattered; jobs in areas offering urban amenities had a high likelihood of being accepted. Higher salary had small effect on doctor, but large effect on nurse, acceptance of rural jobs. At five times current salary levels, 13% (31%) of medical students (doctors) were willing to accept rural jobs. At half this level, 61% (52%) of nursing students (nurses) accepted a rural job. The strategy of reserving seats for specialist training in exchange for rural service had a large effect on job acceptance among doctors, nurses and nursing students. For doctors and nurses, properly staffed and equipped health facilities, and housing had small effects on job acceptance. Rural upbringing was not associated with rural job acceptance. Incentivizing doctors for rural service is expensive. A broader strategy of substantial salary increases with improved living, working environment, and education incentives is necessary. For both doctors and nurses, the usual strategies of moderate salary increases, good facility infrastructure, and housing will not be effective. Non-physician clinicians like nurse-practitioners offer an affordable

  14. Using discrete choice modeling to evaluate the preferences and willingness to pay for leptospirosis vaccine

    PubMed Central

    Arbiol, Joseph; Yabe, Mitsuyasu; Nomura, Hisako; Borja, Maridel; Gloriani, Nina; Yoshida, Shin-ichi

    2015-01-01

    Leptospirosis is highly endemic in the Philippines and a serious concern to public health. Local research on candidate vaccine is moving through the development pipeline. The availability of vaccines alone does not guarantee acceptance because individuals’ vaccination choice decision is influenced by several factors. This study assessed how vaccine attributes and socio-demographic factors affect the acceptability of leptospirosis vaccine; and estimated individuals’ willingness to pay for leptospirosis vaccine. A discrete choice experiment was conducted among leptospirosis and non-leptospirosis case respondents (n = 342) living in Metro Manila. Random Parameters Logit model was used to estimate the relative importance of vaccine attributes and socio-demographic variables on respondents’ leptospirosis vaccination choice decision. The estimated model coefficients were used to derive implicit prices and willingness to pay for leptospirosis vaccine. Both case respondents preferred leptospirosis vaccine with 70–100% efficacy, mild to moderate risk of side-effects, given in a single shot, and at a lower price. Non-leptospirosis case respondents preferred a vaccine with 7 to 10 y of protection, while leptospirosis case respondents preferred a vaccine with 10 y protection. The probability of leptospirosis vaccination acceptance was affected by respondents’ age, education, family size and income, proximity of home to rivers and sewers, and leptospirosis awareness level. Respondents’ willingness to pay for leptospirosis vaccine (US$ 31.14–US$ 65.89) was higher than the Japanese retail price (US$ 21.60-US$ 24.00). Our findings indicated significant potential for introducing leptospirosis vaccine in the Philippine vaccine market. Delivery strategies to ensure equitable access to future leptospirosis vaccine are recommended. PMID:25764105

  15. Eliciting preferences for waterpipe tobacco smoking using a discrete choice experiment: implications for product regulation.

    PubMed

    Salloum, Ramzi G; Maziak, Wasim; Hammond, David; Nakkash, Rima; Islam, Farahnaz; Cheng, Xi; Thrasher, James F

    2015-09-09

    Waterpipe smoking is highly prevalent among university students, and has been increasing in popularity despite mounting evidence showing it is harmful to health. The aim of this study was to measure preferences for waterpipe smoking and determine which product characteristics are most important to smokers. A large university in the Southeastern USA. Adult waterpipe smokers attending the university (N=367). Participants completed an Internet-based discrete choice experiment to reveal their preferences for, and trade-offs between, the attributes of hypothetical waterpipe smoking sessions. Participants were presented with waterpipe lounge menus, each with three fruit-flavoured options and one tobacco flavoured option, in addition to an opt out option. Nicotine content and price were provided for each choice. Participants were randomised to either receive menus with a text-only health-warning message or no message. Multinomial and nested logit models were used to estimate the impact on consumer choice of attributes and between-subject assignment of health warnings respectively. On average, participants preferred fruit-flavoured varieties to tobacco flavour. They were averse to options labelled with higher nicotine content. Females and non-smokers of cigarettes were more likely than their counterparts to prefer flavoured and nicotine-free varieties. Participants exposed to a health warning were more likely to opt out. Fruit-flavoured tobacco and lower nicotine content labels, two strategies widely used by the industry, increase the demand for waterpipe smoking among young adults. Waterpipe-specific regulation should limit the availability of flavoured waterpipe tobacco and require accurate labelling of constituents. Waterpipe-specific tobacco control regulation, along with research to inform policy, is required to curb this emerging public health threat. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence

  16. Rural Clinician Scarcity and Job Preferences of Doctors and Nurses in India: A Discrete Choice Experiment

    PubMed Central

    Rao, Krishna D.; Ryan, Mandy; Shroff, Zubin; Vujicic, Marko; Ramani, Sudha; Berman, Peter

    2013-01-01

    The scarcity of rural doctors has undermined the ability of health systems in low and middle-income countries like India to provide quality services to rural populations. This study examines job preferences of doctors and nurses to inform what works in terms of rural recruitment strategies. Job acceptance of different strategies was compared to identify policy options for increasing the availability of clinical providers in rural areas. In 2010 a Discrete Choice Experiment was conducted in India. The study sample included final year medical and nursing students, and in-service doctors and nurses serving at Primary Health Centers. Eight job attributes were identified and a D-efficient fractional factorial design was used to construct pairs of job choices. Respondent acceptance of job choices was analyzed using multi-level logistic regression. Location mattered; jobs in areas offering urban amenities had a high likelihood of being accepted. Higher salary had small effect on doctor, but large effect on nurse, acceptance of rural jobs. At five times current salary levels, 13% (31%) of medical students (doctors) were willing to accept rural jobs. At half this level, 61% (52%) of nursing students (nurses) accepted a rural job. The strategy of reserving seats for specialist training in exchange for rural service had a large effect on job acceptance among doctors, nurses and nursing students. For doctors and nurses, properly staffed and equipped health facilities, and housing had small effects on job acceptance. Rural upbringing was not associated with rural job acceptance. Incentivizing doctors for rural service is expensive. A broader strategy of substantial salary increases with improved living, working environment, and education incentives is necessary. For both doctors and nurses, the usual strategies of moderate salary increases, good facility infrastructure, and housing will not be effective. Non-physician clinicians like nurse-practitioners offer an affordable

  17. Young People's Preferences for Family Planning Service Providers in Rural Malawi: A Discrete Choice Experiment.

    PubMed

    Michaels-Igbokwe, Christine; Terris-Prestholt, Fern; Lagarde, Mylene; Chipeta, Effie; Cairns, John

    2015-01-01

    To quantify the impact of service provider characteristics on young people's choice of family planning (FP) service provider in rural Malawi in order to identify strategies for increasing access and uptake of FP among youth. A discrete choice experiment was developed to assess the relative impact of service characteristics on preferences for FP service providers among young people (aged 15-24). Four alternative providers were included (government facility, private facility, outreach and community based distribution of FP) and described by six attributes (the distance between participants' home and the service delivery point, frequency of service delivery, waiting time at the facility, service providers' attitude, availability of FP commodities and price). A random parameters logit model was used to estimate preferences for service providers and the likely uptake of services following the expansion of outreach and community based distribution (CBDA) services. In the choice experiment young people were twice as likely to choose a friendly provider (government service odds ratio [OR] = 2.45, p<0.01; private service OR = 1.99, p<0.01; CBDA OR = 1.88, p<0.01) and more than two to three times more likely to choose a provider with an adequate supply of FP commodities (government service OR = 2.48, p<0.01; private service OR = 2.33, p<0.01; CBDA = 3.85, p<0.01). Uptake of community based services was greater than facility based services across a variety of simulated service scenarios indicating that such services may be an effective means of expanding access for youth in rural areas and an important tool for increasing service uptake among youth. Ensuring that services are acceptable to young people may require additional training for service providers in order to ensure that all providers are friendly and non-judgemental when dealing with younger clients and to ensure that supplies are consistently available.

  18. Eliciting preferences for social health insurance in Ethiopia: a discrete choice experiment.

    PubMed

    Obse, Amarech; Ryan, Mandy; Heidenreich, Sebastian; Normand, Charles; Hailemariam, Damen

    2016-12-01

    As low-income countries are initiating health insurance schemes, Ethiopia is also planning to move away from out-of-pocket private payments to health insurance. The success of such a policy depends on understanding and predicting preferences of potential enrolees. This is because a scarce health care budget forces providers and consumers to make trade-offs between potential benefits within a health insurance. An assessment of preferences of potential enrolees can therefore add important information to optimal resource allocation in the design of health insurance. We used a discrete choice experiment to elicit preferences for social health insurance (SHI) among formal sector employees in Ethiopia. Respondents were presented with 18 binary hypothetical choices of SHI. Each insurance package was described by eight policy relevant attributes: premium, enrolment, exclusions, providers and coverage of inpatient services, outpatient services, drugs and tests. A mixed logit model was estimated to determine respondents' willingness to pay (WTP) for the different health insurance attributes. We also predicted probabilities of uptake for alternative SHI scenarios. Health insurance packages with 'no exclusions', 'public and private' providers, low rate of premium and full coverage of tests and drugs were highly valued and had greatest impact on the choices . Other things being equal, respondents were willing to contribute 1.52% (95% confidence interval (CI): 0.71, 2.32) of their salary to a SHI package with no service exclusions having public and private service providers. This is substantially lower than the proposed 3% premium in the draft SHI strategy. For the typical SHI package proposed by the SHI strategy at the time, the uptake probability was predicted to be 29% (95% CI: 0.25, 0.33). The low uptake probability and WTP for the proposed SHI package suggests considering preferences of the potential enrolees' in revisions of the draft SHI strategy for introduction of

  19. Density-dependence across dispersal stages in a hermaphrodite land snail: insights from discrete choice models.

    PubMed

    Dahirel, Maxime; Vardakis, Michalis; Ansart, Armelle; Madec, Luc

    2016-08-01

    Dispersal movements, i.e. movements leading to gene flow, are key behaviours with important, but only partially understood, consequences for the dynamics and evolution of populations. In particular, density-dependent dispersal has been widely described, yet how it is determined by the interaction with individual traits, and whether density effects differ between the three steps of dispersal (departure, transience, and settlement), remains largely unknown. Using a semi-natural landscape, we studied dispersal choices of Cornu aspersum land snails, a species in which negative effects of crowding are well documented, and analysed them using dispersal discrete choice models, a new method allowing the analysis of dispersal decisions by explicitly considering the characteristics of all available alternatives and their interaction with individual traits. Subadults were more dispersive than adults, confirming existing results. In addition, departure and settlement were both density dependent: snails avoided crowded patches at both ends of the dispersal process, and subadults were more reluctant to settle into crowded patches than adults. Moreover, we found support for carry-over effects of release density on subsequent settlement decisions: snails from crowded contexts were more sensitive to density in their subsequent immigration choices. The fact that settlement decisions were informed indicates that costs of prospecting are not as important as previously thought in snails, and/or that snails use alternative ways to collect information, such as indirect social information (e.g. trail following). The observed density-dependent dispersal dynamics may play an important role in the ability of C. aspersum to successfully colonise frequently human-disturbed habitats around the world.

  20. Using discrete choice modeling to evaluate the preferences and willingness to pay for leptospirosis vaccine.

    PubMed

    Arbiol, Joseph; Yabe, Mitsuyasu; Nomura, Hisako; Borja, Maridel; Gloriani, Nina; Yoshida, Shin-ichi

    2015-01-01

    Leptospirosis is highly endemic in the Philippines and a serious concern to public health. Local research on candidate vaccine is moving through the development pipeline. The availability of vaccines alone does not guarantee acceptance because individuals' vaccination choice decision is influenced by several factors. This study assessed how vaccine attributes and socio-demographic factors affect the acceptability of leptospirosis vaccine; and estimated individuals' willingness to pay for leptospirosis vaccine. A discrete choice experiment was conducted among leptospirosis and non-leptospirosis case respondents (n = 342) living in Metro Manila. Random Parameters Logit model was used to estimate the relative importance of vaccine attributes and socio-demographic variables on respondents' leptospirosis vaccination choice decision. The estimated model coefficients were used to derive implicit prices and willingness to pay for leptospirosis vaccine. Both case respondents preferred leptospirosis vaccine with 70-100% efficacy, mild to moderate risk of side-effects, given in a single shot, and at a lower price. Non-leptospirosis case respondents preferred a vaccine with 7 to 10 y of protection, while leptospirosis case respondents preferred a vaccine with 10 y protection. The probability of leptospirosis vaccination acceptance was affected by respondents' age, education, family size and income, proximity of home to rivers and sewers, and leptospirosis awareness level. Respondents' willingness to pay for leptospirosis vaccine (US$ 31.14-US$ 65.89) was higher than the Japanese retail price (US$ 21.60-US$ 24.00). Our findings indicated significant potential for introducing leptospirosis vaccine in the Philippine vaccine market. Delivery strategies to ensure equitable access to future leptospirosis vaccine are recommended.

  1. Modeling the Mental Health Practice Change Preferences of Educators: A Discrete-Choice Conjoint Experiment.

    PubMed

    Cunningham, Charles E; Barwick, Melanie; Short, Kathy; Chen, Yvonne; Rimas, Heather; Ratcliffe, Jenna; Mielko, Stephanie

    2014-01-01

    Schools are sometimes slow to adopt evidence-based strategies for improving the mental health outcomes of students. This study used a discrete-choice conjoint experiment to model factors influencing the decision of educators to adopt strategies for improving children's mental health outcomes. A sample of 1,010 educators made choices between hypothetical mental health practice change strategies composed by systematically varying the four levels of 16 practice change attributes. Latent class analysis yielded two segments with different practice change preferences. Both segments preferred small-group workshops, conducted by engaging experts, teaching skills applicable to all students. Participants expressed little interest in Internet options. The support of colleagues, administrators, and unions exerted a strong influence on the practice change choices of both segments. The Change Ready segment, 77.1 % of the sample, was more intent on adopting new strategies to improve the mental health of students. They preferred that schools, rather than the provincial ministry of education, make practice change decisions, coaching was provided to all participants, and participants received post-training follow-up sessions. The Demand Sensitive segment (22.9 %) was less intent on practice change. They preferred that individual teachers make practice change decisions, recommended discretionary coaching, and chose no post-training follow-up support. This study emphasizes the complex social, organizational, and policy context within which educators make practice change decisions. Efforts to disseminate strategies to improve the mental health outcomes of students need to be informed by the preferences of segments of educators who are sensitive to different dimensions of the practice change process. In the absence of a broad consensus of educators, administrators, and unions, potentially successful practice changes are unlikely to be adopted.

  2. Eliciting preferences for waterpipe tobacco smoking using a discrete choice experiment: implications for product regulation

    PubMed Central

    Salloum, Ramzi G; Maziak, Wasim; Hammond, David; Nakkash, Rima; Islam, Farahnaz; Cheng, Xi; Thrasher, James F

    2015-01-01

    Objectives Waterpipe smoking is highly prevalent among university students, and has been increasing in popularity despite mounting evidence showing it is harmful to health. The aim of this study was to measure preferences for waterpipe smoking and determine which product characteristics are most important to smokers. Setting A large university in the Southeastern USA. Participants Adult waterpipe smokers attending the university (N=367). Design Participants completed an Internet-based discrete choice experiment to reveal their preferences for, and trade-offs between, the attributes of hypothetical waterpipe smoking sessions. Participants were presented with waterpipe lounge menus, each with three fruit-flavoured options and one tobacco flavoured option, in addition to an opt out option. Nicotine content and price were provided for each choice. Participants were randomised to either receive menus with a text-only health-warning message or no message. Outcome measures Multinomial and nested logit models were used to estimate the impact on consumer choice of attributes and between-subject assignment of health warnings respectively. Results On average, participants preferred fruit-flavoured varieties to tobacco flavour. They were averse to options labelled with higher nicotine content. Females and non-smokers of cigarettes were more likely than their counterparts to prefer flavoured and nicotine-free varieties. Participants exposed to a health warning were more likely to opt out. Conclusions Fruit-flavoured tobacco and lower nicotine content labels, two strategies widely used by the industry, increase the demand for waterpipe smoking among young adults. Waterpipe-specific regulation should limit the availability of flavoured waterpipe tobacco and require accurate labelling of constituents. Waterpipe-specific tobacco control regulation, along with research to inform policy, is required to curb this emerging public health threat. PMID:26353876

  3. Rescaling quality of life values from discrete choice experiments for use as QALYs: a cautionary tale

    PubMed Central

    Flynn, Terry N; Louviere, Jordan J; Marley, Anthony AJ; Coast, Joanna; Peters, Tim J

    2008-01-01

    Background Researchers are increasingly investigating the potential for ordinal tasks such as ranking and discrete choice experiments to estimate QALY health state values. However, the assumptions of random utility theory, which underpin the statistical models used to provide these estimates, have received insufficient attention. In particular, the assumptions made about the decisions between living states and the death state are not satisfied, at least for some people. Estimated values are likely to be incorrectly anchored with respect to death (zero) in such circumstances. Methods Data from the Investigating Choice Experiments for the preferences of older people CAPability instrument (ICECAP) valuation exercise were analysed. The values (previously anchored to the worst possible state) were rescaled using an ordinal model proposed previously to estimate QALY-like values. Bootstrapping was conducted to vary artificially the proportion of people who conformed to the conventional random utility model underpinning the analyses. Results Only 26% of respondents conformed unequivocally to the assumptions of conventional random utility theory. At least 14% of respondents unequivocally violated the assumptions. Varying the relative proportions of conforming respondents in sensitivity analyses led to large changes in the estimated QALY values, particularly for lower-valued states. As a result these values could be either positive (considered to be better than death) or negative (considered to be worse than death). Conclusion Use of a statistical model such as conditional (multinomial) regression to anchor quality of life values from ordinal data to death is inappropriate in the presence of respondents who do not conform to the assumptions of conventional random utility theory. This is clearest when estimating values for that group of respondents observed in valuation samples who refuse to consider any living state to be worse than death: in such circumstances the model

  4. Perceived risk and modal choice: risk compensation in transportation systems.

    PubMed

    Noland, R B

    1995-08-01

    A transportation mode choice analysis is performed that examines behavioral responses to perceived risk in the choice of mode for daily commute trips. This methodology provides a technique for examining, by means of disaggregate individual level data, risk-compensating effects in transportation systems. Various measures of perceived risk are examined for explaining modal choice. Other studies have described how safety regulations have resulted in increases in "driving intensity." This study defines one component of driving intensity to be the increased probability of commuting by automobile. The results show that modal shifts occur when risk perceptions for a given mode are reduced. To demonstrate potential risk-compensating effects within the transportation system, an estimate of changes in accident fatalities due to commuting is derived using rough estimates of fatalities per person-mile travelled. It is shown that a given change in the perceived risk of commuting by automobile results in a less than proportionate change in net commuting fatalities. The relative magnitude is dependent on how objective reductions in risk translate into perceived reductions in risk. This study also shows that perceived safety improvements in bicycle transportation have an aggregate elasticity value that is greater than one. This means that bicycle safety improvements attract proportionately more people to bicycle commuting (i.e. a 10% increase in safety results in a greater than 10% increase in the share of people bicycle commuting).

  5. Preferences for long-term care services: willingness to pay estimates derived from a discrete choice experiment.

    PubMed

    Nieboer, Anna P; Koolman, Xander; Stolk, Elly A

    2010-05-01

    Ageing populations increase pressure on long-term care. Optimal resource allocation requires an optimal mix of care services based on costs and benefits. Contrary to costs, benefits remain largely unknown. This study elicits preferences in the general elderly population for long-term care services for varying types of patients. A discrete choice experiment was conducted in a general population subsample aged 50-65 years (N = 1082) drawn from the Dutch Survey Sampling International panel. To ascertain relative preferences for long-term care and willingness to pay for these, participants were asked to choose the best of two care scenarios for four groups of hypothetical patients: frail and demented elderly, with and without partner. The scenarios described long-term care using ten attributes based on Social Production Function theory: hours of care, organized social activities, transportation, living situation, same person delivering care, room for individual preferences, coordination of services, punctuality, time on waiting list, and co-payments. We found the greatest value was attached to same person delivering care and transportation services. Low value was attached to punctuality and room for individual preferences. Nursing homes were generally considered to be detrimental for well-being except for dementia patients without a partner. Overall, long-term care services were thought to produce greatest well-being for the patients 'without a partner' and those 'with dementia'. Individuals combining these two risk factors would benefit the most from all services except transportation which was considered more important for the frail elderly. The results support the notion that long-term care services represent different value for different types of patients and that the value of a service depends upon the social context. Examination of patient profiles confirmed the notion that physical, mental and social vulnerability affect valuation of the services. Policy

  6. Modeling the Information Preferences of Parents of Children with Mental Health Problems: A Discrete Choice Conjoint Experiment

    ERIC Educational Resources Information Center

    Cunningham, Charles E.; Deal, Ken; Rimas, Heather; Buchanan, Don H.; Gold, Michelle; Sdao-Jarvie, Katherine; Boyle, Michael

    2008-01-01

    Although materials informing parents about children's mental health (CMH) problems can improve outcomes, we know relatively little about the design factors that might influence their utilization of available resources. We used a discrete choice conjoint experiment to model the information preferences of parents seeking mental health services for 6…

  7. Evaluating patients' preferences for multiple myeloma therapy, a Discrete-Choice-Experiment.

    PubMed

    Mühlbacher, Axel C; Lincke, Hans-Joachim; Nübling, Matthias

    2008-12-19

    While there is an increasing emphasis on patient empowerment and shared decision making, patients' preferences for attributes associated with their treatment still need to be measured and considered. In the present study, patients' preferences regarding treatment of multiple myeloma (MM) were explored using direct assessment and a Discrete-Choice-Experiment (DCE). After reviewing the literature about preferences of myeloma patients we conducted a qualitative study with three focus groups consisting of six to eight MM-patients each. In order to achieve content validity, we aimed at collecting all relevant factors for an ideal MM-treatment. In a subsequent quantitative study phase, data was collected in an online or paper-pencil self-completed questionnaire. It included sociodemographic data, self-rated health (SF12v2 variation) and patients preferences of therapy characteristics using direct measurement (16 items on a five-point Likert-scale) as well as a Discrete-Choice-Experiment (DCE, eight pairs with eight characteristics). 282 patients answered the questionnaire; 46% female, age: mean 62 yrs (SD=10 years), duration of MM: 5 yrs (SD=3.8 years). Direct measurement showed effectiveness aspects (i.e. high effectiveness, long lasting effects, max. prolonged life expectancy) and further treatment options in the first places, followed by maximal prolonged life expectancy, minor side effects and therapy-free-intervals. In the DCE, alternatives with further treatment options, longer life expectancy, "not always think of the disease" and therapy-free-intervals were more likely to be chosen, giving thus similar results. Besides prolongation of life expectancy and effectiveness of treatment, further treatment options are of foremost importance to multiple myeloma patients. In addition, therapy-free intervals as well as an improved emotional quality of life ("Not always think of the disease") are valued as very important. The combination of direct assessment of importance

  8. Patient preferences for healthcare delivery through community pharmacy settings in the USA: A discrete choice study.

    PubMed

    Feehan, M; Walsh, M; Godin, J; Sundwall, D; Munger, M A

    2017-06-18

    In order to improve public health, it is necessary to facilitate patients' easy access to affordable high-quality primary health care, and one enhanced approach to do so may be to provide primary healthcare services in the community pharmacy setting. Discrete choice experiments to evaluate patient demand for services in pharmacy are relatively limited and have been hampered by a focus on only a few service alternatives, most focusing on changes in more traditional pharmacy services. The study aim was to gauge patient preferences explicitly for primary healthcare services that could be delivered through community pharmacy settings in the USA, using a very large sample to accommodate multiple service delivery options. An online survey was administered to a total of 9202 adult patients from the general population. A subsequent online survey was administered to 50 payer reimbursement decision-makers. The patient survey included a discrete choice experiment (DCE) which showed competing scenarios describing primary care service offerings. The respondents chose which scenario would be most likely to induce them to switch from their current pharmacy, and an optimal patient primary care service model was derived. The likelihood this model would be reimbursed was then determined in the payer survey. The final optimal service configuration that would maximize patient preference included the pharmacy: offering appointments to see a healthcare provider in the pharmacy, having access to their full medical record, provide point-of-care diagnostic testing, offer health preventive screening, provide limited physical examinations such as measuring vital signs, and drug prescribing in the pharmacy. The optimal model had the pharmacist as the provider; however, little change in demand was evident if the provider was a nurse-practitioner or physician's assistant. The demand for this optimal model was 2-fold higher (25.5%; 95% Bayesian precision interval (BPI) 23.5%-27.0%) than for a

  9. Patients’ preferences for osteoporosis drug treatment: a discrete-choice experiment

    PubMed Central

    2014-01-01

    Introduction The patient’s perspective is becoming increasingly important in clinical and policy decisions. In this study, we aimed to evaluate the preferences of patients with, or at risk of, osteoporosis for medication attributes, and to establish how patients trade between these attributes. Methods A discrete choice experiment survey was designed and patients were asked to choose between two hypothetical unlabelled drug treatments (and an opt-out option) that vary in five attributes: efficacy in reducing the risk of fracture, type of potential common side-effects, mode and frequency of administration and out-of-pocket costs. An efficient experimental design was used to construct the treatment option choice sets and a mixed logit panel data model was used to estimate patients’ preferences and trade-offs between attributes. Results A total of 257 patients with, or at risk of, osteoporosis completed the experiment. As expected, patients preferred treatment with higher effectiveness and lower cost. They also preferred either an oral monthly tablet or 6-month subcutaneous injection above weekly oral tablets, 3-month subcutaneous, 3-month intravenous or yearly intravenous injections. Patients disliked being at risk of gastro-intestinal disorders more than being at risk of skin reactions and flu-like symptoms. There was significant variation in preferences across the sample for all attributes except subcutaneous injection. Conclusions This study revealed that osteoporotic patients preferred 6-month subcutaneous injection and oral monthly tablet, and disliked gastro-intestinal disorders. Moreover, patients were willing to pay a personal contribution or to trade treatment efficacy for better levels of other attributes. Preferences for treatment attributes varied across patients and this highlights the importance of clinical decision-making taking individual preferences into account to improve osteoporosis care. PMID:24479410

  10. Characterizing outcome preferences in patients with psychotic disorders: a discrete choice conjoint experiment.

    PubMed

    Zipursky, Robert B; Cunningham, Charles E; Stewart, Bailey; Rimas, Heather; Cole, Emily; Vaz, Stephanie McDermid

    2017-07-01

    The majority of individuals with schizophrenia will achieve a remission of psychotic symptoms, but few will meet criteria for recovery. Little is known about what outcomes are important to patients. We carried out a discrete choice experiment to characterize the outcome preferences of patients with psychotic disorders. Participants (N=300) were recruited from two clinics specializing in psychotic disorders. Twelve outcomes were each defined at three levels and incorporated into a computerized survey with 15 choice tasks. Utility values and importance scores were calculated for each outcome level. Latent class analysis was carried out to determine whether participants were distributed into segments with different preferences. Multinomial logistic regression was used to identify predictors of segment membership. Latent class analysis revealed three segments of respondents. The first segment (48%), which we labeled "Achievement-focused," preferred to have a full-time job, to live independently, to be in a long-term relationship, and to have no psychotic symptoms. The second segment (29%), labeled "Stability-focused," preferred to not have a job, to live independently, and to have some ongoing psychotic symptoms. The third segment (23%), labeled "Health-focused," preferred to not have a job, to live in supervised housing, and to have no psychotic symptoms. Segment membership was predicted by education, socioeconomic status, psychotic symptom severity, and work status. This study has revealed that patients with psychotic disorders are distributed between segments with different outcome preferences. New approaches to improve outcomes for patients with psychotic disorders should be informed by a greater understanding of patient preferences and priorities. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Reduce mortality risk above all else: a discrete-choice experiment in acute coronary syndrome patients.

    PubMed

    Mühlbacher, Axel C; Bethge, Susanne

    2015-01-01

    Cardiovascular disease is the main cause of death in Germany and other industrialized countries. However, until now, little has been known about how people with acute coronary syndrome (ACS) value aspects of their medical treatment. The objective of this study was to evaluate patients' preferences regarding different antiplatelet medication options following an ACS. After identification of patient-relevant treatment attributes (a literature review and qualitative interviews), a discrete-choice experiment (DCE) including five patient-relevant attributes was conducted. The DCE used a forced-choice approach in which no "opt out" was present, as no treatment is not an option after ACS. The attribute and level combinations were created using a fractional-factorial NGene design with priors. Data analysis was performed using a random-effects logit model. An additional generalized linear latent and mixed models (GLLAMM) analysis was performed to evaluate subgroup differences. ACS patients (N = 683) participated in computer-assisted personal interviews. Preference analysis showed a clear dominance of the attribute "mortality risk" (coefficient: 0.803). Ranked second was "side effect: dyspnea" (coefficient: 0.550) followed by "risk of a new myocardial infarction" (coefficient: 0.464) and "side effect: bleeding" (coefficient: 0.400). "Frequency of intake" was less important (coefficient: 0.025). Within the 3-class GLLAMM, the variables "marital status" (p = 0.008), "highest level of education" (p = 0.003), and "body-mass index" (according to World Health Organization cluster; p = 0.014) showed a significant impact on the estimated class probabilities. Our study found "mortality risk" to be of the highest value for patients. Patient-centered care and decision making requires consideration of patient preferences; moreover, the information on preferences can be used to develop effective therapies after an ACS. The data generated will enable healthcare decision makers and

  12. The use of specialty training to retain doctors in Malawi: A discrete choice experiment.

    PubMed

    Mandeville, Kate L; Ulaya, Godwin; Lagarde, Mylène; Muula, Adamson S; Dzowela, Titha; Hanson, Kara

    2016-11-01

    Emigration has contributed to a shortage of doctors in many sub-Saharan African countries. Specialty training is highly valued by doctors and a potential tool for retention. Yet not all types of training may be valued equally. In the first study to examine preferences for postgraduate training in depth, we carried out a discrete choice experiment as part of a cross-sectional survey of all Malawian doctors within seven years of graduation and not yet in specialty training. Over August 2012 to March 2013, 148 doctors took part out of 153 eligible in Malawi. Despite evidence that specialty training is highly sought after, Malawian junior doctors would not accept all types of training. Doctors preferred timely training outside of Malawi in core specialties (internal medicine, general surgery, paediatrics, obstetrics & gynaecology). Specialty preferences are particularly strong, with most junior doctors requiring nearly double their monthly salary to accept training all in Malawi and over six-fold to accept training in ophthalmology (representing a bundle of unpopular but priority specialties). In contrast, the location of work before training did not significantly influence most doctors' choices when guaranteed specialty training. Using a latent class model, we identified four subgroups of junior doctors with distinct preferences. Policy simulations showed that these preferences could be leveraged by policymakers to improve retention in exchange for guaranteed specialty training, however incentivising the uptake of training in priority specialties will only be effective in those with more flexible preferences. These results indicate that indiscriminate expansion of postgraduate training to slow emigration of doctors from sub-Saharan African countries may not be effective unless doctors' preferences are taken into account.

  13. Preferences of overweight and obese patients for weight loss programmes: a discrete-choice experiment

    PubMed Central

    Mühlbacher, Axel; Bethge, Susanne

    2013-01-01

    Introduction Obesity is associated with increased risk of morbidity and mortality and also appears to have an adverse effect on health-related quality of life. Though advances in obesity therapy and rehabilitation can be observed, the long-lasting outcome is dissatisfying to most of the patients and, therefore, the whole health care system. Theory and methodology The study aims to identify key attributes of coordinated weight loss programmes and elicit patients’ preferences for overweight and obesity therapy in rehabilitation programmes. A self-administered survey measuring attitudes and preferences was conducted in Germany in 2009. Discrete-choice experiment scenarios were developed using a fractional factorial design and results analysed using a random effects logit model. Results N=110 patients completed the questionnaire, 51.82% of these were male, the mean age was 53.05 years and mean body mass index was 33.54 kg/m2 (SD 7.73). A total of 823 choices could be included in the final estimation. The most important aspects for the respondents’ selection were care coordination (coefficient 1.473; SE 0.185) and individual therapy (coefficient 1.446; SE 0.188). The aspect ‘infrastructure of care’ (coefficient 0.570; SE 0.175) was less relevant. All attributes led to significant coefficients. Conclusion Patients value coordination of care and individual therapy most highly. So weight reduction therapy should enable patients to receive a structured, coordinated and interpersonal therapy that is tailored to their personal needs, behaviour and circumstances. Patients are willing to forego infrastructure quality in favour of better coordination and structure in their therapy. PMID:24179457

  14. Rural practice preferences among medical students in Ghana: a discrete choice experiment

    PubMed Central

    Johnson, Jennifer C; Gyakobo, Mawuli; Agyei-Baffour, Peter; Asabir, Kwesi; Kotha, S Rani; Kwansah, Janet; Nakua, Emmanuel; Snow, Rachel C; Dzodzomenyo, Mawuli

    2010-01-01

    Abstract Objective To determine how specific job attributes influenced fourth year medical students’ stated preference for hypothetical rural job postings in Ghana. Methods Based on discussions with medical student focus groups and physicians in practice and in the Ministry of Health, we created a discrete choice experiment (DCE) that assessed how students’ stated preference for certain rural postings was influenced by various job attributes: a higher salary, free superior housing, an educational allowance for children, improved equipment, supportive management, shorter contracts before study leave and a car. We conducted the DCE among all fourth year medical students in Ghana using a brief structured questionnaire and used mixed logit models to estimate the utility of each job attribute. Findings Complete data for DCE analysis were available for 302 of 310 (97%) students. All attribute parameter estimates differed significantly from zero and had the expected signs. In the main effects mixed logit model, improved equipment and supportive management were most strongly associated with job preference (β = 1.42; 95% confidence interval, CI: 1.17 to 1.66, and β = 1.17; 95% CI: 0.96 to 1.39, respectively), although shorter contracts and salary bonuses were also associated. Discontinuing the provision of basic housing had a large negative influence (β = −1.59; 95% CI: −1.88 to −1.31). In models including gender interaction terms, women’s preferences were more influenced by supportive management and men’s preferences by superior housing. Conclusion Better working conditions were strongly associated with the stated choice of hypothetical rural postings among fourth year Ghanaian medical students. Studies are needed to find out whether job attributes determine the actual uptake of rural jobs by graduating physicians. PMID:20458371

  15. Prioritising patients for bariatric surgery: building public preferences from a discrete choice experiment into public policy.

    PubMed

    Whitty, Jennifer A; Ratcliffe, Julie; Kendall, Elizabeth; Burton, Paul; Wilson, Andrew; Littlejohns, Peter; Harris, Paul; Krinks, Rachael; Scuffham, Paul A

    2015-10-15

    To derive priority weights for access to bariatric surgery for obese adults, from the perspective of the public. Australian public hospital system. Adults (N=1994), reflecting the age and gender distribution of Queensland and South Australia. A discrete choice experiment in which respondents indicated which of two individuals with different characteristics should be prioritised for surgery in repeated hypothetical choices. Potential surgery recipients were described by seven key characteristics or attributes: body mass index (BMI), presence of comorbid conditions, age, family history, commitment to lifestyle change, time on the surgical wait list and chance of maintaining weight loss following surgery. A multinomial logit model was used to evaluate preferences and derive priority weights (primary analysis), with a latent class model used to explore respondent characteristics that were associated with variation in preference across the sample (see online supplementary analysis). A preference was observed to prioritise individuals who demonstrated a strong commitment to maintaining a healthy lifestyle as well as individuals categorised with very severe (BMI≥50 kg/m2) or (to a lesser extent) severe (BMI≥40 kg/m2) obesity, those who already have obesity-related comorbidity, with a family history of obesity, with a greater chance of maintaining weight loss or who had spent a longer time on the wait list. Lifestyle commitment was considered to be more than twice as important as any other criterion. There was little tendency to prioritise according to the age of the recipient. Respondent preferences were dependent on their BMI, previous experience with weight management surgery, current health state and education level. This study extends our understanding of the publics' preferences for priority setting to the context of bariatric surgery, and derives priority weights that could be used to assist bodies responsible for commissioning bariatric services. Published

  16. Physicians' preferences for prescribing oral and intravenous anticancer drugs: a Discrete Choice Experiment.

    PubMed

    Benjamin, Laure; Cotté, François-Emery; Philippe, Caroline; Mercier, Florence; Bachelot, Thomas; Vidal-Trécan, Gwenaëlle

    2012-04-01

    Although efficacy and tolerability are classical criteria for treatment choice, patient adherence and tariff issues related to novel oral anticancer drugs may also influence therapeutic decisions. We estimated the relative influence of efficacy, tolerability, expected adherence and route of administration of a chemotherapy treatment on 203 French physicians' preferences who participated in a Discrete Choice Experiment (DCE), a quantitative method used to elicit preferences. From a questionnaire with six scenarii, respondents had to choose between two treatments which differed with respect to these four attributes. Scenarii were first presented in a curative setting then in a palliative setting. Efficacy, tolerability and expected adherence had two modalities (good versus moderate) and route of administration had three modalities (intravenous (€286-379/session), oral with the current tariff (€28/consultation), oral with a hypothetical tariff (€114)). Efficacy was the reference criterion in choosing a treatment whatever the therapeutic goal (β: 2.114, p<0.0001 in curative setting versus β: 1.063, p<0.0001 in palliative setting). The oral route of administration was important but only in a palliative setting (β: 0.612, p=0.035, and β: 0.506, p<0.0001 for the current and hypothetical tariff, respectively). Removing the efficacy attribute from logistic regression model, tolerability (β: 1.228, p=0.0001) and expected adherence (β: 1.223, p=0.0001) were influent in curative setting while the route of administration was still predominant in palliative setting (β: 0.431, p<0.0001). Results suggest that economic considerations as well as therapeutic efficacy play a significant role in choosing a treatment. Preference for oral chemotherapy with a hypothetical tariff for a patient support programme should be considered for the development of therapeutic education and healthcare coordination, currently not taken into account in the tariff of oral chemotherapy

  17. Evaluating health workers' potential resistance to new interventions: a role for discrete choice experiments.

    PubMed

    Lagarde, Mylene; Smith Paintain, Lucy; Antwi, Gifti; Jones, Caroline; Greenwood, Brian; Chandramohan, Daniel; Tagbor, Harry; Webster, Jayne

    2011-01-01

    The currently recommended approach for preventing malaria in pregnancy (MiP), intermittent preventive treatment with sulphadoxine-pyrimethamine (SP-IPT), has been questioned due to the spread of resistance to SP. Whilst trials are underway to test the efficacy of future alternative approaches, it is important to start exploring the feasibility of their implementation. This study uses a discrete choice experiment (DCE) method to assess the potential resistance of health workers to changing strategies for control of MiP. In Ashanti region in Ghana, 133 antenatal clinic health workers were presented with 16 choice sets of two alternative policy options, each consisting of a bundle of six attributes representing certain clinical guidelines for controlling MiP (type of approach and drug used), possible associated maternal and neo-natal outcomes, workload and financial incentives. The data were analysed using a random effects logit model. Overall, staff showed a preference for a curative approach with pregnant women tested for malaria parasites and treated only if positive, compared to a preventive approach (OR 1.6; p = 0.001). Increasing the incidence of low birth weight or severe anaemia by 1% would reduce the odds of preferring an approach by 18% and 10% respectively. Midwives were more resistant to potential changes to current guidelines than lower-level cadres. In Ashanti Region, resistance to change by antenatal clinic workers from a policy of SP-IPT to IST would generally be low, and it would disappear amongst midwives if health outcomes for the mother and baby were improved by the new strategy. DCEs are a promising approach to identifying factors that will increase the likelihood of effective implementation of new interventions immediately after their efficacy has been proven.

  18. Preferences for Early Intervention Mental Health Services: A Discrete-Choice Conjoint Experiment.

    PubMed

    Becker, Mackenzie P E; Christensen, Bruce K; Cunningham, Charles E; Furimsky, Ivana; Rimas, Heather; Wilson, Fiona; Jeffs, Lisa; Bieling, Peter J; Madsen, Victoria; Chen, Yvonne Y S; Mielko, Stephanie; Zipursky, Robert B

    2016-02-01

    Early intervention services (EISs) for mental illness may improve outcomes, although treatment engagement is often a problem. Incorporating patients' preferences in the design of interventions improves engagement. A discrete-choice conjoint experiment was conducted in Canada to identify EIS attributes that encourage treatment initiation. Sixteen four-level attributes were formalized into a conjoint survey, completed by patients, family members, and mental health professionals (N=562). Participants were asked which EIS option people with mental illness would contact. Latent-class analysis identified respondent classes characterized by shared preferences. Randomized first-choice simulations predicted which hypothetical options, based on attributes, would result in maximum utilization. Participants in the conventional-service class (N=241, 43%) predicted that individuals would contact traditional services (for example, hospital location and staffed by psychologists or psychiatrists). Membership was associated with being a patient or family member and being male. Participants in the convenient-service class (N=321, 57%) predicted that people would contact services promoting easy access (for example, self-referral and access from home). Membership was associated with being a professional. Both classes predicted that people would contact services that included short wait times, direct contact with professionals, patient autonomy, and psychological treatment information. The convenient-service class predicted that people would use an e-health model, whereas the conventional-service class predicted that people would use a primary care or clinic-hospital model. Provision of a range of services may maximize EIS use. Professionals may be more apt to adopt EISs in line with their beliefs regarding patient preferences. Considering several perspectives is important for service design.

  19. Modeling the hospital safety partnership preferences of patients and their families: a discrete choice conjoint experiment

    PubMed Central

    Cunningham, Charles E; Hutchings, Tracy; Henderson, Jennifer; Rimas, Heather; Chen, Yvonne

    2016-01-01

    Background Patients and their families play an important role in efforts to improve health service safety. Objective The objective of this study is to understand the safety partnership preferences of patients and their families. Method We used a discrete choice conjoint experiment to model the safety partnership preferences of 1,084 patients or those such as parents acting on their behalf. Participants made choices between hypothetical safety partnerships composed by experimentally varying 15 four-level partnership design attributes. Results Participants preferred an approach to safety based on partnerships between patients and staff rather than a model delegating responsibility for safety to hospital staff. They valued the opportunity to participate in point of service safety partnerships, such as identity and medication double checks, that might afford an immediate risk reduction. Latent class analysis yielded two segments. Actively engaged participants (73.3%) comprised outpatients with higher education, who anticipated more benefits to safety partnerships, were more confident in their ability to contribute, and were more intent on participating. They were more likely to prefer a personal engagement strategy, valued scientific evidence, preferred a more active approach to safety education, and advocated disclosure of errors. The passively engaged segment (26.7%) anticipated fewer benefits, were less confident in their ability to contribute, and were less intent on participating. They were more likely to prefer an engagement strategy based on signage. They preferred that staff explain why they thought patients should help make care safer and decide whether errors were disclosed. Inpatients, those with immigrant backgrounds, and those with less education were more likely to be in this segment. Conclusion Health services need to communicate information regarding risks, ask about partnership preferences, create opportunities respecting individual differences, and

  20. Modeling the hospital safety partnership preferences of patients and their families: a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Hutchings, Tracy; Henderson, Jennifer; Rimas, Heather; Chen, Yvonne

    2016-01-01

    Patients and their families play an important role in efforts to improve health service safety. The objective of this study is to understand the safety partnership preferences of patients and their families. We used a discrete choice conjoint experiment to model the safety partnership preferences of 1,084 patients or those such as parents acting on their behalf. Participants made choices between hypothetical safety partnerships composed by experimentally varying 15 four-level partnership design attributes. Participants preferred an approach to safety based on partnerships between patients and staff rather than a model delegating responsibility for safety to hospital staff. They valued the opportunity to participate in point of service safety partnerships, such as identity and medication double checks, that might afford an immediate risk reduction. Latent class analysis yielded two segments. Actively engaged participants (73.3%) comprised outpatients with higher education, who anticipated more benefits to safety partnerships, were more confident in their ability to contribute, and were more intent on participating. They were more likely to prefer a personal engagement strategy, valued scientific evidence, preferred a more active approach to safety education, and advocated disclosure of errors. The passively engaged segment (26.7%) anticipated fewer benefits, were less confident in their ability to contribute, and were less intent on participating. They were more likely to prefer an engagement strategy based on signage. They preferred that staff explain why they thought patients should help make care safer and decide whether errors were disclosed. Inpatients, those with immigrant backgrounds, and those with less education were more likely to be in this segment. Health services need to communicate information regarding risks, ask about partnership preferences, create opportunities respecting individual differences, and ensure a positive response when patients raise

  1. Pharmacists' preferences for providing patient-centered services: a discrete choice experiment to guide health policy.

    PubMed

    Grindrod, Kelly A; Marra, Carlo A; Colley, Lindsey; Tsuyuki, Ross T; Lynd, Larry D

    2010-10-01

    In Canada, most pharmacists are not paid to provide patient-centered services. In other areas of the world these services have suffered from poor adoption by pharmacists. To determine pharmacists' preferences for providing patient-centered services. Senior pharmacy students and pharmacists in British Columbia and Alberta were recruited to complete a discrete choice experiment. In 18 different choice-sets, respondents were asked to choose 1 of 3 options that included 2 different hypothetical patient-centered services and a status quo option. For each hypothetical service, we described the following attributes: service type and setting, personal income and job satisfaction, professional fee, and educational requirements. Multinomial logit and latent class regression models determined respondents' relative preference weights for each attribute. Of 539 respondents who completed the questionnaire, 49% were dispensary pharmacists or managers, 12% were dispensary owners or regional managers, 21% were clinical pharmacists, and 16% were students. When choosing new services, respondents were very averse to having their personal income or job satisfaction decrease. They also preferred a higher professional fee for the service (to be paid to the pharmacy) and preferred a weeklong course or a preceptorship over no education before embarking on new services. Respondents also preferred medication or disease management services, were not interested in screening, and were averse to typical pharmacy services. Finally, respondents preferred the clinic setting over the dispensary. Preferences differed according to several factors including respondents' employment and time in practice. Pharmacists prefer to provide patient-centered services over typical pharmacy services. Most will need to be assured that their income and job satisfaction will be maintained or increased and that they will have access to suitable advanced education. Decision-makers should carefully consider these

  2. Developing attributes and attribute-levels for a discrete choice experiment on micro health insurance in rural Malawi

    PubMed Central

    2014-01-01

    Background Discrete choice experiments (DCEs) are attribute-driven experimental techniques used to elicit stakeholders’ preferences to support the design and implementation of policy interventions. The validity of a DCE, therefore, depends on the appropriate specification of the attributes and their levels. There have been recent calls for greater rigor in implementing and reporting on the processes of developing attributes and attribute-levels for discrete choice experiments (DCEs). This paper responds to such calls by carefully reporting a systematic process of developing micro health insurance attributes and attribute-levels for the design of a DCE in rural Malawi. Methods Conceptual attributes and attribute-levels were initially derived from a literature review which informed the design of qualitative data collection tools to identify context specific attributes and attribute-levels. Qualitative data was collected in August-September 2012 from 12 focus group discussions with community residents and 8 in-depth interviews with health workers. All participants were selected according to stratified purposive sampling. The material was tape-recorded, fully transcribed, and coded by three researchers to identify context-specific attributes and attribute-levels. Expert opinion was used to scale down the attributes and levels. A pilot study confirmed the appropriateness of the selected attributes and levels for a DCE. Results First, a consensus, emerging from an individual level analysis of the qualitative transcripts, identified 10 candidate attributes. Levels were assigned to all attributes based on data from transcripts and knowledge of the Malawian context, derived from literature. Second, through further discussions with experts, four attributes were discarded based on multiple criteria. The 6 remaining attributes were: premium level, unit of enrollment, management structure, health service benefit package, transportation coverage and copayment levels. A final

  3. Developing attributes and attribute-levels for a discrete choice experiment on micro health insurance in rural Malawi.

    PubMed

    Abiiro, Gilbert Abotisem; Leppert, Gerald; Mbera, Grace Bongololo; Robyn, Paul J; De Allegri, Manuela

    2014-05-22

    Discrete choice experiments (DCEs) are attribute-driven experimental techniques used to elicit stakeholders' preferences to support the design and implementation of policy interventions. The validity of a DCE, therefore, depends on the appropriate specification of the attributes and their levels. There have been recent calls for greater rigor in implementing and reporting on the processes of developing attributes and attribute-levels for discrete choice experiments (DCEs). This paper responds to such calls by carefully reporting a systematic process of developing micro health insurance attributes and attribute-levels for the design of a DCE in rural Malawi. Conceptual attributes and attribute-levels were initially derived from a literature review which informed the design of qualitative data collection tools to identify context specific attributes and attribute-levels. Qualitative data was collected in August-September 2012 from 12 focus group discussions with community residents and 8 in-depth interviews with health workers. All participants were selected according to stratified purposive sampling. The material was tape-recorded, fully transcribed, and coded by three researchers to identify context-specific attributes and attribute-levels. Expert opinion was used to scale down the attributes and levels. A pilot study confirmed the appropriateness of the selected attributes and levels for a DCE. First, a consensus, emerging from an individual level analysis of the qualitative transcripts, identified 10 candidate attributes. Levels were assigned to all attributes based on data from transcripts and knowledge of the Malawian context, derived from literature. Second, through further discussions with experts, four attributes were discarded based on multiple criteria. The 6 remaining attributes were: premium level, unit of enrollment, management structure, health service benefit package, transportation coverage and copayment levels. A final step of revision and piloting

  4. Influence of disease activity on RA treatment choices in countries with restricted access to expensive, innovative drugs: a discrete choice experiment among rheumatologists.

    PubMed

    Hifinger, Monika; Hiligsmann, Mickael; Ramiro, Sofia; Watson, Verity; Berghea, Florian; Péntek, Márta; Keat, Andrew; Severens, Johan L; Fautrel, Bruno; Boonen, Annelies

    2017-01-01

    To assess the influence of disease activity of patients with rheumatoid arthritis on treatment choices of rheumatologists in countries with restricted access to expensive, innovative drugs. Rheumatologists from Hungary, Romania and UK were invited to complete two consecutive discrete choice experiments with hypothetical drug treatments for two different patient profiles: high and moderate disease activity. Rheumatologists were asked to choose repeatedly between two unlabelled treatment options that differed in five attributes: efficacy (expected improvement and achieved disease activity state), safety (probability of serious adverse events), patient's preference (level of agreement), total medication costs and cost-effectiveness. A heteroscedastic discrete choice model using interaction terms between attribute levels and patient profiles (binary variable) was used to assess the preferences of rheumatologists towards each attribute and the influence of the patient profile. Overall, 148 rheumatologists completed the survey (46% females, mean age 49 years, 49% academic). For both patient profiles, efficacy dominated the treatment choice over patient's preference, safety and economic aspects. However, for patients with high compared with moderate disease activity, the importance of drug efficacy significantly increased (from 48% for moderate to 57% for high disease activity), whereas the importance of patient's preference significantly decreased (from 15% to 11%). No significant differences were observed for economic and safety considerations. Rheumatologists were willing to give up some efficacy to account for patient's preference when choosing treatments for patients with moderate compared to high disease activity. Disease activity however did not influence importance of economic aspects in treatment choices.

  5. Influence of disease activity on RA treatment choices in countries with restricted access to expensive, innovative drugs: a discrete choice experiment among rheumatologists

    PubMed Central

    Hifinger, Monika; Hiligsmann, Mickael; Ramiro, Sofia; Watson, Verity; Berghea, Florian; Péntek, Márta; Keat, Andrew; Severens, Johan L; Fautrel, Bruno; Boonen, Annelies

    2017-01-01

    Objective To assess the influence of disease activity of patients with rheumatoid arthritis on treatment choices of rheumatologists in countries with restricted access to expensive, innovative drugs. Methods Rheumatologists from Hungary, Romania and UK were invited to complete two consecutive discrete choice experiments with hypothetical drug treatments for two different patient profiles: high and moderate disease activity. Rheumatologists were asked to choose repeatedly between two unlabelled treatment options that differed in five attributes: efficacy (expected improvement and achieved disease activity state), safety (probability of serious adverse events), patient's preference (level of agreement), total medication costs and cost-effectiveness. A heteroscedastic discrete choice model using interaction terms between attribute levels and patient profiles (binary variable) was used to assess the preferences of rheumatologists towards each attribute and the influence of the patient profile. Results Overall, 148 rheumatologists completed the survey (46% females, mean age 49 years, 49% academic). For both patient profiles, efficacy dominated the treatment choice over patient's preference, safety and economic aspects. However, for patients with high compared with moderate disease activity, the importance of drug efficacy significantly increased (from 48% for moderate to 57% for high disease activity), whereas the importance of patient's preference significantly decreased (from 15% to 11%). No significant differences were observed for economic and safety considerations. Conclusion Rheumatologists were willing to give up some efficacy to account for patient's preference when choosing treatments for patients with moderate compared to high disease activity. Disease activity however did not influence importance of economic aspects in treatment choices. PMID:28912960

  6. A discrete choice experiment studying students' preferences for scholarships to private medical schools in Japan.

    PubMed

    Goto, Rei; Kakihara, Hiroaki

    2016-02-09

    The shortage of physicians in rural areas and in some specialties is a societal problem in Japan. Expensive tuition in private medical schools limits access to them particularly for students from middle- and low-income families. One way to reduce this barrier and lessen maldistribution is to offer conditional scholarships to private medical schools. A discrete choice experiment is carried out on a total of 374 students considering application to medical schools. The willingness to receive a conditional scholarship program to private medical schools is analyzed. The probability of attending private medical schools significantly decreased because of high tuition, a postgraduate obligation to provide a service in specific specialty areas, and the length of time of this obligation. An obligation to provide a service in rural regions had no significant effect on this probability. To motivate non-applicants to private medical schools to enroll in such schools, a decrease in tuition to around 1.2 million yen (US$ 12,000) or less, which is twice that of public schools, was found to be necessary. Further, it was found that non-applicants to private medical schools choose to apply to such schools even with restrictions if they have tuition support at the public school level. Conditional scholarships for private medical schools may widen access to medical education and simultaneously provide incentives to work in insufficiently served areas.

  7. Is Best-Worst Scaling Suitable for Health State Valuation? A Comparison with Discrete Choice Experiments.

    PubMed

    Krucien, Nicolas; Watson, Verity; Ryan, Mandy

    2016-12-04

    Health utility indices (HUIs) are widely used in economic evaluation. The best-worst scaling (BWS) method is being used to value dimensions of HUIs. However, little is known about the properties of this method. This paper investigates the validity of the BWS method to develop HUI, comparing it to another ordinal valuation method, the discrete choice experiment (DCE). Using a parametric approach, we find a low level of concordance between the two methods, with evidence of preference reversals. BWS responses are subject to decision biases, with significant effects on individuals' preferences. Non parametric tests indicate that BWS data has lower stability, monotonicity and continuity compared to DCE data, suggesting that the BWS provides lower quality data. As a consequence, for both theoretical and technical reasons, practitioners should be cautious both about using the BWS method to measure health-related preferences, and using HUI based on BWS data. Given existing evidence, it seems that the DCE method is a better method, at least because its limitations (and measurement properties) have been extensively researched. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Using discrete choice experiments within a cost-benefit analysis framework: some considerations.

    PubMed

    McIntosh, Emma

    2006-01-01

    A great advantage of the stated preference discrete choice experiment (SPDCE) approach to economic evaluation methodology is its immense flexibility within applied cost-benefit analyses (CBAs). However, while the use of SPDCEs in healthcare has increased markedly in recent years there has been a distinct lack of equivalent CBAs in healthcare using such SPDCE-derived valuations. This article outlines specific issues and some practical suggestions for consideration relevant to the development of CBAs using SPDCE-derived benefits. The article shows that SPDCE-derived CBA can adopt recent developments in cost-effectiveness methodology including the cost-effectiveness plane, appropriate consideration of uncertainty, the net-benefit framework and probabilistic sensitivity analysis methods, while maintaining the theoretical advantage of the SPDCE approach. The concept of a cost-benefit plane is no different in principle to the cost-effectiveness plane and can be a useful tool for reporting and presenting the results of CBAs.However, there are many challenging issues to address for the advancement of CBA methodology using SPCDEs within healthcare. Particular areas for development include the importance of accounting for uncertainty in SPDCE-derived willingness-to-pay values, the methodology of SPDCEs in clinical trial settings and economic models, measurement issues pertinent to using SPDCEs specifically in healthcare, and the importance of issues such as consideration of the dynamic nature of healthcare and the resulting impact this has on the validity of attribute definitions and context.

  9. Discrete choice modeling of shovelnose sturgeon habitat selection in the Lower Missouri River

    USGS Publications Warehouse

    Bonnot, T.W.; Wildhaber, M.L.; Millspaugh, J.J.; DeLonay, A.J.; Jacobson, R.B.; Bryan, J.L.

    2011-01-01

    Substantive changes to physical habitat in the Lower Missouri River, resulting from intensive management, have been implicated in the decline of pallid (Scaphirhynchus albus) and shovelnose (S. platorynchus) sturgeon. To aid in habitat rehabilitation efforts, we evaluated habitat selection of gravid, female shovelnose sturgeon during the spawning season in two sections (lower and upper) of the Lower Missouri River in 2005 and in the upper section in 2007. We fit discrete choice models within an information theoretic framework to identify selection of means and variability in three components of physical habitat. Characterizing habitat within divisions around fish better explained selection than habitat values at the fish locations. In general, female shovelnose sturgeon were negatively associated with mean velocity between them and the bank and positively associated with variability in surrounding depths. For example, in the upper section in 2005, a 0.5 m s-1 decrease in velocity within 10 m in the bank direction increased the relative probability of selection 70%. In the upper section fish also selected sites with surrounding structure in depth (e.g., change in relief). Differences in models between sections and years, which are reinforced by validation rates, suggest that changes in habitat due to geomorphology, hydrology, and their interactions over time need to be addressed when evaluating habitat selection. Because of the importance of variability in surrounding depths, these results support an emphasis on restoring channel complexity as an objective of habitat restoration for shovelnose sturgeon in the Lower Missouri River.

  10. Valuing QALYs in Relation to Equity Considerations Using a Discrete Choice Experiment.

    PubMed

    van de Wetering, Liesbet; van Exel, Job; Bobinac, Ana; Brouwer, Werner B F

    2015-12-01

    To judge whether an intervention offers value for money, the incremental costs per gained quality-adjusted life-year (QALY) need to be compared with some relevant threshold, which ideally reflects the monetary value of health gains. Literature suggests that this value may depend on the equity context in which health gains are produced, but the value of a QALY in relation to equity considerations has remained largely unexplored. The objective of this study was to estimate the social marginal willingness to pay (MWTP) for QALY gains in different equity subgroups, using a discrete choice experiment (DCE). Both severity of illness (operationalized as proportional shortfall) and fair innings (operationalized as age) were considered as grounds for differentiating the value of health gains. We obtained a sample of 1205 respondents, representative of the adult population of the Netherlands. The data was analysed using panel mixed multinomial logit (MMNL) and latent class models. The panel MMNL models showed counterintuitive results, with more severe health states reducing the probability of receiving treatment. The latent class models revealed distinct preference patterns in the data. MWTP per QALY was sensitive to severity of disease among a substantial proportion of the public, but not to the age of care recipients. These findings emphasize the importance of accounting for preference heterogeneity among the public on value-laden issues such as prioritizing health care, both in research and decision making. This study emphasises the need to further explore the monetary value of a QALY in relation to equity considerations.

  11. Discrete choice modeling of shovelnose sturgeon habitat selection in the Lower Missouri River

    USGS Publications Warehouse

    Bonnot, T.W.; Wildhaber, M.L.; Millspaugh, J.J.; DeLonay, A.J.; Jacobson, R.B.; Bryan, J.L.

    2011-01-01

    Substantive changes to physical habitat in the Lower Missouri River, resulting from intensive management, have been implicated in the decline of pallid (Scaphirhynchus albus) and shovelnose (S. platorynchus) sturgeon. To aid in habitat rehabilitation efforts, we evaluated habitat selection of gravid, female shovelnose sturgeon during the spawning season in two sections (lower and upper) of the Lower Missouri River in 2005 and in the upper section in 2007. We fit discrete choice models within an information theoretic framework to identify selection of means and variability in three components of physical habitat. Characterizing habitat within divisions around fish better explained selection than habitat values at the fish locations. In general, female shovelnose sturgeon were negatively associated with mean velocity between them and the bank and positively associated with variability in surrounding depths. For example, in the upper section in 2005, a 0.5ms-1 decrease in velocity within 10m in the bank direction increased the relative probability of selection 70%. In the upper section fish also selected sites with surrounding structure in depth (e.g., change in relief). Differences in models between sections and years, which are reinforced by validation rates, suggest that changes in habitat due to geomorphology, hydrology, and their interactions over time need to be addressed when evaluating habitat selection. Because of the importance of variability in surrounding depths, these results support an emphasis on restoring channel complexity as an objective of habitat restoration for shovelnose sturgeon in the Lower Missouri River. ?? 2011 Blackwell Verlag, Berlin.

  12. Women and their partners' preferences for Down's syndrome screening tests: a discrete choice experiment.

    PubMed

    Carroll, Fran E; Al-Janabi, Hareth; Flynn, Terry; Montgomery, Alan A

    2013-05-01

    This study aimed to determine quantitatively the attributes of such screening tests that couples placed most value on. A stated preference discrete choice experiment was conducted among a sample of pregnant women and their male partners. One four-level attribute (cost) and three two-level attributes (detection rate, gestation and time to wait for results) were used to generate eight hypothetical pairs of tests. A total of 103 participants fully completed the questionnaire (63 women, 40 men). Overall, the sample was most concerned with test cost. However, latent class analysis showed three groups of participants whose concern for attributes differed, with cost, detection rate and delay in receiving results being the most important to each. Willingness to pay calculations showed that participants who were most concerned with detection rate were prepared to pay more than four times the amount than those most cost-sensitive would pay for the 'best test' option as compared with the 'worst test'. Overall, couples were sensitive to the price of the screening test, but explicit subgroups are also shown that would pay large amounts for improvements in other attributes, particularly detection rates. This could provide important information to policymakers and practitioners in antenatal care, specifically in relation to the trade-offs made when couples decide about antenatal screening tests. © 2013 John Wiley & Sons, Ltd.

  13. How to attract health students to remote areas in Indonesia: a discrete choice experiment.

    PubMed

    Efendi, Ferry; Chen, Ching-Min; Nursalam, Nursalam; Andriyani, Nurul Wachyu Fitriyah; Kurniati, Anna; Nancarrow, Susan Alison

    2016-10-01

    Remote areas of Indonesia lack sufficient health workers to meet the health-care needs of the population. There is an urgent need for evidence regarding interventions to attract health workers and specifically health students to serve in remote areas. The aim of this research was to analyze the job preferences of health students to develop effective policies to improve the recruitment and retention of health students in remote areas. A discrete choice experiment was conducted to investigate health students' preferences regarding job characteristics. This study was conducted in three different regions of Indonesia, with a total included 400 health students. Mixed logit models were used to explore the stated preferences for each attribute. Data were collected from 150 medical, 150 nursing and 100 midwifery students. Medical students gave the highest preference for receiving study assistance, while nursing students viewed salary as the most important. Midwifery students valued advanced quality facilities as an important attribute. This study confirmed the importance of combination interventions in attracting and retaining health workers in remote areas of Indonesia. Money is not the only factor affecting student preferences to take up a rural post; good management and better facilities were viewed as important by all health students. Addressing health student preferences, which are the candidate of future health workforce, would help the nation solve the recruitment and retention issues. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  14. Value judgments for priority setting criteria in genetic testing: a discrete choice experiment.

    PubMed

    Severin, Franziska; Hess, Wolfgang; Schmidtke, Jörg; Mühlbacher, Axel; Rogowski, Wolf

    2015-02-01

    As our understanding of genetics has increased, so has the number of genetic tests that have entered clinical practice. Given the need of many European health care systems to contain costs, the question of how to prioritise genetic tests fairly has become an emerging concern. This study uses a discrete-choice experiment to assess the value judgements of clinical geneticists, patient representatives and other stakeholders regarding the prioritisation of genetic tests. The respondents chose between two hypothetical scenarios that differed in severity of the disease, risk of the disease, aim of the test, medical benefit of the test, and costs of the test. Standard logit models and mixed effects models were used to estimate the weights different stakeholders attached to attribute levels. Responses from 594 participants were analysed. The most highly valued attribute levels were a proven medical benefit of the test, high risk of having the disease and low costs of the test. Results also showed that rankings differ between clinical geneticists and other stakeholders. The priority weights determined within this study can inform the policy debate and improve the consistency of prioritisation in genetics. Further stakeholder deliberation is needed to explore their most appropriate use in decision practice. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  15. Parents’ preferences for vaccinating daughters against human papillomavirus in the Netherlands: a discrete choice experiment

    PubMed Central

    2014-01-01

    Background To generate knowledge about potential improvements to human papillomavirus (HPV) vaccination information and organization strategies, we assessed how aspects of HPV vaccination are associated with parents’ preferences for their daughters’ uptake, and which trade-offs parents are willing to make between these aspects. Methods A discrete choice experiment (DCE) was conducted among parents with a daughter aged 10–12 years. Panel mixed logit regression models were used to determine parents’ preferences for vaccination. Trade-offs were quantified between four vaccination programme aspects: degree of protection against cervical cancer, duration of protection, risk of serious side-effects, and age of vaccination. Results Total response rate was 302/983 (31%). All aspects influenced respondents’ preferences for HPV vaccination (p < 0.05). Respondents preferred vaccination at age 14 years instead of at a younger age. Respondents were willing to trade-off 11% of the degree of protection to obtain life-time protection instead of 25 years. To obtain a vaccination with a risk of serious side-effects of 1/750,000 instead of 1/150,000, respondents were willing to trade-off 21%. Conclusions Uptake may rise if the age ranges for free HPV vaccinations are broadened. Based on the trade-offs parents were willing to make, we conclude that uptake would increase if new evidence indicated outcomes are better than are currently understood, particularly for degree and duration of protection. PMID:24885861

  16. Using discrete choice experiments to value informal care tasks: exploring preference heterogeneity.

    PubMed

    Mentzakis, Emmanouil; Ryan, Mandy; McNamee, Paul

    2011-08-01

    While informal care is a significant part of non-market economic activity, its value is rarely acknowledged, perhaps reflecting a lack of market data. Traditional methods to value such care include opportunity and replacement cost. This study is the first to employ the discrete choice experiment methodology to value informal care tasks. A monetary value is estimated for three tasks (personal care, supervising and household tasks). The relationship between time spent on formal and informal care is also modelled and preference heterogeneity investigated using the Latent Class Model. Complementarity between supervising tasks and formal care is observed. Monetary compensation is important, with willingness to accept per hour values ranging from £0.38 to £0.83 for personal care, £0.75 for supervising and £0.31 to £0.6 for household tasks. Heterogeneity in preferences is observed, with monetary compensation being important for younger people, but insignificant for older individuals. Such heterogeneity is important at the policy level. Values are lower than those generated by opportunity cost and replacement cost methods, perhaps because of the limited ability of revealed preference methods to capture broader aspect of utility. Differences with contingent valuation methods are also observed, suggesting future research should investigate the external validity of the different methods.

  17. Rationalising the 'irrational': a think aloud study of discrete choice experiment responses.

    PubMed

    Ryan, Mandy; Watson, Verity; Entwistle, Vikki

    2009-03-01

    Stated preference methods assume respondents' preferences are consistent with utility theory, but many empirical studies report evidence of preferences that violate utility theory. This evidence is often derived from quantitative tests that occur naturally within, or are added to, stated preference tasks. In this study, we use qualitative methods to explore three axioms of utility theory: completeness, monotonicity, and continuity. We take a novel approach, adopting a 'think aloud' technique to identify violations of the axioms of utility theory and to consider how well the quantitative tests incorporated within a discrete choice experiment are able to detect these. Results indicate that quantitative tests classify respondents as being 'irrational' when qualitative statements would indicate they are 'rational'. In particular, 'non-monotonic' responses can often be explained by respondents inferring additional information beyond what is presented in the task, and individuals who appear to adopt non-compensatory decision-making strategies do so because they rate particular attributes very highly (they are not attempting to simplify the task). The results also provide evidence of 'cost-based responses': respondents assumed tests with higher costs would be of higher quality. The value of including in-depth qualitative validation techniques in the development of stated preference tasks is shown.

  18. Policy interventions to improve rural retention among neurosurgeons in Iran: A discrete choice experiment

    PubMed Central

    Rafiei, Sima; Arab, Mohammad; Rashidian, Arash; Mahmoudi, Mahmood; Rahimi-Movaghar, Vafa

    2015-01-01

    Background: Health workforce shortages in rural and remote areas are a global challenge that almost every health system has to deal with. This study aimed to discover neurosurgeons’ job preferences and propose policy interventions that could possibly increase their retention in rural, remote, or underserved areas. Methods: A discrete choice experiment (DCE) was conducted in November 2014 with a sample of Iranian neurosurgeons selected from five contrary’s provinces representing the geographical diversity. Job attributes included income, dual practice opportunities, workload, proximity to family, clinical infrastructure, housing, educational facilities, and work location. Probit regression model was used to estimate the importance of different job attributes and examine the extent to which neurosurgeons were willing to tradeoff between monetary and nonmonetary attributes. Results: Findings indicated that increased salary, permission to undertake dual practice and access to adequate clinical infrastructure were the most important retention policies. Provision of subsidized housing and educational facilities also increased neurosurgeons’ attraction and retention in rural areas. Conclusion: A range of policy interventions focusing on both monetary and nonmonetary incentives are required to increase neurosurgeons’ retention in rural, remote, or underserved areas. PMID:26885340

  19. Preferences for Policy Options for Deceased Organ Donation for Transplantation: A Discrete Choice Experiment.

    PubMed

    Howard, Kirsten; Jan, Stephen; Rose, John M; Wong, Germaine; Craig, Jonathan C; Irving, Michelle; Tong, Allison; Chadban, Steven; Allen, Richard D; Cass, Alan

    2016-05-01

    Despite broad public support for organ donation, there is a chronic shortage of deceased donor organs. We sought to identify community preferences for features of organ donation policies. A discrete choice study was conducted using an online panel of Australian community respondents older than 18 years. Respondents were presented with scenarios comparing a "new" policy to the current policy. Tradeoffs between 8 policy aspects were quantified using mixed logit and latent class models: registration system, extent of donor family involvement, ease of registration, frequency of confirmation of intent, direct payment, and funeral expense reimbursement, priority for donor's family, and formal recognition of donation. There were 2005 respondents (mean, 44.6 years). We found a strong preference for a new policy. Overall, respondents favored a policy that included: some involvement of the donor's family in the final decision, simple registration processes, less frequent reconfirmation of donation intent, direct payment or funeral expense reimbursement, and formal recognition of donation. However, there was significant preference heterogeneity across respondents, with various respondent groups valuing policy mechanisms differently. Respondents who viewed policy change negatively were also those who would be unlikely to be organ donors anyway, because they tended to hold negative views toward organ donation. Our results suggest that the Australian community are open to alternative organ donation policies including changes to: registration systems, family involvement, and financial and nonfinancial mechanisms. Future policy discussions should not be limited by preconceived notions of what is acceptable to the community, rather informed by actual community values and preferences.

  20. Effects of integrated feedback on discrete bimanual movements in choice reaction time.

    PubMed

    Blinch, Jarrod; de Cellio Martins, Guilherme; Chua, Romeo

    2017-01-01

    The ability to coordinate the simultaneous movements of our arms is limited by a coalition of constraints. Some of these constraints can be overcome when the task conceptualisation is improved. The present study investigated how the movement preparation of bimanual reaching movements was affected by integrated visual feedback of the responses. Previous research has shown that the preparation of bimanual asymmetric movements takes longer than bimanual symmetric movements. The goal of the present study was to determine whether integrated, Lissajous feedback could eliminate this bimanual asymmetric cost. Fifteen participants made unimanual and bimanual symmetric and asymmetric reaches with separate feedback, where there was a cursor and a target for each hand. Participants also made bimanual symmetric and asymmetric movements with integrated feedback; a single cursor and a single target represented the locations and goals of both arms in this condition. The results showed a bimanual asymmetric cost with separate feedback, and that this cost persisted with integrated feedback. We suggest that integrated feedback improved continuous and discrete bimanual movements in other experiments by facilitating error detection and correction processes. We hypothesise that the bimanual asymmetric cost persisted in the present experiment because the uncertainty associated with choice reaction time prevented the facilitated error processing from improving the preparation of the next trial.

  1. An Australian discrete choice experiment to value eq-5d health states.

    PubMed

    Viney, Rosalie; Norman, Richard; Brazier, John; Cronin, Paula; King, Madeleine T; Ratcliffe, Julie; Street, Deborah

    2014-06-01

    Conventionally, generic quality-of-life health states, defined within multi-attribute utility instruments, have been valued using a Standard Gamble or a Time Trade-Off. Both are grounded in expected utility theory but impose strong assumptions about the form of the utility function. Preference elicitation tasks for both are complicated, limiting the number of health states that each respondent can value and, therefore, that can be valued overall. The usual approach has been to value a set of the possible health states and impute values for the remainder. Discrete Choice Experiments (DCEs) offer an attractive alternative, allowing investigation of more flexible specifications of the utility function and greater coverage of the response surface. We designed a DCE to obtain values for EQ-5D health states and implemented it in an Australia-representative online panel (n = 1,031). A range of specifications investigating non-linear preferences with respect to time and interactions between EQ-5D levels were estimated using a random-effects probit model. The results provide empirical support for a flexible utility function, including at least some two-factor interactions. We then constructed a preference index such that full health and death were valued at 1 and 0, respectively, to provide a DCE-based algorithm for Australian cost-utility analyses.

  2. Policy interventions to improve rural retention among neurosurgeons in Iran: A discrete choice experiment.

    PubMed

    Rafiei, Sima; Arab, Mohammad; Rashidian, Arash; Mahmoudi, Mahmood; Rahimi-Movaghar, Vafa

    2015-10-07

    Health workforce shortages in rural and remote areas are a global challenge that almost every health system has to deal with. This study aimed to discover neurosurgeons' job preferences and propose policy interventions that could possibly increase their retention in rural, remote, or underserved areas. A discrete choice experiment (DCE) was conducted in November 2014 with a sample of Iranian neurosurgeons selected from five contrary's provinces representing the geographical diversity. Job attributes included income, dual practice opportunities, workload, proximity to family, clinical infrastructure, housing, educational facilities, and work location. Probit regression model was used to estimate the importance of different job attributes and examine the extent to which neurosurgeons were willing to tradeoff between monetary and nonmonetary attributes. Findings indicated that increased salary, permission to undertake dual practice and access to adequate clinical infrastructure were the most important retention policies. Provision of subsidized housing and educational facilities also increased neurosurgeons' attraction and retention in rural areas. A range of policy interventions focusing on both monetary and nonmonetary incentives are required to increase neurosurgeons' retention in rural, remote, or underserved areas.

  3. Patients' Preferences for the Treatment of Metastatic Castrate-resistant Prostate Cancer: A Discrete Choice Experiment.

    PubMed

    Eliasson, Lina; de Freitas, Hayley M; Dearden, Lindsay; Calimlim, Brian; Lloyd, Andrew J

    2017-04-01

    Patient treatment preferences are increasingly being used to inform health care decision making. This discrete choice experiment assessed how men perceive the risks and benefits of hypothetical treatment options for metastatic castrate-resistant prostate cancer (mCRPC). Treatment attributes for inclusion were identified through a review of the literature and product labels. Expert interviews confirmed clinical appropriateness and patient relevance of the attributes, which included effectiveness (delay in months before chemotherapy), steroid use, possible drug interactions (additional hospital visits for monitoring), fogginess (effects on cognition and memory), fatigue (extreme tiredness), food restrictions, and bone pain. Following a pilot, the final discrete choice experiment included 18 choice sets presenting treatments for mCRPC and was completed by men with mCRPC in France, Germany, and the United Kingdom. Data were analyzed using a conditional logit model, with odds ratios (ORs) used to indicate preference for attributes, and tradeoff measures (TOM) were estimated using the ratio of coefficients. Within each attribute category and with all other factors being equal, participants (N = 285) indicated a strong preference for treatments that fully control bone pain (OR = 12.069 [95% CI, 10.555-13.800]) and for treatments that delay chemotherapy (OR, 1.727 [95% CI, 1.548-1.927]). They also preferred treatments that were associated with the lowest risk of fogginess (OR, 2.115 [95% CI, 1.849-2.420]), a lower risk of fatigue (OR, 1.365 [95% CI 1.219-1.528]), and fewer additional hospital visits (OR, 1.245 [95% CI 1.111-1.397]) than the respective reference categories. Participants preferred to use steroids under advice from a physician (OR, 1.275 [95% CI 1.132-1.437]). Food restrictions related to taking medication were not a significant concern for participants. TOM results indicated that large tradeoffs in effectiveness, fogginess, and fatigue are required for

  4. A Bayesian random effects discrete-choice model for resource selection: Population-level selection inference

    USGS Publications Warehouse

    Thomas, D.L.; Johnson, D.; Griffith, B.

    2006-01-01

    Bayesian hierarchical discrete-choice model for resource selection can provide managers with 2 components of population-level inference: average population selection and variability of selection. Both components are necessary to make sound management decisions based on animal selection.

  5. A Piecewise Bi-Linear Discontinuous Finite Element Spatial Discretization of the Sn Transport Equation

    SciTech Connect

    Bailey, T S; Chang, J H; Warsa, J S; Adams, M L

    2010-12-22

    We present a new spatial discretization of the discrete-ordinates transport equation in two-dimensional Cartesian (X-Y) geometry for arbitrary polygonal meshes. The discretization is a discontinuous finite element method (DFEM) that utilizes piecewise bi-linear (PWBL) basis functions, which are formally introduced in this paper. We also present a series of numerical results on quadrilateral and polygonal grids and compare these results to a variety of other spatial discretizations that have been shown to be successful on these grid types. Finally, we note that the properties of the PWBL basis functions are such that the leading-order piecewise bi-linear discontinuous finite element (PWBLD) solution will satisfy a reasonably accurate diffusion discretization in the thick diffusion limit, making the PWBLD method a viable candidate for many different classes of transport problems.

  6. Examining patient preferences in the treatment of rheumatoid arthritis using a discrete-choice approach

    PubMed Central

    Alten, Rieke; Krüger, Klaus; Rellecke, Julian; Schiffner-Rohe, Julia; Behmer, Olaf; Schiffhorst, Guido; Nolting, Hans-Dieter

    2016-01-01

    Background Biological disease-modifying antirheumatic drugs (bDMARDs) used in second-line treatment of rheumatoid arthritis (RA) are administered parenterally. However, so-called targeted synthetic DMARDs (tsDMARDs) – developed more recently – offer alternative (ie, oral) administration forms in second-line treatment. Since bDMARDs and tsDMARDs can be regarded as equal in terms of efficacy, the present study examines whether such characteristics as route of administration drive RA patients’ treatment choice. This may ultimately suggest superiority of some second-line DMARDs over equally effective options, at least according to RA-patient preferences. Objective The current study assessed the importance of oral administration among other treatment characteristics differing between available second-line DMARDs for RA patients’ preferences using a discrete-choice experiment (DCE). Materials and methods The DCE involved scenarios of three hypothetical treatment options in a d-efficient design with varying levels of key attributes (route and frequency of administration, time till onset of drug effect, combination therapy, possible side effects), as defined by focus groups. Further patient characteristics were recorded by an accompanying questionnaire. In the DCE, patients were asked to choose best and worst options (best–worst scaling). Results were analyzed by count analysis and adjusted regression analysis. Results A total of 1,588 subjects completed the DCE and were eligible for final analyses. Across all characteristics included in the DCE, “oral administration” was most desired and “intravenous infusion” was most strongly rejected. This was followed by “no combination with methotrexate” being strongly preferred and “intake every 1–2 weeks” being strongly rejected. On average, levels of route of administration showed strongest influences on patients’ decisions in post hoc bootstrapping analysis. Conclusion According to the results, an

  7. Managing Minor Ailments; The Public's Preferences for Attributes of Community Pharmacies. A Discrete Choice Experiment.

    PubMed

    Porteous, Terry; Ryan, Mandy; Bond, Christine; Watson, Margaret; Watson, Verity

    2016-01-01

    Demand for health services continues to rise. Greater use of community pharmacy services instead of medical services for minor ailments could help relieve pressure on healthcare providers in high-cost settings. Community pharmacies are recognised sources of treatment and advice for people wishing to manage these ailments. However, increasing the public's use of pharmacy services may depend on attributes of pharmacies and their staff. This study aimed to determine the general public's relative preferences for community pharmacy attributes using a discrete choice experiment (DCE). A UK-wide DCE survey of the general public was conducted using face-to-face computer-assisted personal interviews. Attributes and levels for the DCE were informed by a literature review and a cohort study of community pharmacy customers. The context for the experiment was a minor ailment scenario describing flu-like symptoms. The DCE choice sets described two hypothetical community pharmacy services; respondents were asked to choose which (if either) of the two pharmacies they would prefer to help them manage symptoms. Data from 1,049 interviews were analysed using an error components logit model. Willingness to pay (WTP), a monetary measure of benefit, was estimated for the different attribute levels. When seeking help or treatment for flu-like symptoms, respondents most valued a pharmacy service that would improve their understanding and management of symptoms (WTP = £6.28), provided by staff who are trained (WTP (pharmacist) = £2.63: WTP(trained assistant) = £3.22), friendly and approachable (WTP = £3.38). Waiting time, pharmacy location and availability of parking also contributed to respondents' preferences. WTP for a service comprising the best possible combination of attributes and levels was calculated as £55.43. Attributes of a community pharmacy and its staff may influence people's decisions about which pharmacy they would visit to access treatment and advice for minor

  8. What do UK doctors in training value in a post? A discrete choice experiment.

    PubMed

    Cleland, Jennifer; Johnston, Peter; Watson, Verity; Krucien, Nicolas; Skåtun, Diane

    2016-02-01

    Many individual and job-related factors are known to influence medical careers decision making. Medical trainees' (residents) views of which characteristics of a training post are important to them have been extensively studied but how they trade-off these characteristics is under-researched. Such information is crucial for the development of effective policies to enhance recruitment and retention. Our aim was to investigate the strength of UK foundation doctors' and trainees' preferences for training post characteristics in terms of monetary value. We used an online questionnaire study incorporating a discrete choice experiment (DCE), distributed to foundation programme doctors and doctors in training across all specialty groups within three UK regions, in August-October 2013. The main outcome measures were monetary values for training-post characteristics, based on willingness to forgo and willingness to accept extra income for a change in each job characteristic, calculated from regression coefficients. The questionnaire was answered by 1323 trainees. Good working conditions were the most influential characteristics of a training position. Trainee doctors would need to be compensated by an additional 49.8% above the average earnings within their specialty to move from a post with good working conditions to one with poor working conditions. A training post with limited rather than good opportunities for one's spouse or partner would require compensation of 38.4% above the average earnings within their specialty. Trainees would require compensation of 30.8% above the average earnings within their specialty to move from a desirable to a less desirable locality. These preferences varied only to a limited extent according to individual characteristics. Trainees place most value on good working conditions, good opportunities for their partners and desirable geographical location when making career-related decisions. This intelligence can be used to develop alternative

  9. Understanding HIV-positive patients' preferences for healthcare services: a protocol for a discrete choice experiment

    PubMed Central

    Youssef, Elaney; Cooper, Vanessa; Miners, Alec; Llewellyn, Carrie; Pollard, Alex; Lagarde, Mylene; Sachikonye, Memory; Sabin, Caroline; Foreman, Claire; Perry, Nicky; Nixon, Eileen; Fisher, Martin

    2016-01-01

    Introduction While the care of HIV-positive patients, including the detection and management of comorbidities, has historically been provided in HIV specialist outpatient clinics, recent years have seen a greater involvement of non-HIV specialists and general practitioners (GPs). The aim of this study is to determine whether patients would prefer to see their GP or HIV physician given general symptoms, and to understand what aspects of care influence their preferences. Methods/analysis We have developed and piloted a discrete choice experiment (DCE) to better understand patients' preferences for care of non-HIV-related acute symptoms. The design of the DCE was informed by our exploratory research, including the findings of a systematic literature review and a qualitative study. Additional questionnaire items have been included to measure demographics, service use and experience of non-HIV illnesses and quality of life (EQ5D). We plan to recruit 1000 patients from 14 HIV clinics across South East England. Data will be analysed using random-effects logistic regression and latent class analysis. ORs and 95% CIs will be used to estimate the relative importance of each of the attribute levels. Latent class analysis will identify whether particular groups of people value the service attribute levels differently. Ethics/dissemination Ethical approval for this study was obtained from the Newcastle and North Tyneside Research Ethics Committee (reference number 14/NE/1193). The results will be disseminated at national and international conferences and peer-reviewed publications. A study report, written in plain English, will be made available to all participants. The Patient Advisory Group will develop a strategy for wider dissemination of the findings to patients and the public. PMID:27431895

  10. Factors that influence midwifery students in Ghana when deciding where to practice: a discrete choice experiment.

    PubMed

    Ageyi-Baffour, Peter; Rominski, Sarah; Nakua, Emmanuel; Gyakobo, Mawuli; Lori, Jody R

    2013-05-04

    Mal-distribution of the health workforce with a strong bias for urban living is a major constraint to expanding midwifery services in Ghana. According to the UN Millennium Development Goals (MDG) report, the high risk of dying in pregnancy or childbirth continues in Africa. Maternal death is currently estimated at 350 per 100,000, partially a reflection of the low rates of professional support during birth. Many women in rural areas of Ghana give birth alone or with a non-skilled attendant. Midwives are key healthcare providers in achieving the MDGs, specifically in reducing maternal mortality by three-quarters and reducing by two-thirds the under 5 child mortality rate by 2015. This quantitative research study used a computerized structured survey containing a discrete choice experiment (DCE) to quantify the importance of different incentives and policies to encourage service to deprived, rural and remote areas by upper-year midwifery students following graduation. Using a hierarchical Bayes procedure we estimated individual and mean utility parameters for two hundred and ninety eight third year midwifery students from two of the largest midwifery training schools in Ghana. Midwifery students in our sample identified: 1) study leave after two years of rural service; 2) an advanced work environment with reliable electricity, appropriate technology and a constant drug supply; and 3) superior housing (2 bedroom, 1 bathroom, kitchen, living room, not shared) as the top three motivating factors to accept a rural posting. Addressing the motivating factors for rural postings among midwifery students who are about to graduate and enter the workforce could significantly contribute to the current mal-distribution of the health workforce.

  11. Using discrete choice experiments to go beyond clinical outcomes when evaluating clinical practice.

    PubMed

    Ryan, Mandy; Major, Kirsten; Skåtun, Diane

    2005-08-01

    This study builds on the results of a randomized controlled trial concerned with examining the effect of reducing waiting times on the health status of patients referred for non-urgent rheumatology opinion. No difference in clinical outcomes was found between a 'fast-track' and 'ordinary' appointment system. This suggests that rationing by waiting times is not detrimental to health. However, such an approach ignores the value patients attach to reducing waiting time. To estimate the monetary value of reducing waiting time, as well as changes in duration of appointment and the introduction of a pain management service, in the provision of rheumatology services. Discrete choice experiment (DCE). The main outpatient clinic of the rheumatology service for the Lothian and Borders region. 262 patients who had received a specialist rheumatology opinion--73 had received fast-track treatment, 65 standard care and 124 were non-trial patients. A response rate of 71% was achieved. Patients valued a 9-week reduction in waiting time at 131 pounds sterling. However, the introduction of a pain management service was valued at 209 pounds sterling. Thus, the latter is of more value to respondents. Evidence was also found of the internal consistency and theoretical validity of the DCE approach. The reduction of waiting times is a central plank of NHS policy. Whilst a reduction in waiting time is of value, a pain management service is of more benefit than a 9-week reduction in waiting time. DCE were shown to be a potentially useful technique for valuing different aspects of health care interventions.

  12. Adolescent values for immunisation programs in Australia: A discrete choice experiment.

    PubMed

    Wang, Bing; Chen, Gang; Ratcliffe, Julie; Afzali, Hossein Haji Ali; Giles, Lynne; Marshall, Helen

    2017-01-01

    The importance of adolescent engagement in health decisions and public health programs such as immunisation is becoming increasingly recognised. Understanding adolescent preferences and further identifying barriers and facilitators for immunisation acceptance is critical to the success of adolescent immunisation programs. This study applied a discrete choice experiment (DCE) to assess vaccination preferences in adolescents. This study was conducted as a cross-sectional, national online survey in Australian adolescents. The DCE survey evaluated adolescent vaccination preferences. Six attributes were assessed including disease severity, target for protection, price, location of vaccination provision, potential side effects and vaccine delivery method. A mixed logit model was used to analyse DCE data. This survey was conducted between December 2014 and January 2015. Of 800 adolescents aged 15 to 19 years, stronger preferences were observed overall for: vaccination in the case of a life threatening illness (p<0.001), lower price vaccinations (p<0.001), mild but common side effects (p = 0.004), delivery via a skin patch (p<0.001) and being administered by a family practitioner (p<0.001). Participants suggested that they and their families would be willing to pay AU$394.28 (95%CI: AU$348.40 to AU$446.92) more for a vaccine targeting a life threatening illness than a mild-moderate illness, AU$37.94 (95%CI: AU$19.22 to AU$57.39) more for being vaccinated at a family practitioner clinic than a council immunisation clinic, AU$23.01 (95%CI: AU$7.12 to AU$39.24) more for common but mild and resolving side effects compared to rare but serious side effects, and AU$51.80 (95%CI: AU$30.42 to AU$73.70) more for delivery via a skin patch than injection. Consideration of adolescent preferences may result in improved acceptance of, engagement in and uptake of immunisation programs targeted for this age group.

  13. Public acceptability of population-level interventions to reduce alcohol consumption: a discrete choice experiment.

    PubMed

    Pechey, Rachel; Burge, Peter; Mentzakis, Emmanouil; Suhrcke, Marc; Marteau, Theresa M

    2014-07-01

    Public acceptability influences policy action, but the most acceptable policies are not always the most effective. This discrete choice experiment provides a novel investigation of the acceptability of different interventions to reduce alcohol consumption and the effect of information on expected effectiveness, using a UK general population sample of 1202 adults. Policy options included high, medium and low intensity versions of: Minimum Unit Pricing (MUP) for alcohol; reducing numbers of alcohol retail outlets; and regulating alcohol advertising. Outcomes of interventions were predicted for: alcohol-related crimes; alcohol-related hospital admissions; and heavy drinkers. First, the models obtained were used to predict preferences if expected outcomes of interventions were not taken into account. In such models around half of participants or more were predicted to prefer the status quo over implementing outlet reductions or higher intensity MUP. Second, preferences were predicted when information on expected outcomes was considered, with most participants now choosing any given intervention over the status quo. Acceptability of MUP interventions increased by the greatest extent: from 43% to 63% preferring MUP of £1 to the status quo. Respondents' own drinking behaviour also influenced preferences, with around 90% of non-drinkers being predicted to choose all interventions over the status quo, and with more moderate than heavy drinkers favouring a given policy over the status quo. Importantly, the study findings suggest public acceptability of alcohol interventions is dependent on both the nature of the policy and its expected effectiveness. Policy-makers struggling to mobilise support for hitherto unpopular but promising policies should consider giving greater prominence to their expected outcomes.

  14. Acceptability of Financial Incentives for Health Behaviours: A Discrete Choice Experiment

    PubMed Central

    Giles, Emma L.; Becker, Frauke; Ternent, Laura; Sniehotta, Falko F.; McColl, Elaine

    2016-01-01

    Background Healthy behaviours are important determinants of health and disease, but many people find it difficult to perform these behaviours. Systematic reviews support the use of personal financial incentives to encourage healthy behaviours. There is concern that financial incentives may be unacceptable to the public, those delivering services and policymakers, but this has been poorly studied. Without widespread acceptability, financial incentives are unlikely to be widely implemented. We sought to answer two questions: what are the relative preferences of UK adults for attributes of financial incentives for healthy behaviours? Do preferences vary according to the respondents’ socio-demographic characteristics? Methods We conducted an online discrete choice experiment. Participants were adult members of a market research panel living in the UK selected using quota sampling. Preferences were examined for financial incentives for: smoking cessation, regular physical activity, attendance for vaccination, and attendance for screening. Attributes of interest (and their levels) were: type of incentive (none, cash, shopping vouchers or lottery tickets); value of incentive (a continuous variable); schedule of incentive (same value each week, or value increases as behaviour change is sustained); other information provided (none, written information, face-to-face discussion, or both); and recipients (all eligible individuals, people living in low-income households, or pregnant women). Results Cash or shopping voucher incentives were preferred as much as, or more than, no incentive in all cases. Lower value incentives and those offered to all eligible individuals were preferred. Preferences for additional information provided alongside incentives varied between behaviours. Younger participants and men were more likely to prefer incentives. There were no clear differences in preference according to educational attainment. Conclusions Cash or shopping voucher

  15. Health worker preferences for community-based health insurance payment mechanisms: a discrete choice experiment

    PubMed Central

    2012-01-01

    Background In 2004, a community-based health insurance scheme (CBI) was introduced in Nouna health district, Burkina Faso. Since its inception, coverage has remained low and dropout rates high. One important reason for low coverage and high dropout is that health workers do not support the CBI scheme because they are dissatisfied with the provider payment mechanism of the CBI. Methods A discrete choice experiment (DCE) was used to examine CBI provider payment attributes that influence health workers’ stated preferences for payment mechanisms. The DCE was conducted among 176 health workers employed at one of the 34 primary care facilities or the district hospital in Nouna health district. Conditional logit models with main effects and interactions terms were used for analysis. Results Reimbursement of service fees (adjusted odds ratio (aOR) 1.49, p < 0.001) and CBI contributions for medical supplies and equipment (aOR 1.47, p < 0.001) had the strongest effect on whether the health workers chose a given provider payment mechanism. The odds of selecting a payment mechanism decreased significantly if the mechanism included (i) results-based financing (RBF) payments made through the local health management team (instead of directly to the health workers (aOR 0.86, p < 0.001)) or (ii) RBF payments based on CBI coverage achieved in the health worker’s facility relative to the coverage achieved at other facilities (instead of payments based on the numbers of individuals or households enrolled at the health worker’s facility (aOR 0.86, p < 0.001)). Conclusions Provider payment mechanisms can crucially determine CBI performance. Based on the results from this DCE, revised CBI payment mechanisms were introduced in Nouna health district in January 2011, taking into consideration health worker preferences on how they are paid. PMID:22697498

  16. Acceptability of Financial Incentives for Health Behaviours: A Discrete Choice Experiment.

    PubMed

    Giles, Emma L; Becker, Frauke; Ternent, Laura; Sniehotta, Falko F; McColl, Elaine; Adams, Jean

    2016-01-01

    Healthy behaviours are important determinants of health and disease, but many people find it difficult to perform these behaviours. Systematic reviews support the use of personal financial incentives to encourage healthy behaviours. There is concern that financial incentives may be unacceptable to the public, those delivering services and policymakers, but this has been poorly studied. Without widespread acceptability, financial incentives are unlikely to be widely implemented. We sought to answer two questions: what are the relative preferences of UK adults for attributes of financial incentives for healthy behaviours? Do preferences vary according to the respondents' socio-demographic characteristics? We conducted an online discrete choice experiment. Participants were adult members of a market research panel living in the UK selected using quota sampling. Preferences were examined for financial incentives for: smoking cessation, regular physical activity, attendance for vaccination, and attendance for screening. Attributes of interest (and their levels) were: type of incentive (none, cash, shopping vouchers or lottery tickets); value of incentive (a continuous variable); schedule of incentive (same value each week, or value increases as behaviour change is sustained); other information provided (none, written information, face-to-face discussion, or both); and recipients (all eligible individuals, people living in low-income households, or pregnant women). Cash or shopping voucher incentives were preferred as much as, or more than, no incentive in all cases. Lower value incentives and those offered to all eligible individuals were preferred. Preferences for additional information provided alongside incentives varied between behaviours. Younger participants and men were more likely to prefer incentives. There were no clear differences in preference according to educational attainment. Cash or shopping voucher-type financial incentives for healthy behaviours are

  17. Public acceptability of population-level interventions to reduce alcohol consumption: A discrete choice experiment

    PubMed Central

    Pechey, Rachel; Burge, Peter; Mentzakis, Emmanouil; Suhrcke, Marc; Marteau, Theresa M.

    2014-01-01

    Public acceptability influences policy action, but the most acceptable policies are not always the most effective. This discrete choice experiment provides a novel investigation of the acceptability of different interventions to reduce alcohol consumption and the effect of information on expected effectiveness, using a UK general population sample of 1202 adults. Policy options included high, medium and low intensity versions of: Minimum Unit Pricing (MUP) for alcohol; reducing numbers of alcohol retail outlets; and regulating alcohol advertising. Outcomes of interventions were predicted for: alcohol-related crimes; alcohol-related hospital admissions; and heavy drinkers. First, the models obtained were used to predict preferences if expected outcomes of interventions were not taken into account. In such models around half of participants or more were predicted to prefer the status quo over implementing outlet reductions or higher intensity MUP. Second, preferences were predicted when information on expected outcomes was considered, with most participants now choosing any given intervention over the status quo. Acceptability of MUP interventions increased by the greatest extent: from 43% to 63% preferring MUP of £1 to the status quo. Respondents' own drinking behaviour also influenced preferences, with around 90% of non-drinkers being predicted to choose all interventions over the status quo, and with more moderate than heavy drinkers favouring a given policy over the status quo. Importantly, the study findings suggest public acceptability of alcohol interventions is dependent on both the nature of the policy and its expected effectiveness. Policy-makers struggling to mobilise support for hitherto unpopular but promising policies should consider giving greater prominence to their expected outcomes. PMID:24858928

  18. What do hospital consultants value about their jobs? A discrete choice experiment

    PubMed Central

    Ubach, Cristina; Scott, Anthony; French, Fiona; Awramenko, Morag; Needham, Gillian

    2003-01-01

    Objective To examine the strength of hospital consultants' preferences for various aspects of their work. Design Questionnaire survey including a discrete choice experiment. Setting NHS Scotland. Participants 2923 hospital consultants in Scotland. Main outcome measures Monetary valuations or prices for each job characteristic, based on consultants' willingness to pay and willingness to accept extra income for a change in each job characteristic, calculated from regression coefficients. Results The response rate was 61% (1793 resspondents). Being on call was the most important attribute, as consultants would need to be compensated up to £18 000 (30% of their average net income) (P < 0.001) for a high on-call workload. Compensation of up to £9700 (16% of their net income) (P < 0.001) would be required for consultants to forgo opportunities to undertake non-NHS work. Consultants would be willing to accept £7000 (12% of net income) (P < 0.001) in compensation for fair rather than good working relationships with staff, and £6500 (11% of net income) (P < 0.001) to compensate them for a shortage of staff. The least important characteristic was hours of work, with £562 per year (0.9% of their net income) (P < 0.001) required to induce consultants to work one extra hour per week. These preferences also varied among specific subgroups of consultants. Conclusions Important information on consultants' strength of preferences for characteristics of their job should be used to help to address recruitment and retention problems. Consultants would require increased payment to cover more intensive on-call commitments. Other aspects of working conditions would require smaller increases. PMID:12829556

  19. Patients' preferences for anti-osteoporosis drug treatment: a cross-European discrete choice experiment.

    PubMed

    Hiligsmann, Mickaël; Dellaert, Benedict G; Dirksen, Carmen D; Watson, Verity; Bours, Sandrine; Goemaere, Stefan; Reginster, Jean-Yves; Roux, Christian; McGowan, Bernie; Silke, Carmel; Whelan, Bryan; Diez-Perez, Adolfo; Torres, Elisa; Papadakis, Georgios; Rizzoli, Rene; Cooper, Cyrus; Pearson, Gill; Boonen, Annelies

    2017-07-01

    To estimate the preferences of osteoporotic patients for medication attributes, and analyse data from seven European countries. A discrete choice experiment was conducted in Belgium, France, Ireland, the Netherlands, Spain, Switzerland and the UK. Patients were asked to choose repeatedly between two hypothetical unlabelled drug treatments (and an opt-out option) that varied with respect to four attributes: efficacy in reducing the risk of fracture, type of potential common side effects, and mode and frequency of administration. In those countries in which patients contribute to the cost of their treatment directly, a fifth attribute was added: out-of-pocket cost. A mixed logit panel model was used to estimate patients' preferences. In total, 1124 patients completed the experiment, with a sample of between 98 and 257 patients per country. In all countries, patients preferred treatment with higher effectiveness, and 6-monthly subcutaneous injection was always preferred over weekly oral tablets. In five countries, patients also preferred a monthly oral tablet and yearly i.v. injections over weekly oral tablets. In the three countries where the out-of-pocket cost was included as an attribute, lower costs significantly contributed to the treatment preference. Between countries, there were statistically significant differences for 13 out of 42 attribute/level interactions. We found statistically significant differences in patients' preferences for anti-osteoporosis medications between countries, especially for the mode of administration. Our findings emphasized that international treatment recommendations should allow for local adaptation, and that understanding individual preferences is important if we want to improve the quality of clinical care for patients with osteoporosis.

  20. Improving the public health sector in South Africa: eliciting public preferences using a discrete choice experiment.

    PubMed

    Honda, Ayako; Ryan, Mandy; van Niekerk, Robert; McIntyre, Diane

    2015-06-01

    The introduction of national health insurance (NHI), aimed at achieving universal coverage, is the most important issue currently on the South African health policy agenda. Improvement in public sector health-care provision is crucial for the successful implementation of NHI as, regardless of whether health-care services become more affordable and available, if the quality of the services provided is not acceptable, people will not use the services. Although there has been criticism of the quality of public sector health services, limited research is available to identify what communities regard as the greatest problems with the services. A discrete choice experiment (DCE) was undertaken to elicit public preferences on key dimensions of quality of care when selecting public health facilities in South Africa. Qualitative methods were applied to establish attributes and levels for the DCE. To elicit preferences, interviews with community members were held in two South African provinces: 491 in Western Cape and 499 in Eastern Cape. The availability of necessary medicine at health facilities has the greatest impact on the probability of attending public health facilities. Other clinical quality attributes (i.e. provision of expert advice and provision of a thorough examination) are more valued than non-clinical quality of care attributes (i.e. staff attitude, treatment by doctors or nurses, and waiting time). Treatment by a doctor was less valued than all other attributes. Communities are prepared to tolerate public sector health service characteristics such as a long waiting time, poor staff attitudes and lack of direct access to doctors if they receive the medicine they need, a thorough examination and a clear explanation of the diagnosis and prescribed treatment from health professionals. These findings prioritize issues that the South African government must address in order to meet their commitment to improve public sector health-care service provision. Published

  1. Job preferences among clinical officers in public sector facilities in rural Kenya: a discrete choice experiment.

    PubMed

    Takemura, Toshio; Kielmann, Karina; Blaauw, Duane

    2016-01-08

    Clinical officers (COs), a mid-level cadre of health worker, are the backbone of healthcare provision in rural Kenya. However, the vacancy rate for COs in rural primary healthcare facilities is high. Little is known about factors motivating COs' preferences for rural postings. A discrete choice experiment (DCE) questionnaire was used with 57 COs at public health facilities in nine districts of Nyanza Province, Kenya. The questionnaire was developed on the basis of formative qualitative interviews with COs (n = 5) and examined how five selected job attributes influenced COs' preferences for working in rural areas. Conditional logit models were employed to examine the relative importance of different job attributes. Analysis of the qualitative data revealed five important job attributes influencing COs' preferences: quality of the facility, educational opportunities, housing, monthly salary and promotion. Analysis of the DCE indicated that a 1-year guaranteed study leave after 3 years of service would have the greatest impact on retention, followed by good quality health facility infrastructure and equipment and a 30% salary increase. Sub-group analysis shows that younger COs demonstrated a significantly stronger preference for study leave than older COs. Female COs placed significantly higher value on promotion than male COs. Although both financial incentives and non-financial incentives were effective in motivating COs to stay in post, the study leave intervention was shown to have the strongest impact on COs' retention in our study. Further research is required to examine appropriate interventions at each career stage that might boost COs' professional identity and status but without leading to larger deficits in the availability of generalist COs.

  2. The development of quality indicators in mental healthcare: a discrete choice experiment.

    PubMed

    Schellings, Ron; Essers, Brigitte A B; Kessels, Alfons G; Brunner, Florian; van de Ven, Tijmen; Robben, Paul B M

    2012-08-07

    Health care regulatory agencies perform audits or inspections to judge the quality and safety of health care. This judgment is based on the assessment of a large set of health care indicators as accepted by the profession. However, there is a lack of knowledge about the influence of these indicators and whether a smaller number would be sufficient for a quality assessment or audit procedure. A discrete choice experiment (DCE) was performed for the assessment of quality of care regarding the management of patients with schizophrenia and drug dependency in psychiatric institutes. Based on multidisciplinary guidelines for the treatment of schizophrenia and a visit of (co)inspectors of the Dutch Healthcare Inspectorate at all 33 integrated mental hospitals a set of 51 indicators were assessed in a subsequent interview. With the analysis of the results, 6 attributes were selected for the DCE as quality indicators. Seventy-six percent of all health services (co)inspectors (n = 33) involved in the inspection of mental health services, participated in the experiment. Respondents considered an operational elaborate treatment plan the most important indicator for the assessment of quality of care in a psychiatric institute, followed by a general care program, treatment outcome measurement, and involvement in treatment of patients and relatives. Pharmacotherapy and governance responsibility were valued as less important indicators. The results of this DCE show that there is a prioritisation in the six selected quality indicators. This might help health services (co) inspectors to enhance the efficiency and transparency of the quality of care assessment for patients with schizophrenia and/or drug dependency in psychiatric institutes.

  3. Parental preferences for rotavirus vaccination in young children: a discrete choice experiment.

    PubMed

    Veldwijk, Jorien; Lambooij, Mattijs S; Bruijning-Verhagen, Patricia C J; Smit, Henriette A; de Wit, G Ardine

    2014-10-29

    This study aimed to identify characteristics that affect parental decisions about rotavirus vaccination, to determine the relative importance of those characteristics and subsequently to estimate vaccination coverage for different implementation strategies. A Discrete choice experiment (DCE) questionnaire was sent to the parents of 1250 newborns aged 6 weeks (response rate 37.3%). Mixed-logit models were used to estimate the relative importance of the five included rotavirus vaccine and implementation characteristics; vaccine effectiveness, frequency of severe side effects, protection duration, the healthcare facility that administrates vaccination and out-of-pocket costs. Based on the utility functions of the mixed-logit model, the potential vaccination coverage was estimated for different vaccine scenarios and implementation strategies. All characteristics, except for healthcare facility that administrates vaccination, influenced parental willingness to vaccinate their newborn against rotavirus. Parents were willing to trade 20.2 percentage points vaccine effectiveness for the lowest frequency of severe side effects (i.e., 1 in 1,000,000) or 20.8 percentage points for a higher protection duration. Potential vaccination coverage ranged between 22.7 and 86.2%, depending on vaccine scenario (i.e., vaccine effectiveness and protection duration) and implementation strategy (i.e., out-of-pocket costs and healthcare facility that administrates vaccination). When deciding about vaccination against rotavirus, parents are mostly driven by the out-of-pocket costs, vaccine effectiveness, protection duration, and frequency of severe side effects. The highest vaccination coverage is expected for a vaccine with high effectiveness and protection duration that is implemented within the current National Immunization Program context. Implementation of the same rotavirus vaccine in the free market will result in lowest coverage. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Women's preferences for aspects of labor management: results from a discrete choice experiment.

    PubMed

    Scotland, Graham S; McNamee, Paul; Cheyne, Helen; Hundley, Vanora; Barnett, Carol

    2011-03-01

    The latent phase of labor can vary greatly in duration, and many women are uncertain about when to contact the maternity unit. The aim of this study was to elicit and value women's preferences for some aspects of labor management. A questionnaire was sent to 1,251 women who had recently given birth to their first child at one of 14 maternity units in Scotland. Discrete choice questions were used to measure women's preferences for five attributes of care: number of visits (assessments) before admission to the labor ward, time spent on the labor ward before delivery, mobility during labor, pain relief required, and mode of delivery. Responses were analyzed for the sample as a whole and for subgroups defined by recent experiences of labor. A total of 730 (58.4%) questionnaires were returned and analyzed. Women expressed a preference for fewer visits before admission, shorter times on the labor ward before delivery, mobility during labor, normal vaginal deliveries, and moderate forms of pain relief (Entonox and opiates). Subgroup analysis suggests that women's preferences for pain relief are influenced by their recent labor experience. The elicited preference values provide a means for estimating the tradeoffs women are willing to make between attributes of labor management. Women appear to dislike being turned away from the labor ward before admission for delivery. Extra visits before admission only appear to be a price worth paying if they result in reductions in the duration of time spent on the labor ward, reductions in the chance of being immobilized in hospital during labor, or a lower chance of requiring an instrumental or operative delivery. © 2010, Copyright the Authors. Journal compilation © 2010, Wiley Periodicals, Inc.

  5. Understanding Health Workers’ Job Preferences to Improve Rural Retention in Timor-Leste: Findings from a Discrete Choice Experiment

    PubMed Central

    Smitz, Marc-Francois; Witter, Sophie; Lemiere, Christophe; Eozenou, Patrick Hoang-Vu; Lievens, Tomas; Zaman, Rashid U.; Engelhardt, Kay; Hou, Xiaohui

    2016-01-01

    Background Timor-Leste built its health workforce up from extremely low levels after its war of independence, with the assistance of Cuban training, but faces challenges as the first cohorts of doctors will shortly be freed from their contracts with government. Retaining doctors, nurses and midwives in remote areas requires a good understanding of health worker preferences. Methods The article reports on a discrete choice experiment (DCE) carried out amongst 441 health workers, including 173 doctors, 150 nurses and 118 midwives. Qualitative methods were conducted during the design phase. The attributes which emerged were wages, skills upgrading/specialisation, location, working conditions, transportation and housing. Findings One of the main findings of the study is the relative lack of importance of wages for doctors, which could be linked to high intrinsic motivation, perceptions of having an already highly paid job (relative to local conditions), and/or being in a relatively early stage of their career for most respondents. Professional development provides the highest satisfaction with jobs, followed by the working conditions. Doctors with less experience, males and the unmarried are more flexible about location. For nurses and midwives, skill upgrading emerged as the most cost effective method. Conclusions The study is the first of its kind conducted in Timor-Leste. It provides policy-relevant information to balance financial and non-financial incentives for different cadres and profiles of staff. It also augments a thin literature on the preferences of working doctors (as opposed to medical students) in low and middle income countries and provides insights into the ability to instil motivation to work in rural areas, which may be influenced by rural recruitment and Cuban-style training, with its emphasis on community service. PMID:27846242

  6. Understanding Health Workers' Job Preferences to Improve Rural Retention in Timor-Leste: Findings from a Discrete Choice Experiment.

    PubMed

    Smitz, Marc-Francois; Witter, Sophie; Lemiere, Christophe; Eozenou, Patrick Hoang-Vu; Lievens, Tomas; Zaman, Rashid U; Engelhardt, Kay; Hou, Xiaohui

    2016-01-01

    Timor-Leste built its health workforce up from extremely low levels after its war of independence, with the assistance of Cuban training, but faces challenges as the first cohorts of doctors will shortly be freed from their contracts with government. Retaining doctors, nurses and midwives in remote areas requires a good understanding of health worker preferences. The article reports on a discrete choice experiment (DCE) carried out amongst 441 health workers, including 173 doctors, 150 nurses and 118 midwives. Qualitative methods were conducted during the design phase. The attributes which emerged were wages, skills upgrading/specialisation, location, working conditions, transportation and housing. One of the main findings of the study is the relative lack of importance of wages for doctors, which could be linked to high intrinsic motivation, perceptions of having an already highly paid job (relative to local conditions), and/or being in a relatively early stage of their career for most respondents. Professional development provides the highest satisfaction with jobs, followed by the working conditions. Doctors with less experience, males and the unmarried are more flexible about location. For nurses and midwives, skill upgrading emerged as the most cost effective method. The study is the first of its kind conducted in Timor-Leste. It provides policy-relevant information to balance financial and non-financial incentives for different cadres and profiles of staff. It also augments a thin literature on the preferences of working doctors (as opposed to medical students) in low and middle income countries and provides insights into the ability to instil motivation to work in rural areas, which may be influenced by rural recruitment and Cuban-style training, with its emphasis on community service.

  7. Development of discrete choice model considering internal reference points and their effects in travel mode choice context

    NASA Astrophysics Data System (ADS)

    Sarif; Kurauchi, Shinya; Yoshii, Toshio

    2017-06-01

    In the conventional travel behavior models such as logit and probit, decision makers are assumed to conduct the absolute evaluations on the attributes of the choice alternatives. On the other hand, many researchers in cognitive psychology and marketing science have been suggesting that the perceptions of attributes are characterized by the benchmark called “reference points” and the relative evaluations based on them are often employed in various choice situations. Therefore, this study developed a travel behavior model based on the mental accounting theory in which the internal reference points are explicitly considered. A questionnaire survey about the shopping trip to the CBD in Matsuyama city was conducted, and then the roles of reference points in travel mode choice contexts were investigated. The result showed that the goodness-of-fit of the developed model was higher than that of the conventional model, indicating that the internal reference points might play the major roles in the choice of travel mode. Also shown was that the respondents seem to utilize various reference points: some tend to adopt the lowest fuel price they have experienced, others employ fare price they feel in perceptions of the travel cost.

  8. Addressing health workforce distribution concerns: a discrete choice experiment to develop rural retention strategies in Cameroon

    PubMed Central

    Robyn, Paul Jacob; Shroff, Zubin; Zang, Omer Ramses; Kingue, Samuel; Djienouassi, Sebastien; Kouontchou, Christian; Sorgho, Gaston

    2015-01-01

    Background: Nearly every nation in the world faces shortages of health workers in remote areas. Cameroon is no exception to this. The Ministry of Public Health (MoPH) is currently considering several rural retention strategies to motivate qualified health personnel to practice in remote rural areas. Methods: To better calibrate these mechanisms and to develop evidence-based retention strategies that are attractive and motivating to health workers, a Discrete Choice Experiment (DCE) was conducted to examine what job attributes are most attractive and important to health workers when considering postings in remote areas. The study was carried out between July and August 2012 among 351 medical students, nursing students and health workers in Cameroon. Mixed logit models were used to analyze the data. Results: Among medical and nursing students a rural retention bonus of 75% of base salary (aOR= 8.27, 95% CI: 5.28-12.96, P< 0.001) and improved health facility infrastructure (aOR= 3.54, 95% CI: 2.73-4.58) respectively were the attributes with the largest effect sizes. Among medical doctors and nurse aides, a rural retention bonus of 75% of base salary was the attribute with the largest effect size (medical doctors aOR= 5.60, 95% CI: 4.12-7.61, P< 0.001; nurse aides aOR= 4.29, 95% CI: 3.11-5.93, P< 0.001). On the other hand, improved health facility infrastructure (aOR= 3.56, 95% CI: 2.75-4.60, P< 0.001), was the attribute with the largest effect size among the state registered nurses surveyed. Willingness-to-Pay (WTP) estimates were generated for each health worker cadre for all the attributes. Preference impact measurements were also estimated to identify combination of incentives that health workers would find most attractive. Conclusion: Based on these findings, the study recommends the introduction of a system of substantial monetary bonuses for rural service along with ensuring adequate and functional equipment and uninterrupted supplies. By focusing on the

  9. Risk as an attribute in discrete choice experiments: a systematic review of the literature.

    PubMed

    Harrison, Mark; Rigby, Dan; Vass, Caroline; Flynn, Terry; Louviere, Jordan; Payne, Katherine

    2014-01-01

    Discrete choice experiments (DCEs) are used to elicit preferences of current and future patients and healthcare professionals about how they value different aspects of healthcare. Risk is an integral part of most healthcare decisions. Despite the use of risk attributes in DCEs consistently being highlighted as an area for further research, current methods of incorporating risk attributes in DCEs have not been reviewed explicitly. This study aimed to systematically identify published healthcare DCEs that incorporated a risk attribute, summarise and appraise methods used to present and analyse risk attributes, and recommend best practice regarding including, analysing and transparently reporting the methodology supporting risk attributes in future DCEs. The Web of Science, MEDLINE, EMBASE, PsycINFO and Econlit databases were searched on 18 April 2013 for DCEs that included a risk attribute published since 1995, and on 23 April 2013 to identify studies assessing risk communication in the general (non-DCE) health literature. Healthcare-related DCEs with a risk attribute mentioned or suggested in the title/abstract were obtained and retained in the final review if a risk attribute meeting our definition was included. Extracted data were tabulated and critically appraised to summarise the quality of reporting, and the format, presentation and interpretation of the risk attribute were summarised. This review identified 117 healthcare DCEs that incorporated at least one risk attribute. Whilst there was some evidence of good practice incorporated into the presentation of risk attributes, little evidence was found that developing methods and recommendations from other disciplines about effective methods and validation of risk communication were systematically applied to DCEs. In general, the reviewed DCE studies did not thoroughly report the methodology supporting the explanation of risk in training materials, the impact of framing risk, or exploring the validity of risk

  10. Adolescent values for immunisation programs in Australia: A discrete choice experiment

    PubMed Central

    Chen, Gang; Ratcliffe, Julie; Afzali, Hossein Haji Ali; Giles, Lynne; Marshall, Helen

    2017-01-01

    Objectives The importance of adolescent engagement in health decisions and public health programs such as immunisation is becoming increasingly recognised. Understanding adolescent preferences and further identifying barriers and facilitators for immunisation acceptance is critical to the success of adolescent immunisation programs. This study applied a discrete choice experiment (DCE) to assess vaccination preferences in adolescents. Methods This study was conducted as a cross-sectional, national online survey in Australian adolescents. The DCE survey evaluated adolescent vaccination preferences. Six attributes were assessed including disease severity, target for protection, price, location of vaccination provision, potential side effects and vaccine delivery method. A mixed logit model was used to analyse DCE data. Results This survey was conducted between December 2014 and January 2015. Of 800 adolescents aged 15 to 19 years, stronger preferences were observed overall for: vaccination in the case of a life threatening illness (p<0.001), lower price vaccinations (p<0.001), mild but common side effects (p = 0.004), delivery via a skin patch (p<0.001) and being administered by a family practitioner (p<0.001). Participants suggested that they and their families would be willing to pay AU$394.28 (95%CI: AU$348.40 to AU$446.92) more for a vaccine targeting a life threatening illness than a mild-moderate illness, AU$37.94 (95%CI: AU$19.22 to AU$57.39) more for being vaccinated at a family practitioner clinic than a council immunisation clinic, AU$23.01 (95%CI: AU$7.12 to AU$39.24) more for common but mild and resolving side effects compared to rare but serious side effects, and AU$51.80 (95%CI: AU$30.42 to AU$73.70) more for delivery via a skin patch than injection. Conclusions Consideration of adolescent preferences may result in improved acceptance of, engagement in and uptake of immunisation programs targeted for this age group. PMID:28746348

  11. What do UK medical students value most in their careers? A discrete choice experiment.

    PubMed

    Cleland, Jennifer A; Johnston, Peter; Watson, Verity; Krucien, Nicolas; Skåtun, Diane

    2017-08-01

    Many individual- and job-related factors are known to influence medical careers decision making. Previous research has extensively studied medical trainees' (residents') and students' views of the factors that are important. However, how trainees and students trade off these factors at times of important careers-related decision making is under-researched. Information about trade-offs is crucial to the development of effective policies to enhance the recruitment and retention of junior doctors. Our aim was to investigate the strength of UK medical students' preferences for the characteristics of training posts in terms of monetary value. We distributed a paper questionnaire that included a discrete choice experiment (DCE) to final-year medical students in six diverse medical schools across the UK. The main outcome measure was the monetary value of training post characteristics, based on willingness to forgo and willingness to accept extra income for a change in each job characteristic calculated from regression coefficients. A total of 810 medical students answered the questionnaire. The presence of good working conditions was by far the most influential characteristic of a training position. Medical students consider that, as newly graduated doctors, they will require compensation of an additional 43.68% above average earnings to move from a post with excellent working conditions to one with poor working conditions. Female students value excellent working conditions more highly than male students, whereas older medical students value them less highly than younger students. Students on the point of completing medical school and starting postgraduate training value good working conditions significantly more than they value desirable geographical location, unit reputation, familiarity with the unit or opportunities for partners or spouses. This intelligence can be used to address the crisis in workforce staffing that has developed in the UK and opens up fruitful

  12. Addressing health workforce distribution concerns: a discrete choice experiment to develop rural retention strategies in Cameroon.

    PubMed

    Robyn, Paul Jacob; Shroff, Zubin; Zang, Omer Ramses; Kingue, Samuel; Djienouassi, Sebastien; Kouontchou, Christian; Sorgho, Gaston

    2015-03-01

    Nearly every nation in the world faces shortages of health workers in remote areas. Cameroon is no exception to this. The Ministry of Public Health (MoPH) is currently considering several rural retention strategies to motivate qualified health personnel to practice in remote rural areas. To better calibrate these mechanisms and to develop evidence-based retention strategies that are attractive and motivating to health workers, a Discrete Choice Experiment (DCE) was conducted to examine what job attributes are most attractive and important to health workers when considering postings in remote areas. The study was carried out between July and August 2012 among 351 medical students, nursing students and health workers in Cameroon. Mixed logit models were used to analyze the data. Among medical and nursing students a rural retention bonus of 75% of base salary (aOR= 8.27, 95% CI: 5.28-12.96, P< 0.001) and improved health facility infrastructure (aOR= 3.54, 95% CI: 2.73-4.58) respectively were the attributes with the largest effect sizes. Among medical doctors and nurse aides, a rural retention bonus of 75% of base salary was the attribute with the largest effect size (medical doctors aOR= 5.60, 95% CI: 4.12-7.61, P< 0.001; nurse aides aOR= 4.29, 95% CI: 3.11-5.93, P< 0.001). On the other hand, improved health facility infrastructure (aOR= 3.56, 95% CI: 2.75-4.60, P< 0.001), was the attribute with the largest effect size among the state registered nurses surveyed. Willingness-to-Pay (WTP) estimates were generated for each health worker cadre for all the attributes. Preference impact measurements were also estimated to identify combination of incentives that health workers would find most attractive. Based on these findings, the study recommends the introduction of a system of substantial monetary bonuses for rural service along with ensuring adequate and functional equipment and uninterrupted supplies. By focusing on the analysis of locally relevant, actionable

  13. Patient preferences for treatment of multiple sclerosis with disease-modifying therapies: a discrete choice experiment

    PubMed Central

    Garcia-Dominguez, José Manuel; Muñoz, Delicias; Comellas, Marta; Gonzalbo, Irmina; Lizán, Luis; Polanco Sánchez, Carlos

    2016-01-01

    Objectives To assess disease-modifying therapy (DMT) preferences in a population of patients with multiple sclerosis (MS) and to estimate the association between sociodemographic and clinical factors and these preferences. Methods Preferences for DMTs attributes were measured using a discrete choice experiment. Analysis of preferences was assessed using mixed-logit hierarchical Bayes regression. A multilinear regression was used to evaluate the association between the preferences for each attribute and patients’ demographic and clinical characteristics. A Student’s t-test or Welch’s t-test was used for subgroup comparisons. Results A total of 125 patients were included in the final analysis (62.9% female, mean age 44.5 years, 71.5% with relapsing-remitting MS diagnosis). The most important factor for patients was the possibility of suffering from the side effects of the treatment (relative importance [RI] =50%), followed by a delay in disease progression (RI =19.4%), and route and frequency of administration (RI =14.3%). According to maximum acceptable risk, patients were willing to accept an increase of 3.8% in severity of side effects, for a delay of 1 year in disease progression. Treatment duration was the most prevalent factor affecting preferences, followed by the age of patients, type of MS, level of education, and the type of current treatment. Patients treated orally were significantly more concerned about the route and frequency of administration (P=0.026) than patients on injectable therapy. Naïve patients stated significantly less importance to prevention of relapses (P=0.021) and deterioration of the capacity for performing usual daily life activities (P=0.015). Finally, patients with >5 years since diagnosis were significantly less concerned about preventing disease progression (P=0.021), and more concerned about treatment side effects (P=0.052) than compared with patients with <5 years of MS history. Conclusion The most important attribute for

  14. Variation in intrapartum referral rates in primary midwifery care in the Netherlands: a discrete choice experiment.

    PubMed

    Offerhaus, Pien M; Otten, Wilma; Boxem-Tiemessen, Jolanda C G; de Jonge, Ank; van der Pal-de Bruin, Karin M; Scheepers, Peer L H; Lagro-Janssen, Antoine L M

    2015-04-01

    in midwife-led care models of maternity care, midwives are responsible for intrapartum referrals to the obstetrician or obstetric unit, in order to give their clients access to secondary obstetric care. This study explores the influence of risk perception, policy on routine labour management, and other midwife related factors on intrapartum referral decisions of Dutch midwives. a questionnaire was used, in which a referral decision was asked in 14 early labour scenarios (Discrete Choice Experiment or DCE). The scenarios varied in woman characteristics (BMI, gestational age, the preferred birth location, adequate support by a partner, language problems and coping) and in clinical labour characteristics (cervical dilatation, estimated head-to-cervix pressure, and descent of the head). primary care midwives in the Netherlands. a systematic random selection of 243 practicing primary care midwives. The response rate was 48 per cent (117/243). the Impact Factor of the characteristics in the DCE was calculated using a conjoint analysis. The number of intrapartum referrals to secondary obstetric care in the 14 scenarios of the DCE was calculated as the individual referral score. Risk perception was assessed by respondents׳ estimates of the probability of eight birth outcomes. The associations between midwives׳ policy on management of physiological labour, personal characteristics, workload in the practice, number of midwives in the practice, and referral score were explored. the estimated head-to-cervix pressure and descent of the head had the largest impact on referral decisions in the DCE. The median referral score was five (range 0-14). Estimates of probability on birth outcomes were predominantly overestimating actual risks. Factors significantly associated with a high referral score were: a low estimated probability of a spontaneous vaginal birth (p=0.007), adhering to the active management policy Proactive Support of Labour (PSOL) (p=0.047), and a practice situated

  15. Eliciting health state utilities for Dupuytren’s contracture using a discrete choice experiment

    PubMed Central

    2013-01-01

    Background and purpose An internet-based discrete choice experiment (DCE) was conducted to elicit preferences for a wide range of Dupuytren’s contracture (DC)-related health states. An algorithm was subsequently developed to convert these preferences into health state utilities that can be used to assess DC’s impact on quality of life and the value of its treatments. Methods Health state preferences for varying levels of DC hand severity were elicited via an internet survey from a sample of the UK adult population. Severity levels were defined using a combination of contractures (0, 45, or 90 degrees) in 8 proximal interphalangeal and metacarpophalangeal joints of the index, middle, ring, and little fingers. Right-handed, left-handed, and ambidextrous respondents indicated which hand was preferable in each of the 10 randomly-selected hand-pairings comparing different DC severity levels. For consistency across comparisons, anatomically precise digital hand drawings were used. To anchor preferences onto the traditional 0–1 utility scale used in health economic evaluations, unaffected hands were assigned a utility of 1.0 whereas the utility for a maximally affected hand (i.e., all 8 joints set at 90 degrees of contracture) was derived by asking respondents to indicate what combination of attributes and levels of the EQ-5D-5L profile most accurately reflects the impact of living with such hand. Conditional logistic models were used to estimate indirect utilities, then rescaled to the anchor points on the EQ-5D-5L. Results Estimated utilities based on the responses of 1,745 qualified respondents were 0.49, 0.57, and 0.63 for completely affected dominant hands, non-dominant hands, or ambidextrous hands, respectively. Utility for a dominant hand with 90-degree contracture in t h e metacarpophalangeal joints of the ring and little fingers was estimated to be 0.89. Separately, reducing the contracture of metacarpophalangeal joint for a little finger from 50 to 12

  16. Would you train me with my mental illness? Evidence from a discrete choice experiment.

    PubMed

    Deuchert, Eva; Kauer, Lukas; Meisen Zannol, Flurina

    2013-06-01

    Mental illness is the prime reason for the inflow into disability insurance in many countries. The integration of persons with a disability into the regular labor market is costly and in the case of mentally ill persons, particularly difficult. Supported Education and Employment - a rehabilitation method that directly places patients in a realistic work environment - has been shown to be effective in increasing competitive employment. However, it has not yet been widely implemented. We evaluate ex-ante the willingness to participate in Supported Education and Employment and the barriers to do so from the employer's perspective. We conducted a discrete choice experiment implemented in an online survey. The survey was carried out among all Swiss companies which provide standard dual-track vocational education and training for commercial occupations in Eastern Switzerland. We presented respondents (employees who are responsible for vocational training and/or for the selection of applicants) with a sample of five hypothetical profiles. These profiles vary along different medical diagnoses, different illness related (dys-)functions, and other characteristics that may be associated with a company's willingness to accept the candidate (such as school performance, motivation, and illness related absences). Respondents were asked whether or not they would train this person. 22% of the profiles are accepted. However, our results demonstrate that the hypothetical bias - which is the difference between individual saying what they would do in a hypothetical setting and what they will do when they have the opportunity - is severe. Correcting for this bias using follow-up scales ("Are you sure?") reduces the overall acceptance in our sample to 9%. Keeping in mind the response rate to our survey of 35%, overall acceptance may be as low as 3%. Non-cognitive dysfunctions (e.g. non-adherence to regulations, difficulties with contacts with others) that are related to mental disorders

  17. A discrete choice experiment to determine UK patient preference for attributes of disease modifying treatments in Multiple Sclerosis.

    PubMed

    Bottomley, Catherine; Lloyd, Andrew; Bennett, Gary; Adlard, Nicholas

    2017-08-01

    The recent licensing of Disease Modifying Treatments (DMTs) for Multiple Sclerosis (MS) has increased available treatment options. The aim of this study was to explore MS patients' preference for the different attributes of DMTs in the UK. Attributes (treatment characteristics) for inclusion in the discrete choice experiment (DCE) were determined through published literature and interviews with 12 people with MS. Seven attributes were selected. Participants were presented with three hypothetical treatment options sampled from included attributes and asked for their most/least preferred options. The influence of patient characteristics and demographics on patient preference was also investigated. The DCE was completed by 350 people with MS (81% female, mean age = 39). Results showed that method of taking medication was the strongest determinant of preference (27%; relative importance out of 100%), followed by relapse free rate (21%) and symptom progression (14%). Risk of fatigue (8%) and type of monitoring (6%) were the weakest determinants of preference. Once-daily oral treatment was preferred over all other methods of administration. Participant characteristics did not influence data on strength of preference. This study assumed adequate participant understanding of the discrete choice experiment task, and recruitment targeted those with access to the internet. These results, derived from people with MS in the UK, should be used to inform individual discussions with patients about DMT choices.

  18. Do patients prefer mesh or anterior colporrhaphy for primary correction of anterior vaginal wall prolapse: a labelled discrete choice experiment.

    PubMed

    Notten, K J B; Essers, B A; Weemhoff, M; Rutten, A G H; Donners, J J A E; van Gestel, I; Kruitwagen, R F P M; Roovers, J P W R; Dirksen, C D

    2015-05-01

    We investigated patients' preferences for anterior colporrhaphy or mesh surgery as surgical correction of anterior vaginal wall prolapse. Labelled discrete choice experiment. Three Dutch teaching hospitals. Women with anterior vaginal wall prolapse Pelvic Organ Prolapse Quantification stage 2 or more, indicated for anterior colporrhaphy (n = 100). Discrete choice experiments are an attribute-based survey method for measuring preferences. In this experiment, women were asked to choose between two treatment scenarios, mesh surgery or anterior colporrhaphy. These surgical treatments differed in four treatment attributes: (i) recurrence rate, (ii) exposure rate, (iii) infection rate, (iv) dyspareunia. Data were analysed using a multinomial logit model. Women's preferences for anterior colporrhaphy or mesh surgery for the repair of vaginal wall prolapse. All treatment attributes, i.e. recurrence, exposure, infection and dyspareunia, proved to be significant in the woman's decision to choose mesh surgery (P < 0.001), while only two attributes out of three, recurrence and infection, were significant for anterior colporrhaphy (P < 0.001). The relative importance data showed that with regards to the four statistically significant attributes for mesh, dyspareunia was the most important attribute, and of the two significant attributes for anterior colporrhaphy, the risk of infection. Based on the attributes and levels in our discrete choice experiment, anterior colporrhaphy was preferred in 74% as a primary correction of anterior vaginal wall prolapse, followed by a preference for mesh in 26% of all choices. This study showed that next to the risk of recurrence, other aspects like risk of infection, dyspareunia and exposure play a role in the woman's preference for a surgical treatment. In addition, our results indicate that anterior colporrhaphy is preferred in the majority of the choices, followed by a preference for mesh surgery in a quarter of all choice sets. However

  19. Colloid facilitated transport of lanthanides through discrete fractures in chalk

    NASA Astrophysics Data System (ADS)

    Tran, Emily; Klein Ben-David, Ofra; Teutsch, Nadya; Weisbrod, Noam

    2015-04-01

    Geological disposal of high-level radioactive waste is the internationally agreed-upon, long term solution for the disposal of long lived radionuclides and spent fuel. Eventually, corrosion of the waste canisters may lead to leakage of their hazardous contents, and the radionuclides can ultimately make their way into groundwater and pose a threat to the biosphere. Engineered bentonite barriers placed around nuclear waste repositories are generally considered sufficient to impede the transport of radionuclides from their storage location to the groundwater. However, colloidal-sized mobile bentonite particles eroding from these barriers have come under investigation as a potential transport vector for radionuclides sorbed to them. In addition, the presence of organic matter in groundwater has been shown to additionally facilitate the uptake of radionuclides by the clay colloids. This study aims to evaluate the transport behaviors of radionuclides in colloid-facilitated transport through a fractured chalk matrix and under geochemical conditions representative of the Negev desert, Israel. Lanthanides are considered an acceptable substitute to actinides for research on radionuclide transportation due to their similar chemical behavior. In this study, the migration of Ce both with and without colloidal particles was explored and compared to the migration of a conservative tracer (bromide). Tracer solutions containing known concentrations of Ce, bentonite colloids, humic acid and bromide were prepared in a matrix solution containing salt concentrations representative of that of the average rain water found in the Negev. These solutions were then injected into a flow system constructed around a naturally fractured chalk core. Samples were analyzed for Ce and Br using ICP-MS, and colloid concentrations were determined using spectrophotographic analysis. Breakthrough curves comparing the rates of transportation of each tracer were obtained, allowing for comparison of

  20. Spatial and Angular Moment Analysis of Continuous and Discretized Particle Transport Problems

    NASA Astrophysics Data System (ADS)

    Brantley, Patrick Shawn

    1998-08-01

    A spatial and angular moment analysis of the linear Boltzmann transport equation is used to compute exact flux-weighted average spatial quantities such as the 'center of mass' and 'radius of gyration' of the flux distribution. This moment analysis is valid for multidimensional general-geometry analytic transport problems, posed in an infinite homogeneous medium, with multiple energy groups and anisotropic scattering. The results from the analysis are used in this thesis to assess how accurately approximations to the transport equation compute these flux-weighted average spatial quantities. The first part of this thesis addresses the theoretical analysis of spatial differencing schemes used to discretize the discrete ordinates approximation of the linear Boltzmann transport equation. Discrete ordinates methods have been utilized for many years to obtain numerical solutions of neutron transport problems in which the optical width of the spatial cells is small. The traditional truncation analysis can be used to assess the accuracy of spatial differencing schemes for these problems. The same discrete ordinates methods have in recent years been utilized for radiative transfer problems characterized by optically thick spatial cells and scattering ratios near unity. In this case, an asymptotic diffusion limit analysis has been applied to discretized transport problems in order to assess the accuracy of spatial differencing schemes. At present, theoretical methods for analyzing discretized transport problems with optically intermediate and thick spatial cells and arbitrary scattering ratios are not available. We develop a moment analysis method for theoretically analyzing discrete ordinates spatial differencing schemes that makes no assumptions on the optical thickness of the spatial cells or on the value of the scattering ratio. The second part of this thesis concerns the Simplified PN (SPN) approximation, a multidimensional generalization of the one-dimensional planar

  1. Discrete event simulation model for external yard choice of import container terminal in a port buffer area

    NASA Astrophysics Data System (ADS)

    Rusgiyarto, Ferry; Sjafruddin, Ade; Frazila, Russ Bona; Suprayogi

    2017-06-01

    Increasing container traffic and land acquisition problem for terminal expansion leads to usage of external yard in a port buffer area. This condition influenced the terminal performance because a road which connects the terminal and the external yard was also used by non-container traffic. Location choice problem considered to solve this condition, but the previous research has not taken account a stochastic condition of container arrival rate and service time yet. Bi-level programming framework was used to find optimum location configuration. In the lower-level, there was a problem to construct the equation, which correlated the terminal operation and the road due to different time cycle equilibrium. Container moves from the quay to a terminal gate in a daily unit of time, meanwhile, it moves from the terminal gate to the external yard through the road in a minute unit of time. If the equation formulated in hourly unit equilibrium, it cannot catch up the container movement characteristics in the terminal. Meanwhile, if the equation formulated in daily unit equilibrium, it cannot catch up the road traffic movement characteristics in the road. This problem can be addressed using simulation model. Discrete Event Simulation Model was used to simulate import container flow processes in the container terminal and external yard. Optimum location configuration in the upper-level was the combinatorial problem, which was solved by Full Enumeration approach. The objective function of the external yard location model was to minimize user transport cost (or time) and to maximize operator benefit. Numerical experiment was run for the scenario assumption of two container handling ways, three external yards, and thirty-day simulation periods. Jakarta International Container Terminal (JICT) container characteristics data was referred for the simulation. Based on five runs which were 5, 10, 15, 20, and 30 repetitions, operation one of three available external yards (external yard

  2. Neighborhood socioeconomic disadvantage, individual wealth status and patterns of delivery care utilization in Nigeria: a multilevel discrete choice analysis

    PubMed Central

    Aremu, Olatunde; Lawoko, Stephen; Dalal, Koustuv

    2011-01-01

    Background High maternal mortality continues to be a major public health problem in most part of the developing world, including Nigeria. Understanding the utilization pattern of maternal healthcare services has been accepted as an important factor for reducing maternal deaths. This study investigates the effect of neighborhood and individual socioeconomic position on the utilization of different forms of place of delivery among women of reproductive age in Nigeria. Methods A population-based multilevel discrete choice analysis was performed using the most recent population-based 2008 Nigerian Demographic and Health Surveys data of women aged between 15 and 49 years. The analysis was restricted to 15,162 ever-married women from 888 communities across the 36 states of the federation including the Federal Capital Territory of Abuja. Results The choice of place to deliver varies across the socioeconomic strata. The results of the multilevel discrete choice models indicate that with every other factor controlled for, the household wealth status, women’s occupation, women’s and partner’s high level of education attainment, and possession of health insurance were associated with use of private and government health facilities for child birth relative to home delivery. The results also show that higher birth order and young maternal age were associated with use of home delivery. Living in a highly socioeconomic disadvantaged neighborhood is associated with home birth compared with the patronage of government health facilities. More specifically, the result revealed that choice of facility-based delivery is clustered around the neighborhoods. Conclusion Home delivery, which cuts across all socioeconomic strata, is a common practice among women in Nigeria. Initiatives that would encourage the appropriate use of healthcare facilities at little or no cost to the most disadvantaged should be accorded the utmost priority. PMID:21792338

  3. The Suppression of Energy Discretization Errors in Multigroup Transport Calculations

    SciTech Connect

    Larsen, Edward

    2013-06-17

    The Objective of this project is to develop, implement, and test new deterministric methods to solve, as efficiently as possible, multigroup neutron transport problems having an extremely large number of groups. Our approach was to (i) use the standard CMFD method to "coarsen" the space-angle grid, yielding a multigroup diffusion equation, and (ii) use a new multigrid-in-space-and-energy technique to efficiently solve the multigroup diffusion problem. The overall strategy of (i) how to coarsen the spatial an energy grids, and (ii) how to navigate through the various grids, has the goal of minimizing the overall computational effort. This approach yields not only the fine-grid solution, but also coarse-group flux-weighted cross sections that can be used for other related problems.

  4. Incorporating environmental attitudes in discrete choice models: an exploration of the utility of the awareness of consequences scale.

    PubMed

    Hoyos, David; Mariel, Petr; Hess, Stephane

    2015-02-01

    Environmental economists are increasingly interested in better understanding how people cognitively organise their beliefs and attitudes towards environmental change in order to identify key motives and barriers that stimulate or prevent action. In this paper, we explore the utility of a commonly used psychometric scale, the awareness of consequences (AC) scale, in order to better understand stated choices. The main contribution of the paper is that it provides a novel approach to incorporate attitudinal information into discrete choice models for environmental valuation: firstly, environmental attitudes are incorporated using a reinterpretation of the classical AC scale recently proposed by Ryan and Spash (2012); and, secondly, attitudinal data is incorporated as latent variables under a hybrid choice modelling framework. This novel approach is applied to data from a survey conducted in the Basque Country (Spain) in 2008 aimed at valuing land-use policies in a Natura 2000 Network site. The results are relevant to policy-making because choice models that are able to accommodate underlying environmental attitudes may help in designing more effective environmental policies.

  5. Simulation study to determine the impact of different design features on design efficiency in discrete choice experiments.

    PubMed

    Vanniyasingam, Thuva; Cunningham, Charles E; Foster, Gary; Thabane, Lehana

    2016-07-19

    Discrete choice experiments (DCEs) are routinely used to elicit patient preferences to improve health outcomes and healthcare services. While many fractional factorial designs can be created, some are more statistically optimal than others. The objective of this simulation study was to investigate how varying the number of (1) attributes, (2) levels within attributes, (3) alternatives and (4) choice tasks per survey will improve or compromise the statistical efficiency of an experimental design. A total of 3204 DCE designs were created to assess how relative design efficiency (d-efficiency) is influenced by varying the number of choice tasks (2-20), alternatives (2-5), attributes (2-20) and attribute levels (2-5) of a design. Choice tasks were created by randomly allocating attribute and attribute level combinations into alternatives. Relative d-efficiency was used to measure the optimality of each DCE design. DCE design complexity influenced statistical efficiency. Across all designs, relative d-efficiency decreased as the number of attributes and attribute levels increased. It increased for designs with more alternatives. Lastly, relative d-efficiency converges as the number of choice tasks increases, where convergence may not be at 100% statistical optimality. Achieving 100% d-efficiency is heavily dependent on the number of attributes, attribute levels, choice tasks and alternatives. Further exploration of overlaps and block sizes are needed. This study's results are widely applicable for researchers interested in creating optimal DCE designs to elicit individual preferences on health services, programmes, policies and products. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  6. Simulation study to determine the impact of different design features on design efficiency in discrete choice experiments

    PubMed Central

    Vanniyasingam, Thuva; Cunningham, Charles E; Foster, Gary; Thabane, Lehana

    2016-01-01

    Objectives Discrete choice experiments (DCEs) are routinely used to elicit patient preferences to improve health outcomes and healthcare services. While many fractional factorial designs can be created, some are more statistically optimal than others. The objective of this simulation study was to investigate how varying the number of (1) attributes, (2) levels within attributes, (3) alternatives and (4) choice tasks per survey will improve or compromise the statistical efficiency of an experimental design. Design and methods A total of 3204 DCE designs were created to assess how relative design efficiency (d-efficiency) is influenced by varying the number of choice tasks (2–20), alternatives (2–5), attributes (2–20) and attribute levels (2–5) of a design. Choice tasks were created by randomly allocating attribute and attribute level combinations into alternatives. Outcome Relative d-efficiency was used to measure the optimality of each DCE design. Results DCE design complexity influenced statistical efficiency. Across all designs, relative d-efficiency decreased as the number of attributes and attribute levels increased. It increased for designs with more alternatives. Lastly, relative d-efficiency converges as the number of choice tasks increases, where convergence may not be at 100% statistical optimality. Conclusions Achieving 100% d-efficiency is heavily dependent on the number of attributes, attribute levels, choice tasks and alternatives. Further exploration of overlaps and block sizes are needed. This study's results are widely applicable for researchers interested in creating optimal DCE designs to elicit individual preferences on health services, programmes, policies and products. PMID:27436671

  7. Influence of injection mode on transport properties in kilometer-scale three-dimensional discrete fracture networks

    SciTech Connect

    Hyman, Jeffrey De'Haven; Painter, S. L.; Viswanathan, H.; Makedonska, N.; Karra, S.

    2015-09-12

    We investigate how the choice of injection mode impacts transport properties in kilometer-scale three-dimensional discrete fracture networks (DFN). The choice of injection mode, resident and flux-weighted, is designed to mimic different physical phenomena. It has been hypothesized that solute plumes injected under resident conditions evolve to behave similarly to solutes injected under flux-weighted conditions. Previously, computational limitations have prohibited the large-scale simulations required to investigate this hypothesis. We investigate this hypothesis by using a high-performance DFN suite, dfnWorks, to simulate flow in kilometer-scale three-dimensional DFNs based on fractured granite at the Forsmark site in Sweden, and adopt a Lagrangian approach to simulate transport therein. Results show that after traveling through a pre-equilibrium region, both injection methods exhibit linear scaling of the first moment of travel time and power law scaling of the breakthrough curve with similar exponents, slightly larger than 2. Lastly, the physical mechanisms behind this evolution appear to be the combination of in-network channeling of mass into larger fractures, which offer reduced resistance to flow, and in-fracture channeling, which results from the topology of the DFN.

  8. Influence of injection mode on transport properties in kilometer-scale three-dimensional discrete fracture networks

    DOE PAGES

    Hyman, Jeffrey De'Haven; Painter, S. L.; Viswanathan, H.; ...

    2015-09-12

    We investigate how the choice of injection mode impacts transport properties in kilometer-scale three-dimensional discrete fracture networks (DFN). The choice of injection mode, resident and flux-weighted, is designed to mimic different physical phenomena. It has been hypothesized that solute plumes injected under resident conditions evolve to behave similarly to solutes injected under flux-weighted conditions. Previously, computational limitations have prohibited the large-scale simulations required to investigate this hypothesis. We investigate this hypothesis by using a high-performance DFN suite, dfnWorks, to simulate flow in kilometer-scale three-dimensional DFNs based on fractured granite at the Forsmark site in Sweden, and adopt a Lagrangian approachmore » to simulate transport therein. Results show that after traveling through a pre-equilibrium region, both injection methods exhibit linear scaling of the first moment of travel time and power law scaling of the breakthrough curve with similar exponents, slightly larger than 2. Lastly, the physical mechanisms behind this evolution appear to be the combination of in-network channeling of mass into larger fractures, which offer reduced resistance to flow, and in-fracture channeling, which results from the topology of the DFN.« less

  9. The effect of traffic lights and regulatory statements on the choice between complementary and conventional medicines in Australia: results from a discrete choice experiment.

    PubMed

    Spinks, Jean; Mortimer, Duncan

    2015-01-01

    It has been suggested that complementary medicines are currently 'under-regulated' in some countries due to their potential for harm as a direct result from side-effects or interactions; from delaying more effective care; or from the economic cost of purchasing an ineffective or inappropriate treatment. The requirement of additional labelling on complementary medicine products has been suggested in Australia and may provide additional information to consumers at the point of purchase. This paper details a unique way of testing the potential effects on consumer behaviour of including either a traffic light logo or regulatory statement on labels. Using a discrete choice experiment, data were collected in 2012 in a sample of 521 Australians with either type 2 diabetes or cardiovascular disease. We find that additional labelling can affect consumer behaviour, but in unpredictable ways. The results of this experiment are informative to further the dialogue concerning possible regulatory mechanisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Analysis of discrete reaction-diffusion equations for autocatalysis and continuum diffusion equations for transport

    SciTech Connect

    Wang, Chi-Jen

    2013-01-01

    In this thesis, we analyze both the spatiotemporal behavior of: (A) non-linear “reaction” models utilizing (discrete) reaction-diffusion equations; and (B) spatial transport problems on surfaces and in nanopores utilizing the relevant (continuum) diffusion or Fokker-Planck equations. Thus, there are some common themes in these studies, as they all involve partial differential equations or their discrete analogues which incorporate a description of diffusion-type processes. However, there are also some qualitative differences, as shall be discussed below.

  11. Preferences for breast cancer risk reduction among BRCA1/BRCA2 mutation carriers: a discrete-choice experiment.

    PubMed

    Liede, Alexander; Mansfield, Carol A; Metcalfe, Kelly A; Price, Melanie A; Snyder, Carrie; Lynch, Henry T; Friedman, Sue; Amelio, Justyna; Posner, Joshua; Narod, Steven A; Lindeman, Geoffrey J; Evans, D Gareth

    2017-09-01

    Unaffected women who carry BRCA1 or BRCA2 mutations face difficult choices about reducing their breast cancer risk. Understanding their treatment preferences could help us improve patient counseling and inform drug trials. The objective was to explore preferences for various risk-reducing options among women with germline BRCA1/2 mutations using a discrete-choice experiment survey and to compare expressed preferences with actual behaviors. A discrete-choice experiment survey was designed wherein women choose between hypothetical treatments to reduce breast cancer risk. The hypothetical treatments were characterized by the extent of breast cancer risk reduction, treatment duration, impact on fertility, hormone levels, risk of uterine cancer, and ease and mode of administration. Data were analyzed using a random-parameters logit model. Women were also asked to express their preference between surgical and chemoprevention options and to report on their actual risk-reduction actions. Women aged 25-55 years with germline BRCA1/2 mutations who were unaffected with breast or ovarian cancer were recruited through research registries at five clinics and a patient advocacy group. Between January 2015 and March 2016, 622 women completed the survey. Breast cancer risk reduction was the most important consideration expressed, followed by maintaining fertility. Among the subset of women who wished to have children in future, the ability to maintain fertility was the most important factor, followed by the extent of risk reduction. Many more women said they would take a chemoprevention drug than had actually taken chemoprevention. Women with BRCA1/2 mutations indicated strong preferences for breast cancer risk reduction and maintaining fertility. The expressed desire to have a safe chemoprevention drug available to them was not met by current chemoprevention options.

  12. Words or graphics to present a Discrete Choice Experiment: Does it matter?

    PubMed

    Veldwijk, Jorien; Lambooij, Mattijs S; van Til, Janine A; Groothuis-Oudshoorn, Catharina G M; Smit, Henriëtte A; de Wit, G Ardine

    2015-11-01

    To test whether presenting attribute levels in words or graphics generates different results with respect to attribute level interpretation, relative importance and participation probabilities. Parents of 959 newborns completed a DCE questionnaire that contained two versions of the same nine choice tasks in which the attribute levels were presented in words or graphics. Five attributes related to the decision of parents to vaccinate their newborn against rotavirus were included. Mixed-logit models were conducted to estimate the relative importance of the attribute levels. Respondents who started with the choice tasks in words produced the most consistent answer patterns. All respondents significantly preferred words to graphics. Part-worth utilities and the relative importance of the attribute levels differed based on the words and graphics data, resulting in different probabilities to participate in vaccination. Words were preferred over graphics, resulted in higher choice consistency, and showed more valid attribute level estimates. Graphics did not improve respondents' understanding of the attribute levels. Future research on the use of either words or graphics is recommended in order to establish guidelines on how to develop a valid presentation method for attribute levels in the choice tasks of a DCE. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. Constrained Latent Class Analysis: Simultaneous Classification and Scaling of Discrete Choice Data.

    ERIC Educational Resources Information Center

    Bockenholt, Ulf; Bockenholt, Ingo

    1991-01-01

    A reparameterization of a latent class model is presented to classify and scale nomial and ordered categorical choice data simultaneously. The model extension represents a nonhomogeneous population as a mixture of homogeneous subpopulations. Simulated data and data from a magazine preference survey of 347 college students illustrate the model.…

  14. Contraceptive preferences and use among auto artisanal workers in the informal sector of Kumasi, Ghana: a discrete choice experiment.

    PubMed

    Agyei-Baffour, Peter; Boahemaa, Mary Yaa; Addy, Ernestine A

    2015-04-12

    Contraceptive uptake in Ghana, especially in the Ashanti region remains low. This may be partly due to products' characteristics and choice which are influenced by attribute utility trade-offs by consumers in determining which method offers the optimal combinations, given the needs and desires of the individuals making the choice. The study sought to determine how specific attributes of contraceptives influence artisanal auto mechanics' stated preferences for a hypothetical contraceptive use in the Tafo-Suame industrial area of Kumasi, Ghana. A discrete choice experiment was conducted with artisanal auto mechanics in the study area from May to September 2011. Based on the summary of the attributes from the focus group discussion and in-depth interviews preceded administration of structured questionnaire, a discrete choice experiment (DCE) was created. The attributes used were; side effects, reversibility, ease of use, ability to prevent both pregnancy and sexually transmitted infection (STI's), price and privacy in acquiring and attractiveness of the method. A total of 340 consented respondents aged 15 to 49 years participated in the study. Data were entered in Access and Sawtooth software SSI Web CAPi module and then exported to Stata for analysis. The study showed a universal (99.4%) knowledge on contraception, ever used 87% and currently using a method, 58%. The study revealed that methods' reversibility (β = 21.74; 95% CI: 20.17, 23.3), minimal allergic reaction (β = 13.93; 95% CI: 12.8, 15.05) and no effect on blood pressure (β = 12.71; 95% CI: 11.62, 13.79), were strongly associated with contraceptive preference and use. While contraceptives' ability to prevent "only pregnancy", (β = -15.13: 95% CI: -16.2, -14.02; "only STI's") (β = -11.65; 95% CI: -11.84, -11.46); and interrupt during sexual activity (β = -4.26; 95% CI: -5.19, -3.34), had large negative influence on contraceptive preference and use. The study has documented the

  15. [Preferences for work in primary care among medical students in Minas Gerais State, Brazil: evidence from a discrete choice experiment].

    PubMed

    Girardi, Sabado Nicolau; Carvalho, Cristiana Leite; Maas, Lucas Wan Der; Araujo, Jackson Freire; Massote, Alice Werneck; Stralen, Ana Cristina de Sousa van; Souza, Osmar Ambrósio de

    2017-08-21

    This article presents the results of a discrete choice experiment (DCE) conducted in 2012 with 277 final-year medical students from Minas Gerais State, Brazil. The experiment tested students' preferences concerning future work as physicians in primary health care, based on hypothetical job scenarios aimed at measuring the likelihood of placement in areas with a shortage of doctors. Application of DCE involved (i) a qualitative stage to define the attributes and their respective levels to comprise the job scenarios, (ii) construction and application of the instrument, and (iii) analysis with application of multinomial logit with conditional probability to estimate the weight of attributes and to construct scenarios for choice probability. The results indicate that the job attribute that most impacted students' choice was location, followed by job conditions, pay, access to medical residency, type of employment relationship, and workload. Students from private medical schools, with higher family income, and females were generally more likely to resist job assignments in unsafe urban areas and remote areas of the countryside. The job scenarios that proved most plausible in terms of public intervention were those that combined middle-level wages, good working conditions, and 10 to 20 bonus points on medical residency exams.

  16. Impact of Survey Administration Mode on the Results of a Health-Related Discrete Choice Experiment: Online and Paper Comparison.

    PubMed

    Determann, Domino; Lambooij, Mattijs S; Steyerberg, Ewout W; de Bekker-Grob, Esther W; de Wit, G Ardine

    Electronic data collection is increasingly being used for discrete choice experiments (DCEs). To study whether paper or electronic administration results in measurement effects. Respondents were drawn from the same sample frame (an Internet panel) and completed a nearly identical DCE survey either online or on paper during the same period. A DCE on preferences for basic health insurance served as a case study. We used panel mixed logit models for the analysis. In total, 898 respondents completed the survey: 533 respondents completed the survey online, whereas 365 respondents returned the paper survey. There were no significant differences with respect to sociodemographic characteristics between the respondents in both samples. The median response time was shorter for the online sample than for the paper sample, and a smaller proportion of respondents from the online sample were satisfied with the number of choice sets. Although some willingness- to-pay estimates were higher for the online sample, the elicited preferences for basic health insurance characteristics were similar between both modes of administration. We find no indication that online surveys yield inferior results compared with paper-based surveys, whereas the price per respondent is lower for online surveys. Researchers might want to include fewer choice sets per respondent when collecting DCE data online. Because our findings are based on a nonrandomized DCE that covers one health domain only, research in other domains is needed to support our findings. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  17. Generation of discrete scattering cross sections and demonstration of Monte Carlo charged particle transport in the Milagro IMC code package

    SciTech Connect

    Walsh, J. A.; Palmer, T. S.; Urbatsch, T. J.

    2013-07-01

    A new method for generating discrete scattering cross sections to be used in charged particle transport calculations is investigated. The method of data generation is presented and compared to current methods for obtaining discrete cross sections. The new, more generalized approach allows greater flexibility in choosing a cross section model from which to derive discrete values. Cross section data generated with the new method is verified through a comparison with discrete data obtained with an existing method. Additionally, a charged particle transport capability is demonstrated in the time-dependent Implicit Monte Carlo radiative transfer code package, Milagro. The implementation of this capability is verified using test problems with analytic solutions as well as a comparison of electron dose-depth profiles calculated with Milagro and an already-established electron transport code. An initial investigation of a preliminary integration of the discrete cross section generation method with the new charged particle transport capability in Milagro is also presented. (authors)

  18. Graphics processing unit parallel accelerated solution of the discrete ordinates for photon transport in biological tissues.

    PubMed

    Peng, Kuan; Gao, Xinbo; Qu, Xiaochao; Ren, Nunu; Chen, Xueli; He, Xiaowei; Wang, Xiaorei; Liang, Jimin; Tian, Jie

    2011-07-20

    As a widely used numerical solution for the radiation transport equation (RTE), the discrete ordinates can predict the propagation of photons through biological tissues more accurately relative to the diffusion equation. The discrete ordinates reduce the RTE to a serial of differential equations that can be solved by source iteration (SI). However, the tremendous time consumption of SI, which is partly caused by the expensive computation of each SI step, limits its applications. In this paper, we present a graphics processing unit (GPU) parallel accelerated SI method for discrete ordinates. Utilizing the calculation independence on the levels of the discrete ordinate equation and spatial element, the proposed method reduces the time cost of each SI step by parallel calculation. The photon reflection at the boundary was calculated based on the results of the last SI step to ensure the calculation independence on the level of the discrete ordinate equation. An element sweeping strategy was proposed to detect the calculation independence on the level of the spatial element. A GPU parallel frame called the compute unified device architecture was employed to carry out the parallel computation. The simulation experiments, which were carried out with a cylindrical phantom and numerical mouse, indicated that the time cost of each SI step can be reduced up to a factor of 228 by the proposed method with a GTX 260 graphics card. © 2011 Optical Society of America

  19. Different spatial discretization methods of fault systems on heat transport processes in hard rock aquifers

    NASA Astrophysics Data System (ADS)

    Kruppa, Lisa; König, Christoph M.; Becker, Martin; Seidel, Torsten

    2016-04-01

    Most hard rock aquifers, which are important for geothermal use, contain fractures of different type and scale. These fault systems are of major significance for heat flow in the groundwater. The hydrogeological characterization of fault systems must therefore be part of any site investigation in hard rock aquifers and hydraulically important fault systems need to be appropriately represented in associated numerical models. This contribution discusses different spatial discretization methods of fault systems in three-dimensional groundwater models and their impact on the simulated groundwater flow field as well as density and viscosity dependent heat transport. The analysis includes a comparison of the convergence behavior and numerical stability of the different discretization methods. To ensure defendable results, the utilized numerical model SPRING was first verified against data from the Hydrocoin Level 1 Case 2 project. After verification, the software was used to evaluate the impact of different discretization strategies on steady-state and transient groundwater flow and transport model results. The results show a significant influence of the spatial discretization strategy on predicted flow rates and subsequent mass fluxes as well as energy balances.

  20. The Australian public's preferences for emergency care alternatives and the influence of the presenting context: a discrete choice experiment

    PubMed Central

    Harris, Paul; Whitty, Jennifer A; Kendall, Elizabeth; Ratcliffe, Julie; Wilson, Andrew; Littlejohns, Peter; Scuffham, Paul A

    2015-01-01

    Objectives The current study seeks to quantify the Australian public's preferences for emergency care alternatives and determine if preferences differ depending on presenting circumstances. Setting Increasing presentations to emergency departments have led to overcrowding, long waiting times and suboptimal health system performance. Accordingly, new service models involving the provision of care in alternative settings and delivered by other practitioners continue to be developed. Participants A stratified sample of Australian adults (n=1838), 1382 from Queensland and 456 from South Australia, completed the survey. This included 951 females and 887 males from the 2045 people who met the screening criteria out of the 4354 people who accepted the survey invitation. Interventions A discrete choice experiment was used to elicit preferences in the context of one of four hypothetical scenarios: a possible concussion, a rash/asthma-related problem involving oneself or one's child and an anxiety-related presentation. Mixed logit regression was used to analyse the dependent variable choice and identify the relative importance of care attributes and the propensity to access care in each context. Results Results indicated a preference for treatment by an emergency physician in hospital for possible concussion and treatment by a doctor in ambulatory settings for rash/asthma-related and anxiety-related problems. Participants were consistently willing to wait longer before making trade-offs in the context of the rash/asthma-related scenario compared with when the same problem affected their child. Results suggest a clear preference for lower costs, shorter wait times and strong emphasis on quality care; however, significant preference heterogeneity was observed. Conclusions This study has increased awareness that the public's emergency care choices will differ depending on the presenting context. It has further demonstrated the importance of service quality as a determinant of

  1. Qualitative Assessment of the Application of a Discrete Choice Experiment With Community Health Workers in Uganda: Aligning Incentives With Preferences

    PubMed Central

    Brunie, Aurélie; Chen, Mario; Akol, Angela

    2016-01-01

    ABSTRACT Background: Maximizing the benefits of community health worker (CHW) programs requires strategies for improving motivation, performance, and retention. Discrete choice experiments (DCE) are increasingly used to inform policy response to health workforce shortages in rural areas, and may be of value in the context of CHW programs. Participants are presented with pairs of hypothetical jobs that are described by job attributes with varying levels and are asked what their preferred job is within each pair. Responses are then analyzed quantitatively to obtain information on what attributes are important to participants. We conducted a qualitative assessment to examine the appropriateness and validity of applying a DCE to a new population of CHWs with lower literacy. Methods: In 2011, we conducted a mixed-method study with CHWs in Uganda, consisting of 183 surveys and 43 in-depth interviews (IDIs). The DCE was administered to both survey and IDI participants. This article reports on the qualitative assessment of the implementation of the DCE. We compare DCE responses between survey and IDI participants to determine whether administering the DCE in a qualitative (IDI) context altered responses. We then present additional information collected on CHWs' decision-making processes and their experiences with the DCE in the IDIs. Results: Choices made by IDI participants were consistent with the choices made by survey participants. In-depth exploration of CHWs' observations in answering the DCE suggest that, overall, CHWs comprehended the DCE exercise and made reasoned choices. However, the data revealed some level of cognitive difficulty and highlighted some design and implementation challenges that are important to consider, particularly when applying a DCE to populations with lower literacy. These include the need to keep the number of attributes small; to choose levels that are realistic yet show sufficient range; and to clearly define attributes and their levels

  2. Evaluation of strategies to communicate harmful and potentially harmful constituent (HPHC) information through cigarette package inserts: a discrete choice experiment.

    PubMed

    Salloum, Ramzi G; Louviere, Jordan J; Getz, Kayla R; Islam, Farahnaz; Anshari, Dien; Cho, Yoojin; O'Connor, Richard J; Hammond, David; Thrasher, James F

    2017-07-13

    The US Food and Drug Administration (FDA) has regulatory authority to use inserts to communicate with consumers about harmful and potentially harmful constituents (HPHCs) in tobacco products; however, little is known about the most effective manner for presenting HPHC information. In a discrete choice experiment, participants evaluated eight choice sets, each of which showed two cigarette packages from four different brands and tar levels (high vs low), accompanied by an insert that included between-subject manipulations (ie, listing of HPHCs vs grouping by disease outcome and numeric values ascribed to HPHCs vs no numbers) and within-subject manipulations (ie, 1 of 4 warning topics; statement linking an HPHC with disease vs statement with no HPHC link). For each choice set, participants were asked: (1) which package is more harmful and (2) which motivates them to not smoke; each with a 'no difference' option. Alternative-specific logit models regressed choice on attribute levels. 1212 participants were recruited from an online consumer panel (725 18-29-year-old smokers and susceptible non-smokers and 487 30-64-year-old smokers). Participants were more likely to endorse high-tar products as more harmful than low-tar products, with a greater effect when numeric HPHC information was present. Compared with a simple warning statement, the statement linking HPHCs with disease encouraged quit motivation. Numeric HPHC information on inserts appears to produce misunderstandings that some cigarettes are less harmful than others. Furthermore, brief narratives that link HPHCs to smoking-related disease may promote cessation versus communications that do not explicitly link HPHCs to disease. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  3. Qualitative Assessment of the Application of a Discrete Choice Experiment With Community Health Workers in Uganda: Aligning Incentives With Preferences.

    PubMed

    Brunie, Aurélie; Chen, Mario; Akol, Angela

    2016-12-23

    Maximizing the benefits of community health worker (CHW) programs requires strategies for improving motivation, performance, and retention. Discrete choice experiments (DCE) are increasingly used to inform policy response to health workforce shortages in rural areas, and may be of value in the context of CHW programs. Participants are presented with pairs of hypothetical jobs that are described by job attributes with varying levels and are asked what their preferred job is within each pair. Responses are then analyzed quantitatively to obtain information on what attributes are important to participants. We conducted a qualitative assessment to examine the appropriateness and validity of applying a DCE to a new population of CHWs with lower literacy. In 2011, we conducted a mixed-method study with CHWs in Uganda, consisting of 183 surveys and 43 in-depth interviews (IDIs). The DCE was administered to both survey and IDI participants. This article reports on the qualitative assessment of the implementation of the DCE. We compare DCE responses between survey and IDI participants to determine whether administering the DCE in a qualitative (IDI) context altered responses. We then present additional information collected on CHWs' decision-making processes and their experiences with the DCE in the IDIs. Choices made by IDI participants were consistent with the choices made by survey participants. In-depth exploration of CHWs' observations in answering the DCE suggest that, overall, CHWs comprehended the DCE exercise and made reasoned choices. However, the data revealed some level of cognitive difficulty and highlighted some design and implementation challenges that are important to consider, particularly when applying a DCE to populations with lower literacy. These include the need to keep the number of attributes small; to choose levels that are realistic yet show sufficient range; and to clearly define attributes and their levels. DCEs can be an appropriate approach

  4. The Impact of Cigarette Packaging Design Among Young Females in Canada: Findings From a Discrete Choice Experiment.

    PubMed

    Kotnowski, Kathy; Fong, Geoffrey T; Gallopel-Morvan, Karine; Islam, Towhidul; Hammond, David

    2016-05-01

    The tobacco industry uses various aspects of cigarette packaging design to market to specific groups. The current study examined the relative importance of five cigarette packaging attributes--pack structure (eg, "slims"), brand, branding, warning label size, and price--on perceptions of product taste, harm, and interest in trying, among young females in Canada. A discrete choice experiment was conducted with smoking and nonsmoking females, aged 16 to 24 (N = 448). Respondents were shown 10 choice sets, each containing four packs with different combinations of the attributes: pack structure (slim, lipstick, booklet, traditional); brand ("Vogue," "du Maurier"); branding (branded, plain); warning label size (50%, 75%); and price ($8.45, $10.45). For each choice set, respondents chose the brand that they: (1) would rather try, (2) would taste better, and (3) would be less harmful, or "none." For each outcome, the attributes' impact on consumer choice was analyzed using a multinomial logit model. The multinomial logit analyses revealed that young females weighted pack structure to be most important to their intention to try (46%), judgment of product taste (52%), and judgment of product harm (48%). Price and branding were weighted important in trial intent decisions (23% and 18%, respectively) and product taste judgments (29% and 15%, respectively). Whereas warning label size and brand were weighted important when judging product harm (23% and 17%, respectively). The findings suggest that standardized cigarette packaging may decrease demand and reduce misleading perceptions about product harm among young females. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. A discrete choice experiment investigating preferences for funding drugs used to treat orphan diseases: an exploratory study.

    PubMed

    Mentzakis, Emmanouil; Stefanowska, Patricia; Hurley, Jeremiah

    2011-07-01

    Policy debate about funding criteria for drugs used to treat rare, orphan diseases is gaining prominence. This study presents evidence from a discrete choice experiment using a convenience sample of university students to investigate individual preferences regarding public funding for drugs used to treat rare diseases and common diseases. This pilot study finds that: other things equal, the respondents do not prefer to have the government spend more for drugs used to treat rare diseases; that respondents are not willing to pay more per life year gained for a rare disease than a common disease; and that respondents weigh relevant attributes of the coverage decisions (e.g. costs, disease severity and treatment effectiveness) similarly for both rare and common diseases. The results confirm the importance of severity and treatment effectiveness in preferences for public funding. Although this is the first study of its kind, the results send a cautionary message regarding the special treatment of orphan drugs in coverage decision-making.

  6. A flexible nonlinear diffusion acceleration method for the SN transport equations discretized with discontinuous finite elements

    DOE PAGES

    Schunert, Sebastian; Wang, Yaqi; Gleicher, Frederick; ...

    2017-02-21

    This paper presents a flexible nonlinear diffusion acceleration (NDA) method that discretizes both the SN transport equation and the diffusion equation using the discontinuous finite element method (DFEM). The method is flexible in that the diffusion equation can be discretized on a coarser mesh with the only restriction that it is nested within the transport mesh and the FEM shape function orders of the two equations can be different. The consistency of the transport and diffusion solutions at convergence is defined by using a projection operator mapping the transport into the diffusion FEM space. The diffusion weak form is basedmore » on the modified incomplete interior penalty (MIP) diffusion DFEM discretization that is extended by volumetric drift, interior face, and boundary closure terms. In contrast to commonly used coarse mesh finite difference (CMFD) methods, the presented NDA method uses a full FEM discretized diffusion equation for acceleration. Suitable projection and prolongation operators arise naturally from the FEM framework. Via Fourier analysis and numerical experiments for a one-group, fixed source problem the following properties of the NDA method are established for structured quadrilateral meshes: (1) the presented method is unconditionally stable and effective in the presence of mild material heterogeneities if the same mesh and identical shape functions either of the bilinear or biquadratic type are used, (2) the NDA method remains unconditionally stable in the presence of strong heterogeneities, (3) the NDA method with bilinear elements extends the range of effectiveness and stability by a factor of two when compared to CMFD if a coarser diffusion mesh is selected. In addition, the method is tested for solving the C5G7 multigroup, eigenvalue problem using coarse and fine mesh acceleration. Finally, while NDA does not offer an advantage over CMFD for fine mesh acceleration, it reduces the iteration count required for convergence by almost

  7. The three-dimensional, discrete ordinates neutral particle transport code TORT: An overview

    SciTech Connect

    Azmy, Y.Y.

    1996-12-31

    The centerpiece of the Discrete Ordinates Oak Ridge System (DOORS), the three-dimensional neutral particle transport code TORT is reviewed. Its most prominent features pertaining to large applications, such as adjustable problem parameters, memory management, and coarse mesh methods, are described. Advanced, state-of-the-art capabilities including acceleration and multiprocessing are summarized here. Future enhancement of existing graphics and visualization tools is briefly presented.

  8. A flexible nonlinear diffusion acceleration method for the SN transport equations discretized with discontinuous finite elements

    NASA Astrophysics Data System (ADS)

    Schunert, Sebastian; Wang, Yaqi; Gleicher, Frederick; Ortensi, Javier; Baker, Benjamin; Laboure, Vincent; Wang, Congjian; DeHart, Mark; Martineau, Richard

    2017-06-01

    This work presents a flexible nonlinear diffusion acceleration (NDA) method that discretizes both the SN transport equation and the diffusion equation using the discontinuous finite element method (DFEM). The method is flexible in that the diffusion equation can be discretized on a coarser mesh with the only restriction that it is nested within the transport mesh and the FEM shape function orders of the two equations can be different. The consistency of the transport and diffusion solutions at convergence is defined by using a projection operator mapping the transport into the diffusion FEM space. The diffusion weak form is based on the modified incomplete interior penalty (MIP) diffusion DFEM discretization that is extended by volumetric drift, interior face, and boundary closure terms. In contrast to commonly used coarse mesh finite difference (CMFD) methods, the presented NDA method uses a full FEM discretized diffusion equation for acceleration. Suitable projection and prolongation operators arise naturally from the FEM framework. Via Fourier analysis and numerical experiments for a one-group, fixed source problem the following properties of the NDA method are established for structured quadrilateral meshes: (1) the presented method is unconditionally stable and effective in the presence of mild material heterogeneities if the same mesh and identical shape functions either of the bilinear or biquadratic type are used, (2) the NDA method remains unconditionally stable in the presence of strong heterogeneities, (3) the NDA method with bilinear elements extends the range of effectiveness and stability by a factor of two when compared to CMFD if a coarser diffusion mesh is selected. In addition, the method is tested for solving the C5G7 multigroup, eigenvalue problem using coarse and fine mesh acceleration. While NDA does not offer an advantage over CMFD for fine mesh acceleration, it reduces the iteration count required for convergence by almost a factor of two in

  9. Men's preferences for the treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia: a discrete choice experiment.

    PubMed

    Mankowski, Colette; Ikenwilo, Divine; Heidenreich, Sebastian; Ryan, Mandy; Nazir, Jameel; Newman, Cathy; Watson, Verity

    2016-01-01

    To explore and quantify men's preferences and willingness to pay (WTP) for attributes of medications for lower urinary tract symptoms associated with benign prostatic hyperplasia using a discrete choice experiment. Men in the UK aged ≥45 years with moderate-to-severe lower urinary tract symptoms/benign prostatic hyperplasia (based on self-reported International Prostate Symptom Score ≥8) were recruited. An online discrete choice experiment survey was administered. Eligible men were asked to consider different medication scenarios and select their preferred medication according to seven attributes: daytime and nighttime (nocturia) urinary frequency, urinary urgency, sexual and nonsexual side effects, number of tablets/day, and cost/month. A mixed-logit model was used to estimate preferences and WTP for medication attributes. In all, 247 men completed the survey. Men were willing to trade-off symptom improvements and treatment side effects. Men preferred medications that reduced urinary urgency and reduced day- and nighttime urinary frequency. Men preferred medications without side effects (base-case level), but did not care about the number of tablets per day. WTP for symptomatic improvement was £25.33/month for reduced urgency (urge incontinence to mild urgency), and £6.65/month and £1.39/month for each unit reduction in night- and daytime urination frequency, respectively. The sexual and nonsexual side effects reduced WTP by up to £30.07/month. There was significant heterogeneity in preferences for most attributes, except for reduced urinary urgency from urge incontinence to mild urgency and no fluid during ejaculation (dry orgasm). To compensate for side effects, a medicine for lower urinary tract symptoms/benign prostatic hyperplasia must provide a combination of benefits, such as reduced urgency of urination plus reduced nighttime and/or reduced daytime urination.

  10. Calculating Preference Weights for the Labor and Delivery Index: A Discrete Choice Experiment on Women's Birth Experiences.

    PubMed

    Gärtner, Fania R; de Bekker-Grob, Esther W; Stiggelbout, Anne M; Rijnders, Marlies E; Freeman, Liv M; Middeldorp, Johanna M; Bloemenkamp, Kitty W M; de Miranda, Esteriek; van den Akker-van Marle, M Elske

    2015-09-01

    The aim of this study was to calculate preference weights for the Labor and Delivery Index (LADY-X) to make it suitable as a utility measure for perinatal care studies. In an online discrete choice experiment, 18 pairs of hypothetical scenarios were presented to respondents, from which they had to choose a preferred option. The scenarios describe the birth experience in terms of the seven LADY-X attributes. A D-efficient discrete choice experiment design with priors based on a small sample (N = 110) was applied. Two samples were gathered, women who had recently given birth and subjects from the general population. Both samples were analyzed separately using a panel mixed logit (MMNL) model. Using the panel mixed multinomial logit (MMNL) model results and accounting for preference heterogeneity, we calculated the average preference weights for LADY-X attribute levels. These were transformed to represent a utility score between 0 and 1, with 0 representing the worst and 1 representing the best birth experience. In total, 1097 women who had recently given birth and 367 subjects from the general population participated. Greater value was placed on differences between bottom and middle attribute levels than on differences between middle and top levels. The attributes that resulted in larger utility increases than the other attributes were "feeling of safety" in the sample of women who had recently given birth and "feeling of safety" and "availability of professionals" in the general population sample. By using the derived preference weights, LADY-X has the potential to be used as a utility measure for perinatal (cost-) effectiveness studies. Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  11. Probability and delay of reinforcement as factors in discrete-trial choice.

    PubMed Central

    Mazur, J E

    1985-01-01

    Pigeons chose between two alternatives that differed in the probability of reinforcement and the delay to reinforcement. A peck on the red key always produced a delay of 5 s and then a possible reinforcer. The probability of reinforcement for responding on this key varied from .05 to 1.0 in different conditions. A response on the green key produced a delay of adjustable duration and then a possible reinforcer, with the probability of reinforcement ranging from .25 to 1.0 in different conditions. The green-key delay was increased or decreased many times per session, depending on a subject's previous choices. The purpose of these adjustments was to estimate an indifference point, or a delay that resulted in a subject's choosing each alternative about equally often. In conditions where the probability of reinforcement was five times higher on the green key, the green-key delay averaged about 12 s at the indifference point. In conditions where the probability of reinforcement was twice as high on the green key, the green-key delay at the indifference point was about 8 s with high probabilities and about 6 s with low probabilities. An analysis based on these results and those from studies on delay of reinforcement suggests that pigeons' choices are relatively insensitive to variations in the probability of reinforcement between .2 and 1.0, but quite sensitive to variations in probability between .2 and 0. PMID:4020322

  12. Choice.

    PubMed

    Greenberg, Jay

    2008-09-01

    Understanding how and why analysands make the choices they do is central to both the clinical and the theoretical projects of psychoanalysis. And yet we know very little about the process of choice or about the relationship between choices and motives. A striking parallel is to be found between the ways choice is narrated in ancient Greek texts and the experience of analysts as they observe patients making choices in everyday clinical work. Pursuing this convergence of classical and contemporary sensibilities will illuminate crucial elements of the various meanings of choice, and of the way that these meanings change over the course of psychoanalytic treatment.

  13. Generalized discrete mapping treatment of nonresonant ripple transport in a tokamak

    SciTech Connect

    Albert, J.M.; Boozer, A.H.

    1989-06-01

    A discrete mapping is used to analyze nonresonant ripple transport in a tokamak. Pitch-angle scattering is manifested in two different terms, as in a previous treatment of resonant ripple transport. The mapping is a generalization of one which recovers the standard banana-drift regime. This is one limit of the more general mapping presented here; in the other, the quasilinear value for the diffusion coefficient emerges. When the quasilinear value applies, it can be either much greater or much less than the corresponding banana-drift value, depending on the parameter values of the mapping.

  14. Discrete ordinates (SN) method for the first solution of the transport equation using Chebyshev polynomials

    NASA Astrophysics Data System (ADS)

    Öztürk, Hakan

    2016-11-01

    First estimates for the numerical solution of the one-dimensional neutron transport equation for one-speed neutrons in a finite homogeneous slab is studied. The neutrons are assumed to be scattered isotropically through the medium. Then the discrete ordinates form of the transport equation is solved for the eigenvalue spectrum using the Chebyshev polynomials of second kind in the neutron angular flux. Therefore, the calculated eigenvalues for various values of the c0, the mean number of secondary neutrons per collision, are given in the tables using the Gauss-Chebyshev quadrature set.

  15. Electrodiffusion of molecules in aqueous media: a robust, discretized description for electroporation and other transport phenomena.

    PubMed

    Smith, Kyle C; Weaver, James C

    2012-06-01

    Electrically driven transport of molecules and ions within aqueous electrolytes is of long-standing interest, with direct relevance to applications that include the delivery/release of biologically active solutes to/from cells and tissues. Examples include iontophoretic and electroporation-mediated drug delivery. Here, we describe a robust method for characterizing electrodiffusive transport in physiologic aqueous media. Specifically, we treat the case of solute present in sufficiently low concentration as to negligibly contribute to the total ionic current within the system. In this limiting case, which applies to many systems of interest, the predominant electrical behavior due to small ions is decoupled from solute transport. Thus, electrical behavior may be characterized using existing methods and treated as known in characterizing electrodiffusive molecular transport. First, we present traditional continuum equations governing electrodiffusion of charged solutes within aqueous electrolytes and then adapt them to discretized systems. Second, we examine the time-dependent and steady-state interfacial concentration gradients that result from the combination of diffusion and electrical drift. Third, we show how interfacial concentration gradients are related to electric field strength and duration. Finally, we examine how discretization size affects the accuracy of these methods. Overall these methods are motivated by and well suited to addressing an outstanding goal: estimation of the net ionic and molecular transport facilitated by electroporation in biological systems.

  16. Discrete choice experiment produced estimates of acceptable risks of therapeutic options in cancer patients with febrile neutropenia.

    PubMed

    Sung, Lillian; Alibhai, Shabbir M; Ethier, Marie-Chantal; Teuffel, Oliver; Cheng, Sylvia; Fisman, David; Regier, Dean A

    2012-06-01

    To use a discrete choice experiment (DCE) to describe patient/proxy tolerance for the number of clinic visits, and chances of readmission, intensive care unit admission, and mortality to accept oral outpatient management of low-risk febrile neutropenia. Adults and children aged 12-18 years with cancer and parents of pediatric cancer patients were asked to choose between outpatient oral and inpatient intravenous management of low-risk febrile neutropenia. Using a DCE, we varied the attribute levels with the outpatient option and kept them constant for the inpatient option. Seventy-eight adults, 153 parents, and 43 children provided responses. All four attributes significantly affected choices. The mean tolerance (95% confidence interval) for the number of clinic visits per week was 3.6 (2.2-4.8), 2.1 (1.1-3.2), and 4.3 (2.5-6.0) to accept outpatient management among adults, parents, and children, respectively. With thrice weekly clinic visits and 7.5% chance of readmission, probabilities of accepting the outpatient strategy were 50% (44-54%) for adults, 43% (39-48%) for parents, and 53% (46-59%) for children. Using a DCE, we determined that a 7.5% chance of readmission and clinic visits more frequently than thrice weekly are unlikely to be acceptable. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. A systematic review of the reliability and validity of discrete choice experiments in valuing non-market environmental goods.

    PubMed

    Rakotonarivo, O Sarobidy; Schaafsma, Marije; Hockley, Neal

    2016-12-01

    While discrete choice experiments (DCEs) are increasingly used in the field of environmental valuation, they remain controversial because of their hypothetical nature and the contested reliability and validity of their results. We systematically reviewed evidence on the validity and reliability of environmental DCEs from the past thirteen years (Jan 2003-February 2016). 107 articles met our inclusion criteria. These studies provide limited and mixed evidence of the reliability and validity of DCE. Valuation results were susceptible to small changes in survey design in 45% of outcomes reporting reliability measures. DCE results were generally consistent with those of other stated preference techniques (convergent validity), but hypothetical bias was common. Evidence supporting theoretical validity (consistency with assumptions of rational choice theory) was limited. In content validity tests, 2-90% of respondents protested against a feature of the survey, and a considerable proportion found DCEs to be incomprehensible or inconsequential (17-40% and 10-62% respectively). DCE remains useful for non-market valuation, but its results should be used with caution. Given the sparse and inconclusive evidence base, we recommend that tests of reliability and validity are more routinely integrated into DCE studies and suggest how this might be achieved.

  18. Modeling the information preferences of parents of children with mental health problems: a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Deal, Ken; Rimas, Heather; Buchanan, Don H; Gold, Michelle; Sdao-Jarvie, Katherine; Boyle, Michael

    2008-10-01

    Although materials informing parents about children's mental health (CMH) problems can improve outcomes, we know relatively little about the design factors that might influence their utilization of available resources. We used a discrete choice conjoint experiment to model the information preferences of parents seeking mental health services for 6 to 18 year olds. Parents completed 30 choice tasks presenting experimentally varied combinations of 20 four-level CMH information content, transfer process, and outcome attributes. Latent class analysis revealed three segments with different preferences. Parents in the Action segment (43%) chose materials providing step-by-step solutions to behavioral or emotional problems. They preferred weekly meetings with other parents and coaching calls from a therapist. The Information segment (41%) chose materials helping them understand rather than solve their child's problems. These parents were more sensitive to logistical factors such as receiving information in groups, the location where information was available, the modality in which the information was presented, and the time required to obtain and use the information. The Overwhelmed segment (16%) reported more oppositional and conduct problems, felt their children's difficulties exerted a greater adverse impact on family functioning, and reported higher personal depression scores than those in the Action or Information segments. Nonetheless, they did not choose information about, or solutions to, the problems their children presented. Simulations predicted that maximizing utilization and realizing the potential benefits of CMH information would require knowledge transfer strategies consistent with each segment's preferences.

  19. Modeling the bullying prevention program design recommendations of students from grades five to eight: a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Vaillancourt, Tracy; Cunningham, Lesley J; Chen, Yvonne; Ratcliffe, Jenna

    2011-01-01

    We used a discrete choice conjoint experiment to model the bullying prevention recommendations of 845 students from grades 5 to 8 (aged 9-14). Students made choices between experimentally varied combinations of 14 four-level prevention program attributes. Latent class analysis yielded three segments. The high impact segment (27.1%) recommended uniforms, mandatory recess activities, four playground supervisors, surveillance cameras, and 4-day suspensions when students bully. The moderate impact segment (49.5%) recommended discretionary uniforms and recess activities, four playground supervisors, and 3-day suspensions. Involvement as a bully or bully-victim was associated with membership in a low impact segment (23.4%) that rejected uniforms and surveillance cameras. They recommended fewer anti-bullying activities, discretionary recess activities, fewer playground supervisors, and the 2-day suspensions. Simulations predicted most students would recommend a program maximizing student involvement combining prevention with moderate consequences. The simulated introduction of mandatory uniforms, surveillance cameras, and long suspensions reduced overall support for a comprehensive program, particularly among students involved as bullies or bully-victims.

  20. Survival or Mortality: Does Risk Attribute Framing Influence Decision-Making Behavior in a Discrete Choice Experiment?

    PubMed

    Veldwijk, Jorien; Essers, Brigitte A B; Lambooij, Mattijs S; Dirksen, Carmen D; Smit, Henriette A; de Wit, G Ardine

    2016-01-01

    To test how attribute framing in a discrete choice experiment (DCE) affects respondents' decision-making behavior and their preferences. Two versions of a DCE questionnaire containing nine choice tasks were distributed among a representative sample of the Dutch population aged 55 to 65 years. The DCE consisted of four attributes related to the decision regarding participation in genetic screening for colorectal cancer (CRC). The risk attribute included was framed positively as the probability of surviving CRC and negatively as the probability of dying from CRC. Panel mixed-logit models were used to estimate the relative importance of the attributes. The data of the positively and negatively framed DCE were compared on the basis of direct attribute ranking, dominant decision-making behavior, preferences, and importance scores. The majority (56%) of the respondents ranked survival as the most important attribute in the positively framed DCE, whereas only a minority (8%) of the respondents ranked mortality as the most important attribute in the negatively framed DCE. Respondents made dominant choices based on survival significantly more often than based on mortality. The framing of the risk attribute significantly influenced all attribute-level estimates and resulted in different preference structures among respondents in the positively and negatively framed data set. Risk framing affects how respondents value the presented risk. Positive risk framing led to increased dominant decision-making behavior, whereas negative risk framing led to risk-seeking behavior. Attribute framing should have a prominent part in the expert and focus group interviews, and different types of framing should be used in the pilot version of DCEs as well as in actual DCEs to estimate the magnitude of the effect of choosing different types of framing. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  1. Societal preferences for distributive justice in the allocation of health care resources: a latent class discrete choice experiment.

    PubMed

    Skedgel, Chris; Wailoo, Allan; Akehurst, Ron

    2015-01-01

    Economic theory suggests that resources should be allocated in a way that produces the greatest outputs, on the grounds that maximizing output allows for a redistribution that could benefit everyone. In health care, this is known as QALY (quality-adjusted life-year) maximization. This justification for QALY maximization may not hold, though, as it is difficult to reallocate health. Therefore, the allocation of health care should be seen as a matter of distributive justice as well as efficiency. A discrete choice experiment was undertaken to test consistency with the principles of QALY maximization and to quantify the willingness to trade life-year gains for distributive justice. An empirical ethics process was used to identify attributes that appeared relevant and ethically justified: patient age, severity (decomposed into initial quality and life expectancy), final health state, duration of benefit, and distributional concerns. Only 3% of respondents maximized QALYs with every choice, but scenarios with larger aggregate QALY gains were chosen more often and a majority of respondents maximized QALYs in a majority of their choices. However, respondents also appeared willing to prioritize smaller gains to preferred groups over larger gains to less preferred groups. Marginal analyses found a statistically significant preference for younger patients and a wider distribution of gains, as well as an aversion to patients with the shortest life expectancy or a poor final health state. These results support the existence of an equity-efficiency tradeoff and suggest that well-being could be enhanced by giving priority to programs that best satisfy societal preferences. Societal preferences could be incorporated through the use of explicit equity weights, although more research is required before such weights can be used in priority setting. © The Author(s) 2014.

  2. Young People’s Preferences for Family Planning Service Providers in Rural Malawi: A Discrete Choice Experiment

    PubMed Central

    Michaels-Igbokwe, Christine; Terris-Prestholt, Fern; Lagarde, Mylene; Chipeta, Effie; Cairns, John

    2015-01-01

    Objective To quantify the impact of service provider characteristics on young people’s choice of family planning (FP) service provider in rural Malawi in order to identify strategies for increasing access and uptake of FP among youth. Methods and Findings A discrete choice experiment was developed to assess the relative impact of service characteristics on preferences for FP service providers among young people (aged 15–24). Four alternative providers were included (government facility, private facility, outreach and community based distribution of FP) and described by six attributes (the distance between participants’ home and the service delivery point, frequency of service delivery, waiting time at the facility, service providers’ attitude, availability of FP commodities and price). A random parameters logit model was used to estimate preferences for service providers and the likely uptake of services following the expansion of outreach and community based distribution (CBDA) services. In the choice experiment young people were twice as likely to choose a friendly provider (government service odds ratio [OR] = 2.45, p<0.01; private service OR = 1.99, p<0.01; CBDA OR = 1.88, p<0.01) and more than two to three times more likely to choose a provider with an adequate supply of FP commodities (government service OR = 2.48, p<0.01; private service OR = 2.33, p<0.01; CBDA = 3.85, p<0.01). Uptake of community based services was greater than facility based services across a variety of simulated service scenarios indicating that such services may be an effective means of expanding access for youth in rural areas and an important tool for increasing service uptake among youth. Conclusions Ensuring that services are acceptable to young people may require additional training for service providers in order to ensure that all providers are friendly and non-judgemental when dealing with younger clients and to ensure that supplies are consistently available. PMID

  3. Discrete particle model for sheet flow sediment transport in the nearshore

    NASA Astrophysics Data System (ADS)

    Drake, Thomas G.; Calantoni, Joseph

    2001-09-01

    Fully three-dimensional discrete particle computer simulations of high-concentration sheet flow transport in oscillatory flows quantify the effect of fluid acceleration on bed load transport in highly unsteady flows typical of nearshore marine environments. A simple impulse-momentum approach explains simulation results and forms the basis for adding an acceleration-related term to widely used energetics sediment transport formulae. Transport predicted by the acceleration term becomes increasingly significant as wave shape approaches the sawtooth profile characteristic of surf zone bores. Simulations integrate F = ma and a corresponding set of equations for the torques for each sphere. Normal and tangential forces between contacting particles are linear functions of the distance between sphere centers and the relative tangential displacement at the contact point, respectively; particle interactions are both inelastic and frictional. Pressure gradient forces generated by the passage of surface gravity waves drive fluid and particle motion in a stack of thin horizontal fluid layers that exchange momentum and exert fluid drag, added mass, and buoyancy forces on particles. Transport properties of the simulated granular-fluid assemblage are robust to large variations in material properties of the particles. Simulated transport rates agree with available experimental data for unsteady transport of coarse sands; the mode of bed load motion, dispersion of bed load particles, and particle segregation by size and density are qualitatively consistent with available particle-scale observations of bed load transport of natural particles.

  4. Discrete ordinates transport methods for problems with highly forward-peaked scattering

    SciTech Connect

    Pautz, S.D.

    1998-04-01

    The author examines the solutions of the discrete ordinates (S{sub N}) method for problems with highly forward-peaked scattering kernels. He derives conditions necessary to obtain reasonable solutions in a certain forward-peaked limit, the Fokker-Planck (FP) limit. He also analyzes the acceleration of the iterative solution of such problems and offer improvements to it. He extends the analytic Fokker-Planck limit analysis to the S{sub N} equations. This analysis shows that in this asymptotic limit the S{sub N} solution satisfies a pseudospectral discretization of the FP equation, provided that the scattering term is handled in a certain way (which he describes) and that the analytic transport solution satisfies an analytic FP equation. Similar analyses of various spatially discretized S{sub N} equations reveal that they too produce solutions that satisfy discrete FP equations, given the same provisions. Numerical results agree with these theoretical predictions. He defines a multidimensional angular multigrid (ANMG) method to accelerate the iterative solution of highly forward-peaked problems. The analyses show that a straightforward application of this scheme is subject to high-frequency instabilities. However, by applying a diffusive filter to the ANMG corrections he is able to stabilize this method. Fourier analyses of model problems show that the resulting method is effective at accelerating the convergence rate when the scattering is forward-peaked. The numerical results demonstrate that these analyses are good predictors of the actual performance of the ANMG method.

  5. A spatial discretization scheme for solving the transport equation on unstructured grids of polyhedra

    NASA Astrophysics Data System (ADS)

    Thompson, Kelly Glen

    In this work, we develop a new spatial discretization scheme that may be used to numerically solve the neutron transport equation. This new discretization extends the family of corner balance spatial discretizations to include spatial grids of arbitrary polyhedra. This scheme enforces balance on subcell volumes called corners. It produces a lower triangular matrix for sweeping, is algebraically linear, is non-negative in a source-free absorber, and produces a robust and accurate solution in thick diffusive regions. Using an asymptotic analysis, we design the scheme so that in thick diffusive regions it will attain the same solution as an accurate polyhedral diffusion discretization. We then refine the approximations in the scheme to reduce numerical diffusion in vacuums, and we attempt to capture a second order truncation error. After we develop this Upstream Comer Balance Linear (UCBL) discretization we analyze its characteristics in several limits. We complete a full diffusion limit analysis showing that we capture the desired diffusion discretization in optically thick and highly scattering media. We review the upstream and linear properties of our discretization and then demonstrate that our scheme captures strictly non-negative solutions in source-free purely absorbing media. We then demonstrate the minimization of numerical diffusion of a beam and then demonstrate that the scheme is, in general, first order accurate. We also note that for slab-like problems our method actually behaves like a second-order method over a range of cell thicknesses that are of practical interest. We also discuss why our scheme is first order accurate for truly 3D problems and suggest changes in the algorithm that should make it a second-order accurate scheme. Finally, we demonstrate 3D UCBL's performance on several very different test problems. We show good performance in diffusive and streaming problems. We analyze truncation error in a 3D problem and demonstrate robustness in a

  6. A Spatial Discretization Scheme for Solving the Transport Equation on Unstructured Grids of Polyhedra

    SciTech Connect

    Thompson, Kelly Glen

    2000-11-01

    In this work, we develop a new spatial discretization scheme that may be used to numerically solve the neutron transport equation. This new discretization extends the family of corner balance spatial discretizations to include spatial grids of arbitrary polyhedra. This scheme enforces balance on subcell volumes called corners. It produces a lower triangular matrix for sweeping, is algebraically linear, is non-negative in a source-free absorber, and produces a robust and accurate solution in thick diffusive regions. Using an asymptotic analysis, we design the scheme so that in thick diffusive regions it will attain the same solution as an accurate polyhedral diffusion discretization. We then refine the approximations in the scheme to reduce numerical diffusion in vacuums, and we attempt to capture a second order truncation error. After we develop this Upstream Corner Balance Linear (UCBL) discretization we analyze its characteristics in several limits. We complete a full diffusion limit analysis showing that we capture the desired diffusion discretization in optically thick and highly scattering media. We review the upstream and linear properties of our discretization and then demonstrate that our scheme captures strictly non-negative solutions in source-free purely absorbing media. We then demonstrate the minimization of numerical diffusion of a beam and then demonstrate that the scheme is, in general, first order accurate. We also note that for slab-like problems our method actually behaves like a second-order method over a range of cell thicknesses that are of practical interest. We also discuss why our scheme is first order accurate for truly 3D problems and suggest changes in the algorithm that should make it a second-order accurate scheme. Finally, we demonstrate 3D UCBL's performance on several very different test problems. We show good performance in diffusive and streaming problems. We analyze truncation error in a 3D problem and demonstrate robustness in a

  7. Modeling mental health information preferences during the early adult years: a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Walker, John R; Eastwood, John D; Westra, Henny; Rimas, Heather; Chen, Yvonne; Marcus, Madalyn; Swinson, Richard P; Bracken, Keyna; The Mobilizing Minds Research Group

    2014-04-01

    Although most young adults with mood and anxiety disorders do not seek treatment, those who are better informed about mental health problems are more likely to use services. The authors used conjoint analysis to model strategies for providing information about anxiety and depression to young adults. Participants (N = 1,035) completed 17 choice tasks presenting combinations of 15 four-level attributes of a mental health information strategy. Latent class analysis yielded 3 segments. The virtual segment (28.7%) preferred working independently on the Internet to obtain information recommended by young adults who had experienced anxiety or depression. Self-assessment options and links to service providers were more important to this segment. Conventional participants (30.1%) preferred books or pamphlets recommended by a doctor, endorsed by mental health professionals, and used with a doctor's support. They would devote more time to information acquisition but were less likely to use Internet social networking options. Brief sources of information were more important to the low interest segment (41.2%). All segments preferred information about alternative ways to reduce anxiety or depression rather than psychological approaches or medication. Maximizing the use of information requires active and passive approaches delivered through old-media (e.g., books) and new-media (e.g., Internet) channels.

  8. Modeling Mental Health Information Preferences During the Early Adult Years: A Discrete Choice Conjoint Experiment

    PubMed Central

    Cunningham, Charles E.; Walker, John R.; Eastwood, John D.; Westra, Henny; Rimas, Heather; Chen, Yvonne; Marcus, Madalyn; Swinson, Richard P.; Bracken, Keyna

    2013-01-01

    Although most young adults with mood and anxiety disorders do not seek treatment, those who are better informed about mental health problems are more likely to use services. The authors used conjoint analysis to model strategies for providing information about anxiety and depression to young adults. Participants (N = 1,035) completed 17 choice tasks presenting combinations of 15 four-level attributes of a mental health information strategy. Latent class analysis yielded 3 segments. The virtual segment (28.7%) preferred working independently on the Internet to obtain information recommended by young adults who had experienced anxiety or depression. Self-assessment options and links to service providers were more important to this segment. Conventional participants (30.1%) preferred books or pamphlets recommended by a doctor, endorsed by mental health professionals, and used with a doctor's support. They would devote more time to information acquisition but were less likely to use Internet social networking options. Brief sources of information were more important to the low interest segment (41.2%). All segments preferred information about alternative ways to reduce anxiety or depression rather than psychological approaches or medication. Maximizing the use of information requires active and passive approaches delivered through old-media (e.g. books) and new-media (e.g., Internet) channels. PMID:24266450

  9. Three Dimensional Flow, Transport and Geomechanical Simulations in Discrete Fracture Network Under Condition of Uncertainty

    NASA Astrophysics Data System (ADS)

    Ryerson, F. J.; Ezzedine, S. M.; Glascoe, L. G.; Antoun, T. H.

    2011-12-01

    Fractures and fracture networks are the principle pathways for migration of water, heat and mass in enhanced geothermal systems, oil and gas reservoirs, CO2 leakage from saline aquifers, and radioactive and toxic industrial wastes from underground storage repositories. A major issue to overcome when characterizing a fractured reservoir is that of data limitation due to accessibility and affordability. Moreover, the ability to map discontinuities in the rock with available geological and geophysical tools tends to decrease particularly as the scale of the discontinuity goes down. Data collected are often reduced to probability distribution functions for predictive modeling and simulation in a stochastic framework such as stochastic discrete fracture network. Stochastic discrete fracture network models enable probabilistic assessment of flow, transport and geomechanical phenomena that are not adequately captured using continuum models. Despite the fundamental uncertainties inherited within the probabilistic reduction of the sparse data collected, very little work has been conducted on quantifying uncertainty on the reduced probabilistic distribution functions. In the current study, we investigate the impact of parameter uncertainties of the distribution functions that characterize discrete fracture networks on the flow, heat and mass transport and geomechanics. Numerical results of first, second and third moments, normalized to a base case scenario, are presented and compared to theoretical results extended from percolation theory. (Prepared by LLNL under Contract DE-AC52-07NA27344)

  10. Understanding transporter specificity and the discrete appearance of channel-like gating domains in transporters

    PubMed Central

    Diallinas, George

    2014-01-01

    Transporters are ubiquitous proteins mediating the translocation of solutes across cell membranes, a biological process involved in nutrition, signaling, neurotransmission, cell communication and drug uptake or efflux. Similarly to enzymes, most transporters have a single substrate binding-site and thus their activity follows Michaelis-Menten kinetics. Substrate binding elicits a series of structural changes, which produce a transporter conformer open toward the side opposite to the one from where the substrate was originally bound. This mechanism, involving alternate outward- and inward-facing transporter conformers, has gained significant support from structural, genetic, biochemical and biophysical approaches. Most transporters are specific for a given substrate or a group of substrates with similar chemical structure, but substrate specificity and/or affinity can vary dramatically, even among members of a transporter family that show high overall amino acid sequence and structural similarity. The current view is that transporter substrate affinity or specificity is determined by a small number of interactions a given solute can make within a specific binding site. However, genetic, biochemical and in silico modeling studies with the purine transporter UapA of the filamentous ascomycete Aspergillus nidulans have challenged this dogma. This review highlights results leading to a novel concept, stating that substrate specificity, but also transport kinetics and transporter turnover, are determined by subtle intramolecular interactions between a major substrate binding site and independent outward- or cytoplasmically-facing gating domains, analogous to those present in channels. This concept is supported by recent structural evidence from several, phylogenetically and functionally distinct transporter families. The significance of this concept is discussed in relationship to the role and potential exploitation of transporters in drug action. PMID:25309439

  11. Getting to School: A Proposal for a Federal School Choice Transportation Tax Credit.

    ERIC Educational Resources Information Center

    Ehrenberg, Eric L.

    1996-01-01

    Describes different forms of school choice plans and the arguments in favor of and against such plans. Proposes a federal tax credit for the transportation costs for parents who enroll their children in schools of choice. Offers evidence that other federal tax credits have influenced the behavior they were designed to influence. (58 footnotes)…

  12. Discrete Element Method simulations of the saturation of aeolian sand transport

    NASA Astrophysics Data System (ADS)

    Pähtz, Thomas; Omeradžić, Amir; Carneiro, Marcus V.; Araújo, Nuno A. M.; Herrmann, Hans J.

    2015-03-01

    The saturation length of aeolian sand transport (Ls), characterizing the distance needed by wind-blown sand to adapt to changes in the wind shear, is essential for accurate modeling of the morphodynamics of Earth's sandy landscapes and for explaining the formation and shape of sand dunes. In the last decade, it has become a widely accepted hypothesis that Ls is proportional to the characteristic distance needed by transported particles to reach the wind speed (the "drag length"). Here we challenge this hypothesis. From extensive numerical Discrete Element Method simulations, we find that, for medium and strong winds, Ls∝Vs2/g, where Vs is the saturated value of the average speed of sand particles traveling above the surface and g is the gravitational constant. We show that this proportionality is consistent with a recent analytical model, in which the drag length is just one of four similarly important length scales relevant for sand transport saturation.

  13. Alternative-Specific and Case-Specific Factors Involved in the Decisions of Islamic School Teachers Affecting Teacher Retention: A Discrete Choice Experiment

    ERIC Educational Resources Information Center

    Abd-El-Hafez, Alaa Karem

    2015-01-01

    Teacher retention is a concern in all educational sectors in America. It is of special importance to Islamic schools, which tend to lack the resources necessary in recruiting and training new teachers. This dissertation addressed this problem in full-time Islamic schools in New York State by conducting a discrete choice experiment, which reflects…

  14. Alternative-Specific and Case-Specific Factors Involved in the Decisions of Islamic School Teachers Affecting Teacher Retention: A Discrete Choice Experiment

    ERIC Educational Resources Information Center

    Abd-El-Hafez, Alaa Karem

    2015-01-01

    Teacher retention is a concern in all educational sectors in America. It is of special importance to Islamic schools, which tend to lack the resources necessary in recruiting and training new teachers. This dissertation addressed this problem in full-time Islamic schools in New York State by conducting a discrete choice experiment, which reflects…

  15. Understanding rational non-adherence to medications. A discrete choice experiment in a community sample in Australia

    PubMed Central

    2012-01-01

    Background In spite of the potential impact upon population health and expenditure, interventions promoting medication adherence have been found to be of moderate effectiveness and cost effectiveness. Understanding the relative influence of factors affecting patient medication adherence decisions and the characteristics of individuals associated with variation in adherence will lead to a better understanding of how future interventions should be designed and targeted. This study aims to explore medication-taking decisions that may underpin intentional medication non-adherence behaviour amongst a community sample and the relative importance of medication specific factors and patient background characteristics contributing to those decisions. Methods A discrete choice experiment conducted through a web-enabled online survey was used to estimate the relative importance of eight medication factors (immediate and long-term medication harms and benefits, cost, regimen, symptom severity, alcohol restrictions) on the preference to continue taking a medication. To reflect more closely what usually occurs in practice, non-disease specific medication and health terms were used to mimic decisions across multiple medications and conditions.161 general community participants, matching the national Australian census data (age, gender) were recruited through an online panel provider (participation rate: 10%) in 2010. Results Six of the eight factors (i.e. immediate and long-term medication harms and benefits, cost, and regimen) had a significant influence on medication choice. Patient background characteristics did not improve the model. Respondents with private health insurance appeared less sensitive to cost then those without private health insurance. In general, health outcomes, framed as a side-effect, were found to have a greater influence over adherence than outcomes framed as therapeutic benefits. Conclusions Medication-taking decisions are the subject of rational choices

  16. GPU accelerated simulations of 3D deterministic particle transport using discrete ordinates method

    NASA Astrophysics Data System (ADS)

    Gong, Chunye; Liu, Jie; Chi, Lihua; Huang, Haowei; Fang, Jingyue; Gong, Zhenghu

    2011-07-01

    Graphics Processing Unit (GPU), originally developed for real-time, high-definition 3D graphics in computer games, now provides great faculty in solving scientific applications. The basis of particle transport simulation is the time-dependent, multi-group, inhomogeneous Boltzmann transport equation. The numerical solution to the Boltzmann equation involves the discrete ordinates ( Sn) method and the procedure of source iteration. In this paper, we present a GPU accelerated simulation of one energy group time-independent deterministic discrete ordinates particle transport in 3D Cartesian geometry (Sweep3D). The performance of the GPU simulations are reported with the simulations of vacuum boundary condition. The discussion of the relative advantages and disadvantages of the GPU implementation, the simulation on multi GPUs, the programming effort and code portability are also reported. The results show that the overall performance speedup of one NVIDIA Tesla M2050 GPU ranges from 2.56 compared with one Intel Xeon X5670 chip to 8.14 compared with one Intel Core Q6600 chip for no flux fixup. The simulation with flux fixup on one M2050 is 1.23 times faster than on one X5670.

  17. GPU accelerated simulations of 3D deterministic particle transport using discrete ordinates method

    SciTech Connect

    Gong Chunye; Liu Jie; Chi Lihua; Huang Haowei; Fang Jingyue; Gong Zhenghu

    2011-07-01

    Graphics Processing Unit (GPU), originally developed for real-time, high-definition 3D graphics in computer games, now provides great faculty in solving scientific applications. The basis of particle transport simulation is the time-dependent, multi-group, inhomogeneous Boltzmann transport equation. The numerical solution to the Boltzmann equation involves the discrete ordinates (S{sub n}) method and the procedure of source iteration. In this paper, we present a GPU accelerated simulation of one energy group time-independent deterministic discrete ordinates particle transport in 3D Cartesian geometry (Sweep3D). The performance of the GPU simulations are reported with the simulations of vacuum boundary condition. The discussion of the relative advantages and disadvantages of the GPU implementation, the simulation on multi GPUs, the programming effort and code portability are also reported. The results show that the overall performance speedup of one NVIDIA Tesla M2050 GPU ranges from 2.56 compared with one Intel Xeon X5670 chip to 8.14 compared with one Intel Core Q6600 chip for no flux fixup. The simulation with flux fixup on one M2050 is 1.23 times faster than on one X5670.

  18. Women's preferences for obstetric care in rural Ethiopia: a population-based discrete choice experiment in a region with low rates of facility delivery.

    PubMed

    Kruk, M E; Paczkowski, M M; Tegegn, A; Tessema, F; Hadley, C; Asefa, M; Galea, S

    2010-11-01

    Delivery attended by skilled professionals is essential to reducing maternal mortality. Although the facility delivery rate in Ethiopia's rural areas is extremely low, little is known about which health system characteristics most influence women's preferences for delivery services. In this study, women's preferences for attributes of health facilities for delivery in rural Ethiopia were investigated. A population-based discrete choice experiment (DCE) was fielded in Gilgel Gibe, in southwest Ethiopia, among women with a delivery in the past 5 years. Women were asked to select a hypothetical health facility for future delivery from two facilities on a picture card. A hierarchical Bayesian procedure was used to estimate utilities associated with facility attributes: distance, type of provider, provider attitude, drugs and medical equipment, transport and cost. 1006 women completed 8045 DCE choice tasks. Among them, 93.8% had delivered their last child at home. The attributes with the greatest influence on the overall utility of a health facility for delivery were availability of drugs and equipment (mean β=3.9, p<0.01), seeing a doctor versus a health extension worker (mean β=2.1, p<0.01) and a receptive provider attitude (mean β=1.4, p<0.01). Women in rural southwest Ethiopia who have limited personal experience with facility delivery nonetheless value health facility attributes that indicate high technical quality: availability of drugs and equipment and physician providers. Well-designed policy experiments that measure the contribution of quality improvements to facility delivery rates in Ethiopia and other countries with low health service utilisation and high maternal mortality may inform national efforts to reduce maternal mortality.

  19. A discrete choice experiment to explore patients' willingness to risk disease relapse from treatment withdrawal in psoriatic arthritis.

    PubMed

    Rothery, Claire; Bojke, Laura; Richardson, Gerry; Bojke, Chris; Moverley, Anna; Coates, Laura; Thorp, Liz; Waxman, Robin; Helliwell, Philip

    2016-12-01

    The objective of this study is to assess patient preferences for treatment-related benefits and risk of disease relapse in the management of low disease states of psoriatic arthritis (PsA). Focus groups with patients and a literature review were undertaken to determine the characteristics of treatment and symptoms of PsA important to patients. Patient preferences were assessed using a discrete choice experiment which compared hypothetical treatment profiles of the risk and benefits of treatment withdrawal. The risk outcome included increased risk of disease relapse, while benefit outcomes included reduced sickness/nausea from medication and changes in health-related quality of life. Each patient completed 12 choice sets comparing treatment profiles. Preference weights were estimated using a logic regression model, and the maximum acceptable risk in disease relapse for a given improvement in benefit outcomes was elicited. Final sample included 136 patients. Respondents attached the greatest importance to eliminating severe side effects of sickness/nausea and the least importance to a change in risk of relapse. Respondents were willing to accept an increase in the risk of relapse of 32.6 % in order to eliminate the side effects of sickness/nausea. For improvements in health status, the maximum acceptable risk in relapse was comparable to a movement from some to no sickness/nausea. The study suggests that patients in low disease states of PsA are willing to accept greater risks of relapse for improvements in side effects of sickness/nausea and overall health status, with the most important benefit attribute being the elimination of severe sickness or nausea.

  20. Job Preferences of Nurses and Midwives for Taking Up a Rural Job in Peru: A Discrete Choice Experiment

    PubMed Central

    Huicho, Luis; Miranda, J. Jaime; Diez-Canseco, Francisco; Lema, Claudia; Lescano, Andrés G.; Lagarde, Mylene; Blaauw, Duane

    2012-01-01

    Background Robust evidence on interventions to improve the shortage of health workers in rural areas is needed. We assessed stated factors that would attract short-term contract nurses and midwives to work in a rural area of Peru. Methods and Findings A discrete choice experiment (DCE) was conducted to evaluate the job preferences of nurses and midwives currently working on a short-term contract in the public sector in Ayacucho, Peru. Job attributes, and their levels, were based on literature review, qualitative interviews and focus groups of local health personnel and policy makers. A labelled design with two choices, rural community or Ayacucho city, was used. Job attributes were tailored to these settings. Multiple conditional logistic regressions were used to assess the determinants of job preferences. Then we used the best-fitting estimated model to predict the impact of potential policy incentives on the probability of choosing a rural job or a job in Ayacucho city. We studied 205 nurses and midwives. The odds of choosing an urban post was 14.74 times than that of choosing a rural one. Salary increase, health center-type of facility and scholarship for specialization were preferred attributes for choosing a rural job. Increased number of years before securing a permanent contract acted as a disincentive for both rural and urban jobs. Policy simulations showed that the most effective attraction package to uptake a rural job included a 75% increase in salary plus scholarship for a specialization, which would increase the proportion of health workers taking a rural job from 36.4% up to 60%. Conclusions Urban jobs were more strongly preferred than rural ones. However, combined financial and non-financial incentives could almost double rural job uptake by nurses and midwifes. These packages may provide meaningful attraction strategies to rural areas and should be considered by policy makers for implementation. PMID:23284636

  1. Ordinal preference elicitation methods in health economics and health services research: using discrete choice experiments and ranking methods.

    PubMed

    Ali, Shehzad; Ronaldson, Sarah

    2012-09-01

    The predominant method of economic evaluation is cost-utility analysis, which uses cardinal preference elicitation methods, including the standard gamble and time trade-off. However, such approach is not suitable for understanding trade-offs between process attributes, non-health outcomes and health outcomes to evaluate current practices, develop new programmes and predict demand for services and products. Ordinal preference elicitation methods including discrete choice experiments and ranking methods are therefore commonly used in health economics and health service research. Cardinal methods have been criticized on the grounds of cognitive complexity, difficulty of administration, contamination by risk and preference attitudes, and potential violation of underlying assumptions. Ordinal methods have gained popularity because of reduced cognitive burden, lower degree of abstract reasoning, reduced measurement error, ease of administration and ability to use both health and non-health outcomes. The underlying assumptions of ordinal methods may be violated when respondents use cognitive shortcuts, or cannot comprehend the ordinal task or interpret attributes and levels, or use 'irrational' choice behaviour or refuse to trade-off certain attributes. CURRENT USE AND GROWING AREAS: Ordinal methods are commonly used to evaluate preference for attributes of health services, products, practices, interventions, policies and, more recently, to estimate utility weights. AREAS FOR ON-GOING RESEARCH: There is growing research on developing optimal designs, evaluating the rationalization process, using qualitative tools for developing ordinal methods, evaluating consistency with utility theory, appropriate statistical methods for analysis, generalizability of results and comparing ordinal methods against each other and with cardinal measures.

  2. Preferences for evidence-based practice dissemination in addiction agencies serving women: a discrete-choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Henderson, Joanna; Niccols, Alison; Dobbins, Maureen; Sword, Wendy; Chen, Yvonne; Mielko, Stephanie; Milligan, Karen; Lipman, Ellen; Thabane, Lehana; Schmidt, Louis

    2012-08-01

      To model variables influencing the dissemination of evidence-based practices to addiction service providers and administrators.   A discrete-choice conjoint experiment. We systematically varied combinations of 16 dissemination variables that might influence the adoption of evidence-based practices. Participants chose between sets of variables.   Canadian agencies (n = 333) providing addiction services to women.   Service providers and administrators (n = 1379).   We estimated the relative importance and optimal level of each dissemination variable. We used latent class analysis to identify subsets of participants with different preferences and simulated the conditions under which participants would use more demanding professional development options.   Three subsets of participants were identified: outcome-sensitive (52%), process-sensitive (29.6%) and demand-sensitive (18.2%). Across all participants, the number of clients who were expected to benefit from an evidence-based practice exerted the most influence on dissemination choices. If a practice was seen as feasible, co-worker and administrative support influenced decisions. Client benefits were most important to outcome-sensitive participants; type of dissemination process (e.g. active versus passive learning) was more important to process-sensitive participants. Brief options with little follow-up were preferred by demand-sensitive participants. Simulations predicted that initiatives selected and endorsed by government funders would reduce participation.   Clinicians and administrators are more likely to adopt evidence-based addiction practices if the practice is seen as helpful to clients, and if it is supported by co-workers and program administration. © 2012 The Authors, Addiction © 2012 Society for the Study of Addiction.

  3. Differences in waiting list prioritization preferences of occupational therapists, elderly people and persons with disabilities: a discrete choice experiment.

    PubMed

    Raymond, Marie-Hélène; Demers, Louise; Feldman, Debbie E

    2017-08-07

    To compare the preferences of occupational therapists, elderly people and adults with disabilities regarding prioritization criteria for occupational therapy waiting lists in home care. Discrete choice experiment survey. Respondents completed eight choice tasks where they were asked to choose which of two referral scenarios should be prioritized for services. Scenarios varied in terms of four attributes reflecting competing issues that come into play in waiting list prioritization: the person's ability to shower, ability to enter and exit the home, history of falls and time already spent on the waiting list. The survey was mailed to occupational therapists working in home care and community-dwelling elderly or disabled persons. Not applicable. 241 home-based occupational therapists, 226 elderly persons from a bank of research participants and 247 adults with physical disabilities recruited through community organizations. The dependent variable was whether the referral scenario was prioritized or not in each question. Results were analyzed through logistic regression using conditional logit models. Prioritization preferences differed between groups (p < 0.001). Occupational therapists most strongly prioritized people who had had a few falls (OR vs. no falls = 48.9) whereas elderly people and adults with disabilities most strongly prioritized people who were unable to enter and exit the home (OR vs. no difficulty entering and exiting the home = 30.8 for elderly people and 16.9 for persons with disabilities.) CONCLUSIONS: Our results highlight the gap between the priorities of home-based occupational therapists and their target clientele. Although further inquiry is needed to inform priority-setting, the findings emphasize the importance of public or patient involvement in decisions on waiting list prioritization. Copyright © 2017. Published by Elsevier Inc.

  4. Priority setting in the Austrian healthcare system: results from a discrete choice experiment and implications for mental health.

    PubMed

    Mentzakis, Emmanouil; Paolucci, Francesco; Rubicko, Georg

    2014-06-01

    The impact of mental conditions is expected to be among the highest ranked causes of illness in high income countries by 2020. With changing health needs, policy makers have to make choices in an environment with increasingly constrained resources and competing demands. Discrete choice experiments have been identified as a useful approach to inform and support decision-making in health care systems and, in particular, its rationing. Policymakers, researchers and health practitioners from Austria participated in an experiment designed to elicit preferences for efficiency and equity in a generic priority setting framework. Using aggregate criteria an empirical measure of the efficiency/equity trade-off is calculated and a selection of health care interventions, including mental health, are ranked in composite league tables (CLTs). With the exception of severity of the condition, all equity parameters decrease attractiveness of an intervention, whereas the opposite holds for all three efficiency criteria. The efficiency/equity ratio (i.e. decision-makers' preference for efficiency over equity) is 3.5 and 5 for interventions targeted at younger and middle age populations, respectively, while for older populations this ratio is negative implying a rejection of all equity criteria. Irrespective of such differences interventions targeting mental health rank highly on all CLTs. Based on system-wide generic decision making criteria, mental health is shown to be a top priority for Austria. Preference-based approaches might offer complementary information to policymakers in priority setting decisions and a useful tool to support rationale rather than ad hoc decision-making.

  5. Generalized perturbation theory using two-dimensional, discrete ordinates transport theory

    SciTech Connect

    Childs, R.L.

    1980-06-01

    Perturbation theory for changes in linear and bilinear functionals of the forward and adjoint fluxes in a critical reactor has been implemented using two-dimensional discrete ordinates transport theory. The computer program DOT IV was modified to calculate the generalized functions GAMMA and GAMMA*. Demonstration calculations were performed for changes in a reaction-rate ratio and a reactivity worth caused by system perturbations. The perturbation theory predictions agreed with direct calculations to within about 2%. A method has been developed for calculating higher lambda eigenvalues and eigenfunctions using techniques similar to those developed for generalized functions. Demonstration calculations have been performed to obtain these eigenfunctions.

  6. Low-energy electron transport with the method of discrete ordinates

    NASA Technical Reports Server (NTRS)

    Bartine, D. E.; Alsmiller, R. G., Jr.; Mynatt, F. R.; Engle, W. W., Jr.; Barish, J.

    1972-01-01

    The one-dimensional discrete ordinates code ANISN was adapted to transport low energy (a few MeV) electrons. Calculated results obtained with ANISN were compared with experimental data for transmitted electron energy and angular distribution data for electrons normally incident on aluminum slabs of various thicknesses. The calculated and experimental results are in good agreement for a thin slab (0.2 of the electron range), but not for the thicker slabs (0.6 of the electron range). Calculated results obtained with ANISN were also compared with results obtained using Monte Carlo methods.

  7. A Polar Discrete Ordinate Radiation Transport Method for 2D ALE Meshes in HYDRA

    NASA Astrophysics Data System (ADS)

    Chang, Britton; Marinak, Marty; Weber, Chris; Peterson, Luc

    2016-10-01

    The Polar Discrete Ordinate Radiation Transport Method in HYDRA has been extended to handle general 2D r-z meshes. Previously the method was only for orthogonal 2D meshes. The new method can be employed with the ALE methodology for managing mesh motion that is used to simulate Rayleigh-Taylor and Richtmyer-Meshkov instabilities on NIF capsule implosions. The results of an examination of this kind will be compared to those obtained by the corresponding diffusion method. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

  8. A Coupled Discrete/Continuum Model for Describing Cancer-Therapeutic Transport in the Lung

    PubMed Central

    Erbertseder, Karin; Reichold, Johannes; Flemisch, Bernd; Jenny, Patrick; Helmig, Rainer

    2012-01-01

    We propose a computational simulation framework for describing cancer-therapeutic transport in the lung. A discrete vascular graph model (VGM) is coupled to a double-continuum model (DCM) to determine the amount of administered therapeutic agent that will reach the cancer cells. An alveolar cell carcinoma is considered. The processes in the bigger blood vessels (arteries, arterioles, venules and veins) are described by the VGM. The processes in the alveolar capillaries and the surrounding tissue are represented by a continuum approach for porous media. The system of equations of the coupled discrete/continuum model contains terms that account for degradation processes of the therapeutic agent, the reduction of the number of drug molecules by the lymphatic system and the interaction of the drug with the tissue cells. The functionality of the coupled discrete/continuum model is demonstrated in example simulations using simplified pulmonary vascular networks, which are designed to show-off the capabilities of the model rather than being physiologically accurate. PMID:22438873

  9. Farmers' valuation of incentives to produce genetically modified organism-free milk: Insights from a discrete choice experiment in Germany.

    PubMed

    Schreiner, J A; Latacz-Lohmann, U

    2015-11-01

    This paper investigates farmers' willingness to participate in a genetically modified organism (GMO)-free milk production scheme offered by some German dairy companies. The empirical analysis is based upon discrete choice experiments with 151 dairy farmers from 2 regions in Germany. A conditional logit estimation reveals a strong positive effect of the price premium on offer. Reliable feed monitoring and free technical support increase the likelihood of scheme adoption, the latter however only in farms that have been receiving technical support in other fields. By contrast, any interference with the entrepreneurial autonomy of farmers, through pre-arranged feed procurement or prescriptive advice on the part of the dairy company, lowers acceptance probabilities. Farmers' attitudes toward cultivation of genetically modified soy, their assessment of the market potential of GMO-free milk and future feed prices were found to be significant determinants of adoption, as are farmer age, educational status, and current feeding regimens. Respondents requested on average a mark-up of 0.80 eurocents per kilogram of milk to accept a contract. Comparison of the estimates for the 2 regions suggests that farmers in northern Germany are, on average, more likely to convert to genetically modified-free production; however, farmers in the south are, ceteris paribus, more responsive to an increase in the price premium offered. A latent class model reveals significant differences in the valuation of scheme attributes between 2 latent classes of adopters and nonadopters. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  10. Preferences for genetic testing for colorectal cancer within a population-based screening program: a discrete choice experiment

    PubMed Central

    Veldwijk, Jorien; Lambooij, Mattijs S; Kallenberg, Frank G J; van Kranen, Henk J; Bredenoord, Annelien L; Dekker, Evelien; Smit, Henriëtte A; de Wit, G Ardine

    2016-01-01

    This study explored individuals' preferences for genetic testing for colorectal cancer (CRC) in a screening situation and their willingness to participate in genetic testing for Lynch syndrome, familial adenomatous polyposis (FAP), and familial colorectal cancer (FCC). For that purpose, 532 respondents aged 55–65 years completed a Discrete Choice Experiment. Using panel latent class models, the preferences for two screening situation characteristics (the probability of being genetically predisposed and the probability of developing CRC) and screening test characteristics (the frequency of preventive colonoscopies and CRC survival) were estimated. Based on these preferences, respondents' willingness to participate in the three screening initiatives was estimated. Lower-educated respondents and respondents who express serious anxiety and worries found colonoscopy frequency and the probability of developing CRC relatively more important and survival relatively less important compared with higher-educated respondents and respondents who express no anxiety and worries. These differences in preferences resulted in opposite preferences for participation in FCC and FAP screening. In conclusion, the general population is willing to participate in genetic screening for CRC. If individuals are suspected of genetic or familial CRC, they should at least be informed about their increased risk of being genetically predisposed and about the importance of participating in all preventive follow-up colonoscopies in order to maximize survival. PMID:26036860

  11. Testing a discrete choice experiment including duration to value health states for large descriptive systems: Addressing design and sampling issues

    PubMed Central

    Bansback, Nick; Hole, Arne Risa; Mulhern, Brendan; Tsuchiya, Aki

    2014-01-01

    There is interest in the use of discrete choice experiments that include a duration attribute (DCETTO) to generate health utility values, but questions remain on its feasibility in large health state descriptive systems. This study examines the stability of DCETTO to estimate health utility values from the five-level EQ-5D, an instrument with depicts 3125 different health states. Between January and March 2011, we administered 120 DCETTO tasks based on the five-level EQ-5D to a total of 1799 respondents in the UK (each completed 15 DCETTO tasks on-line). We compared models across different sample sizes and different total numbers of observations. We found the DCETTO coefficients were generally consistent, with high agreement between individual ordinal preferences and aggregate cardinal values. Keeping the DCE design and the total number of observations fixed, subsamples consisting of 10 tasks per respondent with an intermediate sized sample, and 15 tasks with a smaller sample provide similar results in comparison to the whole sample model. In conclusion, we find that the DCETTO is a feasible method for developing values for larger descriptive systems such as EQ-5D-5L, and find evidence supporting important design features for future valuation studies that use the DCETTO. PMID:24908173

  12. Testing a discrete choice experiment including duration to value health states for large descriptive systems: addressing design and sampling issues.

    PubMed

    Bansback, Nick; Hole, Arne Risa; Mulhern, Brendan; Tsuchiya, Aki

    2014-08-01

    There is interest in the use of discrete choice experiments that include a duration attribute (DCETTO) to generate health utility values, but questions remain on its feasibility in large health state descriptive systems. This study examines the stability of DCETTO to estimate health utility values from the five-level EQ-5D, an instrument with depicts 3125 different health states. Between January and March 2011, we administered 120 DCETTO tasks based on the five-level EQ-5D to a total of 1799 respondents in the UK (each completed 15 DCETTO tasks on-line). We compared models across different sample sizes and different total numbers of observations. We found the DCETTO coefficients were generally consistent, with high agreement between individual ordinal preferences and aggregate cardinal values. Keeping the DCE design and the total number of observations fixed, subsamples consisting of 10 tasks per respondent with an intermediate sized sample, and 15 tasks with a smaller sample provide similar results in comparison to the whole sample model. In conclusion, we find that the DCETTO is a feasible method for developing values for larger descriptive systems such as EQ-5D-5L, and find evidence supporting important design features for future valuation studies that use the DCETTO. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Is the value of a life or life-year saved context specific? Further evidence from a discrete choice experiment

    PubMed Central

    Mortimer, Duncan; Segal, Leonie

    2008-01-01

    Background A number of recent findings imply that the value of a life saved, life-year (LY) saved or quality-adjusted life year (QALY) saved varies depending on the characteristics of the life, LY or QALY under consideration. Despite these findings, budget allocations continue to be made as if all healthy life-years are equivalent. This continued focus on simple health maximisation is partly attributable to gaps in the available evidence. The present study attempts to close some of these gaps. Methods Discrete choice experiment to estimate the marginal rate of substitution between cost, effectiveness and various non-health arguments. Odds of selecting profile B over profile A estimated via binary logistic regression. Marginal rates of substitution between attributes (including cost) then derived from estimated regression coefficients. Results Respondents were more likely to select less costly, more effective interventions with a strong evidence base where the beneficiary did not contribute to their illness. Results also suggest that respondents preferred prevention over cure. Interventions for young children were most preferred, followed by interventions for young adults, then interventions for working age adults and with interventions targeted at the elderly given lowest priority. Conclusion Results confirm that a trade-off exists between cost, effectiveness and non-health arguments when respondents prioritise health programs. That said, it is true that respondents were more likely to select less costly, more effective interventions – confirming that it is an adjustment to, rather than an outright rejection of, simple health maximisation that is required. PMID:18489787

  14. Deriving welfare measures from discrete choice experiments: inconsistency between current methods and random utility and welfare theory.

    PubMed

    Lancsar, Emily; Savage, Elizabeth

    2004-09-01

    Discrete choice experiments (DCEs) are being used increasingly in health economics to elicit preferences for products and programs. The results of such experiments have been used to calculate measures of welfare or more specifically, respondents' 'willingness to pay' (WTP) for products and programs and their 'marginal willingness to pay' (MWTP) for the attributes that make up such products and programs. In this note we show that the methods currently used to derive measures of welfare from DCEs in the health economics literature are not consistent with random utility theory (RUT), or with microeconomic welfare theory more generally. The inconsistency with welfare theory is an important limitation on the use of such WTP estimates in cost-benefit analyses. We describe an alternative method of deriving measures of welfare (compensating variation) from DCEs that is consistent with RUT and is derived using welfare theory. We demonstrate its use in an empirical application to derive the WTP for asthma medication and compare it to the results elicited from the method currently used in the health economics literature.

  15. Patients' Preferences for Outcome, Process and Cost Attributes in Cancer Treatment: A Systematic Review of Discrete Choice Experiments.

    PubMed

    Bien, Daniela R; Danner, Marion; Vennedey, Vera; Civello, Daniele; Evers, Silvia M; Hiligsmann, Mickaël

    2017-03-31

    As several studies have been conducted to elicit patients' preferences for cancer treatment, it is important to provide an overview and synthesis of these studies. This study aimed to systematically review discrete choice experiments (DCEs) about patients' preferences for cancer treatment and assessed the relative importance of outcome, process and cost attributes. A systematic literature review was conducted using PubMed and EMBASE to identify all DCEs investigating patients' preferences for cancer treatment between January 2010 and April 2016. Data were extracted using a predefined extraction sheet, and a reporting quality assessment was applied to all studies. Attributes were classified into outcome, process and cost attributes, and their relative importance was assessed. A total of 28 DCEs were identified. More than half of the studies (56%) received an aggregate score lower than 4 on the PREFS (Purpose, Respondents, Explanation, Findings, Significance) 5-point scale. Most attributes were related to outcome (70%), followed by process (25%) and cost (5%). Outcome attributes were most often significant (81%), followed by process (73%) and cost (67%). The relative importance of outcome attributes was ranked highest in 82% of the cases where it was included, followed by cost (43%) and process (12%). This systematic review suggests that attributes related to cancer treatment outcomes are the most important for patients. Process and cost attributes were less often included in studies but were still (but less) important to patients in most studies. Clinicians and decision makers should be aware that attribute importance might be influenced by level selection for that attribute.

  16. Preferences of Bulgarian consumers for quality, access and price attributes of healthcare services-result of a discrete choice experiment.

    PubMed

    van de Schoot, Thijs; Pavlova, Milena; Atanasova, Elka; Groot, Wim

    2017-01-01

    The aim of the study is to determine the preferences of Bulgarian citizens regarding the provision of healthcare services. A survey was carried out in Bulgaria among a nationally representative sample of 1003 respondents. Both a discrete choice experiment and a self-explicated ranking of outpatient and inpatient service attributes were included in the survey. The data are analyzed to elicit the preferences of Bulgarian healthcare consumers for service attributes and to compare them with previous studies in Bulgaria and other countries in Central and Eastern Europe. The reputation and skills of the care provider appear to be relatively most important to the respondents, followed by the state of the equipment, the condition of the facility and the attitude of the staff. The fee-level and access-related attributes (waiting and traveling time) emerged as less important. Overall, consumers in Bulgaria value the quality of healthcare provision very highly. Yet, there are some statistically significant differences between socio-demographic groups. In general, Bulgarian healthcare consumers are willing to accept higher prices for the services they use, when this comes with improved quality of services. These findings comply with findings in previous studies in Bulgaria and in the region. Given the quality problems in the Bulgarian healthcare sector, our findings indicate that priority has to be given to the improvement of healthcare quality when the Bulgarian government invests in this sector. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  17. How to make rural jobs more attractive to health workers. Findings from a discrete choice experiment in Tanzania.

    PubMed

    Kolstad, Julie Riise

    2011-02-01

    The geographical imbalance of the health workforce in Tanzania represents a serious problem when it comes to delivering crucial health services to a large share of the population. This study provides new quantitative information about how to make jobs in rural areas more attractive to newly educated clinical officers (COs). A unique data set stemming from a discrete choice experiment with CO finalists in Tanzania is applied. The results show that offering continuing education after a certain period of service is one of the most powerful recruitment instruments the authorities have available. Increased salaries and hardship allowances will also substantially increase recruitment in rural areas. Offers of decent housing and good infrastructure, including the provision of equipment, will increase recruitment to rural remote areas but not as much as higher wages and offers of education. Women are less responsive to pecuniary incentives and are more concerned with factors that directly allow them to do a good job, while those with parents living in a remote rural area are generally less responsive to the proposed policies. When the willingness to help other people is a strong motivating force, policies that improve the conditions for helping people appear particularly effective.

  18. Do Financial Incentives Influence GPs' Decisions to Do After-hours Work? A Discrete Choice Labour Supply Model.

    PubMed

    Broadway, Barbara; Kalb, Guyonne; Li, Jinhu; Scott, Anthony

    2017-02-20

    This paper analyses doctors' supply of after-hours care (AHC), and how it is affected by personal and family circumstances as well as the earnings structure. We use detailed survey data from a large sample of Australian General Practitioners (GPs) to estimate a structural, discrete choice model of labour supply and AHC. This allows us to jointly model GPs' decisions on the number of daytime-weekday working hours and the probability of providing AHC. We simulate GPs' labour supply responses to an increase in hourly earnings, both in a daytime-weekday setting and for AHC. GPs increase their daytime-weekday working hours if their hourly earnings in this setting increase, but only to a very small extent. GPs are somewhat more likely to provide AHC if their hourly earnings in that setting increase, but again, the effect is very small and only evident in some subgroups. Moreover, higher earnings in weekday-daytime practice reduce the probability of providing AHC, particularly for men. Increasing GPs' earnings appears to be at best relatively ineffective in encouraging increased provision of AHC and may even prove harmful if incentives are not well targeted. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Preferences for support services among adolescents and young adults with cancer or a blood disorder: a discrete choice experiment.

    PubMed

    Goodall, Stephen; King, Madeleine; Ewing, Jane; Smith, Narelle; Kenny, Patricia

    2012-10-01

    Life-threatening illnesses in young people are traumatic for patients and their families. Support services can help patients and families deal with various non-medical impacts of diagnosis, disease and treatment. The aim of this study was to determine which types of support are most valued by adolescents and young adults (AYA) with cancer or blood disorders and their families. A discrete choice experiment (DCE). Separate experiments were conducted with AYA and their carers. Completed surveys were returned by 83 patients and 78 carers. AYA preferred emotional support for themselves (either by counsellors and/or peers), emotional support for their family, financial support and assistance returning to school/work over services relating to cultural and spiritual needs. Covariate analysis indicated female AYA were more likely than males to prefer emotional support, while males were more likely to prefer assistance returning to work/school. Carers preferred emotional support for their AYA and assistance returning to school/work. Like AYA, they were indifferent about services relating to cultural and spiritual needs. Providing the types of support services that people prefer should maximise effectiveness. This study suggests that AYA patients require support services that included financial aid, assistance returning to work/study, emotional support for themselves and for their family. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  20. Using discrete choice modeling to generate resource selection functions for female polar bears in the Beaufort Sea

    USGS Publications Warehouse

    Durner, George M.; Amstrup, Steven C.; Nielson, Ryan M.; McDonald, Trent; Huzurbazar, Snehalata

    2004-01-01

    Polar bears (Ursus maritimus) depend on ice-covered seas to satisfy life history requirements. Modern threats to polar bears include oil spills in the marine environment and changes in ice composition resulting from climate change. Managers need practical models that explain the distribution of bears in order to assess the impacts of these threats. We explored the use of discrete choice models to describe habitat selection by female polar bears in the Beaufort Sea. Using stepwise procedures we generated resource selection models of habitat use. Sea ice characteristics and ocean depths at known polar bear locations were compared to the same features at randomly selected locations. Models generated for each of four seasons confirmed complexities of habitat use by polar bears and their response to numerous factors. Bears preferred shallow water areas where different ice types intersected. Variation among seasons was reflected mainly in differential selection of total ice concentration, ice stages, floe sizes, and their interactions. Distance to the nearest ice interface was a significant term in models for three seasons. Water depth was selected as a significant term in all seasons, possibly reflecting higher productivity in shallow water areas. Preliminary tests indicate seasonal models can predict polar bear distribution based on prior sea ice data.

  1. Developing attributes for discrete choice experiments in health: a systematic literature review and case study of alcohol misuse interventions

    PubMed Central

    Helter, Timea Mariann; Boehler, Christian Ernst Heinrich

    2016-01-01

    Abstract Discrete choice experiments (DCEs) become increasingly popular to value outcomes for health economic studies and gradually gain acceptance as an input into policy decisions. Developing attributes is a key aspect for the design of DCEs, as their results may misguide decision-makers if they are based on an inappropriate set of attributes. However, the area lacks guidance, and current health-related DCE studies vary considerably in their methods of attribute development, with the consequent danger of providing an unreliable input for policy decisions. The aim of this article is to inform the progress toward a more systematic approach to attribute development for DCE studies in health. A systematic review of the published health-related DCE literature was conducted to lay the foundations for a generic framework which was tested in a case study of alcohol misuse interventions. Four stages of a general attribute development process emerged: (i) raw data collection; (ii) data reduction; (iii) removing inappropriate attributes; and (iv) wording. The case study compared and contrasted a qualitative and mixed-methods approach for the development of attributes for DCEs in the area of alcohol misuse interventions. This article provides a reference point for the design of future DCE experiments in health. PMID:27695386

  2. A discrete choice experiment to assess people living with HIV's (PLWHIV's) preferences for GP or HIV clinic appointments

    PubMed Central

    Miners, A H; Llewellyn, C D; Cooper, V L; Youssef, E; Pollard, A J; Lagarde, M; Sabin, C; Nixon, E; Sachikonye, M; Perry, N; Fisher, M

    2017-01-01

    Objectives To understand which aspects of general practitioner (GP) and HIV clinic appointments people living with HIV (PLWHIV) most value when seeking advice for new health problems. Methods A discrete choice experiment using a convenience sample of people diagnosed with HIV. Participants were recruited from 14 general HIV clinics in the South East of England between December 2014 and April 2015. ORs were calculated using conditional logit (CLOGIT) and latent class models (LCMs). Results A total of 1106 questionnaires were returned. Most participants were male (85%), white (74%) and were men who have sex with men (69%). The CLOGIT analysis showed people particularly valued shorter appointment waiting times (ORs between 1.52 and 3.62, p<0.001 in all instances). The LCM analysis showed there were two distinct classes, with 59% and 41% of respondents likely to be in each. The first class generally preferred GP to HIV clinic appointments and particularly valued ‘being seen quickly’. For example, they had strong preferences for shorter appointment waiting times and longer GP opening hours. People in the second class also valued shorter waiting times, but they had a strong general preference for HIV clinic rather than GP appointments. Conclusions PLWHIV value many aspects of care for new health problems, particularly short appointment waiting times. However, they appear split in their general willingness to engage with GPs. PMID:27535762

  3. Patient preferences for dry powder inhaler attributes in asthma and chronic obstructive pulmonary disease in France: a discrete choice experiment.

    PubMed

    Hawken, Natalia; Torvinen, Saku; Neine, Mohamed-Elmoctar; Amri, Ikbel; Toumi, Mondher; Aballéa, Samuel; Plich, Adam; Roche, Nicolas

    2017-07-06

    Dry powder inhalers (DPIs) are often used in asthma and chronic obstructive pulmonary disease (COPD) therapies. Using the discrete choice experiment (DCE) methodology, this study conducted in France was designed to assess patients' preferences for different attributes of DPIs. Attributes of DPIs were defined based on a literature review, patient focus group discussions and interviews with healthcare professionals (qualitative phase of the study). An online survey was then conducted among French patients with asthma or COPD to elicit patient preferences and willingness to pay (WTP) for these attributes using the DCE methodology (quantitative phase). A fractional factorial design including three blocks of 12 choice sets was created. Each choice set comprised three alternatives: two fictitious inhalers and the patient's current inhaler. Marginal utilities were estimated using a ranked ordered logit model. Interactions between attributes and disease (asthma or COPD) were tested. Six DPI attributes were defined based on the qualitative phase: ease of use/fool-proof priming; accurate and easy-to-read dose counter; dose confirmation; hygiene of the mouthpiece; flexibility of the device handling; ability to use the inhaler with breathing difficulties. Overall, 201 patients with asthma and 93 with COPD were included in the online survey. Patients with asthma placed most value on an inhaler that requires one step for dose preparation (WTP €4.83 [95% CI: €3.77-€5.90], relative to an inhaler requiring four steps) and one that could be used during episodes of breathing difficulties (WTP €4.49 [95% CI: €2.95-€6.02]). Patients with COPD placed most value on an inhaler that could be used during episodes of breathing difficulties (WTP €7.70 [95% CI: €5.65-€9.76]) and on the accuracy of the dose counter (WTP €5.87 [95% CI: €3.98-€ 7.77]). This study suggests that asthma and COPD patients would be willing to change their inhaler if they were offered the option

  4. Distribution Iteration: A Robust Alternative to Source Iteration for Solving the Discrete Ordinates Radiation Transport Equations in Slab and XY - Geometries

    DTIC Science & Technology

    2008-09-15

    differential equation that is coupled in space and angle. The discrete ordinates method discretizes the BTE in space and angle and the resulting...RADIATION TRANSPORT EQUATIONS IN SLAB AND XY - GEOMETRIES DISSERTATION Nicholas J. Prins, Lieutenant Colonel, USA AFIT/DS/ENP/08-S04...SOLVING THE DISCRETE ORDINATES RADIATION TRANSPORT EQUATIONS IN SLAB AND XY - GEOMETRIES DISSERTATION Presented to the Faculty Graduate

  5. Numerical Experiments on Advective Transport in Large Three-Dimensional Discrete Fracture Networks

    NASA Astrophysics Data System (ADS)

    Makedonska, N.; Painter, S. L.; Karra, S.; Gable, C. W.

    2013-12-01

    Modeling of flow and solute transport in discrete fracture networks is an important approach for understanding the migration of contaminants in impermeable hard rocks such as granite, where fractures provide dominant flow and transport pathways. The discrete fracture network (DFN) model attempts to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. An integrated DFN meshing [1], flow, and particle tracking [2] simulation capability that enables accurate flow and particle tracking simulation on large DFNs has recently been developed. The new capability has been used in numerical experiments on advective transport in large DFNs with tens of thousands of fractures and millions of computational cells. The modeling procedure starts from the fracture network generation using a stochastic model derived from site data. A high-quality computational mesh is then generated [1]. Flow is then solved using the highly parallel PFLOTRAN [3] code. PFLOTRAN uses the finite volume approach, which is locally mass conserving and thus eliminates mass balance problems during particle tracking. The flow solver provides the scalar fluxes on each control volume face. From the obtained fluxes the Darcy velocity is reconstructed for each node in the network [4]. Velocities can then be continuously interpolated to any point in the domain of interest, thus enabling random walk particle tracking. In order to describe the flow field on fractures intersections, the control volume cells on intersections are split into four planar polygons, where each polygon corresponds to a piece of a fracture near the intersection line. Thus

  6. dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

    SciTech Connect

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; Gable, Carl W.; Painter, Scott L.; Viswanathan, Hari S.

    2015-11-01

    DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in an intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.

  7. dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

    DOE PAGES

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; ...

    2015-11-01

    DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in anmore » intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.« less

  8. Comparing discrete fracture and continuum models to predict contaminant transport in fractured porous media.

    PubMed

    Blessent, Daniela; Jørgensen, Peter R; Therrien, René

    2014-01-01

    We used the FRAC3Dvs numerical model (Therrien and Sudicky 1996) to compare the dual-porosity (DP), equivalent porous medium (EPM), and discrete fracture matrix diffusion (DFMD) conceptual models to predict field-scale contaminant transport in a fractured clayey till aquitard. The simulations show that the DP, EPM, and DFMD models could be equally well calibrated to reproduce contaminant breakthrough in the till aquitard for a base case. In contrast, when groundwater velocity and degradation rates are modified with respect to the base case, the DP method simulated contaminant concentrations up to three orders of magnitude different from those calculated by the DFMD model. In previous simulations of well-characterized column experiments, the DFMD method reproduced observed changes in solute transport for a range of flow and transport conditions comparable to those of the field-scale simulations, while the DP and EPM models required extensive recalibration to avoid high magnitude errors in predicted mass transport. The lack of robustness with respect to variable flow and transport conditions suggests that DP models and effective porosity EPM models have limitations for predicting cause-effect relationships in environmental planning. The study underlines the importance of obtaining well-characterized experimental data for further studies and evaluation of model key process descriptions and model suitability. © 2013, National Groundwater Association.

  9. A Comprehensive Flow, Heat and Mass Transport Uncertainty Quantification in Discrete Fracture Network Systems

    NASA Astrophysics Data System (ADS)

    Ezzedine, S. M.

    2010-12-01

    Fractures and fracture networks are the principle pathways for migration of water, heat and mass in enhanced geothermal systems, oil and gas reservoirs, CO2 leakage from saline aquifers, and radioactive and toxic industrial wastes from underground storage repositories. A major issue to overcome when characterizing a fractured reservoir is that of data limitation due to accessibility and affordability. Moreover, the ability to map discontinuities in the rock with available geological and geophysical tools tends to decrease particularly as the scale of the discontinuity goes down. Geological characterization data include measurements of fracture density, orientation, extent, and aperture, and are based on analysis of outcrops, borehole optical and acoustic televiewer logs, aerial photographs, and core samples among others. All of these measurements are taken at the field scale through a very sparse limited number of deep boreholes. These types of data are often reduced to probability distributions function for predictive modeling and simulation in a stochastic framework such as stochastic discrete fracture network. Stochastic discrete fracture network models enable, through Monte Carlo realizations and simulations, for probabilistic assessment of flow and transport phenomena that are not adequately captured using continuum models. Despite the fundamental uncertainties inherited within the probabilistic reduction of the sparse data collected, very little work has been conducted on quantifying uncertainty on the reduced probabilistic distribution functions. In the current study, using nested Monte Carlo simulations, we present the impact of parameter uncertainties of the distribution functions that characterize discrete fracture networks on the flow, heat and mass transport. Numerical results of first, second and third moments, normalized to a base case scenario, are presented and compared to theoretical results extended from percolation theory.

  10. Using a discrete choice experiment to elicit time trade-off and willingness-to-pay amounts for influenza health-related quality of life at different ages.

    PubMed

    Prosser, Lisa A; Payne, Katherine; Rusinak, Donna; Shi, Ping; Messonnier, Mark

    2013-04-01

    Recent research suggests that values for health-related quality of life may vary with the age of the patient. Traditional health state valuation questions and discrete choice experiments are two approaches that could be used to value health. To measure whether public values for health vary with the age of the affected individual. A discrete choice experiment was administered via the Internet in December 2007 to measure preferences for different attributes of influenza-related health-related quality of life: age of hypothetical affected individual (range 1-85 years), length of episode (days of illness), severity of illness (workdays lost) and time trade-off or willingness-to-pay amounts. Each respondent answered identical choice questions for a hypothetical family member and for himself/herself. Data on sociodemographic characteristics and influenza illness experience were also collected. Respondents were US adults randomly sampled from an Internet survey panel (n = 1,012). The relative value of attributes was estimated using generalized estimating equations and controlling for sociodemographic characteristics and illness experience. Marginal time traded and marginal willingness to pay using discrete choice and traditional time trade-off or willingness-to-pay questions were compared. Respondents preferred shorter influenza episodes but did not significantly prefer fewer workdays lost if episode length was held constant. Respondents were more likely to choose to avert uncomplicated illness in children and less likely to choose to avert uncomplicated illness in working-age adults. Marginal time trade-off and willingness-to-pay amounts elicited using discrete choice questions were larger than those elicited using direct valuation questions. Approaches that assume values for health-related quality of life do not vary with the age of a patient may bias economic analyses that use these values. If patient age could affect valuations, then age should be included in the

  11. The Effect of Conduction and Thermal Dispersion on Heat Transport in a Discrete Fracture

    NASA Astrophysics Data System (ADS)

    Novakowski, Kent; Yang, Fan

    2017-04-01

    In typical theoretical or experimental studies of heat migration in discrete fractures, conduction and thermal dispersion are commonly neglected from the fracture heat transport equation, assuming heat conduction into the matrix is predominant. In this study analytical and numerical models are used to investigate the significance of conduction and thermal dispersion in the plane of the fracture for point and line sources geometries. The analytical models account for advective, conductive and dispersive heat transport in both the longitudinal and transverse directions in the fracture. The heat transport in the fracture is coupled with a matrix equation in which heat is conducted in the direction perpendicular to the fracture. In the numerical model, the governing heat transport processes are the same as the analytical models; however, the matrix conduction is considered in both longitudinal and transverse directions. Firstly, we demonstrate that longitudinal conduction and dispersion are critical processes that influence heat transport in fractured rock environments, especially for small apertures (eg. 100 microns or less), high flow rate conditions (eg. velocity greater than 50 m/day) and early time (eg. less than 10 days). Secondly, transverse thermal dispersion in the fracture plane is also observed to be an important transport process leading to retardation of the migrating heat front particularly at late time (eg. after 40 days of hot water injection). Solutions which neglect dispersion in the transverse direction underestimate the locations of heat fronts at late time by a significant margin. Finally, the results of this study also suggest that the geometry of the heat sources has significant effects on the heat transport in the system. For example, the effects of dispersion in the fracture are observed to decrease when the width of the heat source expands.

  12. Public preferences for establishing nephrology facilities in Greenland: estimating willingness-to-pay using a discrete choice experiment.

    PubMed

    Kjær, Trine; Bech, Mickael; Kronborg, Christian; Mørkbak, Morten Raun

    2013-10-01

    At present there are no nephrology facilities in Greenland. Greenlandic patients with renal failure needing dialysis thus have to travel to Denmark to obtain treatment. For patients in haemodialysis this necessitates a permanent residence in Denmark. Our study was aimed at examining Greenlanders' preferences for establishing nephrology facilities in Greenland at Queen Ingrid's Hospital in Nuuk, and to estimate the associated change in welfare. Preferences were elicited using a discrete choice experiment (DCE). A random sample of 500 individuals of the general population was sent a postal questionnaire in which they were asked to consider the trade-offs of establishing nephrology facilities in Greenland as opposed to the current situation. This involved trading off the benefits of having such facilities in their home country against the costs of the intervention. Besides including a payment attribute described in terms of incremental tax payment, the DCE included two interventions attributes related to (1) the organisation of labour, and (2) the physical settings of the patients. Respondents succeeded in answering the DCE despite cultural and linguistic disparity. We found that all the included attributes had a significant effect on respondents' choices, and that respondents' answers to the DCE were in keeping with their values as stated in the questionnaire. DCE data was analyzed using a random parameter logit model reparametrized in willingness-to-pay space. The results showed that establishing facilities in Greenland were preferred to the current treatment in Denmark. The welfare estimate from the DCE, at DKK 18.74 million, exceeds the estimated annual costs of establishing treatment facilities for patients with chronic renal failure. Given the estimated confidence interval this result seems robust. Establishing facilities in Greenland therefore would appear to be welfare-improving, deriving positive net benefits. Despite the relatively narrow policy focus, we

  13. The association between general practitioner participation in joint teleconsultations and rates of referral: a discrete choice experiment.

    PubMed

    Cravo Oliveira, Tiago; Barlow, James; Bayer, Steffen

    2015-04-21

    Joint consultations - such as teleconsultations - provide opportunities for continuing education of general practitioners (GPs). It has been reported this form of interactive case-based learning may lead to fewer GP referrals, yet these studies have relied on expert opinion and simple frequencies, without accounting for other factors known to influence referrals. We use a survey-based discrete choice experiment of GPs' referral preferences to estimate how referral rates are associated with participation in joint teleconsultations, explicitly controlling for a number of potentially confounding variables. We distributed questionnaires at two meetings of the Portuguese Association of General Practice. GPs were presented with descriptions of patients with dermatological lesions and asked whether they would refer based on the waiting time, the distance to appointment, and pressure from patients for a referral. We analysed GPs' responses to multiple combinations of these factors, coupled with information on GP and practice characteristics, using a binary logit model. We estimated the probabilities of referral of different lesions using marginal effects. Questionnaires were returned by 44 GPs, giving a total of 721 referral choices. The average referral rate for the 11 GPs (25%) who had participated in teleconsultations was 68.1% (range 53-88%), compared to 74.4% (range 47-100%) for the remaining physicians. Participation in teleconsultations was associated with reductions in the probabilities of referral of 17.6% for patients presenting with keratosis (p = 0.02), 42.3% for psoriasis (p < 0.001), 8.4% for melanoma (p = 0.14), and 5.4% for naevus (p = 0.19). The results indicate that GP participation in teleconsultations is associated with overall reductions in referral rates and in variation across GPs, and that these effects are robust to the inclusion of other factors known to influence referrals. The reduction in range, coupled with different effects for different

  14. Adolescent, parent and societal preferences and willingness to pay for meningococcal B vaccine: A Discrete Choice Experiment.

    PubMed

    Marshall, H S; Chen, G; Clarke, M; Ratcliffe, J

    2016-01-27

    Meningococcal B (MenB) vaccines have been licensed in many countries with private purchase the only option until recently, when a funded programme was introduced in the UK. The aim of this study was to explore adolescent/parental values for a variety of salient vaccine attributes (cost, effectiveness, side effect profile) to assess preferences and willingness-to-pay (WTP) for a MenB vaccine. A national cross-sectional population study was conducted in Australia using Discrete Choice Experiment methodology to assess adolescent/parent/adult preferences for attributes related to MenB vaccine. 2003 adults and 502 adolescents completed the survey in 2013. The majority of participants were willing to be vaccinated with MenB vaccine with vaccination opt-out chosen by 11.9% of adolescents and parents, and 18.2% of non-parent adults. A mixed logit regression model examining adolescent/adult preferences indicated consistent findings; the higher the effectiveness, the longer the duration of protection, the less chance of adverse events and the lower the cost, the more likely respondents were to agree to vaccination. For an ideal MenB vaccine, including the most favoured level of each attribute summed together (90% effectiveness, 10 year duration, 1 injection, no adverse events) adolescents would pay AU$251.60 and parents AU$295.10. Adolescents and parents would pay AU$90.70 or AU$127.20 for 90% vaccine effectiveness vs AU$18.50 or AU$16.70 for 70% effectiveness and would want to be financially compensated for 50% effectiveness; pay AU$63.30 or AU$76.40 for 10 years protection; and pay AU$48.50 or AU$49.20 for no vaccine related adverse events. A slight fever post vaccination was a preferred choice with parents and adolescents willing to pay AU$9.60 or AU$12.30 for this attribute. Vaccine effectiveness, adverse events and duration of immunity are important drivers for parental and adolescent decisions about WTP for MenB vaccine and should be included in discussions on the

  15. Validity and Reliability of Willingness-to-Pay Estimates: Evidence from Two Overlapping Discrete-Choice Experiments.

    PubMed

    Telser, Harry; Becker, Karolin; Zweifel, Peter

    2008-12-01

    Discrete-choice experiments (DCEs), while becoming increasingly popular, have rarely been tested for validity and reliability. To address the issues of validity and reliability of willingness-to-accept (WTA) values obtained from DCEs. In particular, to examine whether differences in the attribute set describing a hypothetical product have an influence on preferences and willingness-to-pay (WTP) values of respondents. Two DCEs were designed, featuring hypothetical insurance contracts for Swiss healthcare. The contract attributes were pre-selected in expert sessions with representatives of the Swiss healthcare system, and their relevance was checked in a pre-test. Experiment A contained rather radical health system reform options, while experiment B concentrated on more familiar elements such as co-payment and the benefit catalogue. Three attributes were present in both experiments: delayed access to innovation ('innovation'), restricted drug benefit ('generics'), and the change in the monthly premium ('premium'). The issue to be addressed was whether WTA values for the overlapping attributes were similar, even though they were embedded in widely differing choice sets.Two representative telephone surveys with 1000 people aged >25 years were conducted independently in the German and French parts of Switzerland during September 2003. Socioeconomic variables collected included age, sex, education, total household income, place of residence, occupation, and household size. Three models were estimated (a simple linear model, a model allowing interaction of the price attribute with socioeconomic characteristics, and a model with a full set of interaction terms). The socioeconomic characteristics of the two samples were very similar. Theoretical validity tends to receive empirical support in both experiments in all cases where economic theory makes predictions concerning differences between socioeconomic groups. However, a systematic inappropriate influence on measured WTA

  16. Impact of Geological Characterization Uncertainties on Subsurface Flow & Transport Using a Stochastic Discrete Fracture Network Approach

    NASA Astrophysics Data System (ADS)

    Ezzedine, S. M.

    2009-12-01

    Fractures and fracture networks are the principal pathways for transport of water and contaminants in groundwater systems, enhanced geothermal system fluids, migration of oil and gas, carbon dioxide leakage from carbon sequestration sites, and of radioactive and toxic industrial wastes from underground storage repositories. A major issue to overcome when characterizing a fractured reservoir is that of data limitation due to accessibility and affordability. Moreover, the ability to map discontinuities in the rock with available geological and geophysical tools tends to decrease particularly as the scale of the discontinuity goes down. Geological characterization data include measurements of fracture density, orientation, extent, and aperture, and are based on analysis of outcrops, borehole optical and acoustic televiewer logs, aerial photographs, and core samples, among other techniques. All of these measurements are taken at the field scale through a very sparse limited number of deep boreholes. These types of data are often reduced to probability distribution functions for predictive modeling and simulation in a stochastic framework such as a stochastic discrete fracture network. Stochastic discrete fracture network models enable, through Monte Carlo realizations and simulations, probabilistic assessment of flow and transport phenomena that are not adequately captured using continuum models. Despite the fundamental uncertainties inherited within the probabilistic reduction of the sparse data collected, very little work has been conducted on quantifying uncertainty on the reduced probabilistic distribution functions. In the current study, using nested Monte Carlo simulations, we present the impact of parameter uncertainties of the distribution functions of fracture density, orientation, aperture and size on the flow and transport using topological measures such as fracture connectivity, physical characteristics such as effective hydraulic conductivity tensors, and

  17. Patient and nurse preferences for nurse handover—using preferences to inform policy: a discrete choice experiment protocol

    PubMed Central

    Spinks, Jean; Chaboyer, Wendy; Bucknall, Tracey; Tobiano, Georgia; Whitty, Jennifer A

    2015-01-01

    Introduction Nursing bedside handover in hospital has been identified as an opportunity to involve patients and promote patient-centred care. It is important to consider the preferences of both patients and nurses when implementing bedside handover to maximise the successful uptake of this policy. We outline a study which aims to (1) identify, compare and contrast the preferences for various aspects of handover common to nurses and patients while accounting for other factors, such as the time constraints of nurses that may influence these preferences.; (2) identify opportunities for nurses to better involve patients in bedside handover and (3) identify patient and nurse preferences that may challenge the full implementation of bedside handover in the acute medical setting. Methods and analysis We outline the protocol for a discrete choice experiment (DCE) which uses a survey design common to both patients and nurses. We describe the qualitative and pilot work undertaken to design the DCE. We use a D-efficient design which is informed by prior coefficients collected during the pilot phase. We also discuss the face-to-face administration of this survey in a population of acutely unwell, hospitalised patients and describe how data collection challenges have been informed by our pilot phase. Mixed multinomial logit regression analysis will be used to estimate the final results. Ethics and dissemination This study has been approved by a university ethics committee as well as two participating hospital ethics committees. Results will be used within a knowledge translation framework to inform any strategies that can be used by nursing staff to improve the uptake of bedside handover. Results will also be disseminated via peer-reviewed journal articles and will be presented at national and international conferences. PMID:26560060

  18. Prescriber preferences for behavioural economics interventions to improve treatment of acute respiratory infections: a discrete choice experiment

    PubMed Central

    Gong, Cynthia L; Hay, Joel W; Meeker, Daniella; Doctor, Jason N

    2016-01-01

    Objective To elicit prescribers' preferences for behavioural economics interventions designed to reduce inappropriate antibiotic prescribing, and compare these to actual behaviour. Design Discrete choice experiment (DCE). Setting 47 primary care centres in Boston and Los Angeles. Participants 234 primary care providers, with an average 20 years of practice. Main outcomes and measures Results of a behavioural economic intervention trial were compared to prescribers' stated preferences for the same interventions relative to monetary and time rewards for improved prescribing outcomes. In the randomised controlled trial (RCT) component, the 3 computerised prescription order entry-triggered interventions studied included: Suggested Alternatives (SA), an alert that populated non-antibiotic treatment options if an inappropriate antibiotic was prescribed; Accountable Justifications (JA), which prompted the prescriber to enter a justification for an inappropriately prescribed antibiotic that would then be documented in the patient's chart; and Peer Comparison (PC), an email periodically sent to each prescriber comparing his/her antibiotic prescribing rate with those who had the lowest rates of inappropriate antibiotic prescribing. A DCE study component was administered to determine whether prescribers felt SA, JA, PC, pay-for-performance or additional clinic time would most effectively reduce their inappropriate antibiotic prescribing. Willingness-to-pay (WTP) was calculated for each intervention. Results In the RCT, PC and JA were found to be the most effective interventions to reduce inappropriate antibiotic prescribing, whereas SA was not significantly different from controls. In the DCE however, regardless of treatment intervention received during the RCT, prescribers overwhelmingly preferred SA, followed by PC, then JA. WTP estimates indicated that each intervention would be significantly cheaper to implement than pay-for-performance incentives of $200/month

  19. An exploration of parents’ preferences for foot care in juvenile idiopathic arthritis: a possible role for the discrete choice experiment

    PubMed Central

    2014-01-01

    Background An increased awareness of patients’ and parents’ care preferences regarding foot care is desirable from a clinical perspective as such information may be utilised to optimise care delivery. The aim of this study was to examine parents’ preferences for, and valuations of foot care and foot-related outcomes in juvenile idiopathic arthritis (JIA). Methods A discrete choice experiment (DCE) incorporating willingness-to-pay (WTP) questions was conducted by surveying 42 parents of children with JIA who were enrolled in a randomised-controlled trial of multidisciplinary foot care at a single UK paediatric rheumatology outpatients department. Attributes explored were: levels of pain; mobility; ability to perform activities of daily living (ADL); waiting time; referral route; and footwear. The DCE was administered at trial baseline. DCE data were analysed using a multinomial-logit-regression model to estimate preferences and relative importance of attributes of foot care. A stated-preference WTP question was presented to estimate parents’ monetary valuation of health and service improvements. Results Every attribute in the DCE was statistically significant (p < 0.01) except that of cost (p = 0.118), suggesting that all attributes, except cost, have an impact on parents’ preferences for foot care for their child. The magnitudes of the coefficients indicate that the strength of preference for each attribute was (in descending order): improved ability to perform ADL, reductions in foot pain, improved mobility, improved ability to wear desired footwear, multidisciplinary foot care route, and reduced waiting time. Parents’ estimated mean annual WTP for a multidisciplinary foot care service was £1,119.05. Conclusions In terms of foot care service provision for children with JIA, parents appear to prefer improvements in health outcomes over non-health outcomes and service process attributes. Cost was relatively less important than other attributes

  20. How to reform western care payment systems according to physicians, policy makers, healthcare executives and researchers: a discrete choice experiment.

    PubMed

    Kessels, Roselinde; Van Herck, Pieter; Dancet, Eline; Annemans, Lieven; Sermeus, Walter

    2015-05-06

    Many developed countries are reforming healthcare payment systems in order to limit costs and improve clinical outcomes. Knowledge on how different groups of professional stakeholders trade off the merits and downsides of healthcare payment systems is limited. Using a discrete choice experiment we asked a sample of physicians, policy makers, healthcare executives and researchers from Canada, Europe, Oceania, and the United States to choose between profiles of hypothetical outcomes on eleven healthcare performance objectives which may arise from a healthcare payment system reform. We used a Bayesian D-optimal design with partial profiles, which enables studying a large number of attributes, i.e. the eleven performance objectives, in the experiment. Our findings suggest that (a) moving from current payment systems to a value-based system is supported by physicians, despite an income trade-off, if effectiveness and long term cost containment improve. (b) Physicians would gain in terms of overall objective fulfillment in Eastern Europe and the US, but not in Canada, Oceania and Western Europe. Finally, (c) such payment reform more closely aligns the overall fulfillment of objectives between stakeholders such as physicians versus healthcare executives. Although the findings should be interpreted with caution due to the potential selection effects of participants, it seems that the value driven nature of newly proposed and/or introduced care payment reforms is more closely aligned with what stakeholders favor in some health systems, but not in others. Future studies, including the use of random samples, should examine the contextual factors that explain such differences in values and buy-in. C90, C99, E61, I11, I18, O57.

  1. Effects of financial incentives on motivating physical activity among older adults: results from a discrete choice experiment

    PubMed Central

    2014-01-01

    Background There is extensive evidence that regular physical activity confers numerous health benefits. Despite this, high rates of physical inactivity prevail among older adults. This study aimed to ascertain if incentives could be effective in motivating physical activity through improving uptake of walking programs, either with or without an enrolment fee to cover corresponding costs. Methods A discrete-choice conjoint survey was fielded to a national sample of older adults in Singapore. Each respondent was given ten pairs of hypothetical walking programs and asked to choose the option they preferred. Each option varied along several dimensions, including the level and type (cash, voucher, or health savings credit) of incentive and an enrolment fee. For each option, they were asked how likely they would be to join their preferred program. A random utility model (RUM) was used to analyze the responses. Results Results suggest that a free 6-month program with a $500 cash incentive would generate enrolment rates of 58.5%; charging $50 to enroll lowers this to 55.7%. In terms of incentive type, cash payments were the most preferred incentive but not significantly different from supermarket vouchers. Both were preferred to health savings credits and sporting goods vouchers. Concerns of adverse selection were minimal because those who were inactive represented at least 72% of new participants for any offered program(s) and were the majority. Conclusions Study results demonstrate the potential for even modest incentives to increase program uptake among inactive older adults. Moreover, although cash was the most preferred option, supermarket vouchers, which could potentially be purchased at a discount, were a close alternative. Results also suggest that an enrolment fee is a viable option to offset the costs of incentives as it has only minimal impact on participation. PMID:24512102

  2. Application of discrete choice experiment to assess farmers' willingness to report swine diseases in the Red River Delta region, Vietnam.

    PubMed

    Pham, Hoa T T; Peyre, Marisa; Trinh, Tuyen Quang; Nguyen, Oanh Cong; Vu, Ton Dinh; Rukkwamsuk, Theera; Antoine-Moussiaux, Nicolas

    2017-03-01

    A discrete choice experiment (DCE) is carried out to value socio-economic factors influencing the farmer's decision to report swine diseases and to assess the willingness of farmers to report swine diseases. Data were collected between March and July 2015 in two provinces in the Red River Delta, Northern Vietnam, from 196 pig producers by face-to face interview. A conditional logit model is used to measure the relative importance of the socio-economic factors and calculate the expected probability of disease reporting under changes of levels of these factors. Results of the study indicated that the likelihood of compensation and the type of culling implemented (all or only unrecovered pigs) are the two most important factors influencing farmer reporting. Compensation level, movement restriction and delay in compensation payment also have significant impacts on farmer's decision to report animal disease but they are not as important as the above factors. Three different scenarios including changes in six different factors (attributes) are tested to predict probability of animal disease reporting. Under the current situation (uncertainty of being compensated), only 4% of the farmers would report swine disease outbreak to the official surveillance system if the culling policy involves all pigs in affected farms. This number is increased to 26% if culling in affected farms is restricted to unrecovered pigs only. Ensuring certainty of compensation increases reporting probability by up to 50% and 90% if all or only unrecovered pigs are destroyed, respectively. The results of this study are important for improving the performance and sustainability of swine disease surveillance system in Vietnam. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Analysis of farmers' willingness to participate in pasture grazing programs: Results from a discrete choice experiment with German dairy farmers.

    PubMed

    Danne, M; Musshoff, O

    2017-09-01

    Over the last decades, the usage of pasture for grazing of dairy cows has decreased considerably. Pasture grazing programs initiated by dairy companies try to counteract this trend. The present paper investigates farmers' willingness to participate in such grazing programs. A special aim was to quantify the price premiums farmers require for program participation and to identify determinants influencing the premium level. The empirical analysis is based on a discrete choice experiment with 293 German dairy farmers. Models are estimated in terms of willingness to accept. It was found that farmers have no substantial preference for whether the pasture grazing program is financed by the food industry, a governmental scheme, or the dairy company. However, an extension of the annual or daily grazing period results in a decreasing willingness of farmers to participate in a pasture grazing program. In addition, farmers decline the option of a feeding standard prescribing the use of only green fodder when offered an alternative program that merely reduces the amount of concentrated feed or maize silage in the diet. Farmers' with an aversion toward program participation have a significant higher price demand for fulfilling the program requirements. Furthermore, the required price premiums increase with growing milk yields and a greater number of cows kept on the farm. However, if the availability of pasture is high, farmers are more likely to participate. The estimated price premiums and factors influencing farmers' willingness to participate found by this study should be considered by dairies and policymakers to gain insights into the design of possible pasture grazing programs from the perspective of farmers. Thereby, paying price premiums to farmers may increase the attractiveness of pasture grazing, which could finally result in an extended usage of pasture grazing. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  4. The interim service preferences of parents waiting for children's mental health treatment: a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Chen, Yvonne; Deal, Ken; Rimas, Heather; McGrath, Patrick; Reid, Graham; Lipman, Ellen; Corkum, Penny

    2013-08-01

    Parents seeking help for children with mental health problems are often assigned to a waiting list. We used a discrete choice conjoint experiment to model preferences for interim services that might be used while waiting for the formal assessment and treatment process to begin. A sample of 1,059 parents (92 % mothers) seeking mental health services for 4 to 16 year olds chose between hypothetical interim services composed by experimentally varying combinations of the levels of 13 interim service attributes. Latent Class analysis yielded a four-segment solution. All segments preferred interim options helping them understand how agencies work, enhancing their parenting knowledge and skill, and providing an opportunity to understand or begin dealing with their own difficulties. The Group Contact segment (35.1 %) preferred interim services in meetings with other parents, supported by phone contacts, frequent checkup calls, and wait-time updates. Virtual Contact parents (29.2 %) preferred to meet other parents in small internet chat groups supported by e-mail contact. Membership in this segment was linked to higher education and computer skills. Frequent Contact parents (24.4 %) preferred face-to-face interim services supported by weekly progress checks and wait time updates. Limited Contact parents (11.3 %) were less intent on using interim services. They preferred to pursue interim services alone, with contacts by phone, supported by fewer check-up calls and less frequent wait time updates. All segments were more likely to enroll in interim services involving their child.

  5. Using a Discrete Choice Conjoint Experiment to Engage Stakeholders in the Design of an Outpatient Children's Health Center.

    PubMed

    Cunningham, Charles E; Niccols, Alison; Rimas, Heather; Robicheau, Randi; Anderson, Colleen; DeVries, Bart

    2016-01-01

    To engage users in the design of a regional child and youth health center. The perspective of users should be an integral component of a patient-centered, evidence-based approach to the design of health facilities. We conducted a discrete choice conjoint experiment (DCE), a method from marketing research and health economics, as a component of a strategy to engage users in the preconstruction planning process. A sample of 467 participants (290 staff and 177 clients or community stakeholders) completed the DCE. Latent class analysis identified three segments with different design preferences. A group we termed an enhanced design (57%) segment preferred a fully featured facility with personal contacts at the start of visits (in-person check-in, personal waiting room notification, volunteer-assisted wayfinding, and visible security), a family resource center with a health librarian, and an outdoor playground equipped with covered heated pathways. The self-guided design segment (11%), in contrast, preferred a design allowing a more independent use of the facility (e.g., self-check-in at computer kiosks, color-coded wayfinding, and a self-guided family resource center). Designs affording privacy and personal contact with staff were important to the private design segment (32%). The theme and decor of the building was less important than interactive features and personal contacts. A DCE allowed us to engage users in the planning process by estimating the value of individual design elements, identifying segments with differing views, informing decisions regarding design trade-offs, and simulating user response to design options.

  6. Stated Preferences of Doctors for Choosing a Job in Rural Areas of Peru: A Discrete Choice Experiment

    PubMed Central

    Miranda, J. Jaime; Diez-Canseco, Francisco; Lema, Claudia; Lescano, Andrés G.; Lagarde, Mylene; Blaauw, Duane; Huicho, Luis

    2012-01-01

    Background Doctors’ scarcity in rural areas remains a serious problem in Latin America and Peru. Few studies have explored job preferences of doctors working in underserved areas. We aimed to investigate doctors’ stated preferences for rural jobs. Methods and Findings A labelled discrete choice experiment (DCE) was performed in Ayacucho, an underserved department of Peru. Preferences were assessed for three locations: rural community, Ayacucho city (Ayacucho’s capital) and other provincial capital city. Policy simulations were run to assess the effect of job attributes on uptake of a rural post. Multiple conditional logistic regressions were used to assess the relative importance of job attributes and of individual characteristics. A total of 102 doctors participated. They were five times more likely to choose a job post in Ayacucho city over a rural community (OR 4.97, 95%CI 1.2; 20.54). Salary increases and bonus points for specialization acted as incentives to choose a rural area, while increase in the number of years needed to get a permanent post acted as a disincentive. Being male and working in a hospital reduced considerably chances of choosing a rural job, while not living with a partner increased them. Policy simulations showed that a package of 75% salary increase, getting a permanent contract after two years in rural settings, and getting bonus points for further specialisation increased rural job uptake from 21% to 77%. A package of 50% salary increase plus bonus points for further specialisation would also increase the rural uptake from 21% to 52%. Conclusions Doctors are five times more likely to favour a job in urban areas over rural settings. This strong preference needs to be overcome by future policies aimed at improving the scarcity of rural doctors. Some incentives, alone or combined, seem feasible and sustainable, whilst others may pose a high fiscal burden. PMID:23272065

  7. A Piecewise Linear Discontinuous Finite Element Spatial Discretization of the Transport Equation in 2D Cylindrical Geometry

    SciTech Connect

    Bailey, T S; Adams, M L; Chang, J H

    2008-10-01

    We present a new spatial discretization of the discrete-ordinates transport equation in two-dimensional cylindrical (RZ) geometry for arbitrary polygonal meshes. This discretization is a discontinuous finite element method that utilizes the piecewise linear basis functions developed by Stone and Adams. We describe an asymptotic analysis that shows this method to be accurate for many problems in the thick diffusion limit on arbitrary polygons, allowing this method to be applied to radiative transfer problems with these types of meshes. We also present numerical results for multiple problems on quadrilateral grids and compare these results to the well-known bi-linear discontinuous finite element method.

  8. Transport of phase space densities through tetrahedral meshes using discrete flow mapping

    NASA Astrophysics Data System (ADS)

    Bajars, Janis; Chappell, David J.; Søndergaard, Niels; Tanner, Gregor

    2017-01-01

    Discrete flow mapping was recently introduced as an efficient ray based method determining wave energy distributions in complex built up structures. Wave energy densities are transported along ray trajectories through polygonal mesh elements using a finite dimensional approximation of a ray transfer operator. In this way the method can be viewed as a smoothed ray tracing method defined over meshed surfaces. Many applications require the resolution of wave energy distributions in three-dimensional domains, such as in room acoustics, underwater acoustics and for electromagnetic cavity problems. In this work we extend discrete flow mapping to three-dimensional domains by propagating wave energy densities through tetrahedral meshes. The geometric simplicity of the tetrahedral mesh elements is utilised to efficiently compute the ray transfer operator using a mixture of analytic and spectrally accurate numerical integration. The important issue of how to choose a suitable basis approximation in phase space whilst maintaining a reasonable computational cost is addressed via low order local approximations on tetrahedral faces in the position coordinate and high order orthogonal polynomial expansions in momentum space.

  9. Unidirectional transport of wave packets through tilted discrete breathers in nonlinear lattices with asymmetric defects

    NASA Astrophysics Data System (ADS)

    Bai, Xiao-Dong; Malomed, Boris A.; Deng, Fu-Guo

    2016-09-01

    We consider the transfer of lattice wave packets through a tilted discrete breather (TDB) in opposite directions in the discrete nonlinear Schrödinger model with asymmetric defects, which may be realized as a Bose-Einstein condensate trapped in a deep optical lattice, or as optical beams in a waveguide array. A unidirectional transport mode is found, in which the incident wave packets, whose energy belongs to a certain interval between full reflection and full passage regions, pass the TDB only in one direction, while in the absence of the TDB, the same lattice admits bidirectional propagation. The operation of this mode is accurately explained by an analytical consideration of the respective energy barriers. The results suggest that the TDB may emulate the unidirectional propagation of atomic and optical beams in various settings. In the case of the passage of the incident wave packet, the scattering TDB typically shifts by one lattice unit in the direction from which the wave packet arrives, which is an example of the tractor-beam effect, provided by the same system, in addition to the rectification of incident waves.

  10. Designing a Text Messaging Intervention to Improve Physical Activity Behavior Among Low-Income Latino Patients With Diabetes: A Discrete-Choice Experiment, Los Angeles, 2014–2015

    PubMed Central

    Wu, Shinyi; Beale, Elizabeth

    2016-01-01

    Introduction Automated text messaging can deliver self-management education to activate self-care behaviors among people with diabetes. We demonstrated how a discrete-choice experiment was used to determine the features of a text-messaging intervention that are important to urban, low-income Latino patients with diabetes and that could support improvement in their physical activity behavior. Methods In a discrete-choice experiment from December 2014 through August 2015 we conducted a survey to elicit information on patient preferences for 5 features of a text-messaging intervention. We described 2 hypothetical interventions and in 7 pairwise comparisons asked respondents to indicate which they preferred. Respondents (n = 125) were recruited in person from a diabetes management program of a safety-net ambulatory care clinic in Los Angeles; clinicians referred patients to the research assistant after routine clinic visits. Data were analyzed by using conditional logistic regression. Results We found 2 intervention features that were considered by the survey respondents to be important: 1) the frequency of text messaging and 2) physical activity behavior-change education (the former being more important than the latter). Physical activity goal setting, feedback on physical activity performance, and social support were not significantly important. Conclusion A discrete-choice experiment is a feasible way to elicit information on patient preferences for a text-messaging intervention designed to support behavior change. However, discrepancies may exist between patients’ stated preferences and their actual behavior. Future research should validate and expand our findings. PMID:28005532

  11. Finger-powered electrophoretic transport of discrete droplets for portable digital microfluidics.

    PubMed

    Peng, Cheng; Wang, Yide; Sungtaek Ju, Y

    2016-07-07

    We report a finger-powered digital microfluidic device based on the electrophoretic transport of discrete droplets (EPD). An array of piezoelectric elements is connected in parallel to metal electrodes immersed in dielectric fluids. When deflected in a controlled sequence via human finger power, the piezoelectric elements charge and actuate droplets across each electrode pair through electrophoretic force. Successful droplet transportation requires the piezoelectric elements to provide both sufficient charge and voltage pulse duration. We quantify these requirements using numerical models to predict the electrical charges induced on the droplets and the corresponding electrophoretic forces. The models are experimentally validated by comparing the predicted and measured droplet translational velocities. We successfully demonstrated transport and merging of aqueous droplets over a range of droplet radii (0.6-0.9 mm). We further showed direct manipulation of body fluids, including droplets of saliva and urine, using our finger-powered EPD device. To facilitate practical implementation of multistep assays based on the approach, a hand/finger-rotated drum system with a programmable pattern of protrusions is designed to induce deflections of multiple piezoelectric elements and demonstrate programmable fluidic functions. An electrode-to-piezoelectric element connection scheme to minimize the number of piezoelectric elements necessary for a sequence of microfluidic functions is also explored. The present work establishes an engineering foundation to enable design and implementation of finger-powered portable EPD microfluidic devices.

  12. Built Environment Influences on Healthy Transportation Choices: Bicycling versus Driving

    PubMed Central

    Brauer, Michael; Setton, Eleanor M.; Teschke, Kay

    2010-01-01

    A growing body of evidence links the built environment to physical activity levels, health outcomes, and transportation behaviors. However, little of this research has focused on cycling, a sustainable transportation option with great potential for growth in North America. This study examines associations between decisions to bicycle (versus drive) and the built environment, with explicit consideration of three different spatial zones that may be relevant in travel behavior: trip origins, trip destinations, and along the route between. We analyzed 3,280 utilitarian bicycle and car trips in Metro Vancouver, Canada made by 1,902 adults, including both current and potential cyclists. Objective measures were developed for built environment characteristics related to the physical environment, land use patterns, the road network, and bicycle-specific facilities. Multilevel logistic regression was used to model the likelihood that a trip was made by bicycle, adjusting for trip distance and personal demographics. Separate models were constructed for each spatial zone, and a global model examined the relative influence of the three zones. In total, 31% (1,023 out of 3,280) of trips were made by bicycle. Increased odds of bicycling were associated with less hilliness; higher intersection density; less highways and arterials; presence of bicycle signage, traffic calming, and cyclist-activated traffic lights; more neighborhood commercial, educational, and industrial land uses; greater land use mix; and higher population density. Different factors were important within each spatial zone. Overall, the characteristics of routes were more influential than origin or destination characteristics. These findings indicate that the built environment has a significant influence on healthy travel decisions, and spatial context is important. Future research should explicitly consider relevant spatial zones when investigating the relationship between physical activity and urban form. PMID

  13. Built environment influences on healthy transportation choices: bicycling versus driving.

    PubMed

    Winters, Meghan; Brauer, Michael; Setton, Eleanor M; Teschke, Kay

    2010-12-01

    A growing body of evidence links the built environment to physical activity levels, health outcomes, and transportation behaviors. However, little of this research has focused on cycling, a sustainable transportation option with great potential for growth in North America. This study examines associations between decisions to bicycle (versus drive) and the built environment, with explicit consideration of three different spatial zones that may be relevant in travel behavior: trip origins, trip destinations, and along the route between. We analyzed 3,280 utilitarian bicycle and car trips in Metro Vancouver, Canada made by 1,902 adults, including both current and potential cyclists. Objective measures were developed for built environment characteristics related to the physical environment, land use patterns, the road network, and bicycle-specific facilities. Multilevel logistic regression was used to model the likelihood that a trip was made by bicycle, adjusting for trip distance and personal demographics. Separate models were constructed for each spatial zone, and a global model examined the relative influence of the three zones. In total, 31% (1,023 out of 3,280) of trips were made by bicycle. Increased odds of bicycling were associated with less hilliness; higher intersection density; less highways and arterials; presence of bicycle signage, traffic calming, and cyclist-activated traffic lights; more neighborhood commercial, educational, and industrial land uses; greater land use mix; and higher population density. Different factors were important within each spatial zone. Overall, the characteristics of routes were more influential than origin or destination characteristics. These findings indicate that the built environment has a significant influence on healthy travel decisions, and spatial context is important. Future research should explicitly consider relevant spatial zones when investigating the relationship between physical activity and urban form.

  14. Flux extrapolation models used in the DOT IV discrete ordinates neutron transport code

    SciTech Connect

    Tomlinson, E.T.; Rhoades, W.A.; Engle, W.W. Jr.

    1980-05-01

    The DOT IV code solves the Boltzmann transport equation in two dimensions using the method of discrete ordinates. Special techniques have been incorporated in this code to mitigate the effects of flux extrapolation error in space meshes of practical size. This report presents the flux extrapolation models as they appear in DOT IV. A sample problem is also presented to illustrate the effects of the various models on the resultant flux. Convergence of the various models to a single result as the mesh is refined is also examined. A detailed comparison with the widely used TWOTRAN II code is reported. The features which cause DOT and TWOTRAN to differ in the converged results are completely observed and explained.

  15. Semianalytic solution for transport of a two-member decay chain in discrete parallel fractures

    NASA Astrophysics Data System (ADS)

    Hansen, Scott K.

    2013-09-01

    A wide variety of analytic solutions have been developed for 1-D contaminant transport, but to date the author is aware of none modeling a decay chain in parallel discrete fractures in porous media. In this note, the derivation is presented for a two-species first-order decay chain in such an environment, with an arbitrary concentration history specified upgradient, fracture advection, and diffusion into the porous matrix. The solution is presented in brief, followed by corroboration of its numerical implementation against two different existing numerical codes. An appendix contains a detailed derivation of the solution, and a Mathematica notebook that implements it and may be used by practitioners is enclosed as supporting information.

  16. Development of perturbation Monte Carlo methods for polarized light transport in a discrete particle scattering model

    PubMed Central

    Nguyen, Jennifer; Hayakawa, Carole K.; Mourant, Judith R.; Venugopalan, Vasan; Spanier, Jerome

    2016-01-01

    We present a polarization-sensitive, transport-rigorous perturbation Monte Carlo (pMC) method to model the impact of optical property changes on reflectance measurements within a discrete particle scattering model. The model consists of three log-normally distributed populations of Mie scatterers that approximate biologically relevant cervical tissue properties. Our method provides reflectance estimates for perturbations across wavelength and/or scattering model parameters. We test our pMC model performance by perturbing across number densities and mean particle radii, and compare pMC reflectance estimates with those obtained from conventional Monte Carlo simulations. These tests allow us to explore different factors that control pMC performance and to evaluate the gains in computational efficiency that our pMC method provides. PMID:27231642

  17. Development of perturbation Monte Carlo methods for polarized light transport in a discrete particle scattering model.

    PubMed

    Nguyen, Jennifer; Hayakawa, Carole K; Mourant, Judith R; Venugopalan, Vasan; Spanier, Jerome

    2016-05-01

    We present a polarization-sensitive, transport-rigorous perturbation Monte Carlo (pMC) method to model the impact of optical property changes on reflectance measurements within a discrete particle scattering model. The model consists of three log-normally distributed populations of Mie scatterers that approximate biologically relevant cervical tissue properties. Our method provides reflectance estimates for perturbations across wavelength and/or scattering model parameters. We test our pMC model performance by perturbing across number densities and mean particle radii, and compare pMC reflectance estimates with those obtained from conventional Monte Carlo simulations. These tests allow us to explore different factors that control pMC performance and to evaluate the gains in computational efficiency that our pMC method provides.

  18. Analysis of Massively Parallel Discrete-Ordinates Transport Sweep Algorithms with Collisions

    SciTech Connect

    Bailey, T S; Falgout, R D

    2008-10-14

    We present theoretical scaling models for a variety of discrete-ordinates sweep algorithms. In these models, we pay particular attention to the way each algorithm handles collisions. A collision is defined as a processor having multiple angles with ready to be swept during one stage of the sweep. The models also take into account how subdomains are assigned to processors and how angles are grouped during the sweep. We describe a data driven algorithm that resolves collisions efficiently during the sweep as well as other algorithms that have been designed to avoid collisions completely. Our models are validated using the ARGES and AMTRAN transport codes. We then use the models to study and predict scaling trends in all of the sweep algorithms.

  19. Moving Toward Patient-Centered Care in Africa: A Discrete Choice Experiment of Preferences for Delivery Care among 3,003 Tanzanian Women.

    PubMed

    Larson, Elysia; Vail, Daniel; Mbaruku, Godfrey M; Kimweri, Angela; Freedman, Lynn P; Kruk, Margaret E

    2015-01-01

    In order to develop patient-centered care we need to know what patients want and how changing socio-demographic factors shape their preferences. We fielded a structured questionnaire that included a discrete choice experiment to investigate women's preferences for place of delivery care in four rural districts of Pwani Region, Tanzania. The discrete choice experiment consisted of six attributes: kind treatment by the health worker, health worker medical knowledge, modern equipment and medicines, facility privacy, facility cleanliness, and cost of visit. Each woman received eight choice questions. The influence of potential supply- and demand- side factors on patient preferences was evaluated using mixed logit models. 3,003 women participated in the discrete choice experiment (93% response rate) completing 23,947 choice tasks. The greatest predictor of health facility preference was kind treatment by doctor (β = 1.13, p<0.001), followed by having a doctor with excellent medical knowledge (β = 0.89 p<0.001) and modern medical equipment and drugs (β = 0.66 p<0.001). Preferences for all attributes except kindness and cost were changed with changes to education, primiparity, media exposure and distance to nearest hospital. Care quality, both technical and interpersonal, was more important than clinic inputs such as equipment and cleanliness. These results suggest that while basic clinic infrastructure is necessary, it is not sufficient for provision of high quality, patient-centered care. There is an urgent need to build an adequate, competent, and kind health workforce to raise facility delivery and promote patient-centered care.

  20. Time dependent discrete ordinates neutron transport using distribution iteration in XYZ geometry

    NASA Astrophysics Data System (ADS)

    Dishaw, James R.

    The distribution iteration (DI) algorithm, developed by Wager [32] and Prins [28], for solving the Boltzmann Transport Equation (BTE) has proven, with further development, to be a robust alternative to von Neumann iteration on the scattering source, aka source iteration (SI). Previous work with DI was based on the time-independent form of the transport equation. In this research, the DI algorithm was (1) Improved to provide faster, more efficient, robust convergence; (2) Extended to XYZ geometry; (3) Extended to Multigroup Energy treatment; (4) Extended to solve the time-dependent form of the Boltzmann Transport Equation. The discrete ordinates equations for approximating the BTE have been solved using SI since the discrete ordinates method was developed at Los Alamos Scientific Laboratory by 1953. However, SI is often inefficient by itself and requires an accelerator in order to produce results efficiently and reliably. The acceleration schemes that are in use in production codes are Diffusion Synthetic Acceleration (DSA) and Transport Synthetic Acceleration (TSA). DSA is ineffective for some problems, and cannot be extended to high-performance spatial quadratures. TSA is less effective than DSA and fails for some problems. Krylov acceleration has been explored in recent years, but has many parameters that require problem-dependent tuning for efficiency and effectiveness. The DI algorithm is an alternative to source iteration that, in our testing, does not require an accelerator. I developed a formal verification plan and executed it to verify the results produced by my code that implemented DI with the above features. A new, matrix albedo, boundary condition treatment was developed and implemented so that infinite-medium benchmarks could be included in the verification test suite. The DI algorithm was modified for parallel efficiency and the prior instability of the refinement sweep was corrected. The testing revealed that DI performed as well or faster than

  1. Evaluating the effect of internal aperture variability on transport in kilometer scale discrete fracture networks

    SciTech Connect

    Makedonska, Nataliia; Hyman, Jeffrey D.; Karra, Satish; Painter, Scott L.; Gable, Carl W.; Viswanathan, Hari S.

    2016-08-01

    The apertures of natural fractures in fractured rock are highly heterogeneous. However, in-fracture aperture variability is often neglected in flow and transport modeling and individual fractures are assumed to have uniform aperture distribution. The relative importance of in-fracture variability in flow and transport modeling within kilometer18 scale field–scale fracture networks has been under a matter of debate for a long time because the flow in each single fracture is controlled not only by in-fracture variability but also by boundary conditions. Computational limitations have previously prohibited researchers from investigating the relative importance of in-fracture variability in flow and transport modeling within large-scale fracture networks. We address this question by incorporating internal heterogeneity of individual fractures into 23 flow simulations within kilometer scale three-dimensional fracture networks, where fracture intensity, P32 (ratio between total fracture area and domain volume) is between 0.027 and 0.031 [1/m]. A recently developed discrete fracture network (DFN) simulation capability, dfnWorks, is used to generate DFNs that include in-fracture aperture variability represented by a stationary log-normal stochastic field with various correlation lengths and variances. The Lagrangian transport parameters, non-reacting travel time and cumulative retention, are calculated along particles streamlines. It is observed that due to local flow channeling early particle travel times are more sensitive to in-fracture variability than the tails of travel time distributions, where no significant effect of the in-fracture transmissivity variations and spatial correlation length is observed.

  2. Evaluating the effect of internal aperture variability on transport in kilometer scale discrete fracture networks

    SciTech Connect

    Makedonska, Nataliia; Hyman, Jeffrey D.; Karra, Satish; Painter, Scott L.; Gable, Carl W.; Viswanathan, Hari S.

    2016-08-01

    The apertures of natural fractures in fractured rock are highly heterogeneous. However, in-fracture aperture variability is often neglected in flow and transport modeling and individual fractures are assumed to have uniform aperture distribution. The relative importance of in-fracture variability in flow and transport modeling within kilometer-scale fracture networks has been under debate for a long time, since the flow in each single fracture is controlled not only by in-fracture variability but also by boundary conditions. Computational limitations have previously prohibited researchers from investigating the relative importance of in-fracture variability in flow and transport modeling within large-scale fracture networks. We address this question by incorporating internal heterogeneity of individual fractures into flow simulations within kilometer scale three-dimensional fracture networks, where fracture intensity, P32 (ratio between total fracture area and domain volume) is between 0.027 and 0.031 [1/m]. The recently developed discrete fracture network (DFN) simulation capability, dfnWorks, is used to generate kilometer scale DFNs that include in-fracture aperture variability represented by a stationary log-normal stochastic field with various correlation lengths and variances. The Lagrangian transport parameters, non-reacting travel time, , and cumulative retention, , are calculated along particles streamlines. As a result, it is observed that due to local flow channeling early particle travel times are more sensitive to in-fracture aperture variability than the tails of travel time distributions, where no significant effect of the in-fracture aperture variations and spatial correlation length is observed.

  3. Evaluating the effect of internal aperture variability on transport in kilometer scale discrete fracture networks

    DOE PAGES

    Makedonska, Nataliia; Hyman, Jeffrey D.; Karra, Satish; ...

    2016-08-01

    The apertures of natural fractures in fractured rock are highly heterogeneous. However, in-fracture aperture variability is often neglected in flow and transport modeling and individual fractures are assumed to have uniform aperture distribution. The relative importance of in-fracture variability in flow and transport modeling within kilometer-scale fracture networks has been under debate for a long time, since the flow in each single fracture is controlled not only by in-fracture variability but also by boundary conditions. Computational limitations have previously prohibited researchers from investigating the relative importance of in-fracture variability in flow and transport modeling within large-scale fracture networks. We addressmore » this question by incorporating internal heterogeneity of individual fractures into flow simulations within kilometer scale three-dimensional fracture networks, where fracture intensity, P32 (ratio between total fracture area and domain volume) is between 0.027 and 0.031 [1/m]. The recently developed discrete fracture network (DFN) simulation capability, dfnWorks, is used to generate kilometer scale DFNs that include in-fracture aperture variability represented by a stationary log-normal stochastic field with various correlation lengths and variances. The Lagrangian transport parameters, non-reacting travel time, , and cumulative retention, , are calculated along particles streamlines. As a result, it is observed that due to local flow channeling early particle travel times are more sensitive to in-fracture aperture variability than the tails of travel time distributions, where no significant effect of the in-fracture aperture variations and spatial correlation length is observed.« less

  4. Patients' and physicians' preferences for type 2 diabetes mellitus treatments in Spain and Portugal: a discrete choice experiment.

    PubMed

    Morillas, Carlos; Feliciano, Rosa; Catalina, Pablo Fernández; Ponte, Carla; Botella, Marta; Rodrigues, João; Esmatjes, Enric; Lafita, Javier; Lizán, Luis; Llorente, Ignacio; Morales, Cristóbal; Navarro-Pérez, Jorge; Orozco-Beltran, Domingo; Paz, Silvia; Ramirez de Arellano, Antonio; Cardoso, Cristina; Tribaldos Causadias, Maribel

    2015-01-01

    To assess Spanish and Portuguese patients' and physicians' preferences regarding type 2 diabetes mellitus (T2DM) treatments and the monthly willingness to pay (WTP) to gain benefits or avoid side effects. An observational, multicenter, exploratory study focused on routine clinical practice in Spain and Portugal. Physicians were recruited from multiple hospitals and outpatient clinics, while patients were recruited from eleven centers operating in the public health care system in different autonomous communities in Spain and Portugal. Preferences were measured via a discrete choice experiment by rating multiple T2DM medication attributes. Data were analyzed using the conditional logit model. Three-hundred and thirty (n=330) patients (49.7% female; mean age 62.4 [SD: 10.3] years, mean T2DM duration 13.9 [8.2] years, mean body mass index 32.5 [6.8] kg/m(2), 41.8% received oral + injected medication, 40.3% received oral, and 17.6% injected treatments) and 221 physicians from Spain and Portugal (62% female; mean age 41.9 [SD: 10.5] years, 33.5% endocrinologists, 66.5% primary-care doctors) participated. Patients valued avoiding a gain in bodyweight of 3 kg/6 months (WTP: €68.14 [95% confidence interval: 54.55-85.08]) the most, followed by avoiding one hypoglycemic event/month (WTP: €54.80 [23.29-82.26]). Physicians valued avoiding one hypoglycemia/week (WTP: €287.18 [95% confidence interval: 160.31-1,387.21]) the most, followed by avoiding a 3 kg/6 months gain in bodyweight and decreasing cardiovascular risk (WTP: €166.87 [88.63-843.09] and €154.30 [98.13-434.19], respectively). Physicians and patients were willing to pay €125.92 (73.30-622.75) and €24.28 (18.41-30.31), respectively, to avoid a 1% increase in glycated hemoglobin, and €143.30 (73.39-543.62) and €42.74 (23.89-61.77) to avoid nausea. Both patients and physicians in Spain and Portugal are willing to pay for the health benefits associated with improved diabetes treatment, the most important

  5. What matters in type 2 diabetes mellitus oral treatment? A discrete choice experiment to evaluate patient preferences.

    PubMed

    Mühlbacher, Axel; Bethge, Susanne

    2016-12-01

    The aim of this empirical study is to evaluate patient preferences for different characteristics of oral type 2 diabetes mellitus (T2DM) treatment. As T2DM treatment requires strict adherence, patient needs and preferences should be taken into consideration. Based on a qualitative and quantitative analysis, a discrete choice experiment (DCE) was applied to identify patient preferences. Apart from six identical attributes (adjustment of glycated hemoglobin [HbA1c], prevention of hypoglycemia, risk of genital infection, risk of gastrointestinal problems, risk of urinary tract infection, and weight change), one continuous variable of either "additional healthy life years" (AHY) or "additional costs" attribute (AC) was included. The DCE was conducted using a fractional factorial design, and the statistical data analysis used random effect logit models. In total, N = 626 (N = 318 AHY + N = 308 AC) T2DM patients participated in the survey. The estimation revealed a clear dominance for prevention of hypoglycemia (coefficient 0.937) and adjustment of HbA1c (coefficient 0.541). The attributes, "additional healthy life years" (coefficient 0.458) or "additional costs" (coefficient 0.420), were in the middle rank and both of significant impact. The side effects, risk of genital infection (coefficient 0.301), risk of gastrointestinal problems (coefficient 0.296), and risk of urinary tract infection (coefficient 0.241) followed in this respective order. Possible weight change (coefficient 0.047) was of less importance (last rank) to the patients in this evaluation. These survey results demonstrate how much a (hypothetical) T2DM oral treatment characteristic affects the treatment decision. The preference data can be used for risk-benefit assessment, cost-benefit assessment, and the establishment of patient-oriented evidence. Understanding how patients perceive and value different aspects of diabetes oral treatment is vital to the optimal design and evaluation of treatment

  6. Acupuncture or low frequency infrared treatment for low back pain in Chinese patients: a discrete choice experiment.

    PubMed

    Chen, Li-Chia; Cheng, Li-Jen; Zhang, Yan; He, Xin; Knaggs, Roger D

    2015-01-01

    Acupuncture is a popular but controversial treatment option for low back pain. In China, it is practised as traditional Chinese medicine; other treatment strategies for low back pain are commonly practised as Western medicine. Research on patient preference for low back-pain treatment options has been mainly conducted in Western countries and is limited to a willingness-to-pay approach. A stated-preference, discrete choice experiment was conducted to determine Chinese patient preferences and trade-offs for acupuncture and low frequency infrared treatment in low back pain from September 2011 to August 2012 after approval from the Department of Scientific Research in the study settings. Eight-six adult outpatients who visited the 'traditional medicine department' at a traditional Chinese medicine hospital and the 'rehabilitation department' at a Western medicine hospital in Guangdong Province of China for chronic low back pain during study period participated in an interview survey. A questionnaire containing 10 scenarios (5 attributes in each scenario) was used to ask participants' preference for acupuncture, low frequency infrared treatment or neither option. Validated responses were analysed using a nested-logit model. The decision on whether to receive a therapy was not associated with the expected utility of receiving therapy, female gender and higher out-of-pocket payment significantly decreased chance to receive treatments. Of the utility of receiving either acupuncture or low frequency infrared treatment, the treatment sensation was the most important attribute as an indicator of treatment efficacy, followed by the maximum efficacy, maintenance duration and onset of efficacy, and the out-of-pocket payment. The willingness-to-pay for acupuncture and low frequency infrared treatment were about $618.6 and $592.4 USD per course respectively, demonstrated patients' demand of pain management. The treatment sensation was regarded as an indicator of treatment

  7. Patients’ and physicians’ preferences for type 2 diabetes mellitus treatments in Spain and Portugal: a discrete choice experiment

    PubMed Central

    Morillas, Carlos; Feliciano, Rosa; Catalina, Pablo Fernández; Ponte, Carla; Botella, Marta; Rodrigues, João; Esmatjes, Enric; Lafita, Javier; Lizán, Luis; Llorente, Ignacio; Morales, Cristóbal; Navarro-Pérez, Jorge; Orozco-Beltran, Domingo; Paz, Silvia; Ramirez de Arellano, Antonio; Cardoso, Cristina; Tribaldos Causadias, Maribel

    2015-01-01

    Objective To assess Spanish and Portuguese patients’ and physicians’ preferences regarding type 2 diabetes mellitus (T2DM) treatments and the monthly willingness to pay (WTP) to gain benefits or avoid side effects. Methods An observational, multicenter, exploratory study focused on routine clinical practice in Spain and Portugal. Physicians were recruited from multiple hospitals and outpatient clinics, while patients were recruited from eleven centers operating in the public health care system in different autonomous communities in Spain and Portugal. Preferences were measured via a discrete choice experiment by rating multiple T2DM medication attributes. Data were analyzed using the conditional logit model. Results Three-hundred and thirty (n=330) patients (49.7% female; mean age 62.4 [SD: 10.3] years, mean T2DM duration 13.9 [8.2] years, mean body mass index 32.5 [6.8] kg/m2, 41.8% received oral + injected medication, 40.3% received oral, and 17.6% injected treatments) and 221 physicians from Spain and Portugal (62% female; mean age 41.9 [SD: 10.5] years, 33.5% endocrinologists, 66.5% primary-care doctors) participated. Patients valued avoiding a gain in bodyweight of 3 kg/6 months (WTP: €68.14 [95% confidence interval: 54.55–85.08]) the most, followed by avoiding one hypoglycemic event/month (WTP: €54.80 [23.29–82.26]). Physicians valued avoiding one hypoglycemia/week (WTP: €287.18 [95% confidence interval: 160.31–1,387.21]) the most, followed by avoiding a 3 kg/6 months gain in bodyweight and decreasing cardiovascular risk (WTP: €166.87 [88.63–843.09] and €154.30 [98.13–434.19], respectively). Physicians and patients were willing to pay €125.92 (73.30–622.75) and €24.28 (18.41–30.31), respectively, to avoid a 1% increase in glycated hemoglobin, and €143.30 (73.39–543.62) and €42.74 (23.89–61.77) to avoid nausea. Conclusion Both patients and physicians in Spain and Portugal are willing to pay for the health benefits

  8. Genomic testing to determine drug response: measuring preferences of the public and patients using Discrete Choice Experiment (DCE)

    PubMed Central

    2013-01-01

    Background The extent to which a genomic test will be used in practice is affected by factors such as ability of the test to correctly predict response to treatment (i.e. sensitivity and specificity of the test), invasiveness of the testing procedure, test cost, and the probability and severity of side effects associated with treatment. Methods Using discrete choice experimentation (DCE), we elicited preferences of the public (Sample 1, N = 533 and Sample 2, N = 525) and cancer patients (Sample 3, N = 38) for different attributes of a hypothetical genomic test for guiding cancer treatment. Samples 1 and 3 considered the test/treatment in the context of an aggressive curable cancer (scenario A) while the scenario for sample 2 was based on a non-aggressive incurable cancer (scenario B). Results In aggressive curable cancer (scenario A), everything else being equal, the odds ratio (OR) of choosing a test with 95% sensitivity was 1.41 (versus a test with 50% sensitivity) and willingness to pay (WTP) was $1331, on average, for this amount of improvement in test sensitivity. In this scenario, the OR of choosing a test with 95% specificity was 1.24 times that of a test with 50% specificity (WTP = $827). In non-aggressive incurable cancer (scenario B), the OR of choosing a test with 95% sensitivity was 1.65 (WTP = $1344), and the OR of choosing a test with 95% specificity was 1.50 (WTP = $1080). Reducing severity of treatment side effects from severe to mild was associated with large ORs in both scenarios (OR = 2.10 and 2.24 in scenario A and B, respectively). In contrast, patients had a very large preference for 95% sensitivity of the test (OR = 5.23). Conclusion The type and prognosis of cancer affected preferences for genomically-guided treatment. In aggressive curable cancer, individuals emphasized more on the sensitivity rather than the specificity of the test. In contrast, for a non-aggressive incurable cancer, individuals put similar

  9. Acupuncture or Low Frequency Infrared Treatment for Low Back Pain in Chinese Patients: A Discrete Choice Experiment

    PubMed Central

    Chen, Li-Chia; Cheng, Li-Jen; Zhang, Yan; He, Xin; Knaggs, Roger D.

    2015-01-01

    Acupuncture is a popular but controversial treatment option for low back pain. In China, it is practised as traditional Chinese medicine; other treatment strategies for low back pain are commonly practised as Western medicine. Research on patient preference for low back-pain treatment options has been mainly conducted in Western countries and is limited to a willingness-to-pay approach. A stated-preference, discrete choice experiment was conducted to determine Chinese patient preferences and trade-offs for acupuncture and low frequency infrared treatment in low back pain from September 2011 to August 2012 after approval from the Department of Scientific Research in the study settings. Eight-six adult outpatients who visited the ‘traditional medicine department’ at a traditional Chinese medicine hospital and the ‘rehabilitation department’ at a Western medicine hospital in Guangdong Province of China for chronic low back pain during study period participated in an interview survey. A questionnaire containing 10 scenarios (5 attributes in each scenario) was used to ask participants' preference for acupuncture, low frequency infrared treatment or neither option. Validated responses were analysed using a nested-logit model. The decision on whether to receive a therapy was not associated with the expected utility of receiving therapy, female gender and higher out-of-pocket payment significantly decreased chance to receive treatments. Of the utility of receiving either acupuncture or low frequency infrared treatment, the treatment sensation was the most important attribute as an indicator of treatment efficacy, followed by the maximum efficacy, maintenance duration and onset of efficacy, and the out-of-pocket payment. The willingness-to-pay for acupuncture and low frequency infrared treatment were about $618.6 and $592.4 USD per course respectively, demonstrated patients' demand of pain management. The treatment sensation was regarded as an indicator of treatment

  10. The monetary value of patient-centred care: results from a discrete choice experiment in Dutch fertility care.

    PubMed

    Huppelschoten, Aleida G; Verkerk, Eva W; Appleby, John; Groenewoud, Hans; Adang, Eddy M M; Nelen, Willianne L D M; Kremer, Jan A M

    2014-08-01

    What are patients and insurers willing to pay for different aspects of fertility care, with a particular focus on patient-centredness? In fertility care, both patients and health insurers place a high value on patient-centred factors, also when taking into account the effectiveness of fertility care. WHAT IS KNOWN ALREADY?: The benefit patients derive from fertility treatment may arise from several aspects of their care, such as the effectiveness, safety or patient-centred factors. Patient-centredness is recognized as an important, multi-dimensional concept, including domains on the organizational level (e.g. information provision) and on the human level (e.g. patient involvement). We performed a discrete choice experiment (DCE) within 32 Dutch fertility clinics and five large health insurance companies in the Netherlands. A total of 996 infertile patients who underwent at least one treatment cycle for their fertility problem and 84 healthcare insurers participated in the study which was executed in the summer of 2012. All participating patients and health insurers completed a DCE about their preferences in fertility care regarding the effectiveness, patient-centredness of care and additional costs. Logistic regression analysis was subsequently used to determine what both patients and health insurers were willing to pay for a one-step increase in patient-centred care and 1% higher pregnancy rates. Five hundred and fifty patients (55.2%) and 45 healthcare insurers (53.6%) completed the DCE questionnaire. Patients were willing to pay a median amount of €463 for a relevant one-step increase in patient-centred care and €107 for 1% increase in pregnancy rates. Healthcare insurers' valuations were lower: €191 for more patient-centred care and €60 for 1% increase in pregnancy rates. The willingness-to-pay values depended on patients' age, patients' ethnicity, income, and treatment type and on health insurers' age. An important limitation of a DCE study is that

  11. Prioritising wheelchair services for children: a pilot discrete choice experiment to understand how child wheelchair users and their parents prioritise different attributes of wheelchair services.

    PubMed

    Bray, Nathan; Yeo, Seow Tien; Noyes, Jane; Harris, Nigel; Edwards, Rhiannon Tudor

    2016-01-01

    Approximately 95 million children worldwide are disabled; 10 % use a wheelchair. In the UK, an estimated 770,000 children are disabled. National Health Service Wheelchair Services are the largest provider of wheelchairs in the UK; however, recent reports have highlighted issues with these services. This study explores the use of discrete choice experiment methods to inform wheelchair service provision for disabled children based on service user preferences. The aim was to explore how disabled children and their parents prioritise different attributes of wheelchair services. The secondary aims were to compare priorities between parents and disabled children and to explore marginal rate of substitution for incremental changes in attributes. Discrete choice experiments are a method of attribute-based stated preference valuation used by health economists to understand how individuals prioritise different attributes of healthcare services and treatments. We conducted the first pilot discrete choice experiment to explore how disabled children (aged 11 to 18) and their parents prioritise different attributes of hypothetical wheelchair services. Eleven disabled children (aged 11 to 18) and 30 parents of disabled children completed eight pairwise choice tasks based on five service attributes: wheelchair assessment, cost contribution, training, delivery time and frequency of review. Data were analysed using conditional logistic regression. For each pairwise choice, the participants were asked to choose which service scenario (A or B) they preferred. Comprehensiveness of wheelchair assessment and wheelchair delivery time significantly (P < 0.05) affected service preferences of children (β-coefficients = 1.43 [95 % bootstrapped CI = 1.42 to 2.08] and -0.92 [95 % bootstrapped CI = -1.41 to -0.84], respectively) and parents (β-coefficients = 1.53 [95 % bootstrapped CI = 1.45 to 2.16] and -1.37 [95 % bootstrapped CI = -1.99 to -1

  12. Lost in the crowd? Using eye-tracking to investigate the effect of complexity on attribute non-attendance in discrete choice experiments.

    PubMed

    Spinks, Jean; Mortimer, Duncan

    2016-02-03

    The provision of additional information is often assumed to improve consumption decisions, allowing consumers to more accurately weigh the costs and benefits of alternatives. However, increasing the complexity of decision problems may prompt changes in information processing. This is particularly relevant for experimental methods such as discrete choice experiments (DCEs) where the researcher can manipulate the complexity of the decision problem. The primary aims of this study are (i) to test whether consumers actually process additional information in an already complex decision problem, and (ii) consider the implications of any such 'complexity-driven' changes in information processing for design and analysis of DCEs. A discrete choice experiment (DCE) is used to simulate a complex decision problem; here, the choice between complementary and conventional medicine for different health conditions. Eye-tracking technology is used to capture the number of times and the duration that a participant looks at any part of a computer screen during completion of DCE choice sets. From this we can analyse what has become known in the DCE literature as 'attribute non-attendance' (ANA). Using data from 32 participants, we model the likelihood of ANA as a function of choice set complexity and respondent characteristics using fixed and random effects models to account for repeated choice set completion. We also model whether participants are consistent with regard to which characteristics (attributes) they consider across choice sets. We find that complexity is the strongest predictor of ANA when other possible influences, such as time pressure, ordering effects, survey specific effects and socio-demographic variables (including proxies for prior experience with the decision problem) are considered. We also find that most participants do not apply a consistent information processing strategy across choice sets. Eye-tracking technology shows promise as a way of obtaining

  13. 34 CFR 200.48 - Funding for choice-related transportation and supplemental educational services.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Funding for choice-related transportation and supplemental educational services. 200.48 Section 200.48 Education Regulations of the Offices of the Department of Education OFFICE OF ELEMENTARY AND SECONDARY EDUCATION, DEPARTMENT OF EDUCATION TITLE I-IMPROVING...

  14. Going Places, Making Choices: Transportation and the Environment. Curriculum Designed for Grades 9-12.

    ERIC Educational Resources Information Center

    National 4-H Council, Chevy Chase, MD.

    This curriculum packet includes a teacher's introduction and five curriculum units that explore how transportation needs affect the environment, including the quality of air and water, habitat, and global climate. These materials encourage teens to apply wisdom, ingenuity, and sound science to the choices they make. Units are: (1)…

  15. 34 CFR 200.48 - Funding for choice-related transportation and supplemental educational services.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 1 2011-07-01 2011-07-01 false Funding for choice-related transportation and supplemental educational services. 200.48 Section 200.48 Education Regulations of the Offices of the Department of Education OFFICE OF ELEMENTARY AND SECONDARY EDUCATION, DEPARTMENT OF EDUCATION TITLE...

  16. 34 CFR 200.48 - Funding for choice-related transportation and supplemental educational services.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 1 2013-07-01 2013-07-01 false Funding for choice-related transportation and supplemental educational services. 200.48 Section 200.48 Education Regulations of the Offices of the Department of Education OFFICE OF ELEMENTARY AND SECONDARY EDUCATION, DEPARTMENT OF EDUCATION TITLE...

  17. Going Places, Making Choices: Transportation and the Environment. Curriculum Designed for Grades 9-12.

    ERIC Educational Resources Information Center

    National 4-H Council, Chevy Chase, MD.

    This curriculum packet includes a teacher's introduction and five curriculum units that explore how transportation needs affect the environment, including the quality of air and water, habitat, and global climate. These materials encourage teens to apply wisdom, ingenuity, and sound science to the choices they make. Units are: (1)…

  18. The TORT three-dimensional discrete ordinates neutron/photon transport code (TORT version 3)

    SciTech Connect

    Rhoades, W.A.; Simpson, D.B.

    1997-10-01

    TORT calculates the flux or fluence of neutrons and/or photons throughout three-dimensional systems due to particles incident upon the system`s external boundaries, due to fixed internal sources, or due to sources generated by interaction with the system materials. The transport process is represented by the Boltzman transport equation. The method of discrete ordinates is used to treat the directional variable, and a multigroup formulation treats the energy dependence. Anisotropic scattering is treated using a Legendre expansion. Various methods are used to treat spatial dependence, including nodal and characteristic procedures that have been especially adapted to resist numerical distortion. A method of body overlay assists in material zone specification, or the specification can be generated by an external code supplied by the user. Several special features are designed to concentrate machine resources where they are most needed. The directional quadrature and Legendre expansion can vary with energy group. A discontinuous mesh capability has been shown to reduce the size of large problems by a factor of roughly three in some cases. The emphasis in this code is a robust, adaptable application of time-tested methods, together with a few well-tested extensions.

  19. C5 Benchmark Problem with Discrete Ordinate Radiation Transport Code DENOVO

    SciTech Connect

    Yesilyurt, Gokhan; Clarno, Kevin T; Evans, Thomas M; Davidson, Gregory G; Fox, Patricia B

    2011-01-01

    The C5 benchmark problem proposed by the Organisation for Economic Co-operation and Development/Nuclear Energy Agency was modeled to examine the capabilities of Denovo, a three-dimensional (3-D) parallel discrete ordinates (S{sub N}) radiation transport code, for problems with no spatial homogenization. Denovo uses state-of-the-art numerical methods to obtain accurate solutions to the Boltzmann transport equation. Problems were run in parallel on Jaguar, a high-performance supercomputer located at Oak Ridge National Laboratory. Both the two-dimensional (2-D) and 3-D configurations were analyzed, and the results were compared with the reference MCNP Monte Carlo calculations. For an additional comparison, SCALE/KENO-V.a Monte Carlo solutions were also included. In addition, a sensitivity analysis was performed for the optimal angular quadrature and mesh resolution for both the 2-D and 3-D infinite lattices of UO{sub 2} fuel pin cells. Denovo was verified with the C5 problem. The effective multiplication factors, pin powers, and assembly powers were found to be in good agreement with the reference MCNP and SCALE/KENO-V.a Monte Carlo calculations.

  20. Uncollided Flux Techniques for Discrete-Ordinate Radiation Transport Solutions in Rattlesnake

    SciTech Connect

    Ragusa, Jean C.; DeHart, Mark D.

    2016-08-01

    One of the only real-time-resolved measurement tools used at the Transient Test Reactor (TREAT) is the fast-neutron hodoscope. The hodoscope was used for monitoring and measuring fuel motion during a transient pulse. The hodoscope is a line of sight detection and imaging system that provides both temporal and spatial resolution of fuel motion during transients, and in-place measurement of fuel distribution during and after transient experiments. However, the hodoscope relies on fast neutron streaming out of the reactor core, which provides a challenge to transient modeling and simulation. However, use of a first collision source approach can be used to overcome this shortcoming. Hence, the TREAT modeling and simulation team has initiated research to implement such capabilities in the neutron transport code Rattlesnake. This report reviews uncollided flux techniques (first and last collision methods) to be implemented in the Rattlesnake SN code in order to mitigate ray effects in modeling the TREAT reactor+hodoscope system. Angular discretization techniques (SN and PN) for the transport equation are notoriously poor at capturing effectively streaming effects.

  1. Are Health State Valuations from the General Public Biased? A Test of Health State Reference Dependency Using Self-assessed Health and an Efficient Discrete Choice Experiment.

    PubMed

    Jonker, Marcel F; Attema, Arthur E; Donkers, Bas; Stolk, Elly A; Versteegh, Matthijs M

    2016-10-27

    Health state valuations of patients and non-patients are not the same, whereas health state values obtained from general population samples are a weighted average of both. The latter constitutes an often-overlooked source of bias. This study investigates the resulting bias and tests for the impact of reference dependency on health state valuations using an efficient discrete choice experiment administered to a Dutch nationally representative sample of 788 respondents. A Bayesian discrete choice experiment design consisting of eight sets of 24 (matched pairwise) choice tasks was developed, with each set providing full identification of the included parameters. Mixed logit models were used to estimate health state preferences with respondents' own health included as an additional predictor. Our results indicate that respondents with impaired health worse than or equal to the health state levels under evaluation have approximately 30% smaller health state decrements. This confirms that reference dependency can be observed in general population samples and affirms the relevance of prospect theory in health state valuations. At the same time, the limited number of respondents with severe health impairments does not appear to bias social tariffs as obtained from general population samples. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Analysis of physicians' perspectives versus patients' preferences: direct assessment and discrete choice experiments in the therapy of multiple myeloma.

    PubMed

    Mühlbacher, Axel C; Nübling, Matthias

    2011-06-01

    Against the background of patient involvement, understanding patients' preferences for treatments is crucial: Do physicians have the same or a different perception of the patients' preferences? As there is currently no cure for patients with multiple myeloma, primary objectives of treatment are to extend survival at the best possible quality of life. In this study, physicians' beliefs about patients' preferences regarding the treatment of multiple myeloma (MM) were explored in a direct assessment and a discrete choice experiment (DCE), and were compared to the previously explored patients' views. How much do physicians know about their patients' preferences? In a preceding study with German multiple myeloma patients, relevant attributes of an ideal multiple myeloma treatment were collected by reviewing the literature and by conducting a qualitative study with focus groups. The attributes were analyzed using both a direct measurement (16 items on a five-point Likert scale) and a DCE (eight pairs with eight characteristics). For the present study, 30 German physicians reviewed the treatment attributes from the previous study for completeness. A total of 243 physicians participated in the study (including the 30 participants in the pre-test). The direct assessment and the DCE covered four major preference dimensions that both the literature review and the focus groups revealed: Aspects of medical effectiveness (including prolonged life expectancy, effectiveness and long duration of effect), side effects, quality of life (including social, physical and emotional quality of life) and flexibility (breaks in therapy and further treatment options). In the direct measurement of patients' preferences, physicians rated physical quality of life (specified as "reduced mobility or good mobility"), rare side effects and effectiveness aspects (duration of effect, maximal prolonged life expectancy and effectiveness) as the most important attributes from the patients' perspective

  3. Continuous energy, multi-dimensional discrete ordinates transport calculations for problem dependent resonance treatment

    NASA Astrophysics Data System (ADS)

    Zhong, Zhaopeng

    In the past twenty 20 years considerable progress has been made in developing new methods for solving the multi-dimensional transport problem. However the effort devoted to the resonance self-shielding calculation has lagged, and much less progress has been made in enhancing resonance-shielding techniques for generating problem-dependent multi-group cross sections (XS) for the multi-dimensional transport calculations. In several applications, the error introduced by self-shielding methods exceeds that due to uncertainties in the basic nuclear data, and often they can be the limiting factor on the accuracy of the final results. This work is to improve the accuracy of the resonance self-shielding calculation by developing continuous energy multi-dimensional transport calculations for problem dependent self-shielding calculations. A new method has been developed, it can calculate the continuous-energy neutron fluxes for the whole two-dimensional domain, which can be utilized as weighting function to process the self-shielded multi-group cross sections for reactor analysis and criticality calculations, and during this process, the two-dimensional heterogeneous effect in the resonance self-shielding calculation can be fully included. A new code, GEMINEWTRN (Group and Energy-Pointwise Methodology Implemented in NEWT for Resonance Neutronics) has been developed in the developing version of SCALE [1], it combines the energy pointwise (PW) capability of the CENTRM [2] with the two-dimensional discrete ordinates transport capability of lattice physics code NEWT [14]. Considering the large number of energy points in the resonance region (typically more than 30,000), the computational burden and memory requirement for GEMINEWTRN is tremendously large, some efforts have been performed to improve the computational efficiency, parallel computation has been implemented into GEMINEWTRN, which can save the computation and memory requirement a lot; some energy points reducing

  4. Model of the saltation transport by Discrete Element Method coupled with wind interaction

    NASA Astrophysics Data System (ADS)

    Oger, Luc; Valance, Alexandre

    2017-06-01

    We study the Aeolian saltation transport problem by analysing the collision of incident energetic beads with granular packing. We investigate the collision process for the case where the incident bead and those from the packing have identical mechanical properties. We analyse the features of the consecutive collision process. We used a molecular dynamics method known as DEM (soft Discrete Element Method) with 20000 particles (2D). The grains were displayed randomly in a box (250X60). A few incident disks are launched with a constant velocity and angle with high random position to initiate the flow. A wind velocity profile is applied on the flowing zone of the saltation. The velocity profile is obtained by the calculi of the counter-flow due to the local packing fraction induced by the granular flow. We analyse the evolution of the upper surface of the disk packing. In the beginning, the saltation process can be seen as the classical "splash function" in which one bead hits a fully static dense packing. Then, the quasi-fluidized upper layer of the packing creates a completely different behaviour of the "animated splash function". The dilation of the upper surface due to the previous collisions is responsible for a need of less input energy for launching new ejected disks. This phenomenon permits to maintain a constant granular flow with a "small" wind velocity on the surface of the disk bed.

  5. A verification regime for the spatial discretization of the SN transport equations

    SciTech Connect

    Schunert, S.; Azmy, Y.

    2012-07-01

    The order-of-accuracy test in conjunction with the method of manufactured solutions is the current state of the art in computer code verification. In this work we investigate the application of a verification procedure including the order-of-accuracy test on a generic SN transport solver that implements the AHOTN spatial discretization. Different types of semantic errors, e.g. removal of a line of code or changing a single character, are introduced randomly into the previously verified S{sub N} code and the proposed verification procedure is used to identify the coding mistakes (if possible) and classify them. Itemized by error type we record the stage of the verification procedure where the error is detected and report the frequency with which the errors are correctly identified at various stages of the verification. Errors that remain undetected by the verification procedure are further scrutinized to determine the reason why the introduced coding mistake eluded the verification procedure. The result of this work is that the verification procedure based on an order-of-accuracy test finds almost all detectable coding mistakes but rarely, 1.44% of the time, and under certain circumstances can fail. (authors)

  6. Characterization of high order spatial discretizations and lumping techniques for discontinuous finite element SN transport

    SciTech Connect

    Maginot, P. G.; Ragusa, J. C.; Morel, J. E.

    2013-07-01

    We examine several possible methods of mass matrix lumping for discontinuous finite element discrete ordinates transport using a Lagrange interpolatory polynomial trial space. Though positive outflow angular flux is guaranteed with traditional mass matrix lumping in a purely absorbing 1-D slab cell for the linear discontinuous approximation, we show that when used with higher degree interpolatory polynomial trial spaces, traditional lumping does yield strictly positive outflows and does not increase in accuracy with an increase in trial space polynomial degree. As an alternative, we examine methods which are 'self-lumping'. Self-lumping methods yield diagonal mass matrices by using numerical quadrature restricted to the Lagrange interpolatory points. Using equally-spaced interpolatory points, self-lumping is achieved through the use of closed Newton-Cotes formulas, resulting in strictly positive outflows in pure absorbers for odd power polynomials in 1-D slab geometry. By changing interpolatory points from the traditional equally-spaced points to the quadrature points of the Gauss-Legendre or Lobatto-Gauss-Legendre quadratures, it is possible to generate solution representations with a diagonal mass matrix and a strictly positive outflow for any degree polynomial solution representation in a pure absorber medium in 1-D slab geometry. Further, there is no inherent limit to local truncation error order of accuracy when using interpolatory points that correspond to the quadrature points of high order accuracy numerical quadrature schemes. (authors)

  7. Anomalous transport in discrete arcs and simulation of double layers in a model auroral circuit

    NASA Technical Reports Server (NTRS)

    Smith, Robert A.

    1987-01-01

    The evolution and long-time stability of a double layer in a discrete auroral arc requires that the parallel current in the arc, which may be considered uniform at the source, be diverted within the arc to charge the flanks of the U-shaped double-layer potential structure. A simple model is presented in which this current re-distribution is effected by anomalous transport based on electrostatic lower hybrid waves driven by the flank structure itself. This process provides the limiting constraint on the double-layer potential. The flank charging may be represented as that of a nonlinear transmission. A simplified model circuit, in which the transmission line is represented by a nonlinear impedance in parallel with a variable resistor, is incorporated in a 1-d simulation model to give the current density at the DL boundaries. Results are presented for the scaling of the DL potential as a function of the width of the arc and the saturation efficiency of the lower hybrid instability mechanism.

  8. A new transport discretization scheme for arbitrary spatial meshes in XY geometry

    SciTech Connect

    Adams, M.L.

    1991-01-18

    We introduce a new spatial discretization scheme for transport on arbitrary spatial grids in XY geometry. Our arbitrary'' spatial grid is composed of arbitrarily-connected polygons, each of which may have an arbitrary number of sides. We begin our derivation by imposing particle balance on every corner'' of each cell (Consequently, we call our scheme the corner-balance (CB) method.) We complete the derivation by introducing simple closure formulas that relate volume-averaged unknowns to surface-averaged unknowns in each corner. We discuss the relationship of the new scheme to discontinuous finite-element methods and to multiple-balance methods. We demonstrate that on simple grids, the method reduces to very robust schemes that have been studied previously. We discuss the theoretical performance of the method in the thick diffusion limit, and provide numerical results for that limit. We present additional numerical results from simple problems that test the new scheme in other limits. Finally, we offer some concluding remarks about the method. 9 refs., 6 figs.

  9. Anomalous transport in discrete arcs and simulation of double layers in a model auroral circuit

    NASA Technical Reports Server (NTRS)

    Smith, Robert A.

    1987-01-01

    The evolution and long-time stability of a double layer (DL) in a discrete auroral arc requires that the parallel current in the arc, which may be considered uniform at the source, be diverted within the arc to charge the flanks of the U-shaped double layer potential structure. A simple model is presented in which this current redistribution is effected by anomalous transport based on electrostatic lower hybrid waves driven by the flank structure itself. This process provides the limiting constraint on the double layer potential. The flank charging may be represented as that of a nonlinear transmission line. A simplified model circuit, in which the transmission line is represented by a nonlinear impedance in parallel with a variable resistor, is incorporated in a one-dimensional simulation model to give the current density at the DL boundaries. Results are presented for the scaling of the DL potential as a function of the width of the arc and the saturation efficiency of the lower hybrid instability mechanism.

  10. Anomalous transport in discrete arcs and simulation of double layers in a model auroral circuit

    NASA Technical Reports Server (NTRS)

    Smith, Robert A.

    1987-01-01

    The evolution and long-time stability of a double layer in a discrete auroral arc requires that the parallel current in the arc, which may be considered uniform at the source, be diverted within the arc to charge the flanks of the U-shaped double-layer potential structure. A simple model is presented in which this current re-distribution is effected by anomalous transport based on electrostatic lower hybrid waves driven by the flank structure itself. This process provides the limiting constraint on the double-layer potential. The flank charging may be represented as that of a nonlinear transmission. A simplified model circuit, in which the transmission line is represented by a nonlinear impedance in parallel with a variable resistor, is incorporated in a 1-d simulation model to give the current density at the DL boundaries. Results are presented for the scaling of the DL potential as a function of the width of the arc and the saturation efficiency of the lower hybrid instability mechanism.

  11. A Discrete Choice Conjoint Experiment to Evaluate Parent Preferences for Treatment of Young, Medication Naïve Children with ADHD

    PubMed Central

    Waschbusch, Daniel A.; Cunningham, Charles E.; Pelham, William E.; Rimas, Heather L.; Greiner, Andrew R.; Gnagy, Elizabeth M.; Waxmonsky, James; Fabiano, Gregory A.; Robb, Jessica A.; Burrows-MacLean, Lisa; Scime, Mindy; Hoffman, Martin T.

    2014-01-01

    The current study examined treatment preferences of 183 parents of young (average age = 5.8 years; SD = 0.6), medication naïve children with ADHD. Preferences were evaluated using a discrete choice experiment in which parents made choices between different combinations of treatment characteristics, outcomes, and costs. Latent class analysis yielded two segments of parents: (1) Medication Avoidant parents constituted 70.5% of the sample whose treatment decisions were strongly influenced by a desire to avoid medication; (2) Outcome Oriented parents constituted 29.5% of the sample whose treatment decisions were most influenced by a desire for positive treatment outcomes. Parents in the Outcome Oriented segment were more stressed and depressed, had lower socioeconomic status and education, were more likely to be single parents, and had more disruptive and impaired children. Simulations predicted that parents would prefer treatments with behavior therapy over treatments with stimulant medication only. PMID:21722027

  12. Outer magnetospheric resonances and transport: discrete and turbulent cascades in the dynamic pressure and plasma flux

    NASA Astrophysics Data System (ADS)

    Savin, Sergey; Büchner, Jörg; Zelenyi, Lev; Kronberg, Elena; Kozak, Lyudmila; Blecki, Jan; Lezhen, Liudmila; Nemecek, Zdenek; Safrankova, Jana; Skalsky, Alexander; Budaev, Vyacheslav; Amata, Ermanno

    We explore interactions of Supersonic Plasma Streams (SPS) with the Earth magnetosphere in the context of the planetary and astrophysical magnetospheres and of that of laboratory plasmas. The interactions can be inherently non-local and non-equilibrium, and even explosive due to both solar wind (SW) induced and self-generated coherent structures in the multiscale system with the scales ranging from the micro to global scales. We concentrate on the main fundamental processes arising from the SPS cascading and interactions with surface and cavity resonances in the Earth’s magnetosphere, using multi-spacecraft data (SPECTR-R, DOUBLE STAR, CLUSTER, GEOTAIL, ACE, WIND etc.). We will address the following key problems to advance our understanding of anomalous transport and boundary dynamics: - generalizations of the SPS generation mechanisms, e.g., by bow shock (BS) surface or magnetosheath (MSH) cavity resonances, triggering by interplanetary shocks, solar wind (SW) dynamic pressure jumps, foreshock nonlinear structures, etc. - the clarification of BS rippling mechanisms requires base on the relevant databases from the CLUSTER/ DOUBLE STAR/ GEOTAIL/SPECTR-R/ ACE/ WIND spacecraft, which will be used for a statistical analysis targeting the SPS statistical features as extreme events. - substantial part of the SW kinetic energy can be pumped into the BS membrane and MSH cavity modes and initiate further cascades towards higher frequencies. Accordingly we present the multipoint studies of the SPS and of related nonlinear discrete cascades (carried generally by the SPS), along with the transformation of discrete cascades of the dynamic pressure into turbulent cascades. - investigation of spectral and bi-spectral cross-correlations in SW, foreshock, MSH and in vicinity of BS and magnetopause (MP) would demonstrate that both inflow and outflow into/ from magnetosphere can be modulated by the SPS and by the related outer magnetospheric resonances as well. We demonstrate in

  13. Bedload Transport on Steep Slopes with Coupled Modeling Based on the Discrete Element Method

    NASA Astrophysics Data System (ADS)

    Chauchat, J.; Maurin, R.; Chareyre, B.; Frey, P.

    2014-12-01

    After more than a century of research, a clear understanding of the physical processes involved in sediment transport problems is still lacking. In particular, modeling of intergranular interactions and fluid-particle interactions in bedload transport need to be improved. In this contribution, we propose a simple numerical model coupling a Discrete Element Method (DEM) for the grain dynamics with a simple 1D vertical fluid phase model inspired from the two-phase approach [1] in order to contribute to this open question. The Reynolds stress is parameterized by a mixing length model which depends on the integral of the grain volume fraction. The coupling between the grains and the fluid phase is essentially achieved through buoyancy and drag forces. The open source DEM code Yade [2] is used with a linear spring-dashpot contact law that allows the description of the behavior of the particles from the quasi-static to the dynamical state. The model is compared with classical results [3] and with particle-scale experimental results obtained in the quasi-2D flume at IRSTEA, Grenoble [4]. We discuss the closures of the model and the sensitivity to the different physical and numerical parameters. [1] Revil-Baudard, T. and J. Chauchat. A two-phase model for sheet flow regime based on dense granular flow rheology. Journal of Geophysical Research: Oceans, 118(2):619-634, 2013. [2] Šmilauer V. , E. Catalano, B. Chareyre, S. Dorofeenko, J. Duriez, A. Gladky, J. Kozicki, C . Modenese, L. Scholtès, L. Sibille, J. Str.nský, and K. Thoeni. Yade Documentation (V. Šmilauer, ed.), The Yade Project, 1st ed., http://yade-dem.org/doc/., 2010. [3] Meyer-Peter, E. and R. Müller. Formulas for bed-load transport. In Proc. 2nd Meeting, pages 39-64. IAHR, 1948. [4] Frey, P. Particle velocity and concentration profiles in bedload experiments on a steep slope. Earth Surface Processes and Landforms, 39(5):646-655, 2014.

  14. Development of a Quantitative Decision Metric for Selecting the Most Suitable Discretization Method for SN Transport Problems

    NASA Astrophysics Data System (ADS)

    Schunert, Sebastian

    In this work we develop a quantitative decision metric for spatial discretization methods of the SN equations. The quantitative decision metric utilizes performance data from selected test problems for computing a fitness score that is used for the selection of the most suitable discretization method for a particular SN transport application. The fitness score is aggregated as a weighted geometric mean of single performance indicators representing various performance aspects relevant to the user. Thus, the fitness function can be adjusted to the particular needs of the code practitioner by adding/removing single performance indicators or changing their importance via the supplied weights. Within this work a special, broad class of methods is considered, referred to as nodal methods. This class is naturally comprised of the DGFEM methods of all function space families. Within this work it is also shown that the Higher Order Diamond Difference (HODD) method is a nodal method. Building on earlier findings that the Arbitrarily High Order Method of the Nodal type (AHOTN) is also a nodal method, a generalized finite-element framework is created to yield as special cases various methods that were developed independently using profoundly different formalisms. A selection of test problems related to a certain performance aspect are considered: an Method of Manufactured Solutions (MMS) test suite for assessing accuracy and execution time, Lathrop's test problem for assessing resilience against occurrence of negative fluxes, and a simple, homogeneous cube test problem to verify if a method possesses the thick diffusive limit. The contending methods are implemented as efficiently as possible under a common SN transport code framework to level the playing field for a fair comparison of their computational load. Numerical results are presented for all three test problems and a qualitative rating of each method's performance is provided for each aspect: accuracy

  15. Measuring Preferences for a Diabetes Pay-for-Performance for Patient (P4P4P) Program using a Discrete Choice Experiment.

    PubMed

    Chen, Tsung-Tai; Tung, Tao-Hsin; Hsueh, Ya-Seng Arthur; Tsai, Ming-Han; Liang, Hsiu-Mei; Li, Kay-Lun; Chung, Kuo-Piao; Tang, Chao-Hsiun

    2015-07-01

    To elicit a patient's willingness to participate in a diabetes pay-for-performance for patient (P4P4P) program using a discrete choice experiment method. The survey was conducted in March 2013. Our sample was drawn from patients with diabetes at five hospitals in Taiwan (International Classification of Diseases, Ninth Revision, Clinical Modification code 250). The sample size was 838 patients. The discrete choice experiment questionnaire included the attributes monthly cash rewards, exercise time, diet control, and program duration. We estimated a bivariate probit model to derive willingness-to-accept levels after accounting for the characteristics (e.g., severity and comorbidity) of patients with diabetes. The preferred program was a 3-year program involving 30 minutes of exercise per day and flexible diet control. Offering an incentive of approximately US $67 in cash per month appears to increase the likelihood that patients with diabetes will participate in the preferred P4P4P program by approximately 50%. Patients with more disadvantageous characteristics (e.g., elderly, low income, greater comorbidity, and severity) could have less to gain from participating in the program and thus require a higher monetary incentive to compensate for the disutility caused by participating in the program's activities. Our result demonstrates that a modest financial incentive could increase the likelihood of program participation after accounting for the attributes of the P4P4P program and patients' characteristics. Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  16. A flexible nonlinear diffusion acceleration method for the S N transport equations discretized with discontinuous finite elements

    DOE PAGES

    Schunert, Sebastian; Wang, Yaqi; Gleicher, Frederick; ...

    2017-06-01

    This work presents a flexible Nonlinear diffusion acceleration (NDA) method that discretizes both themore » $$S_N$$ transport equation and the diffusion equation using the discontinuous finite element method (DFEM). The method is flexible in that the diffusion equation can be discretized on a coarser mesh with the only restriction that it is nested within the transport mesh and the FEM shape function orders of the two equations can be different. The \\textit{consistency} of the transport and diffusion solutions at convergence is defined by using a projection operator mapping the transport into the diffusion FEM space. The diffusion weak form is based on the modified incomplete interior penalty (MIP) diffusion DFEM discretization that is extended by volumetric drift, face closure, and boundary closure terms. In contrast to commonly used coarse mesh finite difference (CMFD) methods, the presented NDA method uses a full FEM discretized diffusion equation for acceleration. Suitable projection and prolongation operators arise naturally from the FEM framework. Via Fourier analysis and numerical experiments for a one-group, fixed source problem the following properties of the NDA method are established for structured quadrilateral meshes: (1) the presented method is unconditionally stable and effective in the presence of mild material heterogeneities if the same mesh and identical shape functions either of the bilinear or biquadratic type are used, (2) the NDA method remains unconditionally stable in the presence of strong heterogeneities, (3) the NDA method with bilinear elements extends the range of effectiveness and stability by a factor of two when compared to CMFD if a coarser diffusion mesh is selected. In addition, the method is tested for solving the C5G7 multigroup, eigenvalue problem using coarse and fine mesh acceleration. While NDA does not offer an advantage over CMFD for fine mesh acceleration, it reduces the iteration count required for convergence by

  17. A posteriori error estimators for the discrete ordinates approximation of the one-speed neutron transport equation

    SciTech Connect

    O'Brien, S.; Azmy, Y. Y.

    2013-07-01

    When calculating numerical solutions of the neutron transport equation it is important to have a measure of the accuracy of the solution. As the true solution is generally not known, a suitable estimation of the error must be made. The steady state transport equation possesses discretization errors in all its independent variables: angle, energy and space. In this work only spatial discretization errors are considered. An exact transport solution, in which the degree of regularity of the exact flux across the singular characteristic is controlled, is manufactured to determine the numerical solutions true discretization error. This solution is then projected onto a Legendre polynomial space in order to form an exact solution on the same basis space as the numerical solution, Discontinuous Galerkin Finite Element Method (DGFEM), to enable computation of the true error. Over a series of test problems the true error is compared to the error estimated by: Ragusa and Wang (RW), residual source (LER) and cell discontinuity estimators (JD). The validity and accuracy of the considered estimators are primarily assessed by considering the effectivity index and global L2 norm of the error. In general RW excels at approximating the true error distribution but usually under-estimates its magnitude; the LER estimator emulates the true error distribution but frequently over-estimates the magnitude of the true error; the JD estimator poorly captures the true error distribution and generally under-estimates the error about singular characteristics but over-estimates it elsewhere. (authors)

  18. Discontinuous Galerkin discretization of the Reynolds-averaged Navier-Stokes equations with the shear-stress transport model

    NASA Astrophysics Data System (ADS)

    Schoenawa, Stefan; Hartmann, Ralf

    2014-04-01

    In this article we consider the development of Discontinuous Galerkin (DG) methods for the numerical approximation of the Reynolds-averaged Navier-Stokes (RANS) equations with the shear-stress transport (SST) model by Menter. This turbulence model is based on a blending of the Wilcox k-ω model used near the wall and the k-ɛ model used in the rest of the domain where the blending functions depend on the distance to the nearest wall. For the computation of the distance of each quadrature point in the domain to the nearest of the curved, piecewise polynomial wall boundaries, we propose a stabilized continuous finite element (FE) discretization of the eikonal equation. Furthermore, we propose a new wall boundary condition for the dissipation rate ω based on the projection of the analytic near-wall behavior of ω onto the discrete ansatz space of the DG discretization. Finally, we introduce an artificial viscosity to the discretization of the turbulence kinetic energy (k-)equation to suppress oscillations of k near the underresolved boundary layer edge. The wall distance computation based on the continuous FE discretization of the eikonal equation is demonstrated for an internal and three external/aerodynamic flow geometries including a three-element high-lift configuration. The DG discretization of the RANS equations with the SST model is demonstrated for turbulent flows past a flat plate and the RAE2822 airfoil (Cases 9 and 10). The results are compared to the underlying k-ω model and experimental data.

  19. Influence of discrete and continuous culture conditions on human mesenchymal stem cell lineage choice in RGD concentration gradient hydrogels.

    PubMed

    Smith Callahan, Laura A; Policastro, Gina M; Bernard, Sharon L; Childers, Erin P; Boettcher, Ronna; Becker, Matthew L

    2013-09-09

    Stem cells have shown lineage-specific differentiation when cultured on substrates possessing signaling groups derived from the native tissue. A distinct determinant in this process is the concentration of the signaling motif. While several groups have been working actively to determine the specific factors, concentrations, and mechanisms governing the differentiation process, many have been turning to combinatorial and gradient approaches in attempts to optimize the multiple chemical and physical parameters needed for the next advance. However, there has not been a direct comparison between the cellular behavior and differentiation of human mesenchymal stem cells cultured in gradient and discrete substrates, which quantitates the effect of differences caused by cell-produced, soluble factors due to design differences between the culture systems. In this study, the differentiation of human mesenchymal stem cells in continuous and discrete polyethylene glycol dimethacrylate (PEGDM) hydrogels containing an RGD concentration gradient from 0 to 14 mM were examined to study the effects of the different culture conditions on stem-cell behavior. Culture condition was found to affect every osteogenic (alkaline phosphatase, Runx 2, type 1 collagen, bone sailoprotein, and calcium content) and adipogenic marker (oil red and peroxisome proliferator-activated receptor gamma) examined regardless of RGD concentration. Only in the continuous gradient culture did RGD concentration affect human mesenchymal stem-cell lineage commitment with low RGD concentrations expressing higher osteogenic differentiation than high RGD concentrations. Conversely, high RGD concentrations expressed higher adipogenic differentiation than low RGD concentrations. Cytoskeletal actin organization was only affected by culture condition at low RGD concentrations, indicating that it played a limited role in the differences in lineage commitment observed. Therefore, the role of discrete versus gradient

  20. Nonlinear diffusion acceleration for the multigroup transport equation discretized with S{sub N} and continuous FEM with rattlesnake

    SciTech Connect

    Wang, Y.

    2013-07-01

    Nonlinear diffusion acceleration (NDA) can improve the performance of a neutron transport solver significantly especially for the multigroup eigenvalue problems. The high-order transport equation and the transport-corrected low-order diffusion equation form a nonlinear system in NDA, which can be solved via a Picard iteration. The consistency of the correction of the low-order equation is important to ensure the stabilization and effectiveness of the iteration. It also makes the low-order equation preserve the scalar flux of the high-order equation. In this paper, the consistent correction for a particular discretization scheme, self-adjoint angular flux (SAAF) formulation with discrete ordinates method (S{sub N}) and continuous finite element method (CFEM) is proposed for the multigroup neutron transport equation. Equations with the anisotropic scatterings and a void treatment are included. The Picard iteration with this scheme has been implemented and tested with RattleS{sub N}ake, a MOOSE-based application at INL. Convergence results are presented. (authors)

  1. Solution of the within-group multidimensional discrete ordinates transport equations on massively parallel architectures

    NASA Astrophysics Data System (ADS)

    Zerr, Robert Joseph

    2011-12-01

    The integral transport matrix method (ITMM) has been used as the kernel of new parallel solution methods for the discrete ordinates approximation of the within-group neutron transport equation. The ITMM abandons the repetitive mesh sweeps of the traditional source iterations (SI) scheme in favor of constructing stored operators that account for the direct coupling factors among all the cells and between the cells and boundary surfaces. The main goals of this work were to develop the algorithms that construct these operators and employ them in the solution process, determine the most suitable way to parallelize the entire procedure, and evaluate the behavior and performance of the developed methods for increasing number of processes. This project compares the effectiveness of the ITMM with the SI scheme parallelized with the Koch-Baker-Alcouffe (KBA) method. The primary parallel solution method involves a decomposition of the domain into smaller spatial sub-domains, each with their own transport matrices, and coupled together via interface boundary angular fluxes. Each sub-domain has its own set of ITMM operators and represents an independent transport problem. Multiple iterative parallel solution methods have investigated, including parallel block Jacobi (PBJ), parallel red/black Gauss-Seidel (PGS), and parallel GMRES (PGMRES). The fastest observed parallel solution method, PGS, was used in a weak scaling comparison with the PARTISN code. Compared to the state-of-the-art SI-KBA with diffusion synthetic acceleration (DSA), this new method without acceleration/preconditioning is not competitive for any problem parameters considered. The best comparisons occur for problems that are difficult for SI DSA, namely highly scattering and optically thick. SI DSA execution time curves are generally steeper than the PGS ones. However, until further testing is performed it cannot be concluded that SI DSA does not outperform the ITMM with PGS even on several thousand or tens of

  2. How Can the Health System Retain Women in HIV Treatment for a Lifetime? A Discrete Choice Experiment in Ethiopia and Mozambique.

    PubMed

    Kruk, Margaret E; Riley, Patricia L; Palma, Anton M; Adhikari, Sweta; Ahoua, Laurence; Arnaldo, Carlos; Belo, Dercio F; Brusamento, Serena; Cumba, Luisa I G; Dziuban, Eric J; El-Sadr, Wafaa M; Gutema, Yoseph; Habtamu, Zelalem; Heller, Thomas; Kidanu, Aklilu; Langa, Judite; Mahagaja, Epifanio; McCarthy, Carey F; Melaku, Zenebe; Shodell, Daniel; Tsiouris, Fatima; Young, Paul R; Rabkin, Miriam

    2016-01-01

    Option B+, an approach that involves provision of antiretroviral therapy (ART) to all HIV-infected pregnant women for life, is the preferred strategy for prevention of mother to child transmission of HIV. Lifelong retention in care is essential to its success. We conducted a discrete choice experiment in Ethiopia and Mozambique to identify health system characteristics preferred by HIV-infected women to promote continuity of care. Women living with HIV and receiving care at hospitals in Oromia Region, Ethiopia and Zambézia Province, Mozambique were shown nine choice cards and asked to select one of two hypothetical health facilities, each with six varying characteristics related to the delivery of HIV services for long term treatment. Mixed logit models were used to estimate the influence of six health service attributes on choice of clinics. 2,033 women participated in the study (response rate 97.8% in Ethiopia and 94.7% in Mozambique). Among the various attributes of structure and content of lifelong ART services, the most important attributes identified in both countries were respectful provider attitude and ability to obtain non-HIV health services during HIV-related visits. Availability of counseling support services was also a driver of choice. Facility type, i.e., hospital versus health center, was substantially less important. Efforts to enhance retention in HIV care and treatment for pregnant women should focus on promoting respectful care by providers and integrating access to non-HIV health services in the same visit, as well as continuing to strengthen counseling.

  3. A protocol for a discrete choice experiment: understanding preferences of patients with cancer towards their cancer care across metropolitan and rural regions in Australia.

    PubMed

    Wong, Shu Fen; Norman, Richard; Dunning, Trisha L; Ashley, David M; Lorgelly, Paula K

    2014-10-24

    Medical decision-making in oncology is a complicated process and to date there are few studies examining how patients with cancer make choices with respect to different features of their care. It is also unknown whether patient choices vary by geographical location and how location could account for observed rural and metropolitan cancer differences. This paper describes an ongoing study that aims to (1) examine patient and healthcare-related factors that influence choices of patients with cancer; (2) measure and quantify preferences of patients with cancer towards cancer care using a discrete choice experiment (DCE) and (3) explore preference heterogeneity between metropolitan and rural locations. A DCE is being conducted to understand how patients with cancer choose between two clinical scenarios accounting for different patient and healthcare-related factors (and levels). Preliminary qualitative research was undertaken to guide the development of an appropriate DCE design including characteristics that are important and relevant to patients with cancer. A fractional factorial design using the D-efficiency criteria was used to estimate interactions among attributes. Multinomial logistic regression will be used for the primary DCE analysis and to control for sociodemographic and clinical characteristics. The Barwon Health Human Research Ethics Committee approved the study. Findings from the study will be presented in national/international conferences and peer-reviewed journals. Our results will form the basis of a feasibility study to inform the development of a larger scale study into preferences of patients with cancer and their association with cancer outcomes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  4. How Can the Health System Retain Women in HIV Treatment for a Lifetime? A Discrete Choice Experiment in Ethiopia and Mozambique

    PubMed Central

    Kruk, Margaret E.; Riley, Patricia L.; Palma, Anton M.; Adhikari, Sweta; Ahoua, Laurence; Arnaldo, Carlos; Belo, Dercio F.; Brusamento, Serena; Cumba, Luisa I. G.; Dziuban, Eric J.; El-Sadr, Wafaa M.; Gutema, Yoseph; Habtamu, Zelalem; Heller, Thomas; Kidanu, Aklilu; Langa, Judite; Mahagaja, Epifanio; McCarthy, Carey F.; Melaku, Zenebe; Shodell, Daniel; Tsiouris, Fatima; Young, Paul R.; Rabkin, Miriam

    2016-01-01

    Introduction Option B+, an approach that involves provision of antiretroviral therapy (ART) to all HIV-infected pregnant women for life, is the preferred strategy for prevention of mother to child transmission of HIV. Lifelong retention in care is essential to its success. We conducted a discrete choice experiment in Ethiopia and Mozambique to identify health system characteristics preferred by HIV-infected women to promote continuity of care. Methods Women living with HIV and receiving care at hospitals in Oromia Region, Ethiopia and Zambézia Province, Mozambique were shown nine choice cards and asked to select one of two hypothetical health facilities, each with six varying characteristics related to the delivery of HIV services for long term treatment. Mixed logit models were used to estimate the influence of six health service attributes on choice of clinics. Results 2,033 women participated in the study (response rate 97.8% in Ethiopia and 94.7% in Mozambique). Among the various attributes of structure and content of lifelong ART services, the most important attributes identified in both countries were respectful provider attitude and ability to obtain non-HIV health services during HIV-related visits. Availability of counseling support services was also a driver of choice. Facility type, i.e., hospital versus health center, was substantially less important. Conclusions Efforts to enhance retention in HIV care and treatment for pregnant women should focus on promoting respectful care by providers and integrating access to non-HIV health services in the same visit, as well as continuing to strengthen counseling. PMID:27551785

  5. Choice of scalar measure for crystal curvature to image dislocation substructure in terms of discrete orientation data

    NASA Astrophysics Data System (ADS)

    Zisman, Alexander

    2016-04-01

    Starting from Nye's tensor, alternative characteristics of crystal curvature indicative of dislocation content are considered subject to very low thickness of investigated matter under the free surface and discreteness of orientation sampling. Analysis within the framework of continuum mechanics, undertaken to allow for such conditions peculiar to the electron backscatter diffraction (EBSD) technique, has shown the variable part of orientations expressed in a vector form to be most sensitive to lattice defects when projected to the free surface plane. Hence, as verified with EBSD data on a grain junction in a low deformed IF steel, magnitude of the projected field allows one to map plastic strains inhomogeneous within grains whereas divergence of this field distinctly images and quantifies low-angle dislocation boundaries formed at low strains.

  6. Reimagining cost recovery in Pakistan's irrigation system through willingness-to-pay estimates for irrigation water from a discrete choice experiment

    NASA Astrophysics Data System (ADS)

    Bell, Andrew Reid; Shah, M. Azeem Ali; Ward, Patrick S.

    2014-08-01

    It is widely argued that farmers are unwilling to pay adequate fees for surface water irrigation to recover the costs associated with maintenance and improvement of delivery systems. In this paper, we use a discrete choice experiment to study farmer preferences for irrigation characteristics along two branch canals in Punjab Province in eastern Pakistan. We find that farmers are generally willing to pay well in excess of current surface water irrigation costs for increased surface water reliability and that the amount that farmers are willing to pay is an increasing function of their existing surface water supply as well as location along the main canal branch. This explicit translation of implicit willingness-to-pay (WTP) for water (via expenditure on groundwater pumping) to WTP for reliable surface water demonstrates the potential for greatly enhanced cost recovery in the Indus Basin Irrigation System via appropriate setting of water user fees, driven by the higher WTP of those currently receiving reliable supplies.

  7. Reimagining cost recovery in Pakistan's irrigation system through willingness-to-pay estimates for irrigation water from a discrete choice experiment.

    PubMed

    Bell, Andrew Reid; Shah, M Azeem Ali; Ward, Patrick S

    2014-08-01

    It is widely argued that farmers are unwilling to pay adequate fees for surface water irrigation to recover the costs associated with maintenance and improvement of delivery systems. In this paper, we use a discrete choice experiment to study farmer preferences for irrigation characteristics along two branch canals in Punjab Province in eastern Pakistan. We find that farmers are generally willing to pay well in excess of current surface water irrigation costs for increased surface water reliability and that the amount that farmers are willing to pay is an increasing function of their existing surface water supply as well as location along the main canal branch. This explicit translation of implicit willingness-to-pay (WTP) for water (via expenditure on groundwater pumping) to WTP for reliable surface water demonstrates the potential for greatly enhanced cost recovery in the Indus Basin Irrigation System via appropriate setting of water user fees, driven by the higher WTP of those currently receiving reliable supplies.

  8. Reimagining cost recovery in Pakistan's irrigation system through willingness-to-pay estimates for irrigation water from a discrete choice experiment

    PubMed Central

    Bell, Andrew Reid; Shah, M Azeem Ali; Ward, Patrick S

    2014-01-01

    It is widely argued that farmers are unwilling to pay adequate fees for surface water irrigation to recover the costs associated with maintenance and improvement of delivery systems. In this paper, we use a discrete choice experiment to study farmer preferences for irrigation characteristics along two branch canals in Punjab Province in eastern Pakistan. We find that farmers are generally willing to pay well in excess of current surface water irrigation costs for increased surface water reliability and that the amount that farmers are willing to pay is an increasing function of their existing surface water supply as well as location along the main canal branch. This explicit translation of implicit willingness-to-pay (WTP) for water (via expenditure on groundwater pumping) to WTP for reliable surface water demonstrates the potential for greatly enhanced cost recovery in the Indus Basin Irrigation System via appropriate setting of water user fees, driven by the higher WTP of those currently receiving reliable supplies. PMID:25552779

  9. Evaluating consumer preferences for healthy eating from Community Kitchens in low-income urban areas: A discrete choice experiment of Comedores Populares in Peru.

    PubMed

    Buttorff, Christine; Trujillo, Antonio J; Diez-Canseco, Francisco; Bernabe-Ortiz, Antonio; Miranda, J Jaime

    2015-09-01

    Many low-income individuals from around the world rely on local food vendors for daily sustenance. These small vendors quickly provide convenient, low-priced, tasty foods, however, they may be low in nutritional value. These vendors serve as an opportunity to use established delivery channels to explore the introduction of healthier products, e.g. fresh salad and fruits, to low-income populations. We sought to understand preferences for items prepared in Comedores Populares (CP), government-supported food vendors serving low-income Peruvians, to determine whether it would be feasible to introduce healthier items, specifically fruits and vegetables. We used a best-worst discrete choice experiment (DCE) that allowed participants to select their favorite and least favorite option from a series of three hypothetical menus. The characteristics were derived from a series of formative qualitative interviews conducted previously in the CPs. We examined preferences for six characteristics: price, salad, soup, sides, meat and fruit. A total of 432 individuals, from two districts in Lima, Peru responded to a discrete choice experiment and demographic survey in 2012. For the DCE, price contributed the most to individual's utility relative to the other attributes, with salad and soup following closely. Sides (e.g. rice and beans) were the least important. The willingness to pay for a meal with a large main course and salad was 2.6 Nuevos Soles, roughly a 1 Nuevo Sol increase from the average menu price, or USD $0.32 dollars. The willingness to pay for a meal with fruit was 1.6 Nuevo Soles. Overall, the perceived quality of service and food served in the CPs is high. The willingness to pay indicates that healthier additions to meals are feasible. Understanding consumer preferences can help policy makers design healthier meals in an organization with the potential to scale up to reach a considerable number of low-income families. Copyright © 2015 Elsevier Ltd. All rights

  10. Men’s preferences for the treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia: a discrete choice experiment

    PubMed Central

    Mankowski, Colette; Ikenwilo, Divine; Heidenreich, Sebastian; Ryan, Mandy; Nazir, Jameel; Newman, Cathy; Watson, Verity

    2016-01-01

    Objective To explore and quantify men’s preferences and willingness to pay (WTP) for attributes of medications for lower urinary tract symptoms associated with benign prostatic hyperplasia using a discrete choice experiment. Subjects and methods Men in the UK aged ≥45 years with moderate-to-severe lower urinary tract symptoms/benign prostatic hyperplasia (based on self-reported International Prostate Symptom Score ≥8) were recruited. An online discrete choice experiment survey was administered. Eligible men were asked to consider different medication scenarios and select their preferred medication according to seven attributes: daytime and nighttime (nocturia) urinary frequency, urinary urgency, sexual and nonsexual side effects, number of tablets/day, and cost/month. A mixed-logit model was used to estimate preferences and WTP for medication attributes. Results In all, 247 men completed the survey. Men were willing to trade-off symptom improvements and treatment side effects. Men preferred medications that reduced urinary urgency and reduced day- and nighttime urinary frequency. Men preferred medications without side effects (base-case level), but did not care about the number of tablets per day. WTP for symptomatic improvement was £25.33/month for reduced urgency (urge incontinence to mild urgency), and £6.65/month and £1.39/month for each unit reduction in night- and daytime urination frequency, respectively. The sexual and nonsexual side effects reduced WTP by up to £30.07/month. There was significant heterogeneity in preferences for most attributes, except for reduced urinary urgency from urge incontinence to mild urgency and no fluid during ejaculation (dry orgasm). Conclusion To compensate for side effects, a medicine for lower urinary tract symptoms/benign prostatic hyperplasia must provide a combination of benefits, such as reduced urgency of urination plus reduced nighttime and/or reduced daytime urination. PMID:27920507

  11. An empirical comparison of methods for analyzing correlated data from a discrete choice survey to elicit patient preference for colorectal cancer screening

    PubMed Central

    2012-01-01

    Background A discrete choice experiment (DCE) is a preference survey which asks participants to make a choice among product portfolios comparing the key product characteristics by performing several choice tasks. Analyzing DCE data needs to account for within-participant correlation because choices from the same participant are likely to be similar. In this study, we empirically compared some commonly-used statistical methods for analyzing DCE data while accounting for within-participant correlation based on a survey of patient preference for colorectal cancer (CRC) screening tests conducted in Hamilton, Ontario, Canada in 2002. Methods A two-stage DCE design was used to investigate the impact of six attributes on participants' preferences for CRC screening test and willingness to undertake the test. We compared six models for clustered binary outcomes (logistic and probit regressions using cluster-robust standard error (SE), random-effects and generalized estimating equation approaches) and three models for clustered nominal outcomes (multinomial logistic and probit regressions with cluster-robust SE and random-effects multinomial logistic model). We also fitted a bivariate probit model with cluster-robust SE treating the choices from two stages as two correlated binary outcomes. The rank of relative importance between attributes and the estimates of β coefficient within attributes were used to assess the model robustness. Results In total 468 participants with each completing 10 choices were analyzed. Similar results were reported for the rank of relative importance and β coefficients across models for stage-one data on evaluating participants' preferences for the test. The six attributes ranked from high to low as follows: cost, specificity, process, sensitivity, preparation and pain. However, the results differed across models for stage-two data on evaluating participants' willingness to undertake the tests. Little within-patient correlation (ICC ≈ 0) was

  12. An empirical comparison of methods for analyzing correlated data from a discrete choice survey to elicit patient preference for colorectal cancer screening.

    PubMed

    Cheng, Ji; Pullenayegum, Eleanor; Marshall, Deborah A; Marshall, John K; Thabane, Lehana

    2012-02-20

    A discrete choice experiment (DCE) is a preference survey which asks participants to make a choice among product portfolios comparing the key product characteristics by performing several choice tasks. Analyzing DCE data needs to account for within-participant correlation because choices from the same participant are likely to be similar. In this study, we empirically compared some commonly-used statistical methods for analyzing DCE data while accounting for within-participant correlation based on a survey of patient preference for colorectal cancer (CRC) screening tests conducted in Hamilton, Ontario, Canada in 2002. A two-stage DCE design was used to investigate the impact of six attributes on participants' preferences for CRC screening test and willingness to undertake the test. We compared six models for clustered binary outcomes (logistic and probit regressions using cluster-robust standard error (SE), random-effects and generalized estimating equation approaches) and three models for clustered nominal outcomes (multinomial logistic and probit regressions with cluster-robust SE and random-effects multinomial logistic model). We also fitted a bivariate probit model with cluster-robust SE treating the choices from two stages as two correlated binary outcomes. The rank of relative importance between attributes and the estimates of β coefficient within attributes were used to assess the model robustness. In total 468 participants with each completing 10 choices were analyzed. Similar results were reported for the rank of relative importance and β coefficients across models for stage-one data on evaluating participants' preferences for the test. The six attributes ranked from high to low as follows: cost, specificity, process, sensitivity, preparation and pain. However, the results differed across models for stage-two data on evaluating participants' willingness to undertake the tests. Little within-patient correlation (ICC ≈ 0) was found in stage-one data, but

  13. Using choice experiments to assess people's preferences for railway transports of hazardous materials.

    PubMed

    Winslott Hiselius, Lena

    2005-10-01

    This article investigates whether the choice experiment approach can be used to assess people's preferences and the determinants of these preferences in order to estimate the costs and benefits of different configurations of the transport of hazardous materials by rail. Changes in the exposure to hazardous materials that people are subjected to are used rather than changes in accident risk. To the best knowledge of the author, this has not been done before in a study of people's preferences toward hazardous materials. A mail survey, carried out in two cities in Sweden, is used to obtain tentative estimates of the willingness to pay for a reduction in exposure as well as the willingness to accept an increase in exposure. Special attention is given to viability, since the complexity of the activity studied, transport of hazardous materials, and the method used pose particular challenges. The response rate and tests of validity and consistency indicate that this method can be applied. Moreover, the results suggest that studies of this kind may provide guidance on changes in the transport of hazardous materials, especially because policymakers may influence the attributes presented here. Referring to the exposure of hazardous materials highlights the importance of providing the respondents with adequate information regarding hazardous transports. An important finding is that the amount of background information may have some effect on the stated preferences.

  14. Role of serotonin transporter function in rat orbitofrontal cortex in impulsive choice.

    PubMed

    Darna, Mahesh; Chow, Jonathan J; Yates, Justin R; Charnigo, Richard J; Beckmann, Joshua S; Bardo, Michael T; Dwoskin, Linda P

    2015-10-15

    Impulsivity is a multi-faceted personality construct that plays a prominent role in drug abuse vulnerability. Dysregulation of 5-hydroxytryptamine (serotonin, 5-HT) systems in subregions of the prefrontal cortex has been implicated in impulsivity. Extracellular 5-HT concentrations are regulated by 5-HT transporters (SERTs), indicating that these transporters may be important molecular targets underlying individual differences in impulsivity and drug abuse vulnerability. The present study evaluated the role of SERT in mediating individual differences in impulsivity. Rats were tested for both impulsive action using the cued go/no-go task and for impulsive choice using a delay discounting task in a counterbalanced design. Following behavioral evaluation, Km and Vmax were obtained from kinetic analysis of [(3)H]5-HT uptake by SERT using synaptosomes prepared from both orbitofrontal cortex (OFC) and medial prefrontal cortex (mPFC) obtained from each individual rat. Vmax for SERT in OFC, but not mPFC, was negatively correlated with mean adjusted delay scores in the delay discounting task. In contrast, Vmax for SERT in OFC and mPFC was not correlated with performance in the cued go/no-go task. To further evaluate the relationship between SERT function and impulsive choice, a selective SERT inhibitor, fluoxetine (0, 15, 50 and 150pmol/side) was microinjected bilaterally into OFC and effects on the delay discounting task determined. Following stabilization of behavior, fluoxetine increased mean adjusted delay scores (decreased impulsivity) in high impulsive rats compared to saline microinjection, but had no effect in low impulsive rats. These ex vivo and in vivo results suggest that enhanced SERT function in OFC underlies high impulsive choice behavior.

  15. Willingness-to-pay for water quality improvements in Chinese rivers: an empirical test on the ordering effects of multiple-bounded discrete choices.

    PubMed

    Wang, Hua; He, Jie; Kim, Yoonhee; Kamata, Takuya

    2013-12-15

    This paper presents a study of the willingness-to-pay (WTP) for surface water quality improvement in China. In the Huaping County of Yunnan Province, we found that people are willing to pay 74 Yuan (or US$12.33 in 2012 prices) per household per month (or 5% of household income) continuously for five years to achieve an improvement of water quality in the two major local rivers from the current Grade IV to Grade III, which denotes a level suitable for swimming and fishing and matches the water quality level from 10 years ago. This WTP study is based on an actual investment project that was under serious consideration by the government and is based on the multiple-bounded discrete choice (MBDC) approach, which explicitly recognizes the potential uncertainties involved in the study. The potential ordering effects associated with the MBDC approach are empirically tested, and the results indicate that although the presentation order of the polychotomous likelihood choices may not have a significant impact on the WTP estimation, the presentation order of bid levels may have a significant impact. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Acceptability and Preferences for Hypothetical Rectal Microbicides among a Community Sample of Young Men Who Have Sex with Men and Transgender Women in Thailand: A Discrete Choice Experiment.

    PubMed

    Newman, Peter A; Cameron, Michael P; Roungprakhon, Surachet; Tepjan, Suchon; Scarpa, Riccardo

    2016-11-01

    Rectal microbicides (RMs) may offer substantial benefits in expanding HIV prevention options for key populations. From April to August 2013, we conducted Tablet-Assisted Survey Interviewing, including a discrete choice experiment, with participants recruited from gay entertainment venues and community-based organizations in Chiang Mai and Pattaya, Thailand. Among 408 participants, 74.5 % were young men who have sex with men, 25.5 % transgender women, with mean age = 24.3 years. One-third (35.5 %) had ≤9th grade education; 63.4 % engaged in sex work. Overall, 83.4 % reported they would definitely use a RM, with more than 2-fold higher odds of choice of a RM with 99 versus 50 % efficacy, and significantly higher odds of choosing gel versus suppository, intermittent versus daily dosing, and prescription versus over-the-counter. Sex workers were significantly more likely to use a RM immediately upon availability, with greater tolerance for moderate efficacy and daily dosing. Engaging key populations in assessing RM preferences may support biomedical research and evidence-informed interventions to optimize the effectiveness of RMs in HIV prevention.

  17. Determining Preferences Related to HIV Counselling and Testing Services Among High School Learners in KwaZulu-Natal: A Discrete Choice Experiment.

    PubMed

    Strauss, Michael; George, Gavin L; Rhodes, Bruce D

    2016-11-16

    A key strategy of the South African national response to HIV is the scale-up of HIV counselling and testing (HCT) in the 15-49 years age group. The integrated school health policy aims to guide the roll out of youth-friendly health services including the provision of HCT in schools. Using a discrete choice experiment to examine preferences regarding the attributes of HCT service packages, this study identifies barriers to and facilitators of HCT among high school learners. Monetary considerations were found to have the strongest effect of any attribute on choice, whilst confidentiality was found to be a primary concern for learners considering HCT. Policy makers and service providers must ensure that confidentiality is maintained, and could consider using monetary incentives as a way of increasing uptake of HCT. Programmes designed to reduce social stigma and improve education and knowledge dissemination around HCT and HIV, are vital in creating demand for HCT and changing attitudes among young people.

  18. Verification of Three Dimensional Triangular Prismatic Discrete Ordinates Transport Code ENSEMBLE-TRIZ by Comparison with Monte Carlo Code GMVP

    NASA Astrophysics Data System (ADS)

    Homma, Yuto; Moriwaki, Hiroyuki; Ohki, Shigeo; Ikeda, Kazumi

    2014-06-01

    This paper deals with verification of three dimensional triangular prismatic discrete ordinates transport calculation code ENSEMBLE-TRIZ by comparison with multi-group Monte Carlo calculation code GMVP in a large fast breeder reactor. The reactor is a 750 MWe electric power sodium cooled reactor. Nuclear characteristics are calculated at beginning of cycle of an initial core and at beginning and end of cycle of equilibrium core. According to the calculations, the differences between the two methodologies are smaller than 0.0002 Δk in the multi-plication factor, relatively about 1% in the control rod reactivity, and 1% in the sodium void reactivity.

  19. An analytical discrete ordinates solution for a nodal model of a two-dimensional neutron transport problem

    SciTech Connect

    Filho, J. F. P.

    2013-07-01

    In this work, an analytical discrete ordinates method is used to solve a nodal formulation of a neutron transport problem in x, y-geometry. The proposed approach leads to an important reduction in the order of the associated eigenvalue systems, when combined with the classical level symmetric quadrature scheme. Auxiliary equations are proposed, as usually required for nodal methods, to express the unknown fluxes at the boundary introduced as additional unknowns in the integrated equations. Numerical results, for the problem defined by a two-dimensional region with a spatially constant and isotropically emitting source, are presented and compared with those available in the literature. (authors)

  20. Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

    SciTech Connect

    Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.; Gable, Carl W.; Karra, Satish

    2015-09-16

    The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates mass balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.

  1. Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

    DOE PAGES

    Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.; ...

    2015-09-16

    The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates massmore » balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.« less

  2. Using qualitative research to facilitate the interpretation of quantitative results from a discrete choice experiment: insights from a survey in elderly ophthalmologic patients

    PubMed Central

    Vennedey, Vera; Danner, Marion; Evers, Silvia MAA; Fauser, Sascha; Stock, Stephanie; Dirksen, Carmen D; Hiligsmann, Mickaël

    2016-01-01

    Background Age-related macular degeneration (AMD) is the leading cause of visual impairment and blindness in industrialized countries. Currently, mainly three treatment options are available, which are all intravitreal injections, but differ with regard to the frequency of injections needed, their approval status, and cost. This study aims to estimate patients’ preferences for characteristics of treatment options for neovascular AMD. Methods An interviewer-assisted discrete choice experiment was conducted among patients suffering from AMD treated with intravitreal injections. A Bayesian efficient design was used for the development of 12 choice tasks. In each task patients indicated their preference for one out of two treatment scenarios described by the attributes: side effects, approval status, effect on visual function, injection and monitoring frequency. While answering the choice tasks, patients were asked to think aloud and explain the reasons for choosing or rejecting specific characteristics. Quantitative data were analyzed with a mixed multinomial logit model. Results Eighty-six patients completed the questionnaire. Patients significantly preferred treatments that improve visual function, are approved, are administered in a pro re nata regimen (as needed), and are accompanied by bimonthly monitoring. Patients significantly disliked less frequent monitoring visits (every 4 months) and explained this was due to fear of deterioration being left unnoticed, and in turn experiencing disease deterioration. Significant preference heterogeneity was found for all levels except for bimonthly monitoring visits and severe, rare eye-related side effects. Patients gave clear explanations of their individual preferences during the interviews. Conclusion Significant preference trends were discernible for the overall sample, despite the preference heterogeneity for most treatment characteristics. Patients like to be monitored and treated regularly, but not too frequently

  3. Toward Patient-Centered Telerehabilitation Design: Understanding Chronic Pain Patients’ Preferences for Web-Based Exercise Telerehabilitation Using a Discrete Choice Experiment

    PubMed Central

    Groothuis-Oudshoorn, Catharina GM; Vollenbroek-Hutten, Miriam MR; IJzerman, Maarten J

    2017-01-01

    Background Patient-centered design that addresses patients’ preferences and needs is considered an important aim for improving health care systems. At present, within the field of pain rehabilitation, patients’ preferences regarding telerehabilitation remain scarcely explored and little is known about the optimal combination between human and electronic contact from the patients’ perspective. In addition, limited evidence is available about the best way to explore patients’ preferences. Therefore, the assessment of patients’ preferences regarding telemedicine is an important step toward the design of effective patient-centered care. Objective To identify which telerehabilitation treatment options patients with chronic pain are most likely to accept as alternatives to conventional rehabilitation and assess which treatment attributes are most important to them. Methods A discrete choice experiment with 15 choice tasks, combining 6 telerehabilitation treatment characteristics, was designed. Each choice task consisted of 2 hypothetical treatment scenarios and 1 opt-out scenario. Relative attribute importance was estimated using a bivariate probit regression analysis. One hundred and thirty surveys were received, of which 104 were usable questionnaires; thus, resulting in a total of 1547 observations. Results Physician communication mode, the use of feedback and monitoring technology (FMT), and exercise location were key drivers of patients’ treatment preferences (P<.001). Patients were willing to accept less frequent physician consultation offered mainly through video communication, provided that they were offered FMT and some face-to-face consultation and could exercise outside their home environment at flexible exercise hours. Home-based telerehabilitation scenarios with minimal physician supervision were the least preferred. A reduction in health care premiums would make these telerehabilitation scenarios as attractive as conventional clinic

  4. Household Size and the Decision to Purchase Health Insurance in Cambodia: Results of a Discrete-Choice Experiment with Scale Adjustment.

    PubMed

    Ozawa, Sachiko; Grewal, Simrun; Bridges, John F P

    2016-04-01

    Community-based health insurance (CBHI) schemes have been introduced in low- and middle-income countries to increase health service utilization and provide financial protection from high healthcare expenditures. We assess the impact of household size on decisions to enroll in CBHI and demonstrate how to correct for group disparity in scale (i.e. variance differences). A discrete choice experiment was conducted across five CBHI attributes. Preferences were elicited through forced-choice paired comparison choice tasks designed based on D-efficiency. Differences in preferences were examined between small (1-4 family members) and large (5-12 members) households using conditional logistic regression. Swait and Louviere test was used to identify and correct for differences in scale. One-hundred and sixty households were surveyed in Northwest Cambodia. Increased insurance premium was associated with disutility [odds ratio (OR) 0.61, p < 0.01], while significant increase in utility was noted for higher hospital fee coverage (OR 10.58, p < 0.01), greater coverage of travel and meal costs (OR 4.08, p < 0.01), and more frequent communication with the insurer (OR 1.33, p < 0.01). While the magnitude of preference for hospital fee coverage appeared larger for the large household group (OR 14.15) compared to the small household group (OR 8.58), differences in scale were observed (p < 0.05). After adjusting for scale (k, ratio of scale between large to small household groups = 1.227, 95 % confidence interval 1.002-1.515), preference differences by household size became negligible. Differences in stated preferences may be due to scale, or variance differences between groups, rather than true variations in preference. Coverage of hospital fees, travel and meal costs are given significant weight in CBHI enrollment decisions regardless of household size. Understanding how community members make decisions about health insurance can inform low- and middle-income countries' paths

  5. Dealing with the health state 'dead' when using discrete choice experiments to obtain values for EQ-5D-5L heath states.

    PubMed

    Ramos-Goñi, Juan Manuel; Rivero-Arias, Oliver; Errea, María; Stolk, Elly A; Herdman, Michael; Cabasés, Juan Manuel

    2013-07-01

    To evaluate two different methods to obtain a dead (0)--full health (1) scale for EQ-5D-5L valuation studies when using discrete choice (DC) modeling. The study was carried out among 400 respondents from Barcelona who were representative of the Spanish population in terms of age, sex, and level of education. The DC design included 50 pairs of health states in five blocks. Participants were forced to choose between two EQ-5D-5L states (A and B). Two extra questions concerned whether A and B were considered worse than dead. Each participant performed ten choice exercises. In addition, values were collected using lead-time trade-off (lead-time TTO), for which 100 states in ten blocks were selected. Each participant performed five lead-time TTO exercises. These consisted of DC models offering the health state 'dead' as one of the choices--for which all participants' responses were used (DCdead)--and a model that included only the responses of participants who chose at least one state as worse than dead (WTD) (DCWTD). The study also estimated DC models rescaled with lead-time TTO data and a lead-time TTO linear model. The DC(dead) and DCWTD models produced relatively similar results, although the coefficients in the DCdead model were slightly lower. The DC model rescaled with lead-time TTO data produced higher utility decrements. Lead-time TTO produced the highest utility decrements. The incorporation of the state 'dead' in the DC models produces results in concordance with DC models that do not include 'dead'.

  6. Simulation and Comparison of Particle Injection in an Indoor Environment Using the Species Transport and Discrete Phase Models

    SciTech Connect

    Zheng, Zhongquan C.; Wei, Zhenglun A.; Bennett, James S.; Yang, Xiaofan

    2012-12-11

    In simulating fluid/solid-particle multiphase -flows, various methods are available. One approach is the combined Euler-Lagrange method, which simulates the fluid phase flow in the Eulerian framework and the discrete phase (particle) motion in the Lagrangian framework simultaneously. The Lagrangian approach, where particle motion is determined by the current state of the fluid phase flow, is also called the discrete phase model (DPM), in the context of numerical flow simulation. In this method, the influence of the particle motions on the fluid flow can be included (two-way interactions) but are more commonly excluded (one-way interactions, when the discrete phase concentration is dilute. The other approach is to treat the particle number concentration as a continuous species, a necessarily passive quantity determined by the fluid flow, with no influences from the particles on the fluid flow (one-way interactions only), except to the extent the discrete phase “continuum” alters the overall fluid properties, such as density. In this paper, we compare these two methods with experimental data for an indoor environmental chamber. The effects of injection particle numbers and the related boundary conditions are investigated. In the Euler-Lagrange interaction or DPM model for incompressible flow, the Eulerian continuous phase is governed by the Reynolds-averaged N-S (RANS) equations. The motions of particles are governed by Newton’s second law. The effects of particle motions are communicated to the continuous phase through a force term in the RANS equations. The second formulation is a pure Eulerian type, where only the particle-number concentration is addressed, rather than the motion of each individual particle. The fluid flow is governed by the same RANS equations without the particle force term. The particle-number concentration is simulated by a species transport equation. Comparisons among the models and with experimental and literature data are presented

  7. Discrete-event simulation of nuclear-waste transport in geologic sites subject to disruptive events. Final report

    SciTech Connect

    Aggarwal, S.; Ryland, S.; Peck, R.

    1980-06-19

    This report outlines a methodology to study the effects of disruptive events on nuclear waste material in stable geologic sites. The methodology is based upon developing a discrete events model that can be simulated on the computer. This methodology allows a natural development of simulation models that use computer resources in an efficient manner. Accurate modeling in this area depends in large part upon accurate modeling of ion transport behavior in the storage media. Unfortunately, developments in this area are not at a stage where there is any consensus on proper models for such transport. Consequently, our work is directed primarily towards showing how disruptive events can be properly incorporated in such a model, rather than as a predictive tool at this stage. When and if proper geologic parameters can be determined, then it would be possible to use this as a predictive model. Assumptions and their bases are discussed, and the mathematical and computer model are described.

  8. Iminoglycinuria and hyperglycinuria are discrete human phenotypes resulting from complex mutations in proline and glycine transporters

    PubMed Central

    Bröer, Stefan; Bailey, Charles G.; Kowalczuk, Sonja; Ng, Cynthia; Vanslambrouck, Jessica M.; Rodgers, Helen; Auray-Blais, Christiane; Cavanaugh, Juleen A.; Bröer, Angelika; Rasko, John E.J.

    2008-01-01

    Iminoglycinuria (IG) is an autosomal recessive abnormality of renal transport of glycine and the imino acids proline and hydroxyproline, but the specific genetic defect(s) have not been determined. Similarly, although the related disorder hyperglycinuria (HG) without iminoaciduria has been attributed to heterozygosity of a putative defective glycine, proline, and hydroxyproline transporter, confirming the underlying genetic defect(s) has been difficult. Here we applied a candidate gene sequencing approach in 7 families first identified through newborn IG screening programs. Both inheritance and functional studies identified the gene encoding the proton amino acid transporter SLC36A2 (PAT2) as the major gene responsible for IG in these families, and its inheritance was consistent with a classical semidominant pattern in which 2 inherited nonfunctional alleles conferred the IG phenotype, while 1 nonfunctional allele was sufficient to confer the HG phenotype. Mutations in SLC36A2 that retained residual transport activity resulted in the IG phenotype when combined with mutations in the gene encoding the imino acid transporter SLC6A20 (IMINO). Additional mutations were identified in the genes encoding the putative glycine transporter SLC6A18 (XT2) and the neutral amino acid transporter SLC6A19 (B0AT1) in families with either IG or HG, suggesting that mutations in the genes encoding these transporters may also contribute to these phenotypes. In summary, although recognized as apparently simple Mendelian disorders, IG and HG exhibit complex molecular explanations depending on a major gene and accompanying modifier genes. PMID:19033659

  9. Patient preferences for treatment of castration-resistant prostate cancer in Japan: a discrete-choice experiment.

    PubMed

    Uemura, Hiroji; Matsubara, Nobuaki; Kimura, Go; Yamaguchi, Akito; Ledesma, Dianne Athene; DiBonaventura, Marco; Mohamed, Ateesha F; Basurto, Enrique; McKinnon, Ian; Wang, Ed; Concialdi, Kristen; Narimatsu, Aya; Aitoku, Yasuko

    2016-11-04

    Up to a fifth of patients diagnosed with prostate cancer (PC) will develop castration-resistant prostate cancer (CRPC), which has been associated with a poor prognosis. The aim of this study was to consider the patient perspective as part of the overall treatment decision-making process for CRPC, given that an alignment between patient preference and prescribing has been shown to benefit patient outcomes. This study examines preferences of patients with CRPC in Japan for treatment features associated with treatments like RA-223, abiraterone, and docetaxel and to examine the extent to which treatment preferences may vary between symptomatic and asymptomatic patients. A two-phase research approach was implemented. In Phase 1, N = 8 patients with CRPC were recruited from a single hospital to complete a qualitative interview to provide feedback on the draft survey. In Phase 2, N = 134 patients with CRPC were recruited from five hospitals to complete a paper survey. The survey included 6 treatment choice questions, each asking patients to choose between two hypothetical treatments for their CRPC. Each treatment alternative was defined by the following attributes: length of overall survival (OS), time to a symptomatic skeletal event (SSE), method of administration, reduction in the risk of bone pain, treatment-associated risk of fatigue and lost work days. A hierarchical Bayesian logistic regression was used to estimate relative preference weights for each attribute level and mean relative importance. A total of N = 133 patients with CRPC completed the survey and were included in the final analysis. Patients had a mean age of 75.4 years (SD = 7.4) and had been diagnosed with PC a mean of 6.5 years prior (SD = 4.4). Over the attribute levels shown, fatigue (relative importance [RI] = 24.9 %, 95 % CI: 24.7 %, 25.1 %) was the most important attribute, followed by reduction in the risk of bone pain (RI = 23.2 %, 95 % CI: 23.0 %, 23.5

  10. Multi-choice stochastic transportation problem involving general form of distributions.

    PubMed

    Quddoos, Abdul; Ull Hasan, Md Gulzar; Khalid, Mohammad Masood

    2014-01-01

    Many authors have presented studies of multi-choice stochastic transportation problem (MCSTP) where availability and demand parameters follow a particular probability distribution (such as exponential, weibull, cauchy or extreme value). In this paper an MCSTP is considered where availability and demand parameters follow general form of distribution and a generalized equivalent deterministic model (GMCSTP) of MCSTP is obtained. It is also shown that all previous models obtained by different authors can be deduced with the help of GMCSTP. MCSTP with pareto, power function or burr-XII distributions are also considered and equivalent deterministic models are obtained. To illustrate the proposed model two numerical examples are presented and solved using LINGO 13.0 software package.

  11. Time Dependent Discrete Ordinates Neutron Transport Using Distribution Iteration in XYZ Geometry

    DTIC Science & Technology

    2007-09-01

    The integro - differential form of the BTE makes it particularly difficult to solve and analytic solutions are only possible for the simplest of problems... equation is transformed into a coupled system of ordinary differential equations . My research is based on fully discretized methods. The means of...a truncated Taylor series expansion as du dt ∣∣∣ tj = uj+1 − uj ∆t . (2.4) The differential equation can be solved for each time step by uj+1 = uj

  12. Factors that influence clinicians' decisions to offer intravenous alteplase in acute ischemic stroke patients with uncertain treatment indication: Results of a discrete choice experiment.

    PubMed

    De Brún, Aoife; Flynn, Darren; Ternent, Laura; Price, Christopher I; Rodgers, Helen; Ford, Gary A; Rudd, Matthew; Lancsar, Emily; Simpson, Stephen; Teah, John; Thomson, Richard G

    2017-01-01

    Background Treatment with intravenous alteplase for eligible patients with acute ischemic stroke is underused, with variation in treatment rates across the UK. This study sought to elucidate factors influencing variation in clinicians' decision-making about this thrombolytic treatment. Methods A discrete choice experiment using hypothetical patient vignettes framed around areas of clinical uncertainty was conducted with UK-based clinicians. Mixed logit regression analyses were conducted on the data. Results A total of 138 clinicians completed the discrete choice experiment. Seven patient factors were individually predictive of increased likelihood of immediately offering IV alteplase (compared to reference levels in brackets): stroke onset time 2 h 30 min [50 min]; pre-stroke dependency mRS 3 [mRS 4]; systolic blood pressure 185 mm/Hg [140 mm/Hg]; stroke severity scores of NIHSS 5 without aphasia, NIHSS 14 and NIHSS 23 [NIHSS 2 without aphasia]; age 85 [68]; Afro-Caribbean [white]. Factors predictive of withholding treatment with IV alteplase were: age 95 [68]; stroke onset time of 4 h 15 min [50 min]; severe dementia [no memory problems]; SBP 200 mm/Hg [140 mm/Hg]. Three clinician-related factors were predictive of an increased likelihood of offering IV alteplase (perceived robustness of the evidence for IV alteplase; thrombolyzing more patients in the past 12 months; and high discomfort with uncertainty) and one with a decreased likelihood (high clinician comfort with treating patients outside the licensing criteria). Conclusions Both patient- and clinician-related factors have a major influence on the use of alteplase to treat patients with acute ischemic stroke. Clinicians' views of the evidence, comfort with uncertainty and treating patients outside the license criteria are important factors to address in programs that seek to reduce variation in care quality regarding treatment with IV alteplase. Further research is needed to further understand

  13. Three-dimensional discrete fracture network simulations of flow and particle transport based on Laxemar site data (Sweden).

    NASA Astrophysics Data System (ADS)

    Frampton, A.; Cvetkovic, V.

    2008-12-01

    Implementing site characterization data to models for simulating flow and transport still remains a formidable challenge, in particular for sparsely fracture rock environments. We present advective flow and particle transport simulations in three-dimensional discrete fracture networks based on Laxemar site characterisation data in Sweden, which is a candidate repository site for high level radioactive waste in the Swedish nuclear waste management program. Field measurements have revealed at least five background fracture sets based on statistically significant orientation data, exhibiting power-law behaviour for fracture size and inferred transmissivity distributions. We study the effect of various interpretations of these background fracture populations, all consistent with the field data, and expose their impact on the behaviour of small scale advective particle transport. In particular, we analyse the inferred correlation between fracture size and transmissivity, together with implications on particle injection mode (flux and resident) and transport law. Furthermore, a fundamental aspect towards understanding tracer migration in subsurface sparsely fractured rock formations is the relationship between the Eulerian flow distribution at a sub-fracture scale with the Lagrangian flow distribution at a characteristic model domain scale. We present a novel approach of accurately inferring the segment-scale Lagrangian distributions from Eulerian distributions obtained from flow simulations. Also, we discuss the potential link to field measurements of fracture specific flow, and how such approaches can be used to improve confidence in model assessment.

  14. Hybrid Upwind Discretization for the Implicit Simulation of Three-Phase Coupled Flow and Transport with Gravity

    NASA Astrophysics Data System (ADS)

    Hamon, F. P.; Mallison, B.; Tchelepi, H.

    2015-12-01

    The systems of algebraic equations arising from implicit (backward-Euler) finite-volume discretization of the conservation laws governing multiphase flow in porous media are quite challenging for nonlinear solvers. In the presence of counter-current flow due to buoyancy, the coupling between flow (pressure) and transport (saturations) is often the cause of nonlinear problems when single-point Phase-Potential Upwinding (PPU) is used. To overcome such convergence problems in practice, the time step is reduced and Newton's method is restarted from the solution at the previous converged time step. Here, we generalize the work of Lee, Efendiev and Tchelepi [Advances in Water Resources, 2015] to propose an Implicit Hybrid Upwinding (IHU) scheme for coupled flow and transport. In the pure transport problem, we show that the numerical flux obtained with IHU is differentiable, monotone and consistent for two and three-phase flow. For coupled flow and transport, we prove saturation physical bounds as well as the existence of a solution to our scheme. Challenging two- and three-phase heterogeneous multi-dimensional numerical tests confirm that the new scheme is non-oscillatory and convergent, and illustrate the superior convergence rate of our IHU-based Newton solver for large time steps.

  15. The Role of Patients’ Age on Their Preferences for Choosing Additional Blood Pressure-Lowering Drugs: A Discrete Choice Experiment in Patients with Diabetes

    PubMed Central

    de Vries, Sieta T.; de Vries, Folgerdiena M.; Dekker, Thijs; Haaijer-Ruskamp, Flora M.; de Zeeuw, Dick; Ranchor, Adelita V.; Denig, Petra

    2015-01-01

    Objectives To assess whether patients’ willingness to add a blood pressure-lowering drug and the importance they attach to specific treatment characteristics differ among age groups in patients with type 2 diabetes. Materials and Methods Patients being prescribed at least an oral glucose-lowering and a blood pressure-lowering drug completed a questionnaire including a discrete choice experiment. This experiment contained choice sets with hypothetical blood pressure-lowering drugs and a no additional drug alternative, which differed in their characteristics (i.e. effects and intake moments). Differences in willingness to add a drug were compared between patients <75 years (non-aged) and ≥75 years (aged) using Pearson χ2-tests. Multinomial logit models were used to assess and compare the importance attached to the characteristics. Results Of the 161 patients who completed the questionnaire, 151 (72%) could be included in the analyses (mean age 68 years; 42% female). Aged patients were less willing to add a drug than non-aged patients (67% versus 84% respectively; P = 0.017). In both age groups, the effect on blood pressure was most important for choosing a drug, followed by the risk of adverse drug events and the risk of death. The effect on limitations due to stroke was only significant in the non-aged group. The effect on blood pressure was slightly more important in the non-aged than the aged group (P = 0.043). Conclusions Aged patients appear less willing to add a preventive drug than non-aged patients. The importance attached to various treatment characteristics does not seem to differ much among age groups. PMID:26445349

  16. Modeling the problem-based learning preferences of McMaster University undergraduate medical students using a discrete choice conjoint experiment.

    PubMed

    Cunningham, Charles E; Deal, Ken; Neville, Alan; Rimas, Heather; Lohfeld, Lynne

    2006-08-01

    To use methods from the field of marketing research to involve students in the redesign of McMaster University's small group, problem-based undergraduate medical education program. We used themes from a focus group conducted in an electronic decision support lab to compose 14 four-level educational attributes. Undergraduate medical students completed a discrete choice experiment composed of 15 web-administered, partial-profile, conjoint-choice tasks. Latent class analysis revealed two segments with different preferences. Segment 1, (86% of students), preferred a problem-based approach with more small group tutorial sessions led by expert tutors who facilitated the tutorial process without teaching didactically. Segment 2, (14% of students), preferred more large group lectures, explicit learning objectives, expert tutors who taught didactically, and streaming options based on learning preferences. Although Segment 1 preferred smaller tutorial groups, simulations predicted these students would trade increases in tutorial group size for a conceptually integrated program that included tutorial problems based on core curriculum concepts, greater integration of the content of clinical skills training sessions and the tutorial curriculum, and a link between clerkship patient selection and the program's curriculum. A majority of both segments would accept a more conceptually integrated program if the savings associated with increases in tutorial group size was reinvested in web-enhanced tutorial processes and computer-simulated health care problems. Most students preferred a small group, web-supported, problem-based learning approach led by content experts who facilitated group process. Students favored a program in which tutorial group problems, clinical skills training sessions and the patients selected for clerkship activities were more closely linked to core curriculum concepts.

  17. Preferences for prenatal diagnosis of sickle-cell disorder: A discrete choice experiment comparing potential service users and health-care providers.

    PubMed

    Hill, Melissa; Oteng-Ntim, Eugene; Forya, Frida; Petrou, Mary; Morris, Stephen; Chitty, Lyn S

    2017-05-15

    Non-invasive prenatal diagnosis (NIPD) for sickle-cell disorder (SCD) is moving closer to implementation and studies considering stakeholder preferences are required to underpin strategies for offering NIPD in clinical practice. Determine service user and provider preferences for key attributes of prenatal diagnostic tests for SCD and examine views on NIPD. A questionnaire that includes a discrete choice experiment was used to determine the preferences of service users and providers for prenatal tests that varied across three attributes: accuracy, time of test and risk of miscarriage. Adults who were carriers of SCD or affected with the condition (N=67) were recruited from haemoglobinopathy clinics at two maternity units. Health professionals, predominately midwives, who offer antenatal care (N=62) were recruited from one maternity unit. No miscarriage risk was a key driver of decision making for both service users and providers. Service providers placed greater emphasis on accuracy than service users. Current uptake of invasive tests was 63%, whilst predicted uptake of NIPD was 93.8%. Many service users (55.4%) and providers (52.5%) think pressure to have prenatal testing will increase when NIPD for SCD becomes available. There are clear differences between service users and health professionals' preferences for prenatal tests for sickle-cell disorder. The safety of NIPD is welcomed by parents and uptake is likely to be high. To promote informed choice, pretest counselling should be balanced and not exclusively focused on test safety. Counselling strategies that are sensitive to feelings of pressure to test will be essential. © 2017 The Authors Health Expectations Published by John Wiley & Sons Ltd.

  18. Statistical Methods for the Analysis of Discrete Choice Experiments: A Report of the ISPOR Conjoint Analysis Good Research Practices Task Force.

    PubMed

    Hauber, A Brett; González, Juan Marcos; Groothuis-Oudshoorn, Catharina G M; Prior, Thomas; Marshall, Deborah A; Cunningham, Charles; IJzerman, Maarten J; Bridges, John F P

    2016-06-01

    Conjoint analysis is a stated-preference survey method that can be used to elicit responses that reveal preferences, priorities, and the relative importance of individual features associated with health care interventions or services. Conjoint analysis methods, particularly discrete choice experiments (DCEs), have been increasingly used to quantify preferences of patients, caregivers, physicians, and other stakeholders. Recent consensus-based guidance on good research practices, including two recent task force reports from the International Society for Pharmacoeconomics and Outcomes Research, has aided in improving the quality of conjoint analyses and DCEs in outcomes research. Nevertheless, uncertainty regarding good research practices for the statistical analysis of data from DCEs persists. There are multiple methods for analyzing DCE data. Understanding the characteristics and appropriate use of different analysis methods is critical to conducting a well-designed DCE study. This report will assist researchers in evaluating and selecting among alternative approaches to conducting statistical analysis of DCE data. We first present a simplistic DCE example and a simple method for using the resulting data. We then present a pedagogical example of a DCE and one of the most common approaches to analyzing data from such a question format-conditional logit. We then describe some common alternative methods for analyzing these data and the strengths and weaknesses of each alternative. We present the ESTIMATE checklist, which includes a list of questions to consider when justifying the choice of analysis method, describing the analysis, and interpreting the results. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  19. Analytical Tests for Ray Effect Errors in Discrete Ordinate Methods for Solving the Neutron Transport Equation

    SciTech Connect

    Chang, B

    2004-03-22

    This paper contains three analytical solutions of transport problems which can be used to test ray-effect errors in the numerical solutions of the Boltzmann Transport Equation (BTE). We derived the first two solutions and the third was shown to us by M. Prasad. Since this paper is intended to be an internal LLNL report, no attempt was made to find the original derivations of the solutions in the literature in order to cite the authors for their work.

  20. Unexpected yes- and no-answering behaviour in the discrete choice approach to elicit willingness to pay: a methodological comparison with payment cards.

    PubMed

    Hammerschmidt, Thomas; Zeitler, Hans-Peter; Leidl, Reiner

    2003-09-01

    When measuring willingness to pay (WTP) by contingent valuation surveys, several elicitation methods can be applied. The most common methods are the discrete choice (DC) approach and payment cards. The purpose of this study was to analyse the convergent validity of both approaches in order to investigate different kinds of answering behaviour in these approaches. Unexpected deviations of the answers in the DC approach from the answers provided on the payment cards were analysed, i.e. unexpected yes- (no-)answering was given when respondents stated to the DC question that they are (not) willing to pay a monetary amount while they stated the opposite on the payment cards. Furthermore, we analysed the feasibility of these two elicitation methods. Each of a group of 92 diabetic patients was asked to state their WTP for reductions of the risk of several diabetic complications by both elicitation methods in two surveys. Both elicitation methods were feasible. Compared with the WTP stated on the payment cards, we found unexpected yes- as well as no-answering behaviour in the DC approach which partly balanced each other. At low bids, there was a tendency that unexpected no-outweighed unexpected yes-answering behaviour. At high bids, unexpected yes- outweighed unexpected no-answering behaviour. Overall, unexpected yes-answering behaviour was predominating. Several explanations for these phenomena remain to be investigated.

  1. An evaluation of patients' willingness to trade symptom-free days for asthma-related treatment risks: a discrete choice experiment.

    PubMed

    McTaggart-Cowan, Helen M; Shi, Peilin; Fitzgerald, J Mark; Anis, Aslam H; Kopec, Jacek A; Bai, Tony R; Soon, Judith A; Lynd, Larry D

    2008-10-01

    Not taking treatment preferences into account may lead to patients' inappropriate use of asthma treatments. The objective of this study was to quantify these preferences, in terms of risk-benefits trade-offs, for six asthma treatment attributes using a discrete choice experiment (DCE). Adult asthma patients (n = 157) participated in the study. The custom-designed DCE measured preferences for treatment effectiveness (symptom-free days), potential risk (oral thrush and tremor/heart palpitation), ease of use (frequency of daily administration and number of inhalers required), and cost. A nested logit model was used to determine the relative preferences of each attribute, from which the marginal rates of substitution were calculated. Segmented models were used to test for interactions between cost and treatment benefit with socioeconomic status and medication use. Relationships between preferences and all attributes were in the hypothesized direction. On average, patients were willing to pay an additional $14 per month to receive one additional symptom-free day, and $26, $79, and $112 monthly to avoid one, two, and three annual episodes of oral thrush, respectively. Income and the magnitude of short-acting beta -agonist use also affected treatment preferences. Overall, asthma patients desired treatments that offered more symptom-free days, but they were willing to trade days without symptoms in exchange for a reduction in adverse events and greater convenience.

  2. “Pay them if it works”: Discrete choice experiments on the acceptability of financial incentives to change health related behaviour

    PubMed Central

    Promberger, Marianne; Dolan, Paul; Marteau, Theresa M.

    2012-01-01

    The use of financial incentives to change health-related behaviour is often opposed by members of the public. We investigated whether the acceptability of incentives is influenced by their effectiveness, the form the incentive takes, and the particular behaviour targeted. We conducted discrete choice experiments, in 2010 with two samples (n = 81 and n = 101) from a self-selected online panel, and in 2011 with an offline general population sample (n = 450) of UK participants to assess the acceptability of incentive-based treatments for smoking cessation and weight loss. We focused on the extent to which this varied with the type of incentive (cash, vouchers for luxury items, or vouchers for healthy groceries) and its effectiveness (ranging from 5% to 40% compared to a standard treatment with effectiveness fixed at 10%). The acceptability of financial incentives increased with effectiveness. Even a small increase in effectiveness from 10% to 11% increased the proportion favouring incentives from 46% to 55%. Grocery vouchers were more acceptable than cash or vouchers for luxury items (about a 20% difference), and incentives were more acceptable for weight loss than for smoking cessation (60% vs. 40%). The acceptability of financial incentives to change behaviour is not necessarily negative but rather is contingent on their effectiveness, the type of incentive and the target behaviour. PMID:23102753

  3. Eliciting preferences for priority setting in genetic testing: a pilot study comparing best-worst scaling and discrete-choice experiments

    PubMed Central

    Severin, Franziska; Schmidtke, Jörg; Mühlbacher, Axel; Rogowski, Wolf H

    2013-01-01

    Given the increasing number of genetic tests available, decisions have to be made on how to allocate limited health-care resources to them. Different criteria have been proposed to guide priority setting. However, their relative importance is unclear. Discrete-choice experiments (DCEs) and best-worst scaling experiments (BWSs) are methods used to identify and weight various criteria that influence orders of priority. This study tests whether these preference eliciting techniques can be used for prioritising genetic tests and compares the empirical findings resulting from these two approaches. Pilot DCE and BWS questionnaires were developed for the same criteria: prevalence, severity, clinical utility, alternatives to genetic testing available, infrastructure for testing and care established, and urgency of care. Interview-style experiments were carried out among different genetics professionals (mainly clinical geneticists, researchers and biologists). A total of 31 respondents completed the DCE and 26 completed the BWS experiment. Weights for the levels of the six attributes were estimated by conditional logit models. Although the results derived from the DCE and BWS experiments differed in detail, we found similar valuation patterns in the DCE and BWS experiments. The respondents attached greatest value to tests with high clinical utility (defined by the availability of treatments that reduce mortality and morbidity) and to testing for highly prevalent conditions. The findings from this study exemplify how decision makers can use quantitative preference eliciting methods to measure aggregated preferences in order to prioritise alternative clinical interventions. Further research is necessary to confirm the survey results. PMID:23486538

  4. [Fertility behavior in Quebec, family allowances, and taxes: results and simulations with a discrete choice model for the years 1975-1987].

    PubMed

    Lefebvre, P; Brouillette, L; Felteau, C

    1994-12-01

    "We suppose that women (couples), who are less than 40 years old, are faced with three types of sequential decisions: the fertility decision, the decision relative to the number of children to have and the decision concerning labour force participation.... We use a nested polychotomous discrete choice model to estimate the responsiveness of the behaviour of 'married' women in Quebec to variations in the expected flow of revenue resulting from changes in the parameters of the personal income tax and in the level of public monetary transfers conditional on the number of children. The model is estimated with micro-data from 9 repeated cross-sections for the years 1975 to 1987 with a full information maximum likelihood method.... This empirical setting is used to simulate the effects of changes made to the fiscal and transfer policies in favor of families with dependent children on fertility, [women's] labor force participation and the importance of spending costs for the two levels of government." (SUMMARY IN ENG)

  5. Public preferences for vaccination programmes during pandemics caused by pathogens transmitted through respiratory droplets - a discrete choice experiment in four European countries, 2013.

    PubMed

    Determann, Domino; Korfage, Ida J; Fagerlin, Angela; Steyerberg, Ewout W; Bliemer, Michiel C; Voeten, Helene A; Richardus, Jan Hendrik; Lambooij, Mattijs S; de Bekker-Grob, Esther W

    2016-06-02

    This study aims to quantify and compare preferences of citizens from different European countries for vaccination programme characteristics during pandemics, caused by pathogens which are transmitted through respiratory droplets. Internet panel members, nationally representative based on age, sex, educational level and region, of four European Union Member States (Netherlands, Poland, Spain, and Sweden, n = 2,068) completed an online discrete choice experiment. These countries, from different geographical areas of Europe, were chosen because of the availability of high-quality Internet panels and because of the cooperation between members of the project entitled Effective Communication in Outbreak Management: development of an evidence-based tool for Europe (ECOM). Data were analysed using panel latent class regression models. In the case of a severe pandemic scenario, vaccine effectiveness was the most important characteristic determining vaccination preference in all countries, followed by the body that advises on vaccination. In Sweden, the advice of family and/or friends and the advice of physicians strongly affected vaccine preferences, in contrast to Poland and Spain, where the advice of (international) health authorities was more decisive. Irrespective of pandemic scenario or vaccination programme characteristics, the predicted vaccination uptakes were lowest in Sweden, and highest in Poland. To increase vaccination uptake during future pandemics, the responsible authorities should align with other important stakeholders in the country and communicate in a coordinated manner.

  6. Preferences for end-of-life care among community-dwelling older adults and patients with advanced cancer: A discrete choice experiment.

    PubMed

    Finkelstein, Eric A; Bilger, Marcel; Flynn, Terry N; Malhotra, Chetna

    2015-11-01

    Singapore is in the midst of several healthcare reforms in efforts to finance and deliver health services for a rapidly aging population. The primary focus of these reforms is to make healthcare services, including those at the end of life (EOL), affordable. Given the increasingly high health care costs at the EOL, policy makers need to consider how best to allocate resources. One strategy is to allocate resources based on the preferences of sub-populations most likely to be affected. This paper thus aims to quantify preferences for EOL care both among community dwelling older adults (CDOAs) and among patients with a life-limiting illness. A discrete choice experiment was administered to CDOAs and advanced cancer patients in Singapore and willingness to pay (WTP) for specific EOL improvements was estimated. We find that patients have a higher WTP for nearly all EOL attributes compared with CDOAs. We also show that, for both groups, moderate life extension is not the most important consideration; WTP for one additional life year is lower than common thresholds for cost-effectiveness. Irrespective of whose preference are considered, the results highlight the importance of pain management and supporting home deaths at the EOL, perhaps at the expense of public funding for costly but only marginally effective treatments. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. An analytic solution method for discrete ordinates transport equations in slab geometry with no spatial truncation error

    SciTech Connect

    Hong, S.G.; Cho, N.Z.

    1999-07-01

    Recently, some authors have devised exact methods with no spatial truncation error for solving the slab geometry discrete ordinates problems. First, Barros and Larsen developed the spectral Green's function (SGF) method where an exact relation between cell-edge and cell-average angular fluxes is derived by using a spectral analysis (i.e., obtaining eigenfunctions). Second, a direct method was developed by using the Laplace transform. More generally in continuous angle, the Fourier transform and inversion were used to provide analytical benchmark solutions. While motivated by Ref. 1, the authors present a new method that gives exact solutions (with no spatial truncation error) of the one-group discrete ordinates transport equations in slab geometry. The method is based on the infinite medium Green's function (IMGF) and Placzek's lemma. The IMGF is derived analytically by spectral analysis. The method yields concise equations resulting in an economical algorithm. The method does not require a set of intermediary parameters that are used in the SGF method and should be solved numerically from a system of linear equations. The unknowns are cell-edge angular fluxes in the present method, whereas in the SGF method there are two types of unknowns: cell-edge and cell-average angular fluxes. In addition, the present method easily allows the source to be distributed arbitrarily in space. Once the final equation for cell-edge angular fluxes is solved, the analytic solution is easily represented in terms of the cell-edge angular fluxes. The numerical results show that the method gives exact solutions of the discrete ordinates equations, independent of mesh size.

  8. Accelerated solution of discrete ordinates approximation to the Boltzmann transport equation via model reduction

    DOE PAGES

    Tencer, John; Carlberg, Kevin; Larsen, Marvin; ...

    2017-06-17

    Radiation heat transfer is an important phenomenon in many physical systems of practical interest. When participating media is important, the radiative transfer equation (RTE) must be solved for the radiative intensity as a function of location, time, direction, and wavelength. In many heat-transfer applications, a quasi-steady assumption is valid, thereby removing time dependence. The dependence on wavelength is often treated through a weighted sum of gray gases (WSGG) approach. The discrete ordinates method (DOM) is one of the most common methods for approximating the angular (i.e., directional) dependence. The DOM exactly solves for the radiative intensity for a finite numbermore » of discrete ordinate directions and computes approximations to integrals over the angular space using a quadrature rule; the chosen ordinate directions correspond to the nodes of this quadrature rule. This paper applies a projection-based model-reduction approach to make high-order quadrature computationally feasible for the DOM for purely absorbing applications. First, the proposed approach constructs a reduced basis from (high-fidelity) solutions of the radiative intensity computed at a relatively small number of ordinate directions. Then, the method computes inexpensive approximations of the radiative intensity at the (remaining) quadrature points of a high-order quadrature using a reduced-order model constructed from the reduced basis. Finally, this results in a much more accurate solution than might have been achieved using only the ordinate directions used to compute the reduced basis. One- and three-dimensional test problems highlight the efficiency of the proposed method.« less

  9. Emittance growth of an nonequilibrium intense electron beam in a transport channel with discrete focusing

    SciTech Connect

    Carlsten, B.E.

    1997-02-01

    The author analyzes the emittance growth mechanisms for a continuous, intense electron beam in a focusing transport channel, over distances short enough that the beam does not reach equilibrium. The emittance grows from the effect of nonlinear forces arising from (1) current density nonuniformities, (2) energy variations leading to nonlinearities in the space-charge force even if the current density is uniform, (3) axial variations in the radial vector potential, (4) an axial velocity shear along the beam, and (5) an energy redistribution of the beam as the beam compresses or expands. The emittance growth is studied analytically and numerically for the cases of balanced flow, tight focusing, and slight beam scalloping, and is additionally studied numerically for an existing 6-MeV induction linear accelerator. Rules for minimizing the emittance along a beamline are established. Some emittance growth will always occur, both from current density nonuniformities that arise along the transport and from beam radius changes along the transport.

  10. Least-squares finite element discretizations of neutron transport equations in 3 dimensions

    SciTech Connect

    Manteuffel, T.A; Ressel, K.J.; Starkes, G.

    1996-12-31

    The least-squares finite element framework to the neutron transport equation introduced in is based on the minimization of a least-squares functional applied to the properly scaled neutron transport equation. Here we report on some practical aspects of this approach for neutron transport calculations in three space dimensions. The systems of partial differential equations resulting from a P{sub 1} and P{sub 2} approximation of the angular dependence are derived. In the diffusive limit, the system is essentially a Poisson equation for zeroth moment and has a divergence structure for the set of moments of order 1. One of the key features of the least-squares approach is that it produces a posteriori error bounds. We report on the numerical results obtained for the minimum of the least-squares functional augmented by an additional boundary term using trilinear finite elements on a uniform tesselation into cubes.

  11. Phase retrieval with the transport-of-intensity equation in an arbitrarily-shaped aperture by iterative discrete cosine transforms

    SciTech Connect

    Huang, Lei; Zuo, Chao; Idir, Mourad; Qu, Weijuan; Asundi, Anand

    2015-04-21

    A novel transport-of-intensity equation (TIE) based phase retrieval method is proposed with putting an arbitrarily-shaped aperture into the optical wavefield. In this arbitrarily-shaped aperture, the TIE can be solved under non-uniform illuminations and even non-homogeneous boundary conditions by iterative discrete cosine transforms with a phase compensation mechanism. Simulation with arbitrary phase, arbitrary aperture shape, and non-uniform intensity distribution verifies the effective compensation and high accuracy of the proposed method. Experiment is also carried out to check the feasibility of the proposed method in real measurement. Comparing to the existing methods, the proposed method is applicable for any types of phase distribution under non-uniform illumination and non-homogeneous boundary conditions within an arbitrarily-shaped aperture, which enables the technique of TIE with hard aperture become a more flexible phase retrieval tool in practical measurements.

  12. Phase retrieval with the transport-of-intensity equation in an arbitrarily-shaped aperture by iterative discrete cosine transforms

    DOE PAGES

    Huang, Lei; Zuo, Chao; Idir, Mourad; ...

    2015-04-21

    A novel transport-of-intensity equation (TIE) based phase retrieval method is proposed with putting an arbitrarily-shaped aperture into the optical wavefield. In this arbitrarily-shaped aperture, the TIE can be solved under non-uniform illuminations and even non-homogeneous boundary conditions by iterative discrete cosine transforms with a phase compensation mechanism. Simulation with arbitrary phase, arbitrary aperture shape, and non-uniform intensity distribution verifies the effective compensation and high accuracy of the proposed method. Experiment is also carried out to check the feasibility of the proposed method in real measurement. Comparing to the existing methods, the proposed method is applicable for any types of phasemore » distribution under non-uniform illumination and non-homogeneous boundary conditions within an arbitrarily-shaped aperture, which enables the technique of TIE with hard aperture become a more flexible phase retrieval tool in practical measurements.« less

  13. Improvements of the boundary projection acceleration technique applied to the discrete-ordinates transport solver in XYZ geometries

    SciTech Connect

    Masiello, E.; Rossi, T.

    2013-07-01

    In this paper we discuss the latest upgrades of the Boundary Projection Acceleration (BPA) applied to the XYZ transport solver of APOLLO3, namely IDT. The acceleration method is a well-known effective technique for the speed-up of the source iterations of the discrete-ordinates method. The BPA in IDT has been improved in three aspects: the taking into account of the residue on boundary conditions as a boundary source for the acceleration problem, the extension of the method to higher order angular moments in the case of anisotropic scattering and, finally, the application of the method to the multigroup iterations for the acceleration of the fission source and k-effective. The spectrum of the method has been Fourier-analyzed to explore the effectiveness. The 3D mock-up geometry of the ZPPR is presented as final study to test the performances of the acceleration on a realistic whole-core 3D calculation. (authors)

  14. Investigation of vertical size segregation in bedload sediment transport with a coupled fluid-discrete element model

    NASA Astrophysics Data System (ADS)

    Frey, Philippe; Maurin, Raphaël; Morchid-Alaoui, Lamia; Gupta, Shashank; Chauchat, Julien

    2017-06-01

    In order to gain understanding of kinetic sieving-type segregation in bedload sediment transport, numerical experiments of two-size particle mixtures were carried out, using a validated coupled fluid-discrete element model developed at Irstea. A 3D 10% steep domain consisting at initial time of a given number of layers of 4 mm particles deposited on top of a coarser 6 mm particle bed, was submitted to a turbulent and supercritical fluid shear flow (Shields numbers of 0.1 and 0.3). The elevation of the centre of mass of the infiltrated fine particles is observed to follow the same logarithmic decrease with time, whatever the initial number of fine layers. This decrease is steeper for a higher Shields number. The main result is that this typical behaviour is related at first order to the shear rate depth profile.

  15. Bayesian methods for model choice and propagation of model uncertainty in groundwater transport modeling

    NASA Astrophysics Data System (ADS)

    Mendes, B. S.; Draper, D.

    2008-12-01

    The issue of model uncertainty and model choice is central in any groundwater modeling effort [Neuman and Wierenga, 2003]; among the several approaches to the problem we favour using Bayesian statistics because it is a method that integrates in a natural way uncertainties (arising from any source) and experimental data. In this work, we experiment with several Bayesian approaches to model choice, focusing primarily on demonstrating the usefulness of the Reversible Jump Markov Chain Monte Carlo (RJMCMC) simulation method [Green, 1995]; this is an extension of the now- common MCMC methods. Standard MCMC techniques approximate posterior distributions for quantities of interest, often by creating a random walk in parameter space; RJMCMC allows the random walk to take place between parameter spaces with different dimensionalities. This fact allows us to explore state spaces that are associated with different deterministic models for experimental data. Our work is exploratory in nature; we restrict our study to comparing two simple transport models applied to a data set gathered to estimate the breakthrough curve for a tracer compound in groundwater. One model has a mean surface based on a simple advection dispersion differential equation; the second model's mean surface is also governed by a differential equation but in two dimensions. We focus on artificial data sets (in which truth is known) to see if model identification is done correctly, but we also address the issues of over and under-paramerization, and we compare RJMCMC's performance with other traditional methods for model selection and propagation of model uncertainty, including Bayesian model averaging, BIC and DIC.References Neuman and Wierenga (2003). A Comprehensive Strategy of Hydrogeologic Modeling and Uncertainty Analysis for Nuclear Facilities and Sites. NUREG/CR-6805, Division of Systems Analysis and Regulatory Effectiveness Office of Nuclear Regulatory Research, U. S. Nuclear Regulatory Commission

  16. Intrinsic and Carrier Colloid-facilitated transport of lanthanides through discrete fractures in chalk

    NASA Astrophysics Data System (ADS)

    Weisbrod, N.; Tran, E. L.; Klein-BenDavid, O.; Teutsch, N.

    2015-12-01

    Geological disposal of high-level radioactive waste is the long term solution for the disposal of long lived radionuclides and spent fuel. However, some radionuclides might be released from these repositories into the subsurface as a result of leakage, which ultimately make their way into groundwater. Engineered bentonite barriers around nuclear waste repositories are generally considered sufficient to impede the transport of radionuclides from their source to the groundwater. However, colloidal-sized mobile bentonite particles ("carrier" colloids) originating from these barriers have come under investigation as a potential transport vector for radionuclides sorbed to them. As lanthanides are generally accepted to have the same chemical behaviors as their more toxic actinide counterparts, lanthanides are considered an acceptable substitute for research on radionuclide transportation. This study aims to evaluate the transport behaviors of lanthanides in colloid-facilitated transport through a fractured chalk matrix and under geochemical conditions representative the Negev desert, Israel. The migration of Ce both with and without colloidal particles was explored and compared to the migration of a conservative tracer (bromide) using a flow system constructed around a naturally fractured chalk core. Results suggest that mobility of Ce as a solute is negligible. In experiments conducted without bentonite colloids, the 1% of the Ce that was recovered migrated as "intrinsic" colloids in the form of carbonate precipitates. However, the total recovery of the Ce increased to 9% when it was injected into the core in the presence of bentonite colloids and 13% when both bentonite and precipitate colloids were injected. This indicates that lanthanides are essentially immobile in chalk as a solute but may be mobile as carbonate precipitates. Bentonite colloids, however, markedly increase the mobility of lanthanides through fractured chalk matrices.

  17. Development of the Adaptive Collision Source Method for Discrete Ordinates Radiation Transport

    NASA Astrophysics Data System (ADS)

    Walters, William J.

    A novel collision source method has been developed to solve the Linear Boltzmann Equation (LBE) more efficiently by adaptation of the angular quadrature order. The angular adaptation method is unique in that the flux from each scattering source iteration is obtained, with potentially a different quadrature order used for each. Traditionally, the flux from every iteration is combined, with the same quadrature applied to the combined flux. Since the scattering process tends to distribute the radiation more evenly over angles (i.e., make it more isotropic), the quadrature requirements generally decrease with each iteration. This method allows for an optimal use of processing power, by using a high order quadrature for the first few iterations that need it, before shifting to lower order quadratures for the remaining iterations. This is essentially an extension of the first collision source method, and is referred to as the adaptive collision source (ACS) method. The ACS methodology has been implemented in the 3-D, parallel, multigroup discrete ordinates code TITAN. This code was tested on a variety of test problems including fixed-source and eigenvalue problems. The ACS implementation in TITAN has shown a reduction in computation time by a factor of 1.5-4 on the fixed-source test problems, for the same desired level of accuracy, as compared to the standard TITAN code.

  18. Discrete and continuum links to a nonlinear coupled transport problem of interacting populations

    NASA Astrophysics Data System (ADS)

    Duong, M. H.; Muntean, A.; Richardson, O. M.

    2017-02-01

    We are interested in exploring interacting particle systems that can be seen as microscopic models for a particular structure of coupled transport flux arising when different populations are jointly evolving. The scenarios we have in mind are inspired by the dynamics of pedestrian flows in open spaces and are intimately connected to cross-diffusion and thermo-diffusion problems holding a variational structure. The tools we use include a suitable structure of the relative entropy controlling TV-norms, the construction of Lyapunov functionals and particular closed-form solutions to nonlinear transport equations, a hydrodynamics limiting procedure due to Philipowski, as well as the construction of numerical approximates to both the continuum limit problem in 2D and to the original interacting particle systems.

  19. Discrete and continuum links to a nonlinear coupled transport problem of interacting populations

    NASA Astrophysics Data System (ADS)

    Duong, M. H.; Muntean, A.; Richardson, O. M.

    2017-07-01

    We are interested in exploring interacting particle systems that can be seen as microscopic models for a particular structure of coupled transport flux arising when different populations are jointly evolving. The scenarios we have in mind are inspired by the dynamics of pedestrian flows in open spaces and are intimately connected to cross-diffusion and thermo-diffusion problems holding a variational structure. The tools we use include a suitable structure of the relative entropy controlling TV-norms, the construction of Lyapunov functionals and particular closed-form solutions to nonlinear transport equations, a hydrodynamics limiting procedure due to Philipowski, as well as the construction of numerical approximates to both the continuum limit problem in 2D and to the original interacting particle systems.

  20. Piecewise linear discretization of Symbolic Implicit Monte Carlo radiation transport in the difference formulation

    SciTech Connect

    Brooks III, E D; Szoke, A; Peterson, J L

    2005-11-15

    We describe a Monte Carlo solution for time dependent photon transport, in the difference formulation with the material in local thermodynamic equilibrium (LTE), that is piecewise linear in its treatment of the material state variable. Our method employs a Galerkin solution for the material energy equation while using Symbolic Implicit Monte Carlo (SIMC) to solve the transport equation. In constructing the scheme, one has the freedom to choose between expanding the material temperature, or the equivalent black body radiation energy density at the material temperature, in terms of finite element basis functions. The former provides a linear treatment of the material energy while the latter provides a linear treatment of the radiative coupling between zones. Subject to the conditional use of a lumped material energy in the vicinity of strong gradients, possible with a linear treatment of the material energy, our approach provides a robust solution for time dependent transport of thermally emitted radiation that can address a wide range of problems. It produces accurate results in the diffusion limit.

  1. Constructing experimental designs for discrete-choice experiments: report of the ISPOR Conjoint Analysis Experimental Design Good Research Practices Task Force.

    PubMed

    Reed Johnson, F; Lancsar, Emily; Marshall, Deborah; Kilambi, Vikram; Mühlbacher, Axel; Regier, Dean A; Bresnahan, Brian W; Kanninen, Barbara; Bridges, John F P

    2013-01-01

    Stated-preference methods are a class of evaluation techniques for studying the preferences of patients and other stakeholders. While these methods span a variety of techniques, conjoint-analysis methods-and particularly discrete-choice experiments (DCEs)-have become the most frequently applied approach in health care in recent years. Experimental design is an important stage in the development of such methods, but establishing a consensus on standards is hampered by lack of understanding of available techniques and software. This report builds on the previous ISPOR Conjoint Analysis Task Force Report: Conjoint Analysis Applications in Health-A Checklist: A Report of the ISPOR Good Research Practices for Conjoint Analysis Task Force. This report aims to assist researchers specifically in evaluating alternative approaches to experimental design, a difficult and important element of successful DCEs. While this report does not endorse any specific approach, it does provide a guide for choosing an approach that is appropriate for a particular study. In particular, it provides an overview of the role of experimental designs for the successful implementation of the DCE approach in health care studies, and it provides researchers with an introduction to constructing experimental designs on the basis of study objectives and the statistical model researchers have selected for the study. The report outlines the theoretical requirements for designs that identify choice-model preference parameters and summarizes and compares a number of available approaches for constructing experimental designs. The task-force leadership group met via bimonthly teleconferences and in person at ISPOR meetings in the United States and Europe. An international group of experimental-design experts was consulted during this process to discuss existing approaches for experimental design and to review the task force's draft reports. In addition, ISPOR members contributed to developing a consensus

  2. [The Trade-Off between Chance of Success and Urgency in Organ Allocation: A Discrete Choice Experiment to Elicit Public Preferences].

    PubMed

    Dao Van, M; Lauerer, M; Schätzlein, V; Nagel, E

    2016-07-01

    According to the German Organ Transplantation Act, donor organs must be allocated with particular regard to chance of success and urgency. However, the objectives of these guiding criteria - the efficient use of available organs and meeting the most urgent need - are in conflict with each other, as success rate of transplantation (TX) ordinarily diminishes when urgency increases. Current allocation guidelines balance these criteria differently depending on the organ. This is only justified in part by medical reasons. Thus, further considerations are essential to develop consistent allocation rules. Therefore, a discussion on the stated trade-off considering the far-reaching consequences of such allocation decisions is indispensable. This also implies taking account of public preferences. In this pilot study, preferences of 250 participants were assessed using a Discrete Choice Experiment. Choice-sets for the allocation of a donor organ included 2 patients, who were characterized by 3 success- and 2 urgency-based attributes. Data analysis was performed by Counting Analysis and Hierarchical Bayes estimation as well as Student's t-tests for subgroup analysis. All attributes influenced allocation decisions significantly (p≤0.01). Both, patients with greater chance of success and higher urgency were preferred. As a whole, chance of success and urgency were equally important for the allocation of organs (53 and 47%, respectively). The importance of the success- and urgency-based criteria was quantified as follows: The post-TX 5-year probability of survival was weighted with 31%, the expected post-TX quality of life and the surgery survival rate with 11% each, the pre-TX 3-month mortality with 35% and the pre-TX quality of life with 12%. Subgroup analysis revealed significant differences. The pilot study was successful in analyzing the balance of the guiding criteria chance of success and urgency without referring to a specific kind of organ. This type of results allows

  3. Effect of Internal Aperture Variability on Tracer Transport in Large Discrete Fracture Networks (DFN)

    NASA Astrophysics Data System (ADS)

    Makedonska, N.; Painter, S. L.; Hyman, J.; Karra, S.; Gable, C. W.; Viswanathan, H. S.

    2015-12-01

    Aperture variability within individual fractures is usually neglected in modeling flow and transport through fractured media. Typically, individual fractures are assumed to be homogeneous. However, in reality, individual fractures are heterogeneous, which may affect flow and transport in fractured media. The relative importance of including in-fracture variability in flow and transport modeling has been under debate for a long time. Previous studies have shown flow channeling on an individual fracture with internal variability, where the fracture is considered isolated from the rest of the fracture network. Although these studies yield some clear insights into the process, the boundary conditions are impractical for field-scale networks, where the realistic boundary conditions are determined by fracture connections in the network. Therefore, flow in a single fracture is controlled not only by in-fracture variability but also by boundary conditions. In order to address the question of the importance of in-fracture variability, the internal heterogeneity of every individual fracture is incorporated into a three-dimensional fracture network, represented by a composition of intersecting fractures. The new DFN simulation capability, dfnWorks, is used to generate a kilometer scale DFNs similar to the Forsmark, Sweden site. In our DFN model, the in-fracture aperture variability is scattered over each cell of the computational mesh along the fracture, representing by a stationary Gaussian random field with various correlation lengths. The Lagrangian particle tracking is conducted in multiple DFN realizations and the flow-dependent Lagrangian parameters, non-reacting travel time, τ, and cumulative reactivity parameter, β, are obtained along particles streamlines. It is shown that early particle travel times are more sensitive to in-fracture aperture variability than tails of travel time distributions, where no significant effect of the aperture variations and spatial

  4. Hybrid discrete-continuum modeling for transport, biofilm development and solid restructuring including electrostatic effects

    NASA Astrophysics Data System (ADS)

    Prechtel, Alexander; Ray, Nadja; Rupp, Andreas

    2017-04-01

    We want to present an approach for the mathematical, mechanistic modeling and numerical treatment of processes leading to the formation, stability, and turnover of soil micro-aggregates. This aims at deterministic aggregation models including detailed mechanistic pore-scale descriptions to account for the interplay of geochemistry and microbiology, and the link to soil functions as, e.g., the porosity. We therefore consider processes at the pore scale and the mesoscale (laboratory scale). At the pore scale transport by diffusion, advection, and drift emerging from electric forces can be taken into account, in addition to homogeneous and heterogeneous reactions of species. In the context of soil micro-aggregates the growth of biofilms or other glueing substances as EPS (extracellular polymeric substances) is important and affects the structure of the pore space in space and time. This model is upscaled mathematically in the framework of (periodic) homogenization to transfer it to the mesoscale resulting in effective coefficients/parameters there. This micro-macro model thus couples macroscopic equations that describe the transport and fluid flow at the scale of the porous medium (mesoscale) with averaged time- and space-dependent coefficient functions. These functions may be explicitly computed by means of auxiliary cell problems (microscale). Finally, the pore space in which the cell problems are defined is time and space dependent and its geometry inherits information from the transport equation's solutions. The microscale problems rely on versatile combinations of cellular automata and discontiuous Galerkin methods while on the mesoscale mixed finite elements are used. The numerical simulations allow to study the interplay between these processes.

  5. Identifying Societal Preferences for River Restoration in a Densely Populated Urban Environment: Evidence from a Discrete Choice Experiment in Central Brussels.

    PubMed

    Chen, Wendy Y; Liekens, Inge; Broekx, Steven

    2017-08-01

    One of the major challenges facing river restoration in densely populated urban areas has been the disparity between the expectations of policy-makers and societal preferences. This study aimed to elicit public preferences and elucidate underlying sources of preference heterogeneity, using the Zenne River in central Brussels, Belgium, as a case study. A discrete choice experiment was administered to a representative sample of the Brussels population. Five attributes were specified, including water quality, ecological status, hydromorphological features of channels, recreational opportunities, and monetary cost. Our econometric analysis based on mixed logit models revealed that overall public would like to have a more natural river (open and naturalized channel, good water quality, and with rich species diversity), while achieving good water quality was the most preferred attribute. Respondents categorized as male, non-Belgian citizen, or not being a member of an environmental organization constituted an inclination to prefer the status quo. Belgian citizens showed a pronounced preference for good biodiversity, and being a member of an environmental organization could moderate the strong preference for good water quality. This study provided insights into the relative attractiveness of key attributes pertaining to river restoration, in general, and served as a useful input to the ongoing discussion concerning the future plan for the Zenne River in Brussels, specifically. Possible implications also exist for other urban river restorations in the rest of Europe, where the Water Framework Directive has become a major impetus for the expansion of freshwater ecosystem restoration from rural and peri-urban areas to densely populated urban areas. Particularly, the cultural heterogeneity of societal preferences should be tested and accounted for to compare the welfare impacts of river restoration and to facilitate benefit transfer, within and between river basins, in the

  6. The introduction of integrated out-of-hours arrangements in England: a discrete choice experiment of public preferences for alternative models of care.

    PubMed

    Gerard, Karen; Lattimer, Val; Surridge, Heidi; George, Steve; Turnbull, Joanne; Burgess, Abigail; Lathlean, Judith; Smith, Helen

    2006-03-01

    To establish which generic attributes of general practice out-of-hours health services are important to the public. A discrete choice experiment postal survey conducted in three English general practitioner (GP) co-operatives. A total of 871 individuals aged 20-70 years registered with a GP. Outcomes were preferences for, and trade-offs between: time to making initial contact, time waiting for advice/treatment, informed of expected waiting time, type of contact, professional providing advice, chance contact relieves anxiety, and utility estimates for valuing current models of care. Response rate was 37%. Respondents valued out-of-hours contact for services for reducing anxiety but this was not the only attribute of importance. They had preferences for the way in which services were organized and valued information about expected waiting time, supporting findings from elsewhere. Participants were most willing to make trade-offs between waiting time and professional person. Of the predicted utility for three models of care utility was higher for fully integrated call management. Greater utility might be achieved if existing services are re-configured more in line with the government's fully integrated call management model. Because the attributes were described in generic terms, the findings can be applied more generally to the plethora of models that exist (and many that might exist in the future). The approach used is important for achieving greater public involvement in how health services develop. Few experiments have elicited public preferences for health services in the UK to date. This study showed valid preferences were expressed but there were problems obtaining representative views from the public.

  7. Have Preferences of Girls Changed Almost 3 Years after the Much Debated Start of the HPV Vaccination Program in the Netherlands? A Discrete Choice Experiment

    PubMed Central

    Hofman, Robine; de Bekker-Grob, Esther W.; Richardus, Jan Hendrik; de Koning, Harry J.; van Ballegooijen, Marjolein; Korfage, Ida J.

    2014-01-01

    Objectives To assess how girls' preferences have changed almost 3 years after the much debated start of the human papillomavirus (HPV) vaccination program. Methods A discrete choice experiment (DCE) was conducted among girls aged 11–15 years who were invited, or were not yet invited, to get vaccinated. A panel latent class model was used to determine girls' preferences for vaccination based on five characteristics: degree of protection against cervical cancer; duration of protection; risk of mild side-effects; age of vaccination; and the number of required doses of the vaccine. Res