Sample size determination for logistic regression on a logit-normal distribution.

PubMed

Kim, Seongho; Heath, Elisabeth; Heilbrun, Lance

2017-06-01

Although the sample size for simple logistic regression can be readily determined using currently available methods, the sample size calculation for multiple logistic regression requires some additional information, such as the coefficient of determination ([Formula: see text]) of a covariate of interest with other covariates, which is often unavailable in practice. The response variable of logistic regression follows a logit-normal distribution which can be generated from a logistic transformation of a normal distribution. Using this property of logistic regression, we propose new methods of determining the sample size for simple and multiple logistic regressions using a normal transformation of outcome measures. Simulation studies and a motivating example show several advantages of the proposed methods over the existing methods: (i) no need for [Formula: see text] for multiple logistic regression, (ii) available interim or group-sequential designs, and (iii) much smaller required sample size.

Generalized Partial Least Squares Approach for Nominal Multinomial Logit Regression Models with a Functional Covariate

ERIC Educational Resources Information Center

Albaqshi, Amani Mohammed H.

2017-01-01

Functional Data Analysis (FDA) has attracted substantial attention for the last two decades. Within FDA, classifying curves into two or more categories is consistently of interest to scientists, but multi-class prediction within FDA is challenged in that most classification tools have been limited to binary response applications. The functional…

Logit Models for the Analysis of Two-Way Categorical Data

ERIC Educational Resources Information Center

Draxler, Clemens

2011-01-01

This article discusses the application of logit models for the analyses of 2-way categorical observations. The models described are generalized linear models using the logit link function. One of the models is the Rasch model (Rasch, 1960). The objective is to test hypotheses of marginal and conditional independence between explanatory quantities…

Categorical Data Analysis Using a Skewed Weibull Regression Model

NASA Astrophysics Data System (ADS)

Caron, Renault; Sinha, Debajyoti; Dey, Dipak; Polpo, Adriano

2018-03-01

In this paper, we present a Weibull link (skewed) model for categorical response data arising from binomial as well as multinomial model. We show that, for such types of categorical data, the most commonly used models (logit, probit and complementary log-log) can be obtained as limiting cases. We further compare the proposed model with some other asymmetrical models. The Bayesian as well as frequentist estimation procedures for binomial and multinomial data responses are presented in details. The analysis of two data sets to show the efficiency of the proposed model is performed.

Gender, Alcohol Consumption Patterns, and Engagement in Sexually Intimate Behaviors among Adolescents and Young Adults in Nha Trang, Viet Nam

ERIC Educational Resources Information Center

Kaljee, Linda M.; Green, Mackenzie S.; Zhan, Min; Riel, Rosemary; Lerdboon, Porntip; Lostutter, Ty W.; Tho, Le Huu; Luong, Vo Van; Minh, Truong Tan

2011-01-01

A randomly selected cross-sectional survey was conducted with 880 youth (16 to 24 years) in Nha Trang City to assess relationships between alcohol consumption and sexual behaviors. A timeline followback method was employed. Chi-square, generalized logit modeling and logistic regression analyses were performed. Of the sample, 78.2% male and 56.1%…

An Analysis of Army Dentists Using Logistic Regression: A Discrete-Time Logit Model for Predicting Retention

DTIC Science & Technology

2009-06-10

Reports (0704 0188), 1215 Jefferson Devis Highway, Suite 1204, Arlington, VA 22202 4302 Respondents should be aware that notwithstanding any other...NAME(S) AND ADDRESS(ES) US Army Medical Department Center and School BLDG 2841 MCCS-HGE-HA (Army-Baylor Program in Health & Business Administration...been used to model negative occurrences in the medical field, such as time to death from a certain disease. However, questions of whether and when

Markov switching multinomial logit model: An application to accident-injury severities.

PubMed

Malyshkina, Nataliya V; Mannering, Fred L

2009-07-01

In this study, two-state Markov switching multinomial logit models are proposed for statistical modeling of accident-injury severities. These models assume Markov switching over time between two unobserved states of roadway safety as a means of accounting for potential unobserved heterogeneity. The states are distinct in the sense that in different states accident-severity outcomes are generated by separate multinomial logit processes. To demonstrate the applicability of the approach, two-state Markov switching multinomial logit models are estimated for severity outcomes of accidents occurring on Indiana roads over a four-year time period. Bayesian inference methods and Markov Chain Monte Carlo (MCMC) simulations are used for model estimation. The estimated Markov switching models result in a superior statistical fit relative to the standard (single-state) multinomial logit models for a number of roadway classes and accident types. It is found that the more frequent state of roadway safety is correlated with better weather conditions and that the less frequent state is correlated with adverse weather conditions.

Genomic-Enabled Prediction of Ordinal Data with Bayesian Logistic Ordinal Regression.

PubMed

Montesinos-López, Osval A; Montesinos-López, Abelardo; Crossa, José; Burgueño, Juan; Eskridge, Kent

2015-08-18

Most genomic-enabled prediction models developed so far assume that the response variable is continuous and normally distributed. The exception is the probit model, developed for ordered categorical phenotypes. In statistical applications, because of the easy implementation of the Bayesian probit ordinal regression (BPOR) model, Bayesian logistic ordinal regression (BLOR) is implemented rarely in the context of genomic-enabled prediction [sample size (n) is much smaller than the number of parameters (p)]. For this reason, in this paper we propose a BLOR model using the Pólya-Gamma data augmentation approach that produces a Gibbs sampler with similar full conditional distributions of the BPOR model and with the advantage that the BPOR model is a particular case of the BLOR model. We evaluated the proposed model by using simulation and two real data sets. Results indicate that our BLOR model is a good alternative for analyzing ordinal data in the context of genomic-enabled prediction with the probit or logit link. Copyright © 2015 Montesinos-López et al.

Bayesian Inference for the Stereotype Regression Model: Application to a Case-control Study of Prostate Cancer

PubMed Central

Ahn, Jaeil; Mukherjee, Bhramar; Banerjee, Mousumi; Cooney, Kathleen A.

2011-01-01

Summary The stereotype regression model for categorical outcomes, proposed by Anderson (1984) is nested between the baseline category logits and adjacent category logits model with proportional odds structure. The stereotype model is more parsimonious than the ordinary baseline-category (or multinomial logistic) model due to a product representation of the log odds-ratios in terms of a common parameter corresponding to each predictor and category specific scores. The model could be used for both ordered and unordered outcomes. For ordered outcomes, the stereotype model allows more flexibility than the popular proportional odds model in capturing highly subjective ordinal scaling which does not result from categorization of a single latent variable, but are inherently multidimensional in nature. As pointed out by Greenland (1994), an additional advantage of the stereotype model is that it provides unbiased and valid inference under outcome-stratified sampling as in case-control studies. In addition, for matched case-control studies, the stereotype model is amenable to classical conditional likelihood principle, whereas there is no reduction due to sufficiency under the proportional odds model. In spite of these attractive features, the model has been applied less, as there are issues with maximum likelihood estimation and likelihood based testing approaches due to non-linearity and lack of identifiability of the parameters. We present comprehensive Bayesian inference and model comparison procedure for this class of models as an alternative to the classical frequentist approach. We illustrate our methodology by analyzing data from The Flint Men’s Health Study, a case-control study of prostate cancer in African-American men aged 40 to 79 years. We use clinical staging of prostate cancer in terms of Tumors, Nodes and Metastatsis (TNM) as the categorical response of interest. PMID:19731262

Network-constrained group lasso for high-dimensional multinomial classification with application to cancer subtype prediction.

PubMed

Tian, Xinyu; Wang, Xuefeng; Chen, Jun

2014-01-01

Classic multinomial logit model, commonly used in multiclass regression problem, is restricted to few predictors and does not take into account the relationship among variables. It has limited use for genomic data, where the number of genomic features far exceeds the sample size. Genomic features such as gene expressions are usually related by an underlying biological network. Efficient use of the network information is important to improve classification performance as well as the biological interpretability. We proposed a multinomial logit model that is capable of addressing both the high dimensionality of predictors and the underlying network information. Group lasso was used to induce model sparsity, and a network-constraint was imposed to induce the smoothness of the coefficients with respect to the underlying network structure. To deal with the non-smoothness of the objective function in optimization, we developed a proximal gradient algorithm for efficient computation. The proposed model was compared to models with no prior structure information in both simulations and a problem of cancer subtype prediction with real TCGA (the cancer genome atlas) gene expression data. The network-constrained mode outperformed the traditional ones in both cases.

Comparison of IRT Likelihood Ratio Test and Logistic Regression DIF Detection Procedures

ERIC Educational Resources Information Center

Atar, Burcu; Kamata, Akihito

2011-01-01

The Type I error rates and the power of IRT likelihood ratio test and cumulative logit ordinal logistic regression procedures in detecting differential item functioning (DIF) for polytomously scored items were investigated in this Monte Carlo simulation study. For this purpose, 54 simulation conditions (combinations of 3 sample sizes, 2 sample…

Nested Logit Models for Multiple-Choice Item Response Data

ERIC Educational Resources Information Center

Suh, Youngsuk; Bolt, Daniel M.

2010-01-01

Nested logit item response models for multiple-choice data are presented. Relative to previous models, the new models are suggested to provide a better approximation to multiple-choice items where the application of a solution strategy precedes consideration of response options. In practice, the models also accommodate collapsibility across all…

Multinomial logistic regression modelling of obesity and overweight among primary school students in a rural area of Negeri Sembilan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghazali, Amirul Syafiq Mohd; Ali, Zalila; Noor, Norlida Mohd

Multinomial logistic regression is widely used to model the outcomes of a polytomous response variable, a categorical dependent variable with more than two categories. The model assumes that the conditional mean of the dependent categorical variables is the logistic function of an affine combination of predictor variables. Its procedure gives a number of logistic regression models that make specific comparisons of the response categories. When there are q categories of the response variable, the model consists of q-1 logit equations which are fitted simultaneously. The model is validated by variable selection procedures, tests of regression coefficients, a significant test ofmore » the overall model, goodness-of-fit measures, and validation of predicted probabilities using odds ratio. This study used the multinomial logistic regression model to investigate obesity and overweight among primary school students in a rural area on the basis of their demographic profiles, lifestyles and on the diet and food intake. The results indicated that obesity and overweight of students are related to gender, religion, sleep duration, time spent on electronic games, breakfast intake in a week, with whom meals are taken, protein intake, and also, the interaction between breakfast intake in a week with sleep duration, and the interaction between gender and protein intake.« less

Multinomial logistic regression modelling of obesity and overweight among primary school students in a rural area of Negeri Sembilan

NASA Astrophysics Data System (ADS)

Ghazali, Amirul Syafiq Mohd; Ali, Zalila; Noor, Norlida Mohd; Baharum, Adam

2015-10-01

Multinomial logistic regression is widely used to model the outcomes of a polytomous response variable, a categorical dependent variable with more than two categories. The model assumes that the conditional mean of the dependent categorical variables is the logistic function of an affine combination of predictor variables. Its procedure gives a number of logistic regression models that make specific comparisons of the response categories. When there are q categories of the response variable, the model consists of q-1 logit equations which are fitted simultaneously. The model is validated by variable selection procedures, tests of regression coefficients, a significant test of the overall model, goodness-of-fit measures, and validation of predicted probabilities using odds ratio. This study used the multinomial logistic regression model to investigate obesity and overweight among primary school students in a rural area on the basis of their demographic profiles, lifestyles and on the diet and food intake. The results indicated that obesity and overweight of students are related to gender, religion, sleep duration, time spent on electronic games, breakfast intake in a week, with whom meals are taken, protein intake, and also, the interaction between breakfast intake in a week with sleep duration, and the interaction between gender and protein intake.

On the development of a semi-nonparametric generalized multinomial logit model for travel-related choices

PubMed Central

Ye, Xin; Pendyala, Ram M.; Zou, Yajie

2017-01-01

A semi-nonparametric generalized multinomial logit model, formulated using orthonormal Legendre polynomials to extend the standard Gumbel distribution, is presented in this paper. The resulting semi-nonparametric function can represent a probability density function for a large family of multimodal distributions. The model has a closed-form log-likelihood function that facilitates model estimation. The proposed method is applied to model commute mode choice among four alternatives (auto, transit, bicycle and walk) using travel behavior data from Argau, Switzerland. Comparisons between the multinomial logit model and the proposed semi-nonparametric model show that violations of the standard Gumbel distribution assumption lead to considerable inconsistency in parameter estimates and model inferences. PMID:29073152

On the development of a semi-nonparametric generalized multinomial logit model for travel-related choices.

PubMed

Wang, Ke; Ye, Xin; Pendyala, Ram M; Zou, Yajie

2017-01-01

A semi-nonparametric generalized multinomial logit model, formulated using orthonormal Legendre polynomials to extend the standard Gumbel distribution, is presented in this paper. The resulting semi-nonparametric function can represent a probability density function for a large family of multimodal distributions. The model has a closed-form log-likelihood function that facilitates model estimation. The proposed method is applied to model commute mode choice among four alternatives (auto, transit, bicycle and walk) using travel behavior data from Argau, Switzerland. Comparisons between the multinomial logit model and the proposed semi-nonparametric model show that violations of the standard Gumbel distribution assumption lead to considerable inconsistency in parameter estimates and model inferences.

An Objective Screening Method for Major Depressive Disorder Using Logistic Regression Analysis of Heart Rate Variability Data Obtained in a Mental Task Paradigm.

PubMed

Sun, Guanghao; Shinba, Toshikazu; Kirimoto, Tetsuo; Matsui, Takemi

2016-01-01

Heart rate variability (HRV) has been intensively studied as a promising biological marker of major depressive disorder (MDD). Our previous study confirmed that autonomic activity and reactivity in depression revealed by HRV during rest and mental task (MT) conditions can be used as diagnostic measures and in clinical evaluation. In this study, logistic regression analysis (LRA) was utilized for the classification and prediction of MDD based on HRV data obtained in an MT paradigm. Power spectral analysis of HRV on R-R intervals before, during, and after an MT (random number generation) was performed in 44 drug-naïve patients with MDD and 47 healthy control subjects at Department of Psychiatry in Shizuoka Saiseikai General Hospital. Logit scores of LRA determined by HRV indices and heart rates discriminated patients with MDD from healthy subjects. The high frequency (HF) component of HRV and the ratio of the low frequency (LF) component to the HF component (LF/HF) correspond to parasympathetic and sympathovagal balance, respectively. The LRA achieved a sensitivity and specificity of 80.0 and 79.0%, respectively, at an optimum cutoff logit score (0.28). Misclassifications occurred only when the logit score was close to the cutoff score. Logit scores also correlated significantly with subjective self-rating depression scale scores ( p  < 0.05). HRV indices recorded during a MT may be an objective tool for screening patients with MDD in psychiatric practice. The proposed method appears promising for not only objective and rapid MDD screening but also evaluation of its severity.

On the potential of models for location and scale for genome-wide DNA methylation data

PubMed Central

2014-01-01

Background With the help of epigenome-wide association studies (EWAS), increasing knowledge on the role of epigenetic mechanisms such as DNA methylation in disease processes is obtained. In addition, EWAS aid the understanding of behavioral and environmental effects on DNA methylation. In terms of statistical analysis, specific challenges arise from the characteristics of methylation data. First, methylation β-values represent proportions with skewed and heteroscedastic distributions. Thus, traditional modeling strategies assuming a normally distributed response might not be appropriate. Second, recent evidence suggests that not only mean differences but also variability in site-specific DNA methylation associates with diseases, including cancer. The purpose of this study was to compare different modeling strategies for methylation data in terms of model performance and performance of downstream hypothesis tests. Specifically, we used the generalized additive models for location, scale and shape (GAMLSS) framework to compare beta regression with Gaussian regression on raw, binary logit and arcsine square root transformed methylation data, with and without modeling a covariate effect on the scale parameter. Results Using simulated and real data from a large population-based study and an independent sample of cancer patients and healthy controls, we show that beta regression does not outperform competing strategies in terms of model performance. In addition, Gaussian models for location and scale showed an improved performance as compared to models for location only. The best performance was observed for the Gaussian model on binary logit transformed β-values, referred to as M-values. Our results further suggest that models for location and scale are specifically sensitive towards violations of the distribution assumption and towards outliers in the methylation data. Therefore, a resampling procedure is proposed as a mode of inference and shown to diminish type I error rate in practically relevant settings. We apply the proposed method in an EWAS of BMI and age and reveal strong associations of age with methylation variability that are validated in an independent sample. Conclusions Models for location and scale are promising tools for EWAS that may help to understand the influence of environmental factors and disease-related phenotypes on methylation variability and its role during disease development. PMID:24994026

Applications manual for logit modes of express bus-fringe parking choices.

DOT National Transportation Integrated Search

1976-01-01

Manual computations and computerized applications of logit models are described. The models demonstrated reflect travel behavior concerning express bus-fringe parking transit. The specific travel issues addressed include the basic automobile vs. expr...

Logits and Tigers and Bears, Oh My! A Brief Look at the Simple Math of Logistic Regression and How It Can Improve Dissemination of Results

ERIC Educational Resources Information Center

Osborne, Jason W.

2012-01-01

Logistic regression is slowly gaining acceptance in the social sciences, and fills an important niche in the researcher's toolkit: being able to predict important outcomes that are not continuous in nature. While OLS regression is a valuable tool, it cannot routinely be used to predict outcomes that are binary or categorical in nature. These…

Logit and probit model in toll sensitivity analysis of Solo-Ngawi, Kartasura-Palang Joglo segment based on Willingness to Pay (WTP)

NASA Astrophysics Data System (ADS)

Handayani, Dewi; Cahyaning Putri, Hera; Mahmudah, AMH

2017-12-01

Solo-Ngawi toll road project is part of the mega project of the Trans Java toll road development initiated by the government and is still under construction until now. PT Solo Ngawi Jaya (SNJ) as the Solo-Ngawi toll management company needs to determine the toll fare that is in accordance with the business plan. The determination of appropriate toll rates will affect progress in regional economic sustainability and decrease the traffic congestion. These policy instruments is crucial for achieving environmentally sustainable transport. Therefore, the objective of this research is to find out how the toll fare sensitivity of Solo-Ngawi toll road based on Willingness To Pay (WTP). Primary data was obtained by distributing stated preference questionnaires to four wheeled vehicle users in Kartasura-Palang Joglo artery road segment. Further data obtained will be analysed with logit and probit model. Based on the analysis, it is found that the effect of fare change on the amount of WTP on the binomial logit model is more sensitive than the probit model on the same travel conditions. The range of tariff change against values of WTP on the binomial logit model is 20% greater than the range of values in the probit model . On the other hand, the probability results of the binomial logit model and the binary probit have no significant difference (less than 1%).

Think twice before you book? Modelling the choice of public vs private dentist in a choice experiment.

PubMed

Kiiskinen, Urpo; Suominen-Taipale, Anna Liisa; Cairns, John

2010-06-01

This study concerns the choice of primary dental service provider by consumers. If the health service delivery system allows individuals to choose between public-care providers or if complementary private services are available, it is typically assumed that utilisation is a three-stage decision process. The patient first makes a decision to seek care, and then chooses the service provider. The final stage, involving decisions over the amount and form of treatment, is not considered here. The paper reports a discrete choice experiment (DCE) designed to evaluate attributes affecting individuals' choice of dental-care provider. The feasibility of the DCE approach in modelling consumers' choice in the context of non-acute need for dental care is assessed. The aim is to test whether a separate two-stage logit, a multinomial logit, or a nested logit best fits the choice process of consumers. A nested logit model of indirect utility functions is estimated and inclusive value (IV) constraints are tested for modelling implications. The results show that non-trading behaviour has an impact on the choice of appropriate modelling technique, but is to some extent dependent on the choice of scenarios offered. It is concluded that for traders multinomial logit is appropriate, whereas for non-traders and on average the nested logit is the method supported by the analyses. The consistent finding in all subgroup analyses is that the traditional two-stage decision process is found to be implausible in the context of consumer's choice of dental-care provider.

Emotional Reactions to Stress among Adolescent Boys and Girls: An Examination of the Mediating Mechanisms Proposed by General Strain Theory

ERIC Educational Resources Information Center

Sigfusdottir, Inga-Dora; Silver, Eric

2009-01-01

This study examines the effects of negative life events on anger and depressed mood among a sample of 7,758 Icelandic adolescents, measured as part of the National Survey of Icelandic Adolescents (Thorlindsson, Sigfusdottir, Bernburg, & Halldorsson, 1998). Using multiple linear regression and multinomial logit regression, we find that (a)…

Application of a Multidimensional Nested Logit Model to Multiple-Choice Test Items

ERIC Educational Resources Information Center

Bolt, Daniel M.; Wollack, James A.; Suh, Youngsuk

2012-01-01

Nested logit models have been presented as an alternative to multinomial logistic models for multiple-choice test items (Suh and Bolt in "Psychometrika" 75:454-473, 2010) and possess a mathematical structure that naturally lends itself to evaluating the incremental information provided by attending to distractor selection in scoring. One potential…

Effect of driver's age and side of impact on crash severity along urban freeways: a mixed logit approach.

PubMed

Haleem, Kirolos; Gan, Albert

2013-09-01

This study identifies geometric, traffic, environmental, vehicle-related, and driver-related predictors of crash injury severity on urban freeways. The study takes advantage of the mixed logit model's ability to account for unobserved effects that are difficult to quantify and may affect the model estimation, such as the driver's reaction at the time of crash. Crashes of 5 years occurring on 89 urban freeway segments throughout the state of Florida in the United States were used. Examples of severity predictors explored include traffic volume, distance of the crash to the nearest ramp, and detailed driver's age, vehicle types, and sides of impact. To show how the parameter estimates could vary, a binary logit model was compared with the mixed logit model. It was found that the at-fault driver's age, traffic volume, distance of the crash to the nearest ramp, vehicle type, side of impact, and percentage of trucks significantly influence severity on urban freeways. Additionally, young at-fault drivers were associated with a significant severity risk increase relative to other age groups. It was also observed that some variables in the binary logit model yielded illogic estimates due to ignoring the random variation of the estimation. Since the at-fault driver's age and side of impact were significant random parameters in the mixed logit model, an in-depth investigation was performed. It was noticed that back, left, and right impacts had the highest risk among middle-aged drivers, followed by young drivers, very young drivers, and finally, old and very old drivers. To reduce side impacts due to lane changing, two primary strategies can be recommended. The first strategy is to conduct campaigns to convey the hazardous effect of changing lanes at higher speeds. The second is to devise in-vehicle side crash avoidance systems to alert drivers of a potential crash risk. The study provided a promising approach to screening the predictors before fitting the mixed logit model using the random forest technique. Furthermore, potential countermeasures were proposed to reduce the severity of impacts. Copyright © 2013 National Safety Council and Elsevier Ltd. All rights reserved.

Advances in nonmarket valuation econometrics: Spatial heterogeneity in hedonic pricing models and preference heterogeneity in stated preference models

NASA Astrophysics Data System (ADS)

Yoo, Jin Woo

In my 1st essay, the study explores Pennsylvania residents. willingness to pay for development of renewable energy technologies such as solar power, wind power, biomass electricity, and other renewable energy using a choice experiment method. Principle component analysis identified 3 independent attitude components that affect the variation of preference, a desire for renewable energy and environmental quality and concern over cost. The results show that urban residents have a higher desire for environmental quality and concern less about cost than rural residents and consequently have a higher willingness to pay to increase renewable energy production. The results of sub-sample analysis show that a representative respondent in rural (urban) Pennsylvania is willing to pay 3.8(5.9) and 4.1(5.7)/month for increasing the share of Pennsylvania electricity generated from wind power and other renewable energy by 1 percent point, respectively. Mean WTP for solar and biomass electricity was not significantly different from zero. In my second essay, heterogeneity of individual WTP for various renewable energy technologies is investigated using several different variants of the multinomial logit model: a simple MNL with interaction terms, a latent class choice model, a random parameter mixed logit choice model, and a random parameter-latent class choice model. The results of all models consistently show that respondents. preference for individual renewable technology is heterogeneous, but the degree of heterogeneity differs for different renewable technologies. In general, the random parameter logit model with interactions and a hybrid random parameter logit-latent class model fit better than other models and better capture respondents. heterogeneity of preference for renewable energy. The impact of the land under agricultural conservation easement (ACE) contract on the values of nearby residential properties is investigated using housing sales data in two Pennsylvania Counties. The spatial-lag (SLM), the spatial error (SEM) and the spatial error component (SEC) models were compared. A geographically weighted regression (GWR) model is estimated to study the spatial heterogeneity of the marginal implicit prices of ACE impact within each county. New hybrid spatial hedonic models, the GWR-SEC and a modified GWR-SEM, are estimated such that both spatial autocorrelation and heterogeneity are accounted. The results show that the coefficient of land under easement contract varies spatially within one county, but not within the other county studied. Also, ACE's are found to have both positive and negative impacts on the values of nearby residential properties. Among global spatial models, the SEM fit better than the SLM and the SEC. Statistical goodness of fit measures showed that the GWR-SEC model fit better than the GWR or the GWR-SEC model. Finally, the GWR-SEC showed spatial autocorrelation is stronger in one county than in the other county.

An Odds Ratio Approach for Detecting DDF under the Nested Logit Modeling Framework

ERIC Educational Resources Information Center

Terzi, Ragip; Suh, Youngsuk

2015-01-01

An odds ratio approach (ORA) under the framework of a nested logit model was proposed for evaluating differential distractor functioning (DDF) in multiple-choice items and was compared with an existing ORA developed under the nominal response model. The performances of the two ORAs for detecting DDF were investigated through an extensive…

Logit Estimation of a Gravity Model of the College Enrollment Decision.

ERIC Educational Resources Information Center

Leppel, Karen

1993-01-01

A study investigated the factors influencing students' decisions about attending a college to which they had been admitted. Logit analysis confirmed gravity model predictions that geographic distance and student ability would most influence the enrollment decision and found other variables, although affecting earlier stages of decision making, did…

Stochastic modeling of consumer preferences for health care institutions.

PubMed

Malhotra, N K

1983-01-01

This paper proposes a stochastic procedure for modeling consumer preferences via LOGIT analysis. First, a simple, non-technical exposition of the use of a stochastic approach in health care marketing is presented. Second, a study illustrating the application of the LOGIT model in assessing consumer preferences for hospitals is given. The paper concludes with several implications of the proposed approach.

A general regression framework for a secondary outcome in case-control studies.

PubMed

Tchetgen Tchetgen, Eric J

2014-01-01

Modern case-control studies typically involve the collection of data on a large number of outcomes, often at considerable logistical and monetary expense. These data are of potentially great value to subsequent researchers, who, although not necessarily concerned with the disease that defined the case series in the original study, may want to use the available information for a regression analysis involving a secondary outcome. Because cases and controls are selected with unequal probability, regression analysis involving a secondary outcome generally must acknowledge the sampling design. In this paper, the author presents a new framework for the analysis of secondary outcomes in case-control studies. The approach is based on a careful re-parameterization of the conditional model for the secondary outcome given the case-control outcome and regression covariates, in terms of (a) the population regression of interest of the secondary outcome given covariates and (b) the population regression of the case-control outcome on covariates. The error distribution for the secondary outcome given covariates and case-control status is otherwise unrestricted. For a continuous outcome, the approach sometimes reduces to extending model (a) by including a residual of (b) as a covariate. However, the framework is general in the sense that models (a) and (b) can take any functional form, and the methodology allows for an identity, log or logit link function for model (a).

Environmental, Spatial, and Sociodemographic Factors Associated with Nonfatal Injuries in Indonesia.

PubMed

Irianti, Sri; Prasetyoputra, Puguh

2017-01-01

Background . The determinants of injuries and their reoccurrence in Indonesia are not well understood, despite their importance in the prevention of injuries. Therefore, this study seeks to investigate the environmental, spatial, and sociodemographic factors associated with the reoccurrence of injuries among Indonesian people. Methods . Data from the 2013 round of the Indonesia Baseline Health Research (IBHR 2013) were analysed using a two-part hurdle regression model. A logit regression model was chosen for the zero-hurdle part , while a zero-truncated negative binomial regression model was selected for the counts part . Odds ratio (OR) and incidence rate ratio (IRR) were the measures of association, respectively. Results . The results suggest that living in a household with distant drinking water source, residing in slum areas, residing in Eastern Indonesia, having low educational attainment, being men, and being poorer are positively related to the likelihood of experiencing injury. Moreover, being a farmer or fishermen, having low educational attainment, and being men are positively associated with the frequency of injuries. Conclusion . This study would be useful to prioritise injury prevention programs in Indonesia based on the environmental, spatial, and sociodemographic characteristics.

Flexible link functions in nonparametric binary regression with Gaussian process priors.

PubMed

Li, Dan; Wang, Xia; Lin, Lizhen; Dey, Dipak K

2016-09-01

In many scientific fields, it is a common practice to collect a sequence of 0-1 binary responses from a subject across time, space, or a collection of covariates. Researchers are interested in finding out how the expected binary outcome is related to covariates, and aim at better prediction in the future 0-1 outcomes. Gaussian processes have been widely used to model nonlinear systems; in particular to model the latent structure in a binary regression model allowing nonlinear functional relationship between covariates and the expectation of binary outcomes. A critical issue in modeling binary response data is the appropriate choice of link functions. Commonly adopted link functions such as probit or logit links have fixed skewness and lack the flexibility to allow the data to determine the degree of the skewness. To address this limitation, we propose a flexible binary regression model which combines a generalized extreme value link function with a Gaussian process prior on the latent structure. Bayesian computation is employed in model estimation. Posterior consistency of the resulting posterior distribution is demonstrated. The flexibility and gains of the proposed model are illustrated through detailed simulation studies and two real data examples. Empirical results show that the proposed model outperforms a set of alternative models, which only have either a Gaussian process prior on the latent regression function or a Dirichlet prior on the link function. © 2015, The International Biometric Society.

Flexible Link Functions in Nonparametric Binary Regression with Gaussian Process Priors

PubMed Central

Li, Dan; Lin, Lizhen; Dey, Dipak K.

2015-01-01

Summary In many scientific fields, it is a common practice to collect a sequence of 0-1 binary responses from a subject across time, space, or a collection of covariates. Researchers are interested in finding out how the expected binary outcome is related to covariates, and aim at better prediction in the future 0-1 outcomes. Gaussian processes have been widely used to model nonlinear systems; in particular to model the latent structure in a binary regression model allowing nonlinear functional relationship between covariates and the expectation of binary outcomes. A critical issue in modeling binary response data is the appropriate choice of link functions. Commonly adopted link functions such as probit or logit links have fixed skewness and lack the flexibility to allow the data to determine the degree of the skewness. To address this limitation, we propose a flexible binary regression model which combines a generalized extreme value link function with a Gaussian process prior on the latent structure. Bayesian computation is employed in model estimation. Posterior consistency of the resulting posterior distribution is demonstrated. The flexibility and gains of the proposed model are illustrated through detailed simulation studies and two real data examples. Empirical results show that the proposed model outperforms a set of alternative models, which only have either a Gaussian process prior on the latent regression function or a Dirichlet prior on the link function. PMID:26686333

Exploratory multinomial logit model-based driver injury severity analyses for teenage and adult drivers in intersection-related crashes.

PubMed

Wu, Qiong; Zhang, Guohui; Ci, Yusheng; Wu, Lina; Tarefder, Rafiqul A; Alcántara, Adélamar Dely

2016-05-18

Teenage drivers are more likely to be involved in severely incapacitating and fatal crashes compared to adult drivers. Moreover, because two thirds of urban vehicle miles traveled are on signal-controlled roadways, significant research efforts are needed to investigate intersection-related teenage driver injury severities and their contributing factors in terms of driver behavior, vehicle-infrastructure interactions, environmental characteristics, roadway geometric features, and traffic compositions. Therefore, this study aims to explore the characteristic differences between teenage and adult drivers in intersection-related crashes, identify the significant contributing attributes, and analyze their impacts on driver injury severities. Using crash data collected in New Mexico from 2010 to 2011, 2 multinomial logit regression models were developed to analyze injury severities for teenage and adult drivers, respectively. Elasticity analyses and transferability tests were conducted to better understand the quantitative impacts of these factors and the teenage driver injury severity model's generality. The results showed that although many of the same contributing factors were found to be significant in the both teenage and adult driver models, certain different attributes must be distinguished to specifically develop effective safety solutions for the 2 driver groups. The research findings are helpful to better understand teenage crash uniqueness and develop cost-effective solutions to reduce intersection-related teenage injury severities and facilitate driver injury mitigation research.

Assessing Success on the Uniform CPA Exam: A Logit Approach.

ERIC Educational Resources Information Center

Brahmasrene, Tantatape; Whitten, Donna

2001-01-01

A logit model was used to test the likelihood of success of 231 candidates on the Uniform Certified Public Accountants Examination. Significant determinants of success included undergraduate grade point average, age, private accounting experience, and gender. (SK)

Logit-normal mixed model for Indian monsoon precipitation

NASA Astrophysics Data System (ADS)

Dietz, L. R.; Chatterjee, S.

2014-09-01

Describing the nature and variability of Indian monsoon precipitation is a topic of much debate in the current literature. We suggest the use of a generalized linear mixed model (GLMM), specifically, the logit-normal mixed model, to describe the underlying structure of this complex climatic event. Four GLMM algorithms are described and simulations are performed to vet these algorithms before applying them to the Indian precipitation data. The logit-normal model was applied to light, moderate, and extreme rainfall. Findings indicated that physical constructs were preserved by the models, and random effects were significant in many cases. We also found GLMM estimation methods were sensitive to tuning parameters and assumptions and therefore, recommend use of multiple methods in applications. This work provides a novel use of GLMM and promotes its addition to the gamut of tools for analysis in studying climate phenomena.

Investigating risk factors of traffic casualties at private highway-railroad grade crossings in the United States.

PubMed

Haleem, Kirolos

2016-10-01

Private highway-railroad grade crossings (HRGCs) are intersections of highways and railroads on roadways that are not maintained by a public authority. Since no public authority maintains private HRGCs, fatal and injury crashes at these locations are of concern. However, no study has been conducted at private HRGCs to identify the safety issues that might exist and how to alleviate them. This study identifies the significant predictors of traffic casualties (including both injuries and fatalities) at private HRGCs in the U.S. using six years of nationwide crashes from 2009 to 2014. Two levels of injury severity were considered, injury (including fatalities and injuries) and no injury. The study investigates multiple predictors, e.g., temporal crash characteristics, geometry, railroad, traffic, vehicle, and environment. The study applies both the mixed logit and binary logit models. The mixed logit model was found to outperform the binary logit model. The mixed logit model revealed that drivers who did not stop, railroad equipment that struck highway users, higher train speeds, non-presence of advance warning signs, concrete road surface type, and cloudy weather were associated with an increase in injuries and fatalities. For example, a one-mile-per-hour higher train speed increases the probability of fatality by 22%. On the contrary, male drivers, PM peak periods, and presence of warning devices at both approaches were associated with a fatality reduction. Potential strategies are recommended to alleviate injuries and fatalities at private HRGCs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Occupational Choice: A Conditional Logit Model with Special Reference to Wage Subsidies and Occupational Choice. Final Report.

ERIC Educational Resources Information Center

Boskin, Michael J.

A model of occupational choice based on the theory of human capital is developed and estimated by conditional logit analysis. The empirical results estimated the probability of individuals with certain characteristics (such as race, sex, age, and education) entering each of 11 occupational groups. The results indicate that individuals tend to…

Patient choice modelling: how do patients choose their hospitals?

PubMed

Smith, Honora; Currie, Christine; Chaiwuttisak, Pornpimol; Kyprianou, Andreas

2018-06-01

As an aid to predicting future hospital admissions, we compare use of the Multinomial Logit and the Utility Maximising Nested Logit models to describe how patients choose their hospitals. The models are fitted to real data from Derbyshire, United Kingdom, which lists the postcodes of more than 200,000 admissions to six different local hospitals. Both elective and emergency admissions are analysed for this mixed urban/rural area. For characteristics that may affect a patient's choice of hospital, we consider the distance of the patient from the hospital, the number of beds at the hospital and the number of car parking spaces available at the hospital, as well as several statistics publicly available on National Health Service (NHS) websites: an average waiting time, the patient survey score for ward cleanliness, the patient safety score and the inpatient survey score for overall care. The Multinomial Logit model is successfully fitted to the data. Results obtained with the Utility Maximising Nested Logit model show that nesting according to city or town may be invalid for these data; in other words, the choice of hospital does not appear to be preceded by choice of city. In all of the analysis carried out, distance appears to be one of the main influences on a patient's choice of hospital rather than statistics available on the Internet.

Academic Achievement of Girls in Rural Schools in Kenya

ERIC Educational Resources Information Center

Mungai, A. M.

2012-01-01

This study examined the effect of two family factors (financial, social capital) and school factors on students' achievement. One hundred eighty two, seventh-grade female students from nine schools in Muranga district, Kenya, were studied. The statistical procedures included logit regression, cross-tabulations, frequency counting and chi-square…

Modeling pedestrian shopping behavior using principles of bounded rationality: model comparison and validation

NASA Astrophysics Data System (ADS)

Zhu, Wei; Timmermans, Harry

2011-06-01

Models of geographical choice behavior have been dominantly based on rational choice models, which assume that decision makers are utility-maximizers. Rational choice models may be less appropriate as behavioral models when modeling decisions in complex environments in which decision makers may simplify the decision problem using heuristics. Pedestrian behavior in shopping streets is an example. We therefore propose a modeling framework for pedestrian shopping behavior incorporating principles of bounded rationality. We extend three classical heuristic rules (conjunctive, disjunctive and lexicographic rule) by introducing threshold heterogeneity. The proposed models are implemented using data on pedestrian behavior in Wang Fujing Street, the city center of Beijing, China. The models are estimated and compared with multinomial logit models and mixed logit models. Results show that the heuristic models are the best for all the decisions that are modeled. Validation tests are carried out through multi-agent simulation by comparing simulated spatio-temporal agent behavior with the observed pedestrian behavior. The predictions of heuristic models are slightly better than those of the multinomial logit models.

Logit-normal mixed model for Indian Monsoon rainfall extremes

NASA Astrophysics Data System (ADS)

Dietz, L. R.; Chatterjee, S.

2014-03-01

Describing the nature and variability of Indian monsoon rainfall extremes is a topic of much debate in the current literature. We suggest the use of a generalized linear mixed model (GLMM), specifically, the logit-normal mixed model, to describe the underlying structure of this complex climatic event. Several GLMM algorithms are described and simulations are performed to vet these algorithms before applying them to the Indian precipitation data procured from the National Climatic Data Center. The logit-normal model was applied with fixed covariates of latitude, longitude, elevation, daily minimum and maximum temperatures with a random intercept by weather station. In general, the estimation methods concurred in their suggestion of a relationship between the El Niño Southern Oscillation (ENSO) and extreme rainfall variability estimates. This work provides a valuable starting point for extending GLMM to incorporate the intricate dependencies in extreme climate events.

Estimation of social value of statistical life using willingness-to-pay method in Nanjing, China.

PubMed

Yang, Zhao; Liu, Pan; Xu, Xin

2016-10-01

Rational decision making regarding the safety related investment programs greatly depends on the economic valuation of traffic crashes. The primary objective of this study was to estimate the social value of statistical life in the city of Nanjing in China. A stated preference survey was conducted to investigate travelers' willingness to pay for traffic risk reduction. Face-to-face interviews were conducted at stations, shopping centers, schools, and parks in different districts in the urban area of Nanjing. The respondents were categorized into two groups, including motorists and non-motorists. Both the binary logit model and mixed logit model were developed for the two groups of people. The results revealed that the mixed logit model is superior to the fixed coefficient binary logit model. The factors that significantly affect people's willingness to pay for risk reduction include income, education, gender, age, drive age (for motorists), occupation, whether the charged fees were used to improve private vehicle equipment (for motorists), reduction in fatality rate, and change in travel cost. The Monte Carlo simulation method was used to generate the distribution of value of statistical life (VSL). Based on the mixed logit model, the VSL had a mean value of 3,729,493 RMB ($586,610) with a standard deviation of 2,181,592 RMB ($343,142) for motorists; and a mean of 3,281,283 RMB ($505,318) with a standard deviation of 2,376,975 RMB ($366,054) for non-motorists. Using the tax system to illustrate the contribution of different income groups to social funds, the social value of statistical life was estimated. The average social value of statistical life was found to be 7,184,406 RMB ($1,130,032). Copyright © 2016 Elsevier Ltd. All rights reserved.

Development and validation of a mortality risk model for pediatric sepsis.

PubMed

Chen, Mengshi; Lu, Xiulan; Hu, Li; Liu, Pingping; Zhao, Wenjiao; Yan, Haipeng; Tang, Liang; Zhu, Yimin; Xiao, Zhenghui; Chen, Lizhang; Tan, Hongzhuan

2017-05-01

Pediatric sepsis is a burdensome public health problem. Assessing the mortality risk of pediatric sepsis patients, offering effective treatment guidance, and improving prognosis to reduce mortality rates, are crucial.We extracted data derived from electronic medical records of pediatric sepsis patients that were collected during the first 24 hours after admission to the pediatric intensive care unit (PICU) of the Hunan Children's hospital from January 2012 to June 2014. A total of 788 children were randomly divided into a training (592, 75%) and validation group (196, 25%). The risk factors for mortality among these patients were identified by conducting multivariate logistic regression in the training group. Based on the established logistic regression equation, the logit probabilities for all patients (in both groups) were calculated to verify the model's internal and external validities.According to the training group, 6 variables (brain natriuretic peptide, albumin, total bilirubin, D-dimer, lactate levels, and mechanical ventilation in 24 hours) were included in the final logistic regression model. The areas under the curves of the model were 0.854 (0.826, 0.881) and 0.844 (0.816, 0.873) in the training and validation groups, respectively.The Mortality Risk Model for Pediatric Sepsis we established in this study showed acceptable accuracy to predict the mortality risk in pediatric sepsis patients.

Development and validation of a mortality risk model for pediatric sepsis

PubMed Central

Chen, Mengshi; Lu, Xiulan; Hu, Li; Liu, Pingping; Zhao, Wenjiao; Yan, Haipeng; Tang, Liang; Zhu, Yimin; Xiao, Zhenghui; Chen, Lizhang; Tan, Hongzhuan

2017-01-01

Abstract Pediatric sepsis is a burdensome public health problem. Assessing the mortality risk of pediatric sepsis patients, offering effective treatment guidance, and improving prognosis to reduce mortality rates, are crucial. We extracted data derived from electronic medical records of pediatric sepsis patients that were collected during the first 24 hours after admission to the pediatric intensive care unit (PICU) of the Hunan Children's hospital from January 2012 to June 2014. A total of 788 children were randomly divided into a training (592, 75%) and validation group (196, 25%). The risk factors for mortality among these patients were identified by conducting multivariate logistic regression in the training group. Based on the established logistic regression equation, the logit probabilities for all patients (in both groups) were calculated to verify the model's internal and external validities. According to the training group, 6 variables (brain natriuretic peptide, albumin, total bilirubin, D-dimer, lactate levels, and mechanical ventilation in 24 hours) were included in the final logistic regression model. The areas under the curves of the model were 0.854 (0.826, 0.881) and 0.844 (0.816, 0.873) in the training and validation groups, respectively. The Mortality Risk Model for Pediatric Sepsis we established in this study showed acceptable accuracy to predict the mortality risk in pediatric sepsis patients. PMID:28514310

An Analysis of Losses to the Southern Commercial Timberland Base

Treesearch

Ian A. Munn; David Cleaves

1998-01-01

Demographic and physical factors influencing the conversion of commercial timberland iu the south to non-forestry uses between the last two Forest Inventory Analysis (FIA) surveys were investigated. GIS techniques linked Census data and FIA plot level data. Multinomial logit regression identified factors associated with losses to the timberland base. Conversion to...

Intrafirm planning and mathematical modeling of owner's equity in industrial enterprises

NASA Astrophysics Data System (ADS)

Ponomareva, S. V.; Zheleznova, I. V.

2018-05-01

The article aims to review the different approaches to intrafirm planning of owner's equity in industrial enterprises. Since charter capital, additional capital and reserve capital do not change in the process of enterprise activity, the main interest lies on the field of share repurchases from shareholders and retained earnings within the owner's equity of the enterprise. In order to study the effect of share repurchases on the activities of the enterprise, let us use such mathematical methods as event study and econometric modeling. This article describes the step-by-step algorithm of carrying out event study and justifies the choice of Logit model in econometric analysis. The article represents basic results of conducted regression analysis on the effect of share repurchases on the key financial indicators in industrial enterprises.

Three-dimensional prediction of soil physical, chemical, and hydrological properties in a forested catchment of the Santa Catalina CZO

NASA Astrophysics Data System (ADS)

Shepard, C.; Holleran, M.; Lybrand, R. A.; Rasmussen, C.

2014-12-01

Understanding critical zone evolution and function requires an accurate assessment of local soil properties. Two-dimensional (2D) digital soil mapping provides a general assessment of soil characteristics across a sampled landscape, but lacks the ability to predict soil properties with depth. The utilization of mass-preserving spline functions enable the extrapolation of soil properties with depth, extending predictive functions to three-dimensions (3D). The present study was completed in the Marshall Gulch (MG) catchment, located in the Santa Catalina Mountains, 30 km northwest of Tucson, Arizona, as part of the Santa Catalina-Jemez Mountains Critical Zone Observatory. Twenty-four soil pits were excavated and described following standard procedures. Mass-preserving splines were used to extrapolate mass carbon (kg C m-2); percent clay, silt, and sand (%); sodium mass flux (kg Na m-2); and pH for 24 sampled soil pits in 1-cm depth increments. Saturated volumetric water content (θs) and volumetric water content at 10 kPa (θ10) were predicted using ROSETTA and established empirical relationships. The described profiles were all sampled to differing depths; to compensate for the unevenness of the profile descriptions, the soil depths were standardized from 0.0 to 1.0 and then split into five equal standard depth sections. A logit-transformation was used to normalize the target variables. Step-wise regressions were calculated using available environmental covariates to predict the properties of each variable across the catchment in each depth section, and interpolated model residuals added back to the predicted layers to generate the final soil maps. Logit-transformed R2 for the predictive functions varied widely, ranging from 0.20 to 0.79, with logit-transformed RMSE ranging from 0.15 to 2.77. The MG catchment was further classified into clusters with similar properties based on the environmental covariates, and representative depth functions for each target variable in each cluster calculated. Mass-preserving splines combined with stepwise regressions are an effective tool for predicting soil physical, chemical, and hydrological properties with depth, enhancing our understanding of the critical zone.

Safety performance of traffic phases and phase transitions in three phase traffic theory.

PubMed

Xu, Chengcheng; Liu, Pan; Wang, Wei; Li, Zhibin

2015-12-01

Crash risk prediction models were developed to link safety to various phases and phase transitions defined by the three phase traffic theory. Results of the Bayesian conditional logit analysis showed that different traffic states differed distinctly with respect to safety performance. The random-parameter logit approach was utilized to account for the heterogeneity caused by unobserved factors. The Bayesian inference approach based on the Markov Chain Monte Carlo (MCMC) method was used for the estimation of the random-parameter logit model. The proposed approach increased the prediction performance of the crash risk models as compared with the conventional logit model. The three phase traffic theory can help us better understand the mechanism of crash occurrences in various traffic states. The contributing factors to crash likelihood can be well explained by the mechanism of phase transitions. We further discovered that the free flow state can be divided into two sub-phases on the basis of safety performance, including a true free flow state in which the interactions between vehicles are minor, and a platooned traffic state in which bunched vehicles travel in successions. The results of this study suggest that a safety perspective can be added to the three phase traffic theory. The results also suggest that the heterogeneity between different traffic states should be considered when estimating the risks of crash occurrences on freeways. Copyright © 2015 Elsevier Ltd. All rights reserved.

Do You Know What You Owe? Students' Understanding of Their Student Loans

ERIC Educational Resources Information Center

Andruska, Emily A.; Hogarth, Jeanne M.; Fletcher, Cynthia Needles; Forbes, Gregory R.; Wohlgemuth, Darin R.

2014-01-01

Using a data set that augments a student survey with administrative data from the Iowa State University Office of Financial Aid, the authors posed two questions: Do students know whether they have student loans? Do students know how much they owe on outstanding student loans? We used logistic and ordered logit regressions to answer these…

The Impact of School Socioeconomic Status on Student-Generated Teacher Ratings

ERIC Educational Resources Information Center

Agnew, Steve

2011-01-01

This paper uses ordinary least squares, logit and probit regressions, along with chi-square analysis applied to nationwide data from the New Zealand ratemyteacher website to establish if there is any correlation between student ratings of their teachers and the socioeconomic status of the school the students attend. The results show that students…

Performance of the likelihood ratio difference (G2 Diff) test for detecting unidimensionality in applications of the multidimensional Rasch model.

PubMed

Harrell-Williams, Leigh; Wolfe, Edward W

2014-01-01

Previous research has investigated the influence of sample size, model misspecification, test length, ability distribution offset, and generating model on the likelihood ratio difference test in applications of item response models. This study extended that research to the evaluation of dimensionality using the multidimensional random coefficients multinomial logit model (MRCMLM). Logistic regression analysis of simulated data reveal that sample size and test length have a large effect on the capacity of the LR difference test to correctly identify unidimensionality, with shorter tests and smaller sample sizes leading to smaller Type I error rates. Higher levels of simulated misfit resulted in fewer incorrect decisions than data with no or little misfit. However, Type I error rates indicate that the likelihood ratio difference test is not suitable under any of the simulated conditions for evaluating dimensionality in applications of the MRCMLM.

Who Is Overeducated and Why? Probit and Dynamic Mixed Multinomial Logit Analyses of Vertical Mismatch in East and West Germany

ERIC Educational Resources Information Center

Boll, Christina; Leppin, Julian Sebastian; Schömann, Klaus

2016-01-01

Overeducation potentially signals a productivity loss. With Socio-Economic Panel data from 1984 to 2011 we identify drivers of educational mismatch for East and West medium and highly educated Germans. Addressing measurement error, state dependence and unobserved heterogeneity, we run dynamic mixed multinomial logit models for three different…

Examining driver injury severity outcomes in rural non-interstate roadway crashes using a hierarchical ordered logit model.

PubMed

Chen, Cong; Zhang, Guohui; Huang, Helai; Wang, Jiangfeng; Tarefder, Rafiqul A

2016-11-01

Rural non-interstate crashes induce a significant amount of severe injuries and fatalities. Examination of such injury patterns and the associated contributing factors is of practical importance. Taking into account the ordinal nature of injury severity levels and the hierarchical feature of crash data, this study employs a hierarchical ordered logit model to examine the significant factors in predicting driver injury severities in rural non-interstate crashes based on two-year New Mexico crash records. Bayesian inference is utilized in model estimation procedure and 95% Bayesian Credible Interval (BCI) is applied to testing variable significance. An ordinary ordered logit model omitting the between-crash variance effect is evaluated as well for model performance comparison. Results indicate that the model employed in this study outperforms ordinary ordered logit model in model fit and parameter estimation. Variables regarding crash features, environment conditions, and driver and vehicle characteristics are found to have significant influence on the predictions of driver injury severities in rural non-interstate crashes. Factors such as road segments far from intersection, wet road surface condition, collision with animals, heavy vehicle drivers, male drivers and driver seatbelt used tend to induce less severe driver injury outcomes than the factors such as multiple-vehicle crashes, severe vehicle damage in a crash, motorcyclists, females, senior drivers, driver with alcohol or drug impairment, and other major collision types. Research limitations regarding crash data and model assumptions are also discussed. Overall, this research provides reasonable results and insight in developing effective road safety measures for crash injury severity reduction and prevention. Copyright © 2016 Elsevier Ltd. All rights reserved.

SU-D-204-05: Fitting Four NTCP Models to Treatment Outcome Data of Salivary Glands Recorded Six Months After Radiation Therapy for Head and Neck Tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mavroidis, P; Price, A; Kostich, M

Purpose: To estimate the radiobiological parameters of four popular NTCP models that describe the dose-response relations of salivary glands to the severity of patient reported dry mouth 6 months post chemo-radiotherapy. To identify the glands, which best correlate with the manifestation of those clinical endpoints. Finally, to evaluate the goodness-of-fit of the NTCP models. Methods: Forty-three patients were treated on a prospective multiinstitutional phase II study for oropharyngeal squamous cell carcinoma. All the patients received 60 Gy IMRT and they reported symptoms using the novel patient reported outcome version of the CTCAE. We derived the individual patient dosimetric data ofmore » the parotid and submandibular glands (SMG) as separate structures as well as combinations. The Lyman-Kutcher-Burman (LKB), Relative Seriality (RS), Logit and Relative Logit (RL) NTCP models were used to fit the patients data. The fitting of the different models was assessed through the area under the receiver operating characteristic curve (AUC) and the Odds Ratio methods. Results: The AUC values were highest for the contralateral parotid for Grade ≥ 2 (0.762 for the LKB, RS, Logit and 0.753 for the RL). For the salivary glands the AUC values were: 0.725 for the LKB, RS, Logit and 0.721 for the RL. For the contralateral SMG the AUC values were: 0.721 for LKB, 0.714 for Logit and 0.712 for RS and RL. The Odds Ratio for the contralateral parotid was 5.8 (1.3–25.5) for all the four NTCP models for the radiobiological dose threshold of 21Gy. Conclusion: It was shown that all the examined NTCP models could fit the clinical data well with very similar accuracy. The contralateral parotid gland appears to correlated best with the clinical endpoints of severe/very severe dry mouth. An EQD2Gy dose of 21Gy appears to be a safe threshold to be used as a constraint in treatment planning.« less

Alcohol Use-Related Problems Among a Rural Indian Population of West Bengal: An Application of the Alcohol Use Disorders Identification Test (AUDIT).

PubMed

Barik, Anamitra; Rai, Rajesh Kumar; Chowdhury, Abhijit

2016-03-01

To examine alcohol use and related problems among a rural subset of the Indian population. The Alcohol Use Disorders Identification Test (AUDIT) was used as part of Health and Demographic Surveillance of 36,611 individuals aged ≥18 years. From this survey data on 3671 current alcohol users were analysed using bivariate and multivariate ordered logit regression. Over 19% of males and 2.4% of females were current alcohol users. Mean ethanol consumption on a typical drinking day among males was estimated to be higher (96.3 gm) than females (56.5 gm). Mean AUDIT score was 11 among current alcohol users. AUDIT showed in the ordered logit regression estimated alcohol use-related problems to be low among women, Scheduled Tribes and unmarried people, whereas alcohol use-related problems registered high among Muslims. This rural population appears to be in need of an effective intervention program, perhaps targeting men and the household, aimed at reducing the level of alcohol use and related problems. © The Author 2015. Medical Council on Alcohol and Oxford University Press. All rights reserved.

Strategies for controlling item exposure in computerized adaptive testing with the partial credit model.

PubMed

Davis, Laurie Laughlin; Dodd, Barbara G

2008-01-01

Exposure control research with polytomous item pools has determined that randomization procedures can be very effective for controlling test security in computerized adaptive testing (CAT). The current study investigated the performance of four procedures for controlling item exposure in a CAT under the partial credit model. In addition to a no exposure control baseline condition, the Kingsbury-Zara, modified-within-.10-logits, Sympson-Hetter, and conditional Sympson-Hetter procedures were implemented to control exposure rates. The Kingsbury-Zara and the modified-within-.10-logits procedures were implemented with 3 and 6 item candidate conditions. The results show that the Kingsbury-Zara and modified-within-.10-logits procedures with 6 item candidates performed as well as the conditional Sympson-Hetter in terms of exposure rates, overlap rates, and pool utilization. These two procedures are strongly recommended for use with partial credit CATs due to their simplicity and strength of their results.

Valuing Non-market Benefits of Rehabilitation of Hydrologic Cycle Improvements in the Anyangcheon Watershed: Using Mixed Logit Models

NASA Astrophysics Data System (ADS)

Yoo, J.; Kong, K.

2010-12-01

This research the findings from a discrete-choice experiment designed to estimate the economic benefits associated with the Anyangcheon watershed improvements in Rep. of Korea. The Anyangcheon watershed has suffered from streamflow depletion and poor stream quality, which often negatively affect instream and near-stream ecologic integrity, as well as water supply. Such distortions in the hydrologic cycle mainly result from rapid increase of impermeable area due to urbanization, decreases of baseflow runoff due to groundwater pumping, and reduced precipitation inputs driven by climate forcing. As well, combined sewer overflows and increase of non-point source pollution from urban regions decrease water quality. The appeal of choice experiments (CE) in economic analysis is that it is based on random utility theory (McFadden, 1974; Ben-Akiva and Lerman, 1985). In contrast to contingent valuation method (CVM), which asks people to choose between a base case and a specific alternative, CE asks people to choice between cases that are described by attributes. The attributes of this study were selected from hydrologic vulnerability components that represent flood damage possibility, instreamflow depletion, water quality deterioration, form of the watershed and tax. Their levels were divided into three grades include status quo. Two grades represented the ideal conditions. These scenarios were constructed from a 35 orthogonal main effect design. This design resulted in twenty-seven choice sets. The design had nine different choice scenarios presented to each respondent. The most popular choice models in use are the conditional logit (CNL). This model provides closed-form choice probability calculation. The shortcoming of CNL comes from irrelevant alternatives (IIA). In this paper, the mixed logit (ML) is applied to allow the coefficient’s variation for random taste heterogeneity in the population. The mixed logit model(with normal distributions for the attributes) fit the data best, indication that allowing for both heterogeneous preferences across households and correlation between repeated choices may represent actual choice behaviors best of all the estimated models. The annual benefits to improve of the Anyancheon watershed for 1% improvement of each attribute was 406.7 billion Won(0.34 billion USD). This study is expected to contribute to the decision-making process for policy-makers by providing useful methodological framework and quantitative information related to watershed improvement projects.Table 1. Estimated Results of Conditional Logit and Mixed Logit Model 1) t-values are shown in brackets

SU-F-T-104: Determining the NTCP Parameters of Pharyngeal Constrictors and Proximal Esophagus for Radiation Induced Swallowing Problems Recorded Six Months After Radiation Therapy for Head and Neck Tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mavroidis, P; Price, A; Kostich, M

Purpose: To estimate the radiobiological parameters of four NTCP models that describe the dose-response relations of pharyngeal constrictors and proximal esophagus regarding the severity of patient reported swallowing problems 6 months post chemo-radiotherapy. To identify the section/structure that best correlates with the manifestation of the clinical endpoints. Finally, to compare the goodness-of-fit of those models. Methods: Forty-three patients were treated on a prospective multi-institutional phase II study for oropharyngeal squamous cell carcinoma. All the patients received 60 Gy IMRT and they reported symptoms using the novel patient reported outcome version of the CTCAE. We derived the individual patient dosimetric datamore » of superior, medium and inferior sections of pharyngeal constrictors (SPC, MPC and IPC), superior and inferior sections of esophagus (SES and IES) as separate structures as well as combinations. The Lyman-Kutcher-Burman (LKB), Relative Seriality (RS), Logit and Relative Logit (RL) NTCP models were used to fit the patient data. The fitting of the different models was assessed through the area under the receiver operating characteristic curve (AUC) and the Odds Ratio methods. Results: The AUC values were highest for the SPC for Grade ≥ 2 (0.719 for the RS and RL models, and 0.716 for LKB and Logit). For Grade ≥ 1, the respective values were 0.699 for RS, LKB and Logit and 0.676 for RL. For MPC the AUC values varied between 0.463–0.477, for IPC between 0.396–0.458, for SES between 0.556–0.613 and for IES between 0.410–0.519. The Odds Ratio for the SPC was 15.6 (1.7–146.4) for RS, LKB and Logit for NTCP of 55%. Conclusion: All the examined NTCP models could fit the clinical data with similar accuracy. The SPC appear to correlate best with the clinical endpoints of swallowing problems. A prospective study could establish the use of NTCP values of SPC as a constraint in treatment planning.« less

Associations of financial stressors and physical intimate partner violence perpetration.

PubMed

Schwab-Reese, Laura M; Peek-Asa, Corinne; Parker, Edith

2016-12-01

Contextual factors, such as exposure to stressors, may be antecedents to IPV perpetration. These contextual factors may be amenable to modification through intervention and prevention. However, few studies have examined specific contextual factors. To begin to address this gap, we examined the associations between financial stressors and three types of physical IPV perpetration. This analysis used data from Wave IV of The National Longitudinal Study of Adolescent to Adult Health. We used logistic regression to examine the associations of financial stressors and each type of IPV (minor, severe, causing injury), and multinomial logit regression to examine the associations of financial stressors and patterns of co-occurring types of IPV perpetration (only minor; only severe; minor and severe; minor, severe, and causing injury; compared with no perpetration). Fewer men perpetrated threats/minor physical IPV (6.7 %) or severe physical IPV (3.4 %) compared with women (11.4 % and 8.8 %, respectively). However, among physical IPV perpetrators, a higher percentage of men (32.0 %) than women (21.0 %) reported their partner was injured as a result of the IPV. In logistic regression models of each type of IPV perpetration, both the number of stressors experienced and several types of financial stressors were associated with perpetrating each type of IPV. Utilities nonpayment, housing nonpayment, food insecurity, and no phone service were associated with increased odds of perpetrating each form of IPV in adjusted analysis. Eviction was associated with perpetrating severe physical IPV but not threats/minor IPV or IPV causing injury. In multinomial logit regression comparing patterns of IPV perpetration to perpetrating no physical IPV, the relationships of financial stressors were less consistent. Food insecurity was associated with perpetrating only minor physical IPV. Comparatively, overall number of financial stressors and four types of financial stressors (utilities nonpayment, housing nonpayment, food insecurity, and disconnected phone service) were associated with perpetrating all three forms of physical IPV. Combined with prior research, our results suggested interventions to improve financial well-being may be a novel way to reduce physical IPV perpetration.

Associations of financial stressors and physical intimate partner violence perpetration.

PubMed

Schwab-Reese, Laura M; Peek-Asa, Corinne; Parker, Edith

Contextual factors, such as exposure to stressors, may be antecedents to IPV perpetration. These contextual factors may be amenable to modification through intervention and prevention. However, few studies have examined specific contextual factors. To begin to address this gap, we examined the associations between financial stressors and three types of physical IPV perpetration. This analysis used data from Wave IV of The National Longitudinal Study of Adolescent to Adult Health. We used logistic regression to examine the associations of financial stressors and each type of IPV (minor, severe, causing injury), and multinomial logit regression to examine the associations of financial stressors and patterns of co-occurring types of IPV perpetration ( only minor; only severe; minor and severe; minor, severe, and causing injury; compared with no perpetration). Fewer men perpetrated threats/minor physical IPV (6.7 %) or severe physical IPV (3.4 %) compared with women (11.4 % and 8.8 %, respectively). However, among physical IPV perpetrators, a higher percentage of men (32.0 %) than women (21.0 %) reported their partner was injured as a result of the IPV. In logistic regression models of each type of IPV perpetration, both the number of stressors experienced and several types of financial stressors were associated with perpetrating each type of IPV. Utilities nonpayment, housing nonpayment, food insecurity, and no phone service were associated with increased odds of perpetrating each form of IPV in adjusted analysis. Eviction was associated with perpetrating severe physical IPV but not threats/minor IPV or IPV causing injury. In multinomial logit regression comparing patterns of IPV perpetration to perpetrating no physical IPV, the relationships of financial stressors were less consistent. Food insecurity was associated with perpetrating only minor physical IPV. Comparatively, overall number of financial stressors and four types of financial stressors (utilities nonpayment, housing nonpayment, food insecurity, and disconnected phone service) were associated with perpetrating all three forms of physical IPV. Combined with prior research, our results suggested interventions to improve financial well-being may be a novel way to reduce physical IPV perpetration.

Analysis of stationary and dynamic factors affecting highway accident occurrence: A dynamic correlated grouped random parameters binary logit approach.

PubMed

Fountas, Grigorios; Sarwar, Md Tawfiq; Anastasopoulos, Panagiotis Ch; Blatt, Alan; Majka, Kevin

2018-04-01

Traditional accident analysis typically explores non-time-varying (stationary) factors that affect accident occurrence on roadway segments. However, the impact of time-varying (dynamic) factors is not thoroughly investigated. This paper seeks to simultaneously identify pre-crash stationary and dynamic factors of accident occurrence, while accounting for unobserved heterogeneity. Using highly disaggregate information for the potential dynamic factors, and aggregate data for the traditional stationary elements, a dynamic binary random parameters (mixed) logit framework is employed. With this approach, the dynamic nature of weather-related, and driving- and pavement-condition information is jointly investigated with traditional roadway geometric and traffic characteristics. To additionally account for the combined effect of the dynamic and stationary factors on the accident occurrence, the developed random parameters logit framework allows for possible correlations among the random parameters. The analysis is based on crash and non-crash observations between 2011 and 2013, drawn from urban and rural highway segments in the state of Washington. The findings show that the proposed methodological framework can account for both stationary and dynamic factors affecting accident occurrence probabilities, for panel effects, for unobserved heterogeneity through the use of random parameters, and for possible correlation among the latter. The comparative evaluation among the correlated grouped random parameters, the uncorrelated random parameters logit models, and their fixed parameters logit counterpart, demonstrate the potential of the random parameters modeling, in general, and the benefits of the correlated grouped random parameters approach, specifically, in terms of statistical fit and explanatory power. Published by Elsevier Ltd.

Modeling the coupled return-spread high frequency dynamics of large tick assets

NASA Astrophysics Data System (ADS)

Curato, Gianbiagio; Lillo, Fabrizio

2015-01-01

Large tick assets, i.e. assets where one tick movement is a significant fraction of the price and bid-ask spread is almost always equal to one tick, display a dynamics in which price changes and spread are strongly coupled. We present an approach based on the hidden Markov model, also known in econometrics as the Markov switching model, for the dynamics of price changes, where the latent Markov process is described by the transitions between spreads. We then use a finite Markov mixture of logit regressions on past squared price changes to describe temporal dependencies in the dynamics of price changes. The model can thus be seen as a double chain Markov model. We show that the model describes the shape of the price change distribution at different time scales, volatility clustering, and the anomalous decrease of kurtosis. We calibrate our models based on Nasdaq stocks and we show that this model reproduces remarkably well the statistical properties of real data.

The choice of discount brand cigarettes: a comparative analysis of International Tobacco Control surveys in Canada and the USA (2002-2005).

PubMed

Nargis, Nigar; Fong, Geoffrey T; Chaloupka, Frank J; Li, Qiang

2014-03-01

Increasing tobacco taxes to increase price is a proven tobacco control measure. This article investigates how smokers respond to tax and price increases in their choice of discount brand cigarettes versus premium brands. To estimate how increase in the tax rate can affect smokers' choice of discount brands versus premium brands. Using data from International Tobacco Control surveys in Canada and the USA, a logit model was constructed to estimate the probability of choosing discount brand cigarettes in response to its price changes relative to premium brands, controlling for individual-specific demographic and socioeconomic characteristics and regional effects. The self-reported price of an individual smoker is used in a random-effects regression model to impute price and to construct the price ratio for discount and premium brands for each smoker, which is used in the logit model. An increase in the ratio of price of discount brand cigarettes to the price of premium brands by 0.1 is associated with a decrease in the probability of choosing discount brands by 0.08 in Canada. No significant effect is observed in case of the USA. The results of the model explain two phenomena: (1) the widened price differential between premium and discount brand cigarettes contributed to the increased share of discount brand cigarettes in Canada in contrast to a relatively steady share in the USA during 2002-2005 and (2) increasing the price ratio of discount brands to premium brands-which occurs with an increase in specific excise tax-may lead to upward shifting from discount to premium brands rather than to downward shifting. These results underscore the significance of studying the effectiveness of tax increases in reducing overall tobacco consumption, particularly for specific excise taxes.

Street choice logit model for visitors in shopping districts.

PubMed

Kawada, Ko; Yamada, Takashi; Kishimoto, Tatsuya

2014-09-01

In this study, we propose two models for predicting people's activity. The first model is the pedestrian distribution prediction (or postdiction) model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation). The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that "have more shops, and are wider and lower". In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive) and CARS (negative). Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive).

Street Choice Logit Model for Visitors in Shopping Districts

PubMed Central

Kawada, Ko; Yamada, Takashi; Kishimoto, Tatsuya

2014-01-01

In this study, we propose two models for predicting people’s activity. The first model is the pedestrian distribution prediction (or postdiction) model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation). The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that “have more shops, and are wider and lower”. In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive) and CARS (negative). Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive). PMID:25379274

Study on Commercialization of Biogasification Systems in Ishikari Bay New Port Area - Proposal of Estimation Method of Collectable Amount of Food Waste by using Binary Logit Model -

NASA Astrophysics Data System (ADS)

Watanabe, Sho; Furuichi, Toru; Ishii, Kazuei

This study proposed an estimation method for collectable amount of food waste considering the food waste generator's cooperation ratio ant the amount of food waste generation, and clarified the factors influencing the collectable amount of food waste. In our method, the cooperation ratio was calculated by using the binary logit model which is often used for the traffic multiple choice question. In order to develop a more precise binary logit model, the factors influencing on the cooperation ratio were extracted by a questionnaire survey asking food waste generator's intention, and the preference investigation was then conducted at the second step. As a result, the collectable amount of food waste was estimated to be 72 [t/day] in the Ishikari bay new port area under a condition of current collection system by using our method. In addition, the most critical factor influencing on the collectable amount of food waste was the treatment fee for households, and was the permitted mixture degree of improper materials for retail trade and restaurant businesses

No rationale for 1 variable per 10 events criterion for binary logistic regression analysis.

PubMed

van Smeden, Maarten; de Groot, Joris A H; Moons, Karel G M; Collins, Gary S; Altman, Douglas G; Eijkemans, Marinus J C; Reitsma, Johannes B

2016-11-24

Ten events per variable (EPV) is a widely advocated minimal criterion for sample size considerations in logistic regression analysis. Of three previous simulation studies that examined this minimal EPV criterion only one supports the use of a minimum of 10 EPV. In this paper, we examine the reasons for substantial differences between these extensive simulation studies. The current study uses Monte Carlo simulations to evaluate small sample bias, coverage of confidence intervals and mean square error of logit coefficients. Logistic regression models fitted by maximum likelihood and a modified estimation procedure, known as Firth's correction, are compared. The results show that besides EPV, the problems associated with low EPV depend on other factors such as the total sample size. It is also demonstrated that simulation results can be dominated by even a few simulated data sets for which the prediction of the outcome by the covariates is perfect ('separation'). We reveal that different approaches for identifying and handling separation leads to substantially different simulation results. We further show that Firth's correction can be used to improve the accuracy of regression coefficients and alleviate the problems associated with separation. The current evidence supporting EPV rules for binary logistic regression is weak. Given our findings, there is an urgent need for new research to provide guidance for supporting sample size considerations for binary logistic regression analysis.

Part-Time Community-College Faculty and the Desire for Full-Time Tenure-Track Positions: Results of a Single Institution Case Study

ERIC Educational Resources Information Center

Jacoby, Dan

2005-01-01

According to data derived from a community-college survey in the state of Washington, the majority of part-time faculty prefer full-time work. Using a logit regression analysis, the study reported in this paper suggests that typical part-timers enter their part-time teaching situations with the intent of becoming full-time, but gradually become…

Low Vision Rehabilitation for Adult African Americans in Two Settings.

PubMed

Draper, Erin M; Feng, Rui; Appel, Sarah D; Graboyes, Marcy; Engle, Erin; Ciner, Elise B; Ellenberg, Jonas H; Stambolian, Dwight

2016-07-01

The Vision Rehabilitation for African Americans with Central Vision Impairment (VISRAC) study is a demonstration project evaluating how modifications in vision rehabilitation can improve the use of functional vision. Fifty-five African Americans 40 years of age and older with central vision impairment were randomly assigned to receive either clinic-based (CB) or home-based (HB) low vision rehabilitation services. Forty-eight subjects completed the study. The primary outcome was the change in functional vision in activities of daily living, as assessed with the Veteran's Administration Low-Vision Visual Function Questionnaire (VFQ-48). This included scores for overall visual ability and visual ability domains (reading, mobility, visual information processing, and visual motor skills). Each score was normalized into logit estimates by Rasch analysis. Linear regression models were used to compare the difference in the total score and each domain score between the two intervention groups. The significance level for each comparison was set at 0.05. Both CB and HB groups showed significant improvement in overall visual ability at the final visit compared with baseline. The CB group showed greater improvement than the HB group (mean of 1.28 vs. 0.87 logits change), though the group difference is not significant (p = 0.057). The CB group visual motor skills score showed significant improvement over the HB group score (mean of 3.30 vs. 1.34 logits change, p = 0.044). The differences in improvement of the reading and visual information processing scores were not significant (p = 0.054 and p = 0.509) between groups. Neither group had significant improvement in the mobility score, which was not part of the rehabilitation program. Vision rehabilitation is effective for this study population regardless of location. Possible reasons why the CB group performed better than the HB group include a number of psychosocial factors as well as the more standardized distraction-free work environment within the clinic setting.

Reading Ability and Reading Engagement in Older Adults With Glaucoma

PubMed Central

Nguyen, Angeline M.; van Landingham, Suzanne W.; Massof, Robert W.; Rubin, Gary S.; Ramulu, Pradeep Y.

2014-01-01

Purpose. We evaluated the impact of glaucoma-related vision loss on reading ability and reading engagement in 10 reading activities. Methods. A total of 63 glaucoma patients and 59 glaucoma suspect controls self-rated their level of reading difficulty for 10 reading items, and responses were analyzed using Rasch analysis to determine reading ability. Reading engagement was assessed by asking subjects to report the number of days per week they engaged in each reading activity. Reading restriction was determined as a decrement in engagement. Results. Glaucoma subjects more often described greater reading difficulty than controls for all tasks except puzzles (P < 0.05). The most difficult reading tasks involved puzzles, books, and finances, while the least difficult reading tasks involved notes, bills, and mail. In multivariable weighted least squares regression models of Rasch-estimated person measures of reading ability, less reading ability was found for glaucoma patients compared to controls (β = −1.60 logits, P < 0.001). Among glaucoma patients, less reading ability was associated with more severe visual field (VF) loss (β = −0.68 logits per 5-dB decrement in better-eye VF mean deviation [MD], P < 0.001) and contrast sensitivity (β = −0.76 logits per 0.1-unit lower log CS, P < 0.001). Each 5-dB decrement in the better-eye VF MD was associated with book reading on 18% fewer days (P = 0.003) and newspaper reading on 10% fewer days (P = 0.008). No statistically significant reading restriction was observed for other reading activities (P > 0.05). Conclusions. Glaucoma patients have less reading ability and engage less in a variety of different reading activities, particularly those requiring sustained reading. Future work should evaluate the mechanisms underlying reading disability in glaucoma to determine how patients can maintain reading ability and engagement. PMID:25052992

Zero adjusted models with applications to analysing helminths count data.

PubMed

Chipeta, Michael G; Ngwira, Bagrey M; Simoonga, Christopher; Kazembe, Lawrence N

2014-11-27

It is common in public health and epidemiology that the outcome of interest is counts of events occurrence. Analysing these data using classical linear models is mostly inappropriate, even after transformation of outcome variables due to overdispersion. Zero-adjusted mixture count models such as zero-inflated and hurdle count models are applied to count data when over-dispersion and excess zeros exist. Main objective of the current paper is to apply such models to analyse risk factors associated with human helminths (S. haematobium) particularly in a case where there's a high proportion of zero counts. The data were collected during a community-based randomised control trial assessing the impact of mass drug administration (MDA) with praziquantel in Malawi, and a school-based cross sectional epidemiology survey in Zambia. Count data models including traditional (Poisson and negative binomial) models, zero modified models (zero inflated Poisson and zero inflated negative binomial) and hurdle models (Poisson logit hurdle and negative binomial logit hurdle) were fitted and compared. Using Akaike information criteria (AIC), the negative binomial logit hurdle (NBLH) and zero inflated negative binomial (ZINB) showed best performance in both datasets. With regards to zero count capturing, these models performed better than other models. This paper showed that zero modified NBLH and ZINB models are more appropriate methods for the analysis of data with excess zeros. The choice between the hurdle and zero-inflated models should be based on the aim and endpoints of the study.

Optimizing the parameters of the Lyman-Kutcher-Burman, Källman, and Logit+EUD models for the rectum - a comparison between normal tissue complication probability and clinical data

NASA Astrophysics Data System (ADS)

Trojková, Darina; Judas, Libor; Trojek, Tomáš

2014-11-01

Minimizing the late rectal toxicity of prostate cancer patients is a very important and widely-discussed topic. Normal tissue complication probability (NTCP) models can be used to evaluate competing treatment plans. In our work, the parameters of the Lyman-Kutcher-Burman (LKB), Källman, and Logit+EUD models are optimized by minimizing the Brier score for a group of 302 prostate cancer patients. The NTCP values are calculated and are compared with the values obtained using previously published values for the parameters. χ2 Statistics were calculated as a check of goodness of optimization.

Psychometric Evaluation of a Cultural Competency Assessment Instrument for Health Professionals

PubMed Central

Haywood, Sonja H.; Goode, Tawara; Gao, Yong; Smith, Kristyn; Bronheim, Suzanne; Flocke, Susan A; Zyzanski, Steve

2012-01-01

Background Few valid and reliable measures exist for health care professionals interested in determining their levels of cultural and linguistic competence. Objective To evaluate the measurement properties of the Cultural Competence Health Practitioner Assessment (CCHPA-129). Methods The CCHPA-129 is a 129-item web-based instrument, developed by the National Center for Cultural Competence (NCCC). Responses on the CCHPA -129 were examined using factor analysis; Rasch modeling; and Differential Item Functioning (DIF) across race, ethnicity, gender, and profession. Subjects 2504 practitioners, including 1864 nurses (RN/LPN,/BSN); 341 clinicians (PA/NP); and 299 physicians (MD/DO), who completed the CCHPA-129 online between 2005 and 2008. Results Three factors representing domains of knowledge, adapting practice, and promoting health for culturally and linguistically diverse populations accounted for 46% of the variance. Among Knowledge factor items, 53% (23/43) fit the Rasch model, item difficulties ranged from −1.01 logits (least difficult) to +1.11 logits (most difficult), separation index (SI) 13.82, and Cronbach’s α 0.92. Forty-seven percent (21/44) Adapting Practice factor items fit the model, item difficulties −0.07 to +1.11 logits, SI 11.59, Cronbach’s α 0.88; and 58% (23/39). Promoting Health factor items fit the model, item difficulties −1.01 to +1.38 logits, SI 22.64, Cronbach’s α 0.92. Early evidence of validity was established by known groups having statistically different scores. Conclusion The 67-item CCHPA-67 is psychometrically sound. This shorted instrument can be used to establish associations between practitioners’ cultural and linguistic competence and health outcomes as well as to evaluate interventions to increase practitioners’ cultural and linguistic competence. PMID:22437625

Contributing factors to vehicle to vehicle crash frequency and severity under rainfall.

PubMed

Jung, Soyoung; Jang, Kitae; Yoon, Yoonjin; Kang, Sanghyeok

2014-09-01

This study combined vehicle to vehicle crash frequency and severity estimations to examine factor impacts on Wisconsin highway safety in rainy weather. Because of data deficiency, the real-time water film depth, the car-following distance, and the vertical curve grade were estimated with available data sources and a GIS analysis to capture rainy weather conditions at the crash location and time. Using a negative binomial regression for crash frequency estimation, the average annual daily traffic per lane, the interaction between the posted speed limit change and the existence of an off-ramp, and the interaction between the travel lane number change and the pavement surface material change were found to increase the likelihood of vehicle to vehicle crashes under rainfall. However, more average daily rainfall per month and a wider left shoulder were identified as factors that decrease the likelihood of vehicle to vehicle crashes. In the crash severity estimation using the multinomial logit model that outperformed the ordered logit model, the travel lane number, the interaction between the travel lane number and the slow grade, the deep water film, and the rear-end collision type were more likely to increase the likelihood of injury crashes under rainfall compared with crashes involving only property damage. As an exploratory data analysis, this study provides insight into potential strategies for rainy weather highway safety improvement, specifically, the following weather-sensitive strategies: road design and ITS implementation for drivers' safety awareness under rainfall. Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

Use of Two-Part Regression Calibration Model to Correct for Measurement Error in Episodically Consumed Foods in a Single-Replicate Study Design: EPIC Case Study

PubMed Central

Agogo, George O.; van der Voet, Hilko; Veer, Pieter van’t; Ferrari, Pietro; Leenders, Max; Muller, David C.; Sánchez-Cantalejo, Emilio; Bamia, Christina; Braaten, Tonje; Knüppel, Sven; Johansson, Ingegerd; van Eeuwijk, Fred A.; Boshuizen, Hendriek

2014-01-01

In epidemiologic studies, measurement error in dietary variables often attenuates association between dietary intake and disease occurrence. To adjust for the attenuation caused by error in dietary intake, regression calibration is commonly used. To apply regression calibration, unbiased reference measurements are required. Short-term reference measurements for foods that are not consumed daily contain excess zeroes that pose challenges in the calibration model. We adapted two-part regression calibration model, initially developed for multiple replicates of reference measurements per individual to a single-replicate setting. We showed how to handle excess zero reference measurements by two-step modeling approach, how to explore heteroscedasticity in the consumed amount with variance-mean graph, how to explore nonlinearity with the generalized additive modeling (GAM) and the empirical logit approaches, and how to select covariates in the calibration model. The performance of two-part calibration model was compared with the one-part counterpart. We used vegetable intake and mortality data from European Prospective Investigation on Cancer and Nutrition (EPIC) study. In the EPIC, reference measurements were taken with 24-hour recalls. For each of the three vegetable subgroups assessed separately, correcting for error with an appropriately specified two-part calibration model resulted in about three fold increase in the strength of association with all-cause mortality, as measured by the log hazard ratio. Further found is that the standard way of including covariates in the calibration model can lead to over fitting the two-part calibration model. Moreover, the extent of adjusting for error is influenced by the number and forms of covariates in the calibration model. For episodically consumed foods, we advise researchers to pay special attention to response distribution, nonlinearity, and covariate inclusion in specifying the calibration model. PMID:25402487

Preferences for tap water attributes within couples: An exploration of alternative mixed logit parameterizations

NASA Astrophysics Data System (ADS)

Scarpa, Riccardo; Thiene, Mara; Hensher, David A.

2012-01-01

Preferences for attributes of complex goods may differ substantially among members of households. Some of these goods, such as tap water, are jointly supplied at the household level. This issue of jointness poses a series of theoretical and empirical challenges to economists engaged in empirical nonmarket valuation studies. While a series of results have already been obtained in the literature, the issue of how to empirically measure these differences, and how sensitive the results are to choice of model specification from the same data, is yet to be clearly understood. In this paper we use data from a widely employed form of stated preference survey for multiattribute goods, namely choice experiments. The salient feature of the data collection is that the same choice experiment was applied to both partners of established couples. The analysis focuses on models that simultaneously handle scale as well as preference heterogeneity in marginal rates of substitution (MRS), thereby isolating true differences between members of couples in their MRS, by removing interpersonal variation in scale. The models employed are different parameterizations of the mixed logit model, including the willingness to pay (WTP)-space model and the generalized multinomial logit model. We find that in this sample there is some evidence of significant statistical differences in values between women and men, but these are of small magnitude and only apply to a few attributes.

Estimating riparian understory vegetation cover with beta regression and copula models

USGS Publications Warehouse

Eskelson, Bianca N.I.; Madsen, Lisa; Hagar, Joan C.; Temesgen, Hailemariam

2011-01-01

Understory vegetation communities are critical components of forest ecosystems. As a result, the importance of modeling understory vegetation characteristics in forested landscapes has become more apparent. Abundance measures such as shrub cover are bounded between 0 and 1, exhibit heteroscedastic error variance, and are often subject to spatial dependence. These distributional features tend to be ignored when shrub cover data are analyzed. The beta distribution has been used successfully to describe the frequency distribution of vegetation cover. Beta regression models ignoring spatial dependence (BR) and accounting for spatial dependence (BRdep) were used to estimate percent shrub cover as a function of topographic conditions and overstory vegetation structure in riparian zones in western Oregon. The BR models showed poor explanatory power (pseudo-R2 ≤ 0.34) but outperformed ordinary least-squares (OLS) and generalized least-squares (GLS) regression models with logit-transformed response in terms of mean square prediction error and absolute bias. We introduce a copula (COP) model that is based on the beta distribution and accounts for spatial dependence. A simulation study was designed to illustrate the effects of incorrectly assuming normality, equal variance, and spatial independence. It showed that BR, BRdep, and COP models provide unbiased parameter estimates, whereas OLS and GLS models result in slightly biased estimates for two of the three parameters. On the basis of the simulation study, 93–97% of the GLS, BRdep, and COP confidence intervals covered the true parameters, whereas OLS and BR only resulted in 84–88% coverage, which demonstrated the superiority of GLS, BRdep, and COP over OLS and BR models in providing standard errors for the parameter estimates in the presence of spatial dependence.

Assessment of Malawian Mothers’ Malaria Knowledge, Healthcare Preferences and Timeliness of Seeking Fever Treatments for Children Under Five

PubMed Central

Oyekale, Abayomi Samuel

2015-01-01

Malaria is one of the major public health problems in Malawi, contributing to the majority of morbidity and mortality among children under five. Ignorance of malaria symptoms results in delayed treatment, which often degenerates into fatal emergencies. This study analyzed the impact of maternal malaria knowledge on healthcare preferences and timeliness of treating children with reported fever. The Malaria Indicator Survey data for 2012, which were adequately weighted, were analyzed using multinomial logit and Poisson regression models. The results showed low maternal average years of formal education (3.52) and average mothers’ age was 27.97 years. Majority of the women (84.98%) associated fever with malaria, while 44.17% associated it with chilling. Also, 54.42% and 32.43% of the children were treated for fever on the same day and the following day that fever started, respectively. About 9.70% paid for fever treatment from their regular incomes, while 51.38% sought treatment from either public or private health centers. Multinomial Logit regression results showed that relative to using of other treatments, probabilities of selecting private hospitals and public health centers increased with age of the household heads, resident in urban areas, mothers’ years of education, number of days taken off for treatment, paying medical bills from regular, occasional and borrowed incomes, and knowledge of diarrhea and shivering as symptoms of malaria. In the Poisson regression results, timeliness of seeking treatment was significantly enhanced by knowledge of fever as malaria symptom, residence in northern and central regions of Malawi and use of income from sale of assets to pay medical bills (p < 0.10).However, delays in treating children was motivated by age of the household heads, number of days taken off to care for sick child and usage of regular, borrowed and other incomes to pay medical bills. (p < 0.05). It was concluded that efficiency of public sector in treating malaria holds significant prospects for fighting malaria in Malawi. However, adequate efforts should be channeled in enhancing the knowledge of women on malaria symptoms, among others. PMID:25584420

Assessment of Malawian mothers' malaria knowledge, healthcare preferences and timeliness of seeking fever treatments for children under five.

PubMed

Oyekale, Abayomi Samuel

2015-01-09

Malaria is one of the major public health problems in Malawi, contributing to the majority of morbidity and mortality among children under five. Ignorance of malaria symptoms results in delayed treatment, which often degenerates into fatal emergencies. This study analyzed the impact of maternal malaria knowledge on healthcare preferences and timeliness of treating children with reported fever. The Malaria Indicator Survey data for 2012, which were adequately weighted, were analyzed using multinomial logit and Poisson regression models. The results showed low maternal average years of formal education (3.52) and average mothers' age was 27.97 years. Majority of the women (84.98%) associated fever with malaria, while 44.17% associated it with chilling. Also, 54.42% and 32.43% of the children were treated for fever on the same day and the following day that fever started, respectively. About 9.70% paid for fever treatment from their regular incomes, while 51.38% sought treatment from either public or private health centers. Multinomial Logit regression results showed that relative to using of other treatments, probabilities of selecting private hospitals and public health centers increased with age of the household heads, resident in urban areas, mothers' years of education, number of days taken off for treatment, paying medical bills from regular, occasional and borrowed incomes, and knowledge of diarrhea and shivering as symptoms of malaria. In the Poisson regression results, timeliness of seeking treatment was significantly enhanced by knowledge of fever as malaria symptom, residence in northern and central regions of Malawi and use of income from sale of assets to pay medical bills (p < 0.10).However, delays in treating children was motivated by age of the household heads, number of days taken off to care for sick child and usage of regular, borrowed and other incomes to pay medical bills. (p < 0.05). It was concluded that efficiency of public sector in treating malaria holds significant prospects for fighting malaria in Malawi. However, adequate efforts should be channeled in enhancing the knowledge of women on malaria symptoms, among others.

Mapping individuals' earthquake preparedness in China

NASA Astrophysics Data System (ADS)

Wu, Guochun; Han, Ziqiang; Xu, Weijin; Gong, Yue

2018-05-01

Disaster preparedness is critical for reducing potential impact. This paper contributes to current knowledge of disaster preparedness using representative national sample data from China, which faces high earthquake risks in many areas of the country. The adoption of earthquake preparedness activities by the general public, including five indicators of material preparedness and five indicators of awareness preparedness, were surveyed and 3245 respondents from all 31 provinces of Mainland China participated in the survey. Linear regression models and logit regression models were used to analyze the effects of potential influencing factors. Overall, the preparedness levels are not satisfied, with a material preparation score of 3.02 (1-5), and awareness preparation score of 2.79 (1-5), nationally. Meanwhile, residents from western China, which has higher earthquake risk, have higher degrees of preparedness. The concern for disaster risk reduction (DRR) and the concern for building safety and participation in public affairs are consistent positive predictors of both material and awareness preparedness. The demographic and socioeconomic variables' effects, such as gender, age, education, income, urban/rural division, and building size, vary according to different preparedness activities. Finally, the paper concludes with a discussion of the theoretical contribution and potential implementation.

A Study of Commuters’ Decision-Making When Delaying Departure for Work-Home Trips

NASA Astrophysics Data System (ADS)

Que, Fangjie; Wang, Wei

2017-12-01

Studies on the travel behaviors and patterns of residents are important to the arrangement of urban layouts and urban traffic planning. However, research on the characteristics of the decision-making behavior regarding departure time is not fully expanded yet. In this paper, the research focuses on commuters’ decision-making behavior regarding departure delay. According to the 2013 travel survey data of Suzhou City, a nested logit (NL) model was built to represent the probabilities of individual choices. Parameter calibration was conducted, so that the significant factors influencing the departure delay were obtained. Ultimately, the results of the NL model indicated that it performed better and with higher precision, compared to the traditional multinomial logit (MNL) model.

Paradoxical ventilator associated pneumonia incidences among selective digestive decontamination studies versus other studies of mechanically ventilated patients: benchmarking the evidence base

PubMed Central

2011-01-01

Introduction Selective digestive decontamination (SDD) appears to have a more compelling evidence base than non-antimicrobial methods for the prevention of ventilator associated pneumonia (VAP). However, the striking variability in ventilator associated pneumonia-incidence proportion (VAP-IP) among the SDD studies remains unexplained and a postulated contextual effect remains untested for. Methods Nine reviews were used to source 45 observational (benchmark) groups and 137 component (control and intervention) groups of studies of SDD and studies of three non-antimicrobial methods of VAP prevention. The logit VAP-IP data were summarized by meta-analysis using random effects methods and the associated heterogeneity (tau2) was measured. As group level predictors of logit VAP-IP, the mode of VAP diagnosis, proportion of trauma admissions, the proportion receiving prolonged ventilation and the intervention method under study were examined in meta-regression models containing the benchmark groups together with either the control (models 1 to 3) or intervention (models 4 to 6) groups of the prevention studies. Results The VAP-IP benchmark derived here is 22.1% (95% confidence interval; 95% CI; 19.2 to 25.5; tau2 0.34) whereas the mean VAP-IP of control groups from studies of SDD and of non-antimicrobial methods, is 35.7 (29.7 to 41.8; tau2 0.63) versus 20.4 (17.2 to 24.0; tau2 0.41), respectively (P < 0.001). The disparity between the benchmark groups and the control groups of the SDD studies, which was most apparent for the highest quality studies, could not be explained in the meta-regression models after adjusting for various group level factors. The mean VAP-IP (95% CI) of intervention groups is 16.0 (12.6 to 20.3; tau2 0.59) and 17.1 (14.2 to 20.3; tau2 0.35) for SDD studies versus studies of non-antimicrobial methods, respectively. Conclusions The VAP-IP among the intervention groups within the SDD evidence base is less variable and more similar to the benchmark than among the control groups. These paradoxical observations cannot readily be explained. The interpretation of the SDD evidence base cannot proceed without further consideration of this contextual effect. PMID:21214897

A model to predict progression in brain-injured patients.

PubMed

Tommasino, N; Forteza, D; Godino, M; Mizraji, R; Alvarez, I

2014-11-01

The study of brain death (BD) epidemiology and the acute brain injury (ABI) progression profile is important to improve public health programs, organ procurement strategies, and intensive care unit (ICU) protocols. The purpose of this study was to analyze the ABI progression profile among patients admitted to ICUs with a Glasgow Coma Score (GCS) ≤8, as well as establishing a prediction model of probability of death and BD. This was a retrospective analysis of prospective data that included all brain-injured patients with GCS ≤8 admitted to a total of four public and private ICUs in Uruguay (N = 1447). The independent predictor factors of death and BD were studied using logistic regression analysis. A hierarchical model consisting of 2 nested logit regression models was then created. With these models, the probabilities of death, BD, and death by cardiorespiratory arrest were analyzed. In the first regression, we observed that as the GCS decreased and age increased, the probability of death rose. Each additional year of age increased the probability of death by 0.014. In the second model, however, BD risk decreased with each year of age. The presence of swelling, mass effect, and/or space-occupying lesion increased BD risk for the same given GCS. In the presence of injuries compatible with intracranial hypertension, age behaved as a protective factor that reduced the probability of BD. Based on the analysis of the local epidemiology, a model to predict the probability of death and BD can be developed. The organ potential donation of a country, region, or hospital can be predicted on the basis of this model, customizing it to each specific situation.

A multilevel model for comorbid outcomes: obesity and diabetes in the US.

PubMed

Congdon, Peter

2010-02-01

Multilevel models are overwhelmingly applied to single health outcomes, but when two or more health conditions are closely related, it is important that contextual variation in their joint prevalence (e.g., variations over different geographic settings) is considered. A multinomial multilevel logit regression approach for analysing joint prevalence is proposed here that includes subject level risk factors (e.g., age, race, education) while also taking account of geographic context. Data from a US population health survey (the 2007 Behavioral Risk Factor Surveillance System or BRFSS) are used to illustrate the method, with a six category multinomial outcome defined by diabetic status and weight category (obese, overweight, normal). The influence of geographic context is partly represented by known geographic variables (e.g., county poverty), and partly by a model for latent area influences. In particular, a shared latent variable (common factor) approach is proposed to measure the impact of unobserved area influences on joint weight and diabetes status, with the latent variable being spatially structured to reflect geographic clustering in risk.

Emotional balances in experimental consumer choices.

PubMed

Mengov, George; Egbert, Henrik; Pulov, Stefan; Georgiev, Kalin

2008-11-01

This paper presents an experiment, which builds a bridge over the gap between neuroscience and the analysis of economic behaviour. We apply the mathematical theory of Pavlovian conditioning, known as Recurrent Associative Gated Dipole (READ), to analyse consumer choices in a computer-based experiment. Supplier reputations, consumer satisfaction, and customer reactions are operationally defined and, together with prices, related to READ's neural dynamics. We recorded our participants' decisions with their timing, and then mapped those decisions on a sequence of events generated by the READ model. To achieve this, all constants in the differential equations were determined using simulated annealing with data from 129 people. READ predicted correctly 96% of all consumer choices in a calibration sample (n=1290), and 87% in a test sample (n=903), thus outperforming logit models. The rank correlations between self-assessed and dipole-generated consumer satisfactions were 89% in the calibration sample and 78% in the test sample, surpassing by a wide margin the best linear regression model.

Complementarity in dietary supplements and foods: are supplement users vegetable eaters?

PubMed

Kang, Hyoung-Goo; Joo, Hailey Hayeon; Choi, Kyong Duk; Lee, Dongmin; Moon, Junghoon

2017-01-01

Background : The consumption of fruits, vegetables, and dietary supplements correlate. Most previous studies have aimed to identify the determinants of supplement uses or the distinct features of supplement users; this literature lacks a discussion on dietary supplement consumption as a predictor of fruit and vegetable consumption. Objective : This study examines how dietary supplement consumption correlates with fruit and vegetable consumption by combining scanner data and surveys of Korean household grocery shopping. Methods : Propensity score matching (PSM) is used to identify the relationship between dietary supplement consumption and fruit and vegetable consumption in a household. A logit regression using supplement consumption as the dependent variable is used. Then, the supplement takers (the treatment group) are matched with non-takers (the control group) based on the propensity scores estimated in the logit regression. The fruit and vegetable consumption levels of the groups are then compared. Results : We found that dietary supplement use is associated with higher fruit and vegetable consumption. This supports the health consciousness hypothesis based on attention bias, availability heuristics, the focusing effect, and the consumption episode effect. It rejects the health substitute hypothesis based on economic substitutes and mental accounting. Conclusions : Future research on the health benefits of dietary supplements should address the complementary consumption of fruits/vegetables and their health benefits to avoid misstating the health effects of supplements.

Complementarity in dietary supplements and foods: are supplement users vegetable eaters?

PubMed Central

Kang, Hyoung-Goo; Joo, Hailey Hayeon; Choi, Kyong Duk; Lee, Dongmin; Moon, Junghoon

2017-01-01

ABSTRACT Background: The consumption of fruits, vegetables, and dietary supplements correlate. Most previous studies have aimed to identify the determinants of supplement uses or the distinct features of supplement users; this literature lacks a discussion on dietary supplement consumption as a predictor of fruit and vegetable consumption. Objective: This study examines how dietary supplement consumption correlates with fruit and vegetable consumption by combining scanner data and surveys of Korean household grocery shopping. Methods: Propensity score matching (PSM) is used to identify the relationship between dietary supplement consumption and fruit and vegetable consumption in a household. A logit regression using supplement consumption as the dependent variable is used. Then, the supplement takers (the treatment group) are matched with non-takers (the control group) based on the propensity scores estimated in the logit regression. The fruit and vegetable consumption levels of the groups are then compared. Results: We found that dietary supplement use is associated with higher fruit and vegetable consumption. This supports the health consciousness hypothesis based on attention bias, availability heuristics, the focusing effect, and the consumption episode effect. It rejects the health substitute hypothesis based on economic substitutes and mental accounting. Conclusions: Future research on the health benefits of dietary supplements should address the complementary consumption of fruits/vegetables and their health benefits to avoid misstating the health effects of supplements. PMID:28904529

Longitudinal analysis of categorical epidemiological data: a study of Three Mile Island.

PubMed

Fienberg, S E; Bromet, E J; Follmann, D; Lambert, D; May, S M

1985-11-01

The accident at the Three Mile Island nuclear power plant in 1979 led to an unprecedented set of events with potentially life threatening implications. This paper focusses on the analysis of a longitudinal study of the psychological well-being of the mothers of young children living within 10 miles of the plant. The initial analyses of the data utilize loglinear/logit model techniques from the contingency table literature, and involve the fitting of a sequence of logit models. The inadequancies of these analyses are noted, and a new class of mixture models for logistic response structures is introduced to overcome the noted shortcomings. The paper includes a brief outline of the methodology relevant for the fitting of these models using the method of maximum likelihood, and then the model is applied to the TMI data. The paper concludes with a discussion of some of the substantive implications of the mixture model analysis.

Design and analysis of simple choice surveys for natural resource management

USGS Publications Warehouse

Fieberg, John; Cornicelli, Louis; Fulton, David C.; Grund, Marrett D.

2010-01-01

We used a simple yet powerful method for judging public support for management actions from randomized surveys. We asked respondents to rank choices (representing management regulations under consideration) according to their preference, and we then used discrete choice models to estimate probability of choosing among options (conditional on the set of options presented to respondents). Because choices may share similar unmodeled characteristics, the multinomial logit model, commonly applied to discrete choice data, may not be appropriate. We introduced the nested logit model, which offers a simple approach for incorporating correlation among choices. This forced choice survey approach provides a useful method of gathering public input; it is relatively easy to apply in practice, and the data are likely to be more informative than asking constituents to rate attractiveness of each option separately.

Using a metal detector to determine lead sinker abundance in waterbird habitat

USGS Publications Warehouse

Duerr, A.E.; DeStefano, S.

2000-01-01

Waterbirds have died of lead poisoning from ingesting lead fishing sinkers in the United States and Europe. Estimating abundance and distribution of sinkers in the environment will help researchers to understand the potential effects of lead poisoning from sinker ingestion. We used a metal detector to test how environmental conditions and sinker characteristics affected detection of sinkers. Odds of detecting a lead sinker depended on the interaction of sinker mass and depth where it was buried (P=0.002). The odds of detecting a sinker increased with mass and decreased with depth buried. Lead split-shot sinkers were less detectable than tin, brass, and stainless steel sinkers. Detecting lead sinkers was not influenced by sinker shape, substrate type, or whether we searched underwater or on land. We developed a model to determine the proportion of sinkers detected when this detector is used to search for sinkers, so sinker abundance can be estimated. The log odds (Logit) of detecting a lead sinker with mass M g buried D cm below the surface was Logit Y= -1.63 + 4.20 M - 0.45 D - 0.27 MD + 0.0002 D2. The probability of detecting a lead sinker was e(Logit Y)/(1 + e(Logit Y)). At the surface, 90% of sinkers with mass 0.9 g will be detected.

Spatial analysis of land use and shallow groundwater vulnerability in the watershed adjacent to Assateague Island National Seashore, Maryland and Virginia, USA

USGS Publications Warehouse

LaMotte, A.E.; Greene, E.A.

2007-01-01

Spatial relations between land use and groundwater quality in the watershed adjacent to Assateague Island National Seashore, Maryland and Virginia, USA were analyzed by the use of two spatial models. One model used a logit analysis and the other was based on geostatistics. The models were developed and compared on the basis of existing concentrations of nitrate as nitrogen in samples from 529 domestic wells. The models were applied to produce spatial probability maps that show areas in the watershed where concentrations of nitrate in groundwater are likely to exceed a predetermined management threshold value. Maps of the watershed generated by logistic regression and probability kriging analysis showing where the probability of nitrate concentrations would exceed 3 mg/L (>0.50) compared favorably. Logistic regression was less dependent on the spatial distribution of sampled wells, and identified an additional high probability area within the watershed that was missed by probability kriging. The spatial probability maps could be used to determine the natural or anthropogenic factors that best explain the occurrence and distribution of elevated concentrations of nitrate (or other constituents) in shallow groundwater. This information can be used by local land-use planners, ecologists, and managers to protect water supplies and identify land-use planning solutions and monitoring programs in vulnerable areas. ?? 2006 Springer-Verlag.

A new strategy to analyze possible association structures between dynamic nocturnal hormone activities and sleep alterations in humans.

PubMed

Kalus, Stefanie; Kneib, Thomas; Steiger, Axel; Holsboer, Florian; Yassouridis, Alexander

2009-04-01

The human sleep process shows dynamic alterations during the night. Methods are needed to examine whether and to what extent such alterations are affected by internal, possibly time-dependent, factors, such as endocrine activity. In an observational study, we examined simultaneously sleep EEG and nocturnal levels of renin, growth hormone (GH), and cortisol (between 2300 and 0700) in 47 healthy volunteers comprising 24 women (41.67 +/- 2.93 yr of age) and 23 men (37.26 +/- 2.85 yr of age). Hormone concentrations were measured every 20 min. Conventional sleep stage scoring at 30-s intervals was applied. Semiparametric multinomial logit models are used to study and quantify possible time-dependent hormone effects on sleep stage transition courses. Results show that increased cortisol levels decrease the probability of transition from rapid-eye-movement (REM) sleep to wakefulness (WAKE) and increase the probability of transition from REM to non-REM (NREM) sleep, irrespective of the time in the night. Via the model selection criterion Akaike's information criterion, it was found that all considered hormone effects on transition probabilities with the initial state WAKE change with time. Similarly, transition from slow-wave sleep (SWS) to light sleep (LS) is affected by a "hormone-time" interaction for cortisol and renin, but not GH. For example, there is a considerable increase in the probability of SWS-LS transition toward the end of the night, when cortisol concentrations are very high. In summary, alterations in human sleep possess dynamic forms and are partially influenced by the endocrine activity of certain hormones. Statistical methods, such as semiparametric multinomial and time-dependent logit regression, can offer ambitious ways to investigate and estimate the association intensities between the nonstationary sleep changes and the time-dependent endocrine activities.

The choice of discount brand cigarettes: A comparative analysis of International Tobacco Control (ITC) Surveys in Canada and the United States (2002–2005)

PubMed Central

Nargis, Nigar; Fong, Geoffrey T.; Chaloupka, Frank J.; Li, Qiang

2014-01-01

Background Increasing tobacco taxes to increase price is a proven tobacco control measure. This paper investigates how smokers respond to tax and price increases in their choice of discount brand cigarettes vs. premium brands. Objective To estimate how increase in the tax rate can affect smokers’ choice of discount brands versus premium brands. Methods Using data from ITC Surveys in Canada and the United States, a logit model was constructed to estimate the probability of choosing discount brand cigarettes in response to its price changes relative to premium brands, controlling for individual-specific demographic and socio-economic characteristics and regional effects. The self-reported price of an individual smoker is used in a random-effects regression model to impute price and to construct the price ratio for discount and premium brands for each smoker, which is used in the logit model. Findings An increase in the ratio of price of discount brand cigarettes to the price of premium brands by 0.1 is associated with a decrease in the probability of choosing discount brands by 0.08 in Canada. No significant effect is observed in case of the United States. Conclusion The results of the model explain two phenomena: (1) the widened price differential between premium and discount brand cigarettes contributed to the increased share of discount brand cigarettes in Canada in contrast to a relatively steady share in the United States during 2002–2005, and (2) increasing the price ratio of discount brands to premium brands—which occurs with an increase in specific excise tax—may lead to upward shifting from discount to premium brands rather than to downward shifting. These results underscore the significance of studying the effectiveness of tax increases in reducing overall tobacco consumption, particularly for specific excise taxes. PMID:23986408

An association between neighbourhood wealth inequality and HIV prevalence in sub-Saharan Africa.

PubMed

Brodish, Paul Henry

2015-05-01

This paper investigates whether community-level wealth inequality predicts HIV serostatus using DHS household survey and HIV biomarker data for men and women ages 15-59 pooled from six sub-Saharan African countries with HIV prevalence rates exceeding 5%. The analysis relates the binary dependent variable HIV-positive serostatus and two weighted aggregate predictors generated from the DHS Wealth Index: the Gini coefficient, and the ratio of the wealth of households in the top 20% wealth quintile to that of those in the bottom 20%. In separate multilevel logistic regression models, wealth inequality is used to predict HIV prevalence within each statistical enumeration area, controlling for known individual-level demographic predictors of HIV serostatus. Potential individual-level sexual behaviour mediating variables are added to assess attenuation, and ordered logit models investigate whether the effect is mediated through extramarital sexual partnerships. Both the cluster-level wealth Gini coefficient and wealth ratio significantly predict positive HIV serostatus: a 1 point increase in the cluster-level Gini coefficient and in the cluster-level wealth ratio is associated with a 2.35 and 1.3 times increased likelihood of being HIV positive, respectively, controlling for individual-level demographic predictors, and associations are stronger in models including only males. Adding sexual behaviour variables attenuates the effects of both inequality measures. Reporting eleven plus lifetime sexual partners increases the odds of being HIV positive over five-fold. The likelihood of having more extramarital partners is significantly higher in clusters with greater wealth inequality measured by the wealth ratio. Disaggregating logit models by sex indicates important risk behaviour differences. Household wealth inequality within DHS clusters predicts HIV serostatus, and the relationship is partially mediated by more extramarital partners. These results emphasize the importance of incorporating higher-level contextual factors, investigating behavioural mediators, and disaggregating by sex in assessing HIV risk in order to uncover potential mechanisms of action and points of preventive intervention.

An association between neighborhood wealth inequality and HIV prevalence in sub-Saharan Africa

PubMed Central

Brodish, Paul Henry

2016-01-01

Summary This paper investigates whether community-level wealth inequality predicts HIV serostatus, using DHS household survey and HIV biomarker data for men and women ages 15-59 pooled from six sub-Saharan African countries with HIV prevalence rates exceeding five percent. The analysis relates the binary dependent variable HIV positive serostatus and two weighted aggregate predictors generated from the DHS Wealth Index: the Gini coefficient, and the ratio of the wealth of households in the top 20% wealth quintile to that of those in the bottom 20%. In separate multilevel logistic regression models, wealth inequality is used to predict HIV prevalence within each SEA, controlling for known individual-level demographic predictors of HIV serostatus. Potential individual-level sexual behavior mediating variables are added to assess attenuation, and ordered logit models investigate whether the effect is mediated through extramarital sexual partnerships. Both the cluster-level wealth Gini coefficient and wealth ratio significantly predict positive HIV serostatus: a 1 point increase in the cluster-level Gini coefficient and in the cluster-level wealth ratio is associated with a 2.35 and 1.3 times increased likelihood of being HIV positive, respectively, controlling for individual-level demographic predictors, and associations are stronger in models including only males. Adding sexual behavior variables attenuates the effects of both inequality measures. Reporting 11 plus lifetime sexual partners increases the odds of being HIV positive over five-fold. The likelihood of having more extramarital partners is significantly higher in clusters with greater wealth inequality measured by the wealth ratio. Disaggregating logit models by sex indicates important risk behavior differences. Household wealth inequality within DHS clusters predicts HIV serostatus, and the relationship is partially mediated by more extramarital partners. These results emphasize the importance of incorporating higher-level contextual factors, investigating behavioral mediators, and disaggregating by sex in assessing HIV risk in order to uncover potential mechanisms of action and points of preventive intervention PMID:24406021

[Econometric and ethical validation of regression logistics. Reducing of the number of patients in the evaluation of mortality].

PubMed

Castiel, D; Herve, C

1992-01-01

In general, a large number of patients is needed to conclude whether the results of a therapeutic strategy are significant or not. One can lower this number with a logit. The method has been proposed in an article published recently (Cost-utility analysis of early thrombolytic therapy, Pharmaco Economics, 1992). The present article is an essay aimed at validating the method, both from the econometric and ethical points of view.

Radiomorphometric analysis of frontal sinus for sex determination.

PubMed

Verma, Saumya; Mahima, V G; Patil, Karthikeya

2014-09-01

Sex determination of unknown individuals carries crucial significance in forensic research, in cases where fragments of skull persist with no likelihood of identification based on dental arch. In these instances sex determination becomes important to rule out certain number of possibilities instantly and helps in establishing a biological profile of human remains. The aim of the study is to evaluate a mathematical method based on logistic regression analysis capable of ascertaining the sex of individuals in the South Indian population. The study was conducted in the department of Oral Medicine and Radiology. The right and left areas, maximum height, width of frontal sinus were determined in 100 Caldwell views of 50 women and 50 men aged 20 years and above, with the help of Vernier callipers and a square grid with 1 square measuring 1mm(2) in area. Student's t-test, logistic regression analysis. The mean values of variables were greater in men, based on Student's t-test at 5% level of significance. The mathematical model based on logistic regression analysis gave percentage agreement of total area to correctly predict the female gender as 55.2%, of right area as 60.9% and of left area as 55.2%. The areas of the frontal sinus and the logistic regression proved to be unreliable in sex determination. (Logit = 0.924 - 0.00217 × right area).

A practical method to test the validity of the standard Gumbel distribution in logit-based multinomial choice models of travel behavior

DOE PAGES

Ye, Xin; Garikapati, Venu M.; You, Daehyun; ...

2017-11-08

Most multinomial choice models (e.g., the multinomial logit model) adopted in practice assume an extreme-value Gumbel distribution for the random components (error terms) of utility functions. This distributional assumption offers a closed-form likelihood expression when the utility maximization principle is applied to model choice behaviors. As a result, model coefficients can be easily estimated using the standard maximum likelihood estimation method. However, maximum likelihood estimators are consistent and efficient only if distributional assumptions on the random error terms are valid. It is therefore critical to test the validity of underlying distributional assumptions on the error terms that form the basismore » of parameter estimation and policy evaluation. In this paper, a practical yet statistically rigorous method is proposed to test the validity of the distributional assumption on the random components of utility functions in both the multinomial logit (MNL) model and multiple discrete-continuous extreme value (MDCEV) model. Based on a semi-nonparametric approach, a closed-form likelihood function that nests the MNL or MDCEV model being tested is derived. The proposed method allows traditional likelihood ratio tests to be used to test violations of the standard Gumbel distribution assumption. Simulation experiments are conducted to demonstrate that the proposed test yields acceptable Type-I and Type-II error probabilities at commonly available sample sizes. The test is then applied to three real-world discrete and discrete-continuous choice models. For all three models, the proposed test rejects the validity of the standard Gumbel distribution in most utility functions, calling for the development of robust choice models that overcome adverse effects of violations of distributional assumptions on the error terms in random utility functions.« less

A practical method to test the validity of the standard Gumbel distribution in logit-based multinomial choice models of travel behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Xin; Garikapati, Venu M.; You, Daehyun

Most multinomial choice models (e.g., the multinomial logit model) adopted in practice assume an extreme-value Gumbel distribution for the random components (error terms) of utility functions. This distributional assumption offers a closed-form likelihood expression when the utility maximization principle is applied to model choice behaviors. As a result, model coefficients can be easily estimated using the standard maximum likelihood estimation method. However, maximum likelihood estimators are consistent and efficient only if distributional assumptions on the random error terms are valid. It is therefore critical to test the validity of underlying distributional assumptions on the error terms that form the basismore » of parameter estimation and policy evaluation. In this paper, a practical yet statistically rigorous method is proposed to test the validity of the distributional assumption on the random components of utility functions in both the multinomial logit (MNL) model and multiple discrete-continuous extreme value (MDCEV) model. Based on a semi-nonparametric approach, a closed-form likelihood function that nests the MNL or MDCEV model being tested is derived. The proposed method allows traditional likelihood ratio tests to be used to test violations of the standard Gumbel distribution assumption. Simulation experiments are conducted to demonstrate that the proposed test yields acceptable Type-I and Type-II error probabilities at commonly available sample sizes. The test is then applied to three real-world discrete and discrete-continuous choice models. For all three models, the proposed test rejects the validity of the standard Gumbel distribution in most utility functions, calling for the development of robust choice models that overcome adverse effects of violations of distributional assumptions on the error terms in random utility functions.« less

Health care seeking patterns and determinants of out-of-pocket expenditure for Malaria for the children under-five in Uganda

PubMed Central

2013-01-01

Background The objectives of this study were to assess the patterns of treatment seeking behaviour for children under five with malaria; and to examine the statistical relationship between out-of-pocket expenditure (OOP) on malaria treatment for under-fives and source of treatment, place of residence, education and wealth characteristics of Uganda households. OOP expenditure on health care is now a development concern due to its negative effect on households’ ability to finance consumption of other basic needs. Methods The 2009 Uganda Malaria Indicator Survey was the source of data on treatment seeking behaviour for under-five children with malaria, and patterns and levels of OOP expenditure for malaria treatment. Binomial logit and Log-lin regression models were estimated. In logit model the dependent variable was a dummy (1=incurred some OOP, 0=none incurred) and independent variables were wealth quintiles, rural versus urban, place of treatment, education level, sub-region, and normal duty disruption. The dependent variable in Log-lin model was natural logarithm of OOP and the independent variables were the same as mentioned above. Results Five key descriptive analysis findings emerge. First, malaria is quite prevalent at 44.7% among children below the age of five. Second, a significant proportion seeks treatment (81.8%). Third, private providers are the preferred option for the under-fives for the treatment of malaria. Fourth, the majority pay about 70.9% for either consultation, medicines, transport or hospitalization but the biggest percent of those who pay, do so for medicines (54.0%). Fifth, hospitalization is the most expensive at an average expenditure of US$7.6 per child, even though only 2.9% of those that seek treatment are hospitalized. The binomial logit model slope coefficients for the variables richest wealth quintile, Private facility as first source of treatment, and sub-regions Central 2, East central, Mid-eastern, Mid-western, and Normal duties disrupted were positive and statistically significant at 99% level of confidence. On the other hand, the Log-lin model slope coefficients for Traditional healer, Sought treatment from one source, Primary educational level, North East, Mid Northern and West Nile variables had a negative sign and were statistically significant at 95% level of confidence. Conclusion The fact that OOP expenditure is still prevalent and private provider is the preferred choice, increasing public provision may not be the sole answer. Plans to improve malaria treatment should explicitly incorporate efforts to protect households from high OOP expenditures. This calls for provision of subsidies to enable the private sector to reduce prices, regulation of prices of malaria medicines, and reduction/removal of import duties on such medicines. PMID:23721217

POLO: a user's guide to Probit Or LOgit analysis.

Treesearch

Jacqueline L. Robertson; Robert M. Russell; N.E. Savin

1980-01-01

This user's guide provides detailed instructions for the use of POLO (Probit Or LOgit), a computer program for the analysis of quantal response data such as that obtained from insecticide bioassays by the techniques of probit or logit analysis. Dosage-response lines may be compared for parallelism or...

Using data mining to predict success in a weight loss trial.

PubMed

Batterham, M; Tapsell, L; Charlton, K; O'Shea, J; Thorne, R

2017-08-01

Traditional methods for predicting weight loss success use regression approaches, which make the assumption that the relationships between the independent and dependent (or logit of the dependent) variable are linear. The aim of the present study was to investigate the relationship between common demographic and early weight loss variables to predict weight loss success at 12 months without making this assumption. Data mining methods (decision trees, generalised additive models and multivariate adaptive regression splines), in addition to logistic regression, were employed to predict: (i) weight loss success (defined as ≥5%) at the end of a 12-month dietary intervention using demographic variables [body mass index (BMI), sex and age]; percentage weight loss at 1 month; and (iii) the difference between actual and predicted weight loss using an energy balance model. The methods were compared by assessing model parsimony and the area under the curve (AUC). The decision tree provided the most clinically useful model and had a good accuracy (AUC 0.720 95% confidence interval = 0.600-0.840). Percentage weight loss at 1 month (≥0.75%) was the strongest predictor for successful weight loss. Within those individuals losing ≥0.75%, individuals with a BMI (≥27 kg m -2 ) were more likely to be successful than those with a BMI between 25 and 27 kg m -2 . Data mining methods can provide a more accurate way of assessing relationships when conventional assumptions are not met. In the present study, a decision tree provided the most parsimonious model. Given that early weight loss cannot be predicted before randomisation, incorporating this information into a post randomisation trial design may give better weight loss results. © 2017 The British Dietetic Association Ltd.

Integration of logistic regression and multicriteria land evaluation to simulation establishment of sustainable paddy field zone in Indramayu Regency, West Java Province, Indonesia

NASA Astrophysics Data System (ADS)

Nahib, Irmadi; Suryanta, Jaka; Niedyawati; Kardono, Priyadi; Turmudi; Lestari, Sri; Windiastuti, Rizka

2018-05-01

Ministry of Agriculture have targeted production of 1.718 million tons of dry grain harvest during period of 2016-2021 to achieve food self-sufficiency, through optimization of special commodities including paddy, soybean and corn. This research was conducted to develop a sustainable paddy field zone delineation model using logistic regression and multicriteria land evaluation in Indramayu Regency. A model was built on the characteristics of local function conversion by considering the concept of sustainable development. Spatial data overlay was constructed using available data, and then this model was built upon the occurrence of paddy field between 1998 and 2015. Equation for the model of paddy field changes obtained was: logit (paddy field conversion) = - 2.3048 + 0.0032*X1 – 0.0027*X2 + 0.0081*X3 + 0.0025*X4 + 0.0026*X5 + 0.0128*X6 – 0.0093*X7 + 0.0032*X8 + 0.0071*X9 – 0.0046*X10 where X1 to X10 were variables that determine the occurrence of changes in paddy fields, with a result value of Relative Operating Characteristics (ROC) of 0.8262. The weakest variable in influencing the change of paddy field function was X7 (paddy field price), while the most influential factor was X1 (distance from river). Result of the logistic regression was used as a weight for multicriteria land evaluation, which recommended three scenarios of paddy fields protection policy: standard, protective, and permissive. The result of this modelling, the priority paddy fields for protected scenario were obtained, as well as the buffer zones for the surrounding paddy fields.

Modeling the Effect of Enlarging Seating Room on Passengers' Preference of Taiwan's Domestic Airlines

NASA Technical Reports Server (NTRS)

Lu, Jin-Long; Tsai, Li-Non

2003-01-01

This study addresses the need for measuring the effect of enlarging seating room in airplane on passengers' preferences of airline in Taiwan. The results can assist Taiwan's domestic air carriers in better understanding their customers' expectations. Stated choice experiment is used to incorporate passengers' trade-offs in the preferred measurement, and three major attributes are taken into account in the stated choice experiment: (1) type of seat (enlarged or not), (2) price, and (3) brand names of airlines. Furthermore, a binary logit model is used to model the choice behavior of air passengers. The findings show that the type of seat is a major significant variable; price and airline's brand are also significant as well. It concludes that air carriers should put more emphasis on the issue of improving the quality of seat comfort. Keywords: Passengers' preference, Enlarged seating room, Stated choice experiment, Binary logit model.

[The role of supply-side characteristics of services in AIDS mortality in Mexico].

PubMed

Bautista-Arredondo, Sergio; Serván-Mori, Edson; Silverman-Retana, Omar; Contreras-Loya, David; Romero-Martínez, Martín; Magis-Rodríguez, Carlos; Uribe-Zúñiga, Patricia; Lozano, Rafael

2015-01-01

To document the association between supply-side determinants and AIDS mortality in Mexico between 2008 and 2013. We analyzed the SALVAR database (system for antiretroviral management, logistics and surveillance) as well as data collected through a nationally representative survey in health facilities. We used multivariate logit regression models to estimate the association between supply-side characteristics, namely management, training and experience of health care providers, and AIDS mortality, distinguishing early and non-early mortality and controlling for clinical indicators of the patients. Clinic status of the patients (initial CD4 and viral load) explain 44.4% of the variability of early mortality across clinics and 13.8% of the variability in non-early mortality. Supply-side characteristics increase explanatory power of the models by 16% in the case of early mortality, and 96% in the case of non-early mortality. Aspects of management and implementation of services contribute significantly to explain AIDS mortality in Mexico. Improving these aspects of the national program, can similarly improve its results.

Short communication: Effect of heat stress on nonreturn rate of Italian Holstein cows.

PubMed

Biffani, S; Bernabucci, U; Vitali, A; Lacetera, N; Nardone, A

2016-07-01

The data set consisted of 1,016,856 inseminations of 191,012 first, second, and third parity Holstein cows from 484 farms. Data were collected from year 2001 through 2007 and included meteorological data from 35 weather stations. Nonreturn rate at 56 d after first insemination (NR56) was considered. A logit model was used to estimate the effect of temperature-humidity index (THI) on reproduction across parities. Then, least squares means were used to detect the THI breakpoints using a 2-phase linear regression procedure. Finally, a multiple-trait threshold model was used to estimate variance components for NR56 in first and second parity cows. A dummy regression variable (t) was used to estimate NR56 decline due to heat stress. The NR56, both for first and second parity cows, was significantly (unfavorable) affected by THI from 4 d before 5 d after the insemination date. Additive genetic variances for NR56 increased from first to second parity both for general and heat stress effect. Genetic correlations between general and heat stress effects were -0.31 for first parity and -0.45 for second parity cows. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Trail impacts in Sagarmatha (Mt. Everest) National Park, Nepal: a logistic regression analysis.

PubMed

Nepal, S K

2003-09-01

A trail study was conducted in the Sagarmatha (Mt. Everest) National Park, Nepal, during 1997-1998. Based on that study, this paper examines the spatial variability of trail conditions and analyzes factors that influence trail conditions. Logistic regression (multinomial logit model) is applied to examine the influence of use and environmental factors on trail conditions. The assessment of trail conditions is based on a four-class rating system: (class I, very little damaged; class II, moderately damaged, class III, heavily damaged; and class IV, severely damaged). Wald statistics and a model classification table have been used for data interpretation. Results indicate that altitude, trail gradient, hazard potential, and vegetation type are positively associated with trail condition. Trails are more degraded at higher altitude, on steep gradients, in areas with natural hazard potential, and within shrub/grassland zones. Strong correlations between high levels of trail degradation and higher frequencies of visitors and lodges were found. A detailed analysis of environmental and use factors could provide valuable information to park managers in their decisions about trail design, layout and maintenance, and efficient and effective visitor management strategies. Comparable studies on high alpine environments are needed to predict precisely the effects of topographic and climatic extremes. More refined approaches and experimental methods are necessary to control the effects of environmental factors.

Calibration power of the Braden scale in predicting pressure ulcer development.

PubMed

Chen, Hong-Lin; Cao, Ying-Juan; Wang, Jing; Huai, Bao-Sha

2016-11-02

Calibration is the degree of correspondence between the estimated probability produced by a model and the actual observed probability. The aim of this study was to investigate the calibration power of the Braden scale in predicting pressure ulcer development (PU). A retrospective analysis was performed among consecutive patients in 2013. The patients were separated into training a group and a validation group. The predicted incidence was calculated using a logistic regression model in the training group and the Hosmer-Lemeshow test was used for assessing the goodness of fit. In the validation cohort, the observed and the predicted incidence were compared by the Chi-square (χ 2 ) goodness of fit test for calibration power. We included 2585 patients in the study, of these 78 patients (3.0%) developed a PU. Between the training and validation groups the patient characteristics were non-significant (p>0.05). In the training group, the logistic regression model for predicting pressure ulcer was Logit(P) = -0.433*Braden score+2.616. The Hosmer-Lemeshow test showed no goodness fit (χ 2 =13.472; p=0.019). In the validation group, the predicted pressure ulcer incidence also did not fit well with the observed incidence (χ 2 =42.154, p=0.000 by Braden scores; and χ 2 =17.223, p=0.001 by Braden scale risk classification). The Braden scale has low calibration power in predicting PU formation.

Analysis of hourly crash likelihood using unbalanced panel data mixed logit model and real-time driving environmental big data.

PubMed

Chen, Feng; Chen, Suren; Ma, Xiaoxiang

2018-06-01

Driving environment, including road surface conditions and traffic states, often changes over time and influences crash probability considerably. It becomes stretched for traditional crash frequency models developed in large temporal scales to capture the time-varying characteristics of these factors, which may cause substantial loss of critical driving environmental information on crash prediction. Crash prediction models with refined temporal data (hourly records) are developed to characterize the time-varying nature of these contributing factors. Unbalanced panel data mixed logit models are developed to analyze hourly crash likelihood of highway segments. The refined temporal driving environmental data, including road surface and traffic condition, obtained from the Road Weather Information System (RWIS), are incorporated into the models. Model estimation results indicate that the traffic speed, traffic volume, curvature and chemically wet road surface indicator are better modeled as random parameters. The estimation results of the mixed logit models based on unbalanced panel data show that there are a number of factors related to crash likelihood on I-25. Specifically, weekend indicator, November indicator, low speed limit and long remaining service life of rutting indicator are found to increase crash likelihood, while 5-am indicator and number of merging ramps per lane per mile are found to decrease crash likelihood. The study underscores and confirms the unique and significant impacts on crash imposed by the real-time weather, road surface, and traffic conditions. With the unbalanced panel data structure, the rich information from real-time driving environmental big data can be well incorporated. Copyright © 2018 National Safety Council and Elsevier Ltd. All rights reserved.

A Note on the Heterogeneous Choice Model

ERIC Educational Resources Information Center

Rohwer, Goetz

2015-01-01

The heterogeneous choice model (HCM) has been proposed as an extension of the standard logit and probit models, which allows taking into account different error variances of explanatory variables. In this note, I show that in an important special case, this model is just another way to specify an interaction effect.

Interferon-based anti-viral therapy for hepatitis C virus infection after renal transplantation: an updated meta-analysis.

PubMed

Wei, Fang; Liu, Junying; Liu, Fen; Hu, Huaidong; Ren, Hong; Hu, Peng

2014-01-01

Hepatitis C virus (HCV) infection is highly prevalent in renal transplant (RT) recipients. Currently, interferon-based (IFN-based) antiviral therapies are the standard approach to control HCV infection. In a post-transplantation setting, however, IFN-based therapies appear to have limited efficacy and their use remains controversial. The present study aimed to evaluate the efficacy and safety of IFN-based therapies for HCV infection post RT. We searched Pubmed, Embase, Web of Knowledge, and The Cochrane Library (1997-2013) for clinical trials in which transplant patients were given Interferon (IFN), pegylated interferon (PEG), interferon plus ribavirin (IFN-RIB), or pegylated interferon plus ribavirin (PEG-RIB). The Sustained Virological Response (SVR) and/or drop-out rates were the primary outcomes. Summary estimates were calculated using the random-effects model of DerSimonian and Laird, with heterogeneity and sensitivity analysis. We identified 12 clinical trials (140 patients in total). The summary estimate for SVR rate, drop-out rate and graft rejection rate was 26.6% (95%CI, 15.0-38.1%), 21.1% (95% CI, 10.9-31.2%) and 4% (95%CI: 0.8%-7.1%), respectively. The overall SVR rate in PEG-based and standard IFN-based therapy was 40.6% (24/59) and 20.9% (17/81), respectively. The most frequent side-effect requiring discontinuation of treatment was graft dysfunction (14 cases, 45.1%). Meta-regression analysis showed the covariates included contribute to the heterogeneity in the SVR logit rate, but not in the drop-out logit rate. The sensitivity analyses by the random model yielded very similar results to the fixed-effects model. IFN-based therapy for HCV infection post RT has poor efficacy and limited safety. PEG-based therapy is a more effective approach for treating HCV infection post-RT than standard IFN-based therapy. Future research is required to develop novel strategies to improve therapeutic efficacy and tolerability, and reduce the liver-related morbidity and mortality in this important patient population.

Topics in Bayesian Hierarchical Modeling and its Monte Carlo Computations

NASA Astrophysics Data System (ADS)

Tak, Hyung Suk

The first chapter addresses a Beta-Binomial-Logit model that is a Beta-Binomial conjugate hierarchical model with covariate information incorporated via a logistic regression. Various researchers in the literature have unknowingly used improper posterior distributions or have given incorrect statements about posterior propriety because checking posterior propriety can be challenging due to the complicated functional form of a Beta-Binomial-Logit model. We derive data-dependent necessary and sufficient conditions for posterior propriety within a class of hyper-prior distributions that encompass those used in previous studies. Frequency coverage properties of several hyper-prior distributions are also investigated to see when and whether Bayesian interval estimates of random effects meet their nominal confidence levels. The second chapter deals with a time delay estimation problem in astrophysics. When the gravitational field of an intervening galaxy between a quasar and the Earth is strong enough to split light into two or more images, the time delay is defined as the difference between their travel times. The time delay can be used to constrain cosmological parameters and can be inferred from the time series of brightness data of each image. To estimate the time delay, we construct a Gaussian hierarchical model based on a state-space representation for irregularly observed time series generated by a latent continuous-time Ornstein-Uhlenbeck process. Our Bayesian approach jointly infers model parameters via a Gibbs sampler. We also introduce a profile likelihood of the time delay as an approximation of its marginal posterior distribution. The last chapter specifies a repelling-attracting Metropolis algorithm, a new Markov chain Monte Carlo method to explore multi-modal distributions in a simple and fast manner. This algorithm is essentially a Metropolis-Hastings algorithm with a proposal that consists of a downhill move in density that aims to make local modes repelling, followed by an uphill move in density that aims to make local modes attracting. The downhill move is achieved via a reciprocal Metropolis ratio so that the algorithm prefers downward movement. The uphill move does the opposite using the standard Metropolis ratio which prefers upward movement. This down-up movement in density increases the probability of a proposed move to a different mode.

School Progress Among Children of Same-Sex Couples.

PubMed

Watkins, Caleb S

2018-06-01

This study uses logit regressions on a pooled sample of children from the 2012, 2013, and 2014 American Community Survey to perform a nationally representative analysis of school progress for a large sample of 4,430 children who reside with same-sex couples. Odds ratios from regressions that compare children between different-sex married couples and same-sex couples fail to show significant differences in normal school progress between households across a variety of sample compositions. Likewise, marginal effects from regressions that compare children with similar family dynamics between different-sex married couples and same-sex couples fail to predict significantly higher probabilities of grade retention for children of same-sex couples. Significantly lower grade retention rates are sometimes predicted for children of same-sex couples than for different-sex married couples, but these differences are sensitive to sample exclusions and do not indicate causal benefits to same-sex parenting.

Wet-season spatial variability of N2O emissions from a tea field in subtropical central China

NASA Astrophysics Data System (ADS)

Fu, X.; Liu, X.; Li, Y.; Shen, J.; Wang, Y.; Zou, G.; Li, H.; Song, L.; Wu, J.

2015-01-01

Tea fields emit large amounts of nitrous oxide (N2O) to the atmosphere. Obtaining accurate estimations of N2O emissions from tea-planted soils is challenging due to strong spatial variability. We examined the spatial variability of N2O emissions from a red-soil tea field in Hunan province, China, on 22 April 2012 (in a wet season) using 147 static mini chambers approximately regular gridded in a 4.0 ha tea field. The N2O fluxes for a 30 min snapshot (10-10.30 a.m.) ranged from -1.73 to 1659.11 g N ha-1 d-1 and were positively skewed with an average flux of 102.24 g N ha-1 d-1. The N2O flux data were transformed to a normal distribution by using a logit function. The geostatistical analyses of our data indicated that the logit-transformed N2O fluxes (FLUX30t) exhibited strong spatial autocorrelation, which was characterized by an exponential semivariogram model with an effective range of 25.2 m. As observed in the wet season, the logit-transformed soil ammonium-N (NH4Nt), soil nitrate-N (NO3Nt), soil organic carbon (SOCt), total soil nitrogen (TSNt) were all found to be significantly correlated with FLUX30t (r=0.57-0.71, p<0.001). Three spatial interpolation methods (ordinary kriging, regression kriging and cokriging) were applied to estimate the spatial distribution of N2O emissions over the study area. Cokriging with NH4Nt and NO3Nt as covariables (r= 0.74 and RMSE =1.18) outperformed ordinary kriging (r= 0.18 and RMSE =1.74), regression kriging with the sample position as a predictor (r= 0.49 and RMSE =1.55) and cokriging with SOCt as a covariable (r= 0.58 and RMSE =1.44). The predictions of the three kriging interpolation methods for the total N2O emissions of the 4.0 ha tea field ranged from 148.2 to 208.1 g N d-1, based on the 30 min snapshots obtained during the wet season. Our findings suggested that to accurately estimate the total N2O emissions over a region, the environmental variables (e.g., soil properties) and the current land use pattern (e.g., tea row transects in the present study) must be included in spatial interpolation. Additionally, compared with other kriging approaches, the cokriging prediction approach showed great advantages in being easily deployed, and more importantly providing accurate regional estimation of N2O emissions from tea-planted soils.

Wet-season spatial variability in N2O emissions from a tea field in subtropical central China

NASA Astrophysics Data System (ADS)

Fu, X.; Liu, X.; Li, Y.; Shen, J.; Wang, Y.; Zou, G.; Li, H.; Song, L.; Wu, J.

2015-06-01

Tea fields emit large amounts of nitrous oxide (N2O) to the atmosphere. Obtaining accurate estimations of N2O emissions from tea-planted soils is challenging due to strong spatial variability. We examined the spatial variability in N2O emissions from a red-soil tea field in Hunan Province, China, on 22 April 2012 (in a wet season) using 147 static mini chambers approximately regular gridded in a 4.0 ha tea field. The N2O fluxes for a 30 min snapshot (10:00-10:30 a.m.) ranged from -1.73 to 1659.11 g N ha-1 d-1 and were positively skewed with an average flux of 102.24 g N ha-1 d-1. The N2O flux data were transformed to a normal distribution by using a logit function. The geostatistical analyses of our data indicated that the logit-transformed N2O fluxes (FLUX30t) exhibited strong spatial autocorrelation, which was characterized by an exponential semivariogram model with an effective range of 25.2 m. As observed in the wet season, the logit-transformed soil ammonium-N (NH4Nt), soil nitrate-N (NO3Nt), soil organic carbon (SOCt) and total soil nitrogen (TSNt) were all found to be significantly correlated with FLUX30t (r = 0.57-0.71, p < 0.001). Three spatial interpolation methods (ordinary kriging, regression kriging and cokriging) were applied to estimate the spatial distribution of N2O emissions over the study area. Cokriging with NH4Nt and NO3Nt as covariables (r = 0.74 and RMSE = 1.18) outperformed ordinary kriging (r = 0.18 and RMSE = 1.74), regression kriging with the sample position as a predictor (r = 0.49 and RMSE = 1.55) and cokriging with SOCt as a covariable (r = 0.58 and RMSE = 1.44). The predictions of the three kriging interpolation methods for the total N2O emissions of 4.0 ha tea field ranged from 148.2 to 208.1 g N d-1, based on the 30 min snapshots obtained during the wet season. Our findings suggested that to accurately estimate the total N2O emissions over a region, the environmental variables (e.g., soil properties) and the current land use pattern (e.g., tea row transects in the present study) must be included in spatial interpolation. Additionally, compared with other kriging approaches, the cokriging prediction approach showed great advantages in being easily deployed and, more importantly, providing accurate regional estimation of N2O emissions from tea-planted soils.

Multiple Sclerosis and Catastrophic Health Expenditure in Iran.

PubMed

Juyani, Yaser; Hamedi, Dorsa; Hosseini Jebeli, Seyede Sedighe; Qasham, Maryam

2016-09-01

There are many disabling medical conditions which can result in catastrophic health expenditure. Multiple Sclerosis is one of the most costly medical conditions through the world which encounter families to the catastrophic health expenditures. This study aims to investigate on what extent Multiple sclerosis patients face catastrophic costs. This study was carried out in Ahvaz, Iran (2014). The study population included households that at least one of their members suffers from MS. To analyze data, Logit regression model was employed by using the default software STATA12. 3.37% of families were encountered with catastrophic costs. Important variables including brand of drug, housing, income and health insurance were significantly correlated with catastrophic expenditure. This study suggests that although a small proportion of MS patients met the catastrophic health expenditure, mechanisms that pool risk and cost (e.g. health insurance) are required to protect them and improve financial and access equity in health care.

Study of the uses of Information and Communication Technologies by Pain Treatment Unit Physicians.

PubMed

Muriel Fernandez, Jorge; Sánchez Ledesma, María José; López Millan, Manuel; García Cenador, María Begoña

2017-05-01

Adequate use of Information and Communication Technologies (ICTs) in health has been shown to save the patient and caregiver time, improve access to the health system, improve diagnosis and control of disease or treatment. All this results in cost savings, and more importantly, they help improve the quality of service and the lives of patients. The purpose of this study is to analyse the differences in the uses of this ICTs between those physicians that belong to Pain Treatment Units (PU) and other physicians that work in pain not linked to these PUs. An online survey, generated by Netquest online survey tool, was sent to both groups of professionals and the data collected was statistical analysed through a logistic regression methodology which is the Logit binomial model. Our results show that those physicians that belong to PUs use ICTs more frequently and consider it more relevant to their clinical practice.

[Factor associated with medicines utilization and expenditure in Mexico].

PubMed

Wirtz, Veronika J; Serván-Mori, Edson; Heredia-Pi, Ileana; Dreser, Anahí; Ávila-Burgos, Leticia

2013-01-01

To analyze medicine utilization and expenditure and associated factors in Mexico, as well as to discuss their implications for pharmaceutical policy. Analysis of a sample of 193,228 individuals from the Mexican National Health and Nutrition Survey 2012. Probability and amount of expenditure were estimated using logit, probit and quantile regression models, evaluating three dimensions of access to medicines: (1) likelihood of utilization of medicines in the event of a health problem, (2) probability of incurring expenses and (3) amount spent on medicines. Individuals affiliated to IMSS were more likely to use medicines (OR=1.2, p<0.05). Being affiliated to the IMSS, ISSSTE or SP reduced the likelihood of spending compared to those without health insurance (about RM 0.7, p<0.01). Median expenditures varied between 195.3 and 274.2 pesos. Factors associated with the use and expenditure on medicines indicate that inequities in the access to medicines persist.

Development and validation of an energy-balance knowledge test for fourth- and fifth-grade students.

PubMed

Chen, Senlin; Zhu, Xihe; Kang, Minsoo

2017-05-01

A valid test measuring children's energy-balance (EB) knowledge is lacking in research. This study developed and validated the energy-balance knowledge test (EBKT) for fourth and fifth grade students. The original EBKT contained 25 items but was reduced to 23 items based on pilot result and intensive expert panel discussion. De-identified data were collected from 468 fourth and fifth grade students enrolled in four schools to examine the psychometric properties of the EBKT items. The Rasch model analysis was conducted using the Winstep 3.65.0 software. Differential item functioning (DIF) analysis flagged 1 item (item #4) functioning differently between boys and girls, which was deleted. The final 22-item EBKT showed desirable model-data fit indices. The items had large variability ranging from -3.58 logit (item #10, the easiest) to 1.70 logit (item #3, the hardest). The average person ability on the test was 0.28 logit (SD = .78). Additional analyses supported known-group difference validity of the EBKT scores in capturing gender- and grade-based ability differences. The test was overall valid but could be further improved by expanding test items to discern various ability levels. For lack of a better test, researchers and practitioners may use the EBKT to assess fourth- and fifth-grade students' EB knowledge.

Changes in cigarette prices, affordability, and brand-tier consumption after a tobacco tax increase in Thailand: Evidence from the Global Adult Tobacco Surveys, 2009 and 2011

PubMed Central

Husain, Muhammad Jami; Kostova, Deliana; Mbulo, Lazarous; Benjakul, Sarunya; Kengganpanich, Mondha; Andes, Linda

2017-01-01

Despite the 2009 implementation of a tobacco tax increase in Thailand, smoking rates remained unchanged between 2009 and 2011. Prior evidence has linked cigarette tax increases to compensatory behaviours aimed at lowering the cost of smoking, such as switching to lower-priced cigarette brands. Using data from 2009 and 2011 Global Adult Tobacco Surveys in Thailand, we estimated unadjusted changes in cigarette prices paid, cigarette affordability, and consumption of cigarettes in three price categories classified as upper-, middle-, and lower-priced brand tiers (or price tertiles). We used ordered logit regression to analyse the correlates of price-tier choice and to estimate the change in price-tier consumption adjusted for demographic and region characteristics. Between 2009 and 2011, real cigarette prices increased, but the affordability of cigarettes remained unchanged overall. There was a significant reduction in the consumption of cigarette brands in the top price-tier overall, accompanied by increases in the consumption of brands in the bottom and middle price-tiers, depending on the region. Adjusted estimates from the logit models indicate that, on average, the proportion of smokers selecting brands from upper- and middle price-tiers decreased while consumption of lower price-tier brands increased during the study period. The estimated shifts in consumption from more expensive to less expensive cigarette brands and the overall lack of change in cigarette affordability in Thailand between 2009 and 2011 are both factors that may have contributed to the observed lack of change in smoking rates after the 2009 tax increase. PMID:28579499

Drivers of multidimensional eco-innovation: empirical evidence from the Brazilian industry.

PubMed

da Silva Rabêlo, Olivan; de Azevedo Melo, Andrea Sales Soares

2018-03-08

The study analyses the relationships between the main drivers of eco-innovation introduced by innovative industries, focused on cooperation strategy. Eco-innovation is analysed by means of a multidimensional identification strategy, showing the relationships between the independent variables and the variable of interest. The literature discussing environmental innovation is different from the one discussing other types of innovation inasmuch as it seeks to grasp its determinants and to mostly highlight the relevance of environmental regulation. The key feature of this paper is that it ascribes special relevance to cooperation strategy with external partners and to the propensity of innovative industry introducing eco-innovation. A sample of 35,060 Brazilian industries were analysed, between 2003 and 2011, by means of Binomial, Multinomial and Ordinal logistic regressions with microdata collected with the research and innovation department (PINTEC) from the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística). The econometric results estimated by the Logit Multinomial method suggest that the cooperation with external partners practiced by innovative industries facilitates the adoption of eco-innovation in dimension 01 with probability of 64.59%, 57.63% in dimension 02 and 81.02% in dimension 03. The data reveal that the higher the degree of eco-innovation complexity, the harder industries seek to obtain cooperation with external partners. When calculating with the Logit Ordinal and Binomial models, cooperation increases the probability that the industry is eco-innovative in 65.09% and 89.34%, respectively. Environmental regulation and innovation in product and information management were also positively correlated as drivers of eco-innovation.

A Multilevel Model for Comorbid Outcomes: Obesity and Diabetes in the US

PubMed Central

Congdon, Peter

2010-01-01

Multilevel models are overwhelmingly applied to single health outcomes, but when two or more health conditions are closely related, it is important that contextual variation in their joint prevalence (e.g., variations over different geographic settings) is considered. A multinomial multilevel logit regression approach for analysing joint prevalence is proposed here that includes subject level risk factors (e.g., age, race, education) while also taking account of geographic context. Data from a US population health survey (the 2007 Behavioral Risk Factor Surveillance System or BRFSS) are used to illustrate the method, with a six category multinomial outcome defined by diabetic status and weight category (obese, overweight, normal). The influence of geographic context is partly represented by known geographic variables (e.g., county poverty), and partly by a model for latent area influences. In particular, a shared latent variable (common factor) approach is proposed to measure the impact of unobserved area influences on joint weight and diabetes status, with the latent variable being spatially structured to reflect geographic clustering in risk. PMID:20616977

Evaluation of Statistical Methods for Modeling Historical Resource Production and Forecasting

NASA Astrophysics Data System (ADS)

Nanzad, Bolorchimeg

This master's thesis project consists of two parts. Part I of the project compares modeling of historical resource production and forecasting of future production trends using the logit/probit transform advocated by Rutledge (2011) with conventional Hubbert curve fitting, using global coal production as a case study. The conventional Hubbert/Gaussian method fits a curve to historical production data whereas a logit/probit transform uses a linear fit to a subset of transformed production data. Within the errors and limitations inherent in this type of statistical modeling, these methods provide comparable results. That is, despite that apparent goodness-of-fit achievable using the Logit/Probit methodology, neither approach provides a significant advantage over the other in either explaining the observed data or in making future projections. For mature production regions, those that have already substantially passed peak production, results obtained by either method are closely comparable and reasonable, and estimates of ultimately recoverable resources obtained by either method are consistent with geologically estimated reserves. In contrast, for immature regions, estimates of ultimately recoverable resources generated by either of these alternative methods are unstable and thus, need to be used with caution. Although the logit/probit transform generates high quality-of-fit correspondence with historical production data, this approach provides no new information compared to conventional Gaussian or Hubbert-type models and may have the effect of masking the noise and/or instability in the data and the derived fits. In particular, production forecasts for immature or marginally mature production systems based on either method need to be regarded with considerable caution. Part II of the project investigates the utility of a novel alternative method for multicyclic Hubbert modeling tentatively termed "cycle-jumping" wherein overlap of multiple cycles is limited. The model is designed in a way that each cycle is described by the same three parameters as conventional multicyclic Hubbert model and every two cycles are connected with a transition width. Transition width indicates the shift from one cycle to the next and is described as weighted coaddition of neighboring two cycles. It is determined by three parameters: transition year, transition width, and gamma parameter for weighting. The cycle-jumping method provides superior model compared to the conventional multicyclic Hubbert model and reflects historical production behavior more reasonably and practically, by better modeling of the effects of technological transitions and socioeconomic factors that affect historical resource production behavior by explicitly considering the form of the transitions between production cycles.

Reconsidering the use of rankings in the valuation of health states: a model for estimating cardinal values from ordinal data

PubMed Central

Salomon, Joshua A

2003-01-01

Background In survey studies on health-state valuations, ordinal ranking exercises often are used as precursors to other elicitation methods such as the time trade-off (TTO) or standard gamble, but the ranking data have not been used in deriving cardinal valuations. This study reconsiders the role of ordinal ranks in valuing health and introduces a new approach to estimate interval-scaled valuations based on aggregate ranking data. Methods Analyses were undertaken on data from a previously published general population survey study in the United Kingdom that included rankings and TTO values for hypothetical states described using the EQ-5D classification system. The EQ-5D includes five domains (mobility, self-care, usual activities, pain/discomfort and anxiety/depression) with three possible levels on each. Rank data were analysed using a random utility model, operationalized through conditional logit regression. In the statistical model, probabilities of observed rankings were related to the latent utilities of different health states, modeled as a linear function of EQ-5D domain scores, as in previously reported EQ-5D valuation functions. Predicted valuations based on the conditional logit model were compared to observed TTO values for the 42 states in the study and to predictions based on a model estimated directly from the TTO values. Models were evaluated using the intraclass correlation coefficient (ICC) between predictions and mean observations, and the root mean squared error of predictions at the individual level. Results Agreement between predicted valuations from the rank model and observed TTO values was very high, with an ICC of 0.97, only marginally lower than for predictions based on the model estimated directly from TTO values (ICC = 0.99). Individual-level errors were also comparable in the two models, with root mean squared errors of 0.503 and 0.496 for the rank-based and TTO-based predictions, respectively. Conclusions Modeling health-state valuations based on ordinal ranks can provide results that are similar to those obtained from more widely analyzed valuation techniques such as the TTO. The information content in aggregate ranking data is not currently exploited to full advantage. The possibility of estimating cardinal valuations from ordinal ranks could also simplify future data collection dramatically and facilitate wider empirical study of health-state valuations in diverse settings and population groups. PMID:14687419

Global Evidence on the Association between Cigarette Graphic Warning Labels and Cigarette Smoking Prevalence and Consumption

PubMed Central

Ngo, Anh; Cheng, Kai-Wen; Huang, Jidong; Chaloupka, Frank J.

2018-01-01

Background: In 2011, the courts ruled in favor of tobacco companies in preventing the implementation of graphic warning labels (GWLs) in the US, stating that FDA had not established the effectiveness of GWLs in reducing smoking. Methods: Data came from various sources: the WHO MPOWER package (GWLs, MPOWER policy measures, cigarette prices), Euromonitor International (smoking prevalence, cigarette consumption), and the World Bank database (countries’ demographic characteristics). The datasets were aggregated and linked using country and year identifiers. Fractional logit regressions and OLS regressions were applied to examine the associations between GWLs and smoking prevalence and cigarette consumption, controlling for MPOWER policy scores, cigarette prices, GDP per capita, unemployment, population aged 15–64 (%), aged 65 and over (%), year indicators, and country fixed effects. Results: GWLs were associated with a 0.9–3 percentage point decrease in adult smoking prevalence and were significantly associated with a reduction of 230–287 sticks in per capita cigarette consumption, compared to countries without GWLs. However, the association between GWLs and cigarette consumption became statistically insignificant once country indicators were included in the models. Conclusions: The implementation of GWLs may be associated with reduced cigarette smoking. PMID:29495581

Global Evidence on the Association between Cigarette Graphic Warning Labels and Cigarette Smoking Prevalence and Consumption.

PubMed

Ngo, Anh; Cheng, Kai-Wen; Shang, Ce; Huang, Jidong; Chaloupka, Frank J

2018-02-28

Background : In 2011, the courts ruled in favor of tobacco companies in preventing the implementation of graphic warning labels (GWLs) in the US, stating that FDA had not established the effectiveness of GWLs in reducing smoking. Methods : Data came from various sources: the WHO MPOWER package (GWLs, MPOWER policy measures, cigarette prices), Euromonitor International (smoking prevalence, cigarette consumption), and the World Bank database (countries' demographic characteristics). The datasets were aggregated and linked using country and year identifiers. Fractional logit regressions and OLS regressions were applied to examine the associations between GWLs and smoking prevalence and cigarette consumption, controlling for MPOWER policy scores, cigarette prices, GDP per capita, unemployment, population aged 15-64 (%), aged 65 and over (%), year indicators, and country fixed effects. Results : GWLs were associated with a 0.9-3 percentage point decrease in adult smoking prevalence and were significantly associated with a reduction of 230-287 sticks in per capita cigarette consumption, compared to countries without GWLs. However, the association between GWLs and cigarette consumption became statistically insignificant once country indicators were included in the models. Conclusions : The implementation of GWLs may be associated with reduced cigarette smoking.

[The importance of memory bias in obtaining age of menarche by recall method in Brazilian adolescents].

PubMed

Castilho, Silvia Diez; Nucci, Luciana Bertoldi; Assuino, Samanta Ramos; Hansen, Lucca Ortolan

2014-06-01

To compare the age at menarche obtained by recall method according to the time elapsed since the event, in order to verify the importance of the recall bias. Were evaluated 1,671 girls (7-18 years) at schools in Campinas-SP regarding the occurrence of menarche by the status quo method (menarche: yes or no) and the recall method (date of menarche, for those who mentioned it). The age at menarche obtained by the status quo method was calculated by logit, which considers the whole group, and the age obtained by the recall method was calculated as the average of the mentioned age at menarche. In this group, the age at menarche was obtained by the difference between the date of the event and the date of birth. Girls who reported menarche (883, 52.8%) were divided into four groups according to the time elapsed since the event. To analyze the results, we used ANOVA and logistic regression for the analysis, with a significance level of 0.05. The age at menarche calculated by logit was 12.14 y/o (95% CI 12.08 to 12.20). Mean ages obtained by recall were: for those who experienced menarche within the previous year 12.26 y/o (±1.14), between > 1-2 years before, 12.29 y (±1.22); between > 2-3 years before, 12.23 y/o (±1.27); and more than 3 years before, 11.55y/o (±1.24), p < 0.001. The age at menarche obtained by the recall method was similar for girls who menstruated within the previous 3 years (and approaches the age calculated by logit); when more than 3 years have passed, the recall bias was significant.

Box-Cox Mixed Logit Model for Travel Behavior Analysis

NASA Astrophysics Data System (ADS)

Orro, Alfonso; Novales, Margarita; Benitez, Francisco G.

2010-09-01

To represent the behavior of travelers when they are deciding how they are going to get to their destination, discrete choice models, based on the random utility theory, have become one of the most widely used tools. The field in which these models were developed was halfway between econometrics and transport engineering, although the latter now constitutes one of their principal areas of application. In the transport field, they have mainly been applied to mode choice, but also to the selection of destination, route, and other important decisions such as the vehicle ownership. In usual practice, the most frequently employed discrete choice models implement a fixed coefficient utility function that is linear in the parameters. The principal aim of this paper is to present the viability of specifying utility functions with random coefficients that are nonlinear in the parameters, in applications of discrete choice models to transport. Nonlinear specifications in the parameters were present in discrete choice theory at its outset, although they have seldom been used in practice until recently. The specification of random coefficients, however, began with the probit and the hedonic models in the 1970s, and, after a period of apparent little practical interest, has burgeoned into a field of intense activity in recent years with the new generation of mixed logit models. In this communication, we present a Box-Cox mixed logit model, original of the authors. It includes the estimation of the Box-Cox exponents in addition to the parameters of the random coefficients distribution. Probability of choose an alternative is an integral that will be calculated by simulation. The estimation of the model is carried out by maximizing the simulated log-likelihood of a sample of observed individual choices between alternatives. The differences between the predictions yielded by models that are inconsistent with real behavior have been studied with simulation experiments.

Airport Choice in Sao Paulo Metropolitan Area: An Application of the Conditional Logit Model

NASA Technical Reports Server (NTRS)

Moreno, Marcelo Baena; Muller, Carlos

2003-01-01

Using the conditional LOGIT model, this paper addresses the airport choice in the Sao Paulo Metropolitan Area. In this region, Guarulhos International Airport (GRU) and Congonhas Airport (CGH) compete for passengers flying to several domestic destinations. The airport choice is believed to be a result of the tradeoff passengers perform considering airport access characteristics, airline level of service characteristics and passenger experience with the analyzed airports. It was found that access time to the airports better explain the airport choice than access distance, whereas direct flight frequencies gives better explanation to the airport choice than the indirect (connections and stops) and total (direct plus indirect) flight frequencies. Out of 15 tested variables, passenger experience with the analyzed airports was the variable that best explained the airport choice in the region. Model specifications considering 1, 2 or 3 variables were tested. The model specification most adjusted to the observed data considered access time, direct flight frequencies in the travel period (morning or afternoon peak) and passenger experience with the analyzed airports. The influence of these variables was therefore analyzed across market segments according to departure airport and flight duration criteria. The choice of GRU (located neighboring Sao Paulo city) is not well explained by the rationality of access time economy and the increase of the supply of direct flight frequencies, while the choice of CGH (located inside Sao Paulo city) is. Access time was found to be more important to passengers flying shorter distances while direct flight frequencies in the travel period were more significant to those flying longer distances. Keywords: Airport choice, Multiple airport region, Conditional LOGIT model, Access time, Flight frequencies, Passenger experience with the analyzed airports, Transportation planning

The Mixed Effects Trend Vector Model

ERIC Educational Resources Information Center

de Rooij, Mark; Schouteden, Martijn

2012-01-01

Maximum likelihood estimation of mixed effect baseline category logit models for multinomial longitudinal data can be prohibitive due to the integral dimension of the random effects distribution. We propose to use multidimensional unfolding methodology to reduce the dimensionality of the problem. As a by-product, readily interpretable graphical…

Logistic quantile regression provides improved estimates for bounded avian counts: A case study of California Spotted Owl fledgling production

USGS Publications Warehouse

Cade, Brian S.; Noon, Barry R.; Scherer, Rick D.; Keane, John J.

2017-01-01

Counts of avian fledglings, nestlings, or clutch size that are bounded below by zero and above by some small integer form a discrete random variable distribution that is not approximated well by conventional parametric count distributions such as the Poisson or negative binomial. We developed a logistic quantile regression model to provide estimates of the empirical conditional distribution of a bounded discrete random variable. The logistic quantile regression model requires that counts are randomly jittered to a continuous random variable, logit transformed to bound them between specified lower and upper values, then estimated in conventional linear quantile regression, repeating the 3 steps and averaging estimates. Back-transformation to the original discrete scale relies on the fact that quantiles are equivariant to monotonic transformations. We demonstrate this statistical procedure by modeling 20 years of California Spotted Owl fledgling production (0−3 per territory) on the Lassen National Forest, California, USA, as related to climate, demographic, and landscape habitat characteristics at territories. Spotted Owl fledgling counts increased nonlinearly with decreasing precipitation in the early nesting period, in the winter prior to nesting, and in the prior growing season; with increasing minimum temperatures in the early nesting period; with adult compared to subadult parents; when there was no fledgling production in the prior year; and when percentage of the landscape surrounding nesting sites (202 ha) with trees ≥25 m height increased. Changes in production were primarily driven by changes in the proportion of territories with 2 or 3 fledglings. Average variances of the discrete cumulative distributions of the estimated fledgling counts indicated that temporal changes in climate and parent age class explained 18% of the annual variance in owl fledgling production, which was 34% of the total variance. Prior fledgling production explained as much of the variance in the fledgling counts as climate, parent age class, and landscape habitat predictors. Our logistic quantile regression model can be used for any discrete response variables with fixed upper and lower bounds.

Depressive symptoms are associated with salivary shedding of Epstein-Barr virus in female adolescents: The role of sex differences.

PubMed

Ford, Jodi L; Stowe, Raymond P

2017-12-01

Adolescent females have a higher prevalence of depression in comparison to their male peers - a disparity that has been increasing over the past decade. Depression is of concern as it is associated with chronic disease and to immune dysregulation, which may be one mechanism linking depression to future pathology. This study examined the extent to which sex moderated the association between depressive symptoms and immune dysregulation during adolescence using Epstein-Barr virus (EBV) reactivation, a biomarker of cellular immune response, as a model. A representative community sample of 259 female and 279 male adolescents aged 11-17 years who were EBV IgG positive were examined. Trained interviewers collected the data during two home visits, one week apart. Depressive symptoms were measured at the first visit using the 9 item short-form of the Center for Epidemiologic Studies-Depression scale. EBV biomarkers were collected via saliva at the second visit and included a qualitative measure of EBV viral capsid antigen immunoglobulin G to assess prior EBV infection and a quantitative measure of EBV DNA to assess the number of viral copies shed in the saliva. In multivariable logistic regression analyses, increasing depressive symptoms were significantly associated with salivary shedding of EBV DNA for adolescent females only (logit=0.66, se=0.30, p<0.05), and the interaction between sex and depressive symptoms on salivary shedding of EBV DNA was statistically significant (logit=-1.19, se=0.42, p<0.01). Sensitivity analyses were conducted in which sex was examined as a moderator in the relationship between depressive symptoms and salivary EBV DNA quantitative copies via Tobit regression; results were consistent with the presented findings. Depressive symptoms are associated with EBV reactivation among EBV positive female adolescents, but not males. Future research is needed to examine EBV reactivation in female adolescents as a mechanism linking depression to future chronic disease and the role of sex hormones in explaining sex differences in the relationship between depressive symptoms and EBV reactivation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Winter weather demand considerations.

DOT National Transportation Integrated Search

2015-04-01

Winter weather has varied effects on travel behavior. Using 418 survey responses from the Northern Virginia : commuting area of Washington, D.C. and binary logit models, this study examines travel related changes under : different types of winter wea...

Modelling Student Misconceptions Using Nested Logit Item Response Models

ERIC Educational Resources Information Center

Yildiz, Mustafa

2017-01-01

Student misconceptions have been studied for decades from a curricular/instructional perspective and from the assessment/test level perspective. Numerous misconception assessment tools have been developed in order to measure students' misconceptions relative to the correct content. Often, these tools are used to make a variety of educational…

Syndromic surveillance models using Web data: the case of scarlet fever in the UK.

PubMed

Samaras, Loukas; García-Barriocanal, Elena; Sicilia, Miguel-Angel

2012-03-01

Recent research has shown the potential of Web queries as a source for syndromic surveillance, and existing studies show that these queries can be used as a basis for estimation and prediction of the development of a syndromic disease, such as influenza, using log linear (logit) statistical models. Two alternative models are applied to the relationship between cases and Web queries in this paper. We examine the applicability of using statistical methods to relate search engine queries with scarlet fever cases in the UK, taking advantage of tools to acquire the appropriate data from Google, and using an alternative statistical method based on gamma distributions. The results show that using logit models, the Pearson correlation factor between Web queries and the data obtained from the official agencies must be over 0.90, otherwise the prediction of the peak and the spread of the distributions gives significant deviations. In this paper, we describe the gamma distribution model and show that we can obtain better results in all cases using gamma transformations, and especially in those with a smaller correlation factor.

Multinomial mixture model with heterogeneous classification probabilities

USGS Publications Warehouse

Holland, M.D.; Gray, B.R.

2011-01-01

Royle and Link (Ecology 86(9):2505-2512, 2005) proposed an analytical method that allowed estimation of multinomial distribution parameters and classification probabilities from categorical data measured with error. While useful, we demonstrate algebraically and by simulations that this method yields biased multinomial parameter estimates when the probabilities of correct category classifications vary among sampling units. We address this shortcoming by treating these probabilities as logit-normal random variables within a Bayesian framework. We use Markov chain Monte Carlo to compute Bayes estimates from a simulated sample from the posterior distribution. Based on simulations, this elaborated Royle-Link model yields nearly unbiased estimates of multinomial and correct classification probability estimates when classification probabilities are allowed to vary according to the normal distribution on the logit scale or according to the Beta distribution. The method is illustrated using categorical submersed aquatic vegetation data. ?? 2010 Springer Science+Business Media, LLC.

Application of LogitBoost Classifier for Traceability Using SNP Chip Data

PubMed Central

Kang, Hyunsung; Cho, Seoae; Kim, Heebal; Seo, Kang-Seok

2015-01-01

Consumer attention to food safety has increased rapidly due to animal-related diseases; therefore, it is important to identify their places of origin (POO) for safety purposes. However, only a few studies have addressed this issue and focused on machine learning-based approaches. In the present study, classification analyses were performed using a customized SNP chip for POO prediction. To accomplish this, 4,122 pigs originating from 104 farms were genotyped using the SNP chip. Several factors were considered to establish the best prediction model based on these data. We also assessed the applicability of the suggested model using a kinship coefficient-filtering approach. Our results showed that the LogitBoost-based prediction model outperformed other classifiers in terms of classification performance under most conditions. Specifically, a greater level of accuracy was observed when a higher kinship-based cutoff was employed. These results demonstrated the applicability of a machine learning-based approach using SNP chip data for practical traceability. PMID:26436917

Application of LogitBoost Classifier for Traceability Using SNP Chip Data.

PubMed

Kim, Kwondo; Seo, Minseok; Kang, Hyunsung; Cho, Seoae; Kim, Heebal; Seo, Kang-Seok

2015-01-01

Consumer attention to food safety has increased rapidly due to animal-related diseases; therefore, it is important to identify their places of origin (POO) for safety purposes. However, only a few studies have addressed this issue and focused on machine learning-based approaches. In the present study, classification analyses were performed using a customized SNP chip for POO prediction. To accomplish this, 4,122 pigs originating from 104 farms were genotyped using the SNP chip. Several factors were considered to establish the best prediction model based on these data. We also assessed the applicability of the suggested model using a kinship coefficient-filtering approach. Our results showed that the LogitBoost-based prediction model outperformed other classifiers in terms of classification performance under most conditions. Specifically, a greater level of accuracy was observed when a higher kinship-based cutoff was employed. These results demonstrated the applicability of a machine learning-based approach using SNP chip data for practical traceability.

Weather impacts on single-vehicle truck crash injury severity.

PubMed

Naik, Bhaven; Tung, Li-Wei; Zhao, Shanshan; Khattak, Aemal J

2016-09-01

The focus of this paper is on illustrating the feasibility of aggregating data from disparate sources to investigate the relationship between single-vehicle truck crash injury severity and detailed weather conditions. Specifically, this paper presents: (a) a methodology that combines detailed 15-min weather station data with crash and roadway data, and (b) an empirical investigation of the effects of weather on crash-related injury severities of single-vehicle truck crashes. Random parameters ordinal and multinomial regression models were used to investigate crash injury severity under different weather conditions, taking into account the individual unobserved heterogeneity. The adopted methodology allowed consideration of environmental, roadway, and climate-related variables in single-vehicle truck crash injury severity. Results showed that wind speed, rain, humidity, and air temperature were linked with single-vehicle truck crash injury severity. Greater recorded wind speed added to the severity of injuries in single-vehicle truck crashes in general. Rain and warmer air temperatures were linked to more severe crash injuries in single-vehicle truck crashes while higher levels of humidity were linked to less severe injuries. Random parameters ordered logit and multinomial logit, respectively, revealed some individual heterogeneity in the data and showed that integrating comprehensive weather data with crash data provided useful insights into factors associated with single-vehicle truck crash injury severity. The research provided a practical method that combined comprehensive 15-min weather station data with crash and roadway data, thereby providing useful insights into crash injury severity of single-vehicle trucks. Those insights are useful for future truck driver educational programs and for truck safety in different weather conditions. Copyright © 2016 Elsevier Ltd and National Safety Council. All rights reserved.

Adjunctive Self-hypnotic Relaxation for Outpatient Medical Procedures: A Prospective Randomized Trial with Women Undergoing Large Core Breast Biopsy

PubMed Central

Lang, Elvira V.; Berbaum, Kevin S.; Faintuch, Salomao; Hatsiopoulou, Olga; Halsey, Noami; Li, Xinyu; Berbaum, Michael L.; Laser, Eleanor; Baum, Janet

2008-01-01

Medical procedures in outpatient settings have limited options of managing pain and anxiety pharmacologically. We therefore assessed whether this can be achieved by adjunct self-hypnotic relaxation in a common and particularly anxiety provoking procedure. 236 women referred for large core needle breast biopsy to an urban tertiary university-affiliated medical center were prospectively randomized to receive standard care (n=76), structured empathic attention (n= 82), or self-hypnotic relaxation (n=78) during their procedures. Patients’ self-ratings at 10 minute-intervals of pain and anxiety on 0–10 verbal analog scales with 0=no pain/anxiety at all, 10=worst pain/anxiety possible, were compared in an ordinal logistic regression model. Women’s anxiety increased significantly in the standard group (logit slope = 0.18, p < 0.001), did not change in the empathy group (slope = −0.04, p = 0.45), and decreased significantly in the hypnosis group (slope = −0.27, p < 0.001). Pain increased significantly in all three groups (logit slopes: standard care = 0.53, empathy = 0.37, hypnosis = 0.34; all p < 0.001) though less steeply with hypnosis and empathy than standard care (p = 0.024 and p = 0.018 respectively). Room time and cost were not significantly different in an univariate ANOVA despite hypnosis and empathy requiring an additional professional: 46 minutes/$161 for standard care, 43 minutes/$163 for empathy, and 39 minutes/$152 for hypnosis. We conclude that, while both structured empathy and hypnosis decrease procedural pain and anxiety, hypnosis provides more powerful anxiety relief without undue cost and thus appears attractive for outpatient pain management. PMID:16959427

A Bayesian Approach for Nonlinear Structural Equation Models with Dichotomous Variables Using Logit and Probit Links

ERIC Educational Resources Information Center

Lee, Sik-Yum; Song, Xin-Yuan; Cai, Jing-Heng

2010-01-01

Analysis of ordered binary and unordered binary data has received considerable attention in social and psychological research. This article introduces a Bayesian approach, which has several nice features in practical applications, for analyzing nonlinear structural equation models with dichotomous data. We demonstrate how to use the software…

The Postsecondary Resource Trinity Model: Exploring the Interaction between Socioeconomic, Academic, and Institutional Resources

ERIC Educational Resources Information Center

Giani, Matt S.

2015-01-01

The purpose of this study is to revisit the widely held assumption that the impact of socioeconomic background declines steadily across educational transitions, particularly at the postsecondary level. Sequential logit modeling, a staple methodological approach for estimating the relative impact of SES across educational stages, is applied to a…

Investigation of hit-and-run crash occurrence and severity using real-time loop detector data and hierarchical Bayesian binary logit model with random effects.

PubMed

Xie, Meiquan; Cheng, Wen; Gill, Gurdiljot Singh; Zhou, Jiao; Jia, Xudong; Choi, Simon

2018-02-17

Most of the extensive research dedicated to identifying the influential factors of hit-and-run (HR) crashes has utilized typical maximum likelihood estimation binary logit models, and none have employed real-time traffic data. To fill this gap, this study focused on investigating factors contributing to HR crashes, as well as the severity levels of HR. This study analyzed 4-year crash and real-time loop detector data by employing hierarchical Bayesian models with random effects within a sequential logit structure. In addition to evaluation of the impact of random effects on model fitness and complexity, the prediction capability of the models was examined. Stepwise incremental sensitivity and specificity were calculated and receiver operating characteristic (ROC) curves were utilized to graphically illustrate the predictive performance of the model. Among the real-time flow variables, the average occupancy and speed from the upstream detector were observed to be positively correlated with HR crash possibility. The average upstream speed and speed difference between upstream and downstream speeds were correlated with the occurrence of severe HR crashes. In addition to real-time factors, other variables found influential for HR and severe HR crashes were length of segment, adverse weather conditions, dark lighting conditions with malfunctioning street lights, driving under the influence of alcohol, width of inner shoulder, and nighttime. This study suggests the potential traffic conditions of HR and severe HR occurrence, which refer to relatively congested upstream traffic conditions with high upstream speed and significant speed deviations on long segments. The above findings suggest that traffic enforcement should be directed toward mitigating risky driving under the aforementioned traffic conditions. Moreover, enforcement agencies may employ alcohol checkpoints to counter driving under the influence (DUI) at night. With regard to engineering improvements, wider inner shoulders may be constructed to potentially reduce HR cases and street lights should be installed and maintained in working condition to make roads less prone to such crashes.

Racial/ethnic disparities in hypertension prevalence: reconsidering the role of chronic stress.

PubMed

Hicken, Margaret T; Lee, Hedwig; Morenoff, Jeffrey; House, James S; Williams, David R

2014-01-01

We investigated the association between anticipatory stress, also known as racism-related vigilance, and hypertension prevalence in Black, Hispanic, and White adults. We used data from the Chicago Community Adult Health Study, a population-representative sample of adults (n = 3105) surveyed in 2001 to 2003, to regress hypertension prevalence on the interaction between race/ethnicity and vigilance in logit models. Blacks reported the highest vigilance levels. For Blacks, each unit increase in vigilance (range = 0-12) was associated with a 4% increase in the odds of hypertension (odds ratio [OR] = 1.04; 95% confidence interval [CI] = 1.00, 1.09). Hispanics showed a similar but nonsignificant association (OR = 1.05; 95% CI = 0.99, 1.12), and Whites showed no association (OR = 0.95; 95% CI = 0.87, 1.03). Vigilance may represent an important and unique source of chronic stress that contributes to the well-documented higher prevalence of hypertension among Blacks than Whites; it is a possible contributor to hypertension among Hispanics but not Whites.

Exploring the climate change concerns of striped catfish producers in the Mekong Delta, Vietnam.

PubMed

Nguyen, Anh Lam; Truong, Minh Hoang; Verreth, Johan Aj; Leemans, Rik; Bosma, Roel H; De Silva, Sena S

2015-01-01

This study investigated the perceptions on and adaptations to climate change impacts of 235 pangasius farmers in the Mekong Delta, Vietnam. Data were collected using semi-structured household surveys in six provinces, from three regions along the Mekong river branches. A Chi-Square test was used to determine the association between variables, and a logit regression model was employed to identify factors correlated with farmer's perception and adaptation. Less than half of respondents were concerned about climate change and sought suitable adaptation measures to alleviate its impacts. Improving information on climate change and introducing early warning systems could improve the adaptive capacity of pangasius farmers, in particularly for those farmers, who were not concerned yet. Farmers relied strongly on technical support from government agencies, but farmers in the coastal provinces did not express the need for training by these institutions. This contrasting result requires further assessment of the effectiveness of adaptation measures such as breeding salinity tolerant pangasius.

Preferences for the sex-composition of children in Europe: a multilevel examination of its effect on progression to a third child.

PubMed

Mills, Melinda; Begall, Katia

2010-03-01

Comparative research on the preferred sex of children in Western societies has generally focused on women only and ignored the role of gender equity and the need for children's economic support in old age. A multilevel analysis extends existing research by examining, for both men and women and across 24 European countries, the effect of the preferred sex-composition of offspring on whether parents have or intend to have a third child. Using the European Social Survey (2004/5), a multilevel (random coefficient) ordered logit regression of that intention (N = 3,323) and a binary logistic multilevel model of the transition to a third child (N = 6,502) demonstrate the presence of a mixed-sex preference. In countries with a high risk of poverty in old age, a preference for sons is found, particularly for men. In societies where there is lower gender equity, both men and women have a significant preference for boys.

Nurses who do not nurse: factors that predict non-nursing work in the U.S. registered nursing labor market.

PubMed

Black, Lisa; Spetz, Joanne; Harrington, Charlene

2010-01-01

Registered nurses (RNs) who work outside of nursing have seldom been examined. This aim of this study was to compare the 122,178 (4%) of RNs who are employed outside of nursing to those who work in nursing jobs in terms of sociodemographic, market, and political variables to determine if these groups are substantively different from one another. Using a logit regression model, wages were a significant predictor of working outside of nursing for unmarried nurses but not for married nurses. Married and unmarried male nurses were more likely to work outside of nursing. Baccalaureate education, children under age 6, higher family income, and years since graduation increased the odds of working outside of nursing for married nurses. Ultimately, identifying characteristics on which these groups differ may inform future policy directions that could target nurses who may leave nursing at a time when retention efforts might be effective to alter their trajectory away from the profession.

Patient satisfaction, empowerment, and health and disability status effects of a disease management-health promotion nurse intervention among Medicare beneficiaries with disabilities.

PubMed

Friedman, Bruce; Wamsley, Brenda R; Liebel, Dianne V; Saad, Zabedah B; Eggert, Gerald M

2009-12-01

To report the impact on patient and informal caregiver satisfaction, patient empowerment, and health and disability status of a primary care-affiliated disease self-management-health promotion nurse intervention for Medicare beneficiaries with disabilities and recent significant health services use. The Medicare Primary and Consumer-Directed Care Demonstration was a 24-month randomized controlled trial that included a nurse intervention. The present study (N = 766) compares the nurse (n = 382) and control (n = 384) groups. Generalized linear models for repeated measures, linear regression, and ordered logit regression were used. The patients whose activities of daily living (ADL) were reported by the same respondent at baseline and 22 months following baseline had significantly fewer dependencies at 22 months than did the control group (p = .038). This constituted the vast majority of respondents. In addition, patient satisfaction significantly improved for 6 of 7 domains, whereas caregiver satisfaction improved for 2 of 8 domains. However, the intervention had no effect on empowerment, self-rated health, the SF-36 physical and mental health summary scores, and the number of dependencies in instrumental ADL. If confirmed in other studies, this intervention holds the potential to reduce the rate of functional decline and improve satisfaction for Medicare beneficiaries with ADL dependence.

Age at menarche in urban Argentinian girls: association with biological and socioeconomic factors.

PubMed

Orden, Alicia B; Vericat, Agustina; Apezteguía, Maria C

2011-01-01

Age at menarche is regarded as a sensitive indicator of physical, biological, and psychosocial environment. The aim of this study was to determine the age at menarche and its association with biological and socioeconomic factors in girls from Santa Rosa (La Pampa, Argentina). An observational cross-sectional study was carried out on 1,221 schoolgirls aged 9-15 years. Menarche data were obtained by the status-quo method. Height, sitting height, weight, arm circumference, tricipital and subscapular skinfolds were measured. We also calculated body mass index, measures of body composition and proportions, and fat distribution. To assess socioeconomic factors, parents completed a self-administered questionnaire about their occupation and education, family size, household, and other family characteristics. The median age at menarche - estimated by the logit method--was 12.84 years (95% CI: 12.71, 12.97). Compared with their premenarcheal age peers, postmenarcheal girls had greater anthropometric dimensions through age 12. After this age, only height was higher in the latter group. Data were processed by fitting two logistic regressions, both including age. The first model included anthropometric variables and birth weight, while the second model included the socioeconomic variables. The significant variables derived from each model were incorporated into a new regression: height, sitting height ratio (first model), and maternal education (second model). These three variables remained significantly associated with menarche. The results suggest a relationship between linear growth and menarche and agree with those found in other populations where the advancement of menarche is associated with improved living conditions. In relatively uniform urban contexts, maternal education may be a good proxy for the standard of living.

A Multinomial Logit Model of Attrition that Distinguishes between Stopout and Dropout Behavior

ERIC Educational Resources Information Center

Stratton, Leslie S.; O'Toole, Dennis M.; Wetzel, James N.

2004-01-01

College attrition rates are of substantial concern to policy makers and economists interested in educational attainment and earnings opportunities. This is not surprising since nationwide, almost one-third of all first-time college students fail to return for their sophomore year. There exists a substantial body of literature seeking to model this…

Heterogeneity in general practitioners' preferences for quality improvement programs: a choice experiment and policy simulation in France.

PubMed

Ammi, Mehdi; Peyron, Christine

2016-12-01

Despite increasing popularity, quality improvement programs (QIP) have had modest and variable impacts on enhancing the quality of physician practice. We investigate the heterogeneity of physicians' preferences as a potential explanation of these mixed results in France, where the national voluntary QIP - the CAPI - has been cancelled due to its unpopularity. We rely on a discrete choice experiment to elicit heterogeneity in physicians' preferences for the financial and non-financial components of QIP. Using mixed and latent class logit models, results show that the two models should be used in concert to shed light on different aspects of the heterogeneity in preferences. In particular, the mixed logit demonstrates that heterogeneity in preferences is concentrated on the pay-for-performance component of the QIP, while the latent class model shows that physicians can be grouped in four homogeneous groups with specific preference patterns. Using policy simulation, we compare the French CAPI with other possible QIPs, and show that the majority of the physician subgroups modelled dislike the CAPI, while favouring a QIP using only non-financial interventions. We underline the importance of modelling preference heterogeneity in designing and implementing QIPs.

Model-based Clustering of Categorical Time Series with Multinomial Logit Classification

NASA Astrophysics Data System (ADS)

Frühwirth-Schnatter, Sylvia; Pamminger, Christoph; Winter-Ebmer, Rudolf; Weber, Andrea

2010-09-01

A common problem in many areas of applied statistics is to identify groups of similar time series in a panel of time series. However, distance-based clustering methods cannot easily be extended to time series data, where an appropriate distance-measure is rather difficult to define, particularly for discrete-valued time series. Markov chain clustering, proposed by Pamminger and Frühwirth-Schnatter [6], is an approach for clustering discrete-valued time series obtained by observing a categorical variable with several states. This model-based clustering method is based on finite mixtures of first-order time-homogeneous Markov chain models. In order to further explain group membership we present an extension to the approach of Pamminger and Frühwirth-Schnatter [6] by formulating a probabilistic model for the latent group indicators within the Bayesian classification rule by using a multinomial logit model. The parameters are estimated for a fixed number of clusters within a Bayesian framework using an Markov chain Monte Carlo (MCMC) sampling scheme representing a (full) Gibbs-type sampler which involves only draws from standard distributions. Finally, an application to a panel of Austrian wage mobility data is presented which leads to an interesting segmentation of the Austrian labour market.

The importance of job training to job satisfaction of older workers.

PubMed

Leppel, Karen; Brucker, Eric; Cochran, Jeremy

2012-01-01

If job training has positive impacts on worker satisfaction, then job training can have desirable consequences for an organization that result both directly through its effects on productivity and indirectly through its effects on job satisfaction. Furthermore, the aging of the workforce implies that older workers will become increasingly important to firms and to the economy. This study, therefore, seeks to examine the relationship between job training and job satisfaction, focusing in particular on U.S. workers born in 1964 or earlier. The results of ordered logit regression analysis indicate that availability and quality of training received directly affect job satisfaction.

Determining the Relationship Between Moral Waivers and Marine Corps Unsuitability Attrition

DTIC Science & Technology

2008-03-01

observed characteristics. However, econometric research indicates that the magnitude of interaction effects estimated via probit or logit models may...1997 to 2005. Multivariate probit models were used to analyze the effects of moral waivers on unsatisfactory service separations. 15. NUMBER OF...files from fiscal years 1997 to 2005. Multivariate probit models were used to analyze the effects of moral waivers on unsatisfactory service

Advanced techniques for modeling avian nest survival

USGS Publications Warehouse

Dinsmore, S.J.; White, Gary C.; Knopf, F.L.

2002-01-01

Estimation of avian nest survival has traditionally involved simple measures of apparent nest survival or Mayfield constant-nest-survival models. However, these methods do not allow researchers to build models that rigorously assess the importance of a wide range of biological factors that affect nest survival. Models that incorporate greater detail, such as temporal variation in nest survival and covariates representative of individual nests represent a substantial improvement over traditional estimation methods. In an attempt to improve nest survival estimation procedures, we introduce the nest survival model now available in the program MARK and demonstrate its use on a nesting study of Mountain Plovers (Charadrius montanus Townsend) in Montana, USA. We modeled the daily survival of Mountain Plover nests as a function of the sex of the incubating adult, nest age, year, linear and quadratic time trends, and two weather covariates (maximum daily temperature and daily precipitation) during a six-year study (1995–2000). We found no evidence for yearly differences or an effect of maximum daily temperature on the daily nest survival of Mountain Plovers. Survival rates of nests tended by female and male plovers differed (female rate = 0.33; male rate = 0.49). The estimate of the additive effect for males on nest survival rate was 0.37 (95% confidence limits were 0.03, 0.71) on a logit scale. Daily survival rates of nests increased with nest age; the estimate of daily nest-age change in survival in the best model was 0.06 (95% confidence limits were 0.04, 0.09) on a logit scale. Daily precipitation decreased the probability that the nest would survive to the next day; the estimate of the additive effect of daily precipitation on the nest survival rate was −1.08 (95% confidence limits were −2.12, −0.13) on a logit scale. Our approach to modeling daily nest-survival rates allowed several biological factors of interest to be easily included in nest survival models and allowed us to generate more biologically meaningful estimates of nest survival.

Risk factors associated with the presence and severity of food insecurity in rural Honduras.

PubMed

Ben-Davies, Maureen E; Kinlaw, Alan; Estrada Del Campo, Yaniré; Bentley, Margaret E; Siega-Riz, Anna Maria

2014-01-01

To identify factors associated with the presence and severity of food insecurity among a sample of Honduran caregivers of young children. Cross-sectional study in which the dependent variable, household food insecurity, was measured using a fourteen-item questionnaire developed and validated in a population of similar cultural context. A predictive modelling strategy used backwards elimination in logistic regression and multinomial logit regression models to compute odds ratios and 95% confidence intervals for food insecurity. Rural Honduras in the department of Intibucá, between March and April 2009. Two-hundred and ninety-eight Honduran caregivers of children aged 6-18 months. Ninety-three per cent of households were classified as having some degree of food insecurity (mild, moderate or severe). After controlling for caregiver age and marital status, compared with caregivers with more than primary-school education, those with less than primary-school education had 3·47 (95% CI 1·34, 8·99) times the odds of severe food insecurity and 2·29 (95% CI 1·00, 5·25) times the odds of moderate food insecurity. Our results also found that child anthropometric status was not associated with the presence or severity of food insecurity. These results show that among the sociodemographic factors assessed, food insecurity in rural Honduras is associated with maternal education. Understanding key factors associated with food insecurity that are unique to Honduras can inform the design of interventions to effectively mitigate the negative impact of food insecurity on children.

Dropout from Secondary Education: All's Well That Begins Well

ERIC Educational Resources Information Center

De Witte, Kristof; Rogge, Nicky

2013-01-01

Despite the increased attention to students leaving secondary education without a diploma numerous students still dropout yearly. This paper makes a distinction between the "individual perspective" and the "institutional perspective" of dropping out. The former is explored by multinominal logit models. We observe that…

Measuring Developmental Students' Mathematics Anxiety

ERIC Educational Resources Information Center

Ding, Yanqing

2016-01-01

This study conducted an item-level analysis of mathematics anxiety and examined the dimensionality of mathematics anxiety in a sample of developmental mathematics students (N = 162) by Multi-dimensional Random Coefficients Multinominal Logit Model (MRCMLM). The results indicate a moderately correlated factor structure of mathematics anxiety (r =…

Willingness to Pay for Improving the Residential Waste Disposal System in Korea: A Choice Experiment Study

NASA Astrophysics Data System (ADS)

Ku, Se-Ju; Yoo, Seung-Hoon; Kwak, Seung-Jun

2009-08-01

This study attempts to apply choice experiments with regard to the residential waste disposal system (RWDS) in Korea by considering various attributes that are related to RWDS. Using data from a survey conducted on 492 households, the empirical analysis yields estimates of the willingness to pay for a clean food-waste collection facility, the collection of small items (such as obsolete mobile phones and add-ons for personal computers), and a more convenient large waste disposal system. The estimation results of multinomial logit models are quite similar to those of nested logit models. The results reveal that residents have preferences for the cleanliness of facilities and the collection of small items. In Korea, residents are required to purchase and attach stickers for the disposal of large items; they want to be able to obtain stickers at not only village offices but also supermarkets. On the other hand, the frequency of waste collection is not a significant factor in the choice of the improved waste management program.

Willingness to pay for improving the residential waste disposal system in Korea: a choice experiment study.

PubMed

Ku, Se-Ju; Yoo, Seung-Hoon; Kwak, Seung-Jun

2009-08-01

This study attempts to apply choice experiments with regard to the residential waste disposal system (RWDS) in Korea by considering various attributes that are related to RWDS. Using data from a survey conducted on 492 households, the empirical analysis yields estimates of the willingness to pay for a clean food-waste collection facility, the collection of small items (such as obsolete mobile phones and add-ons for personal computers), and a more convenient large waste disposal system. The estimation results of multinomial logit models are quite similar to those of nested logit models. The results reveal that residents have preferences for the cleanliness of facilities and the collection of small items. In Korea, residents are required to purchase and attach stickers for the disposal of large items; they want to be able to obtain stickers at not only village offices but also supermarkets. On the other hand, the frequency of waste collection is not a significant factor in the choice of the improved waste management program.

Competitive assessment of aerospace systems using system dynamics

NASA Astrophysics Data System (ADS)

Pfaender, Jens Holger

Aircraft design has recently experienced a trend away from performance centric design towards a more balanced approach with increased emphasis on engineering an economically successful system. This approach focuses on bringing forward a comprehensive economic and life-cycle cost analysis. Since the success of any system also depends on many external factors outside of the control of the designer, this traditionally has been modeled as noise affecting the uncertainty of the design. However, this approach is currently lacking a strategic treatment of necessary early decisions affecting the probability of success of a given concept in a dynamic environment. This suggests that the introduction of a dynamic method into a life-cycle cost analysis should allow the analysis of the future attractiveness of such a concept in the presence of uncertainty. One way of addressing this is through the use of a competitive market model. However, existing market models do not focus on the dynamics of the market. Instead, they focus on modeling and predicting market share through logit regression models. The resulting models exhibit relatively poor predictive capabilities. The method proposed here focuses on a top-down approach that integrates a competitive model based on work in the field of system dynamics into the aircraft design process. Demonstrating such integration is one of the primary contributions of this work, which previously has not been demonstrated. This integration is achieved through the use of surrogate models, in this case neural networks. This enabled not only the practical integration of analysis techniques, but also reduced the computational requirements so that interactive exploration as envisioned was actually possible. The example demonstration of this integration is built on the competition in the 250 seat large commercial aircraft market exemplified by the Boeing 767-400ER and the Airbus A330-200. Both aircraft models were calibrated to existing performance and certification data and then integrated into the system dynamics market model. The market model was then calibrated with historical market data. This calibration showed a much improved predictive capability as compared to the conventional logit regression models. An additional advantage of this dynamic model is that to realize this improved capability, no additional explanatory variables were required. Furthermore, the resulting market model was then integrated into a prediction profiler environment with a time variant Monte-Carlo analysis resulting in a unique trade-off environment. This environment was shown to allow interactive trade-off between aircraft design decisions and economic considerations while allowing the exploration potential market success in the light of varying external market conditions and scenarios. The resulting method is capable of reduced decision support uncertainty and identification of robust design decisions in future scenarios with a high likelihood of occurrence with special focus on the path dependent nature of future implications of decisions. Furthermore, it was possible to demonstrate the increased importance of design and technology choices on the competitiveness in scenarios with drastic increases in commodity prices during the time period modeled. Another use of the existing outputs of the Monte-Carlo analysis was then realized by showing them on a multivariate scatter plot. This plot was then shown to enable by appropriate grouping of variables to enable the top down definition of an aircraft design, also known as inverse design. In other words this enables the designer to define strategic market and return on investment goals for a number of scenarios, for example the development of fuel prices, and then directly see which specific aircraft designs meet these goals.

Developing the Impossible Figures Task to Assess Visual-Spatial Talents among Chinese Students: A Rasch Measurement Model Analysis

ERIC Educational Resources Information Center

Chan, David W.

2010-01-01

Data of item responses to the Impossible Figures Task (IFT) from 492 Chinese primary, secondary, and university students were analyzed using the dichotomous Rasch measurement model. Item difficulty estimates and person ability estimates located on the same logit scale revealed that the pooled sample of Chinese students, who were relatively highly…

Joint Analysis of Binomial and Continuous Traits with a Recursive Model: A Case Study Using Mortality and Litter Size of Pigs

PubMed Central

Varona, Luis; Sorensen, Daniel

2014-01-01

This work presents a model for the joint analysis of a binomial and a Gaussian trait using a recursive parametrization that leads to a computationally efficient implementation. The model is illustrated in an analysis of mortality and litter size in two breeds of Danish pigs, Landrace and Yorkshire. Available evidence suggests that mortality of piglets increased partly as a result of successful selection for total number of piglets born. In recent years there has been a need to decrease the incidence of mortality in pig-breeding programs. We report estimates of genetic variation at the level of the logit of the probability of mortality and quantify how it is affected by the size of the litter. Several models for mortality are considered and the best fits are obtained by postulating linear and cubic relationships between the logit of the probability of mortality and litter size, for Landrace and Yorkshire, respectively. An interpretation of how the presence of genetic variation affects the probability of mortality in the population is provided and we discuss and quantify the prospects of selecting for reduced mortality, without affecting litter size. PMID:24414548

Predicting juvenile recidivism: new method, old problems.

PubMed

Benda, B B

1987-01-01

This prediction study compared three statistical procedures for accuracy using two assessment methods. The criterion is return to a juvenile prison after the first release, and the models tested are logit analysis, predictive attribute analysis, and a Burgess procedure. No significant differences are found between statistics in prediction.

Choice-Based Segmentation as an Enrollment Management Tool

ERIC Educational Resources Information Center

Young, Mark R.

2002-01-01

This article presents an approach to enrollment management based on target marketing strategies developed from a choice-based segmentation methodology. Students are classified into "switchable" or "non-switchable" segments based on their probability of selecting specific majors. A modified multinomial logit choice model is used to identify…

Essays on pricing dynamics, price dispersion, and nested logit modelling

NASA Astrophysics Data System (ADS)

Verlinda, Jeremy Alan

The body of this dissertation comprises three standalone essays, presented in three respective chapters. Chapter One explores the possibility that local market power contributes to the asymmetric relationship observed between wholesale costs and retail prices in gasoline markets. I exploit an original data set of weekly gas station prices in Southern California from September 2002 to May 2003, and take advantage of highly detailed station and local market-level characteristics to determine the extent to which spatial differentiation influences price-response asymmetry. I find that brand identity, proximity to rival stations, bundling and advertising, operation type, and local market features and demographics each influence a station's predicted asymmetric relationship between prices and wholesale costs. Chapter Two extends the existing literature on the effect of market structure on price dispersion in airline fares by modeling the effect at the disaggregate ticket level. Whereas past studies rely on aggregate measures of price dispersion such as the Gini coefficient or the standard deviation of fares, this paper estimates the entire empirical distribution of airline fares and documents how the shape of the distribution is determined by market structure. Specifically, I find that monopoly markets favor a wider distribution of fares with more mass in the tails while duopoly and competitive markets exhibit a tighter fare distribution. These findings indicate that the dispersion of airline fares may result from the efforts of airlines to practice second-degree price discrimination. Chapter Three adopts a Bayesian approach to the problem of tree structure specification in nested logit modelling, which requires a heavy computational burden in calculating marginal likelihoods. I compare two different techniques for estimating marginal likelihoods: (1) the Laplace approximation, and (2) reversible jump MCMC. I apply the techniques to both a simulated and a travel mode choice data set, and find that model selection is invariant to prior specification, while model derivatives like willingness-to-pay are notably sensitive to model choice. I also find that the Laplace approximation is remarkably accurate in spite of the potential for nested logit models to have irregular likelihood surfaces.

International Climate Migration: Evidence for the Climate Inhibitor Mechanism and the Agricultural Pathway

PubMed Central

Nawrotzki, Raphael J.; Bakhtsiyarava, Maryia

2016-01-01

Research often assumes that, in rural areas of developing countries, adverse climatic conditions increase (climate driver mechanism) rather than reduce (climate inhibitor mechanism) migration, and that the impact of climate on migration is moderated by changes in agricultural productivity (agricultural pathway). Using representative census data in combination with high-resolution climate data derived from the novel Terra Populus system, we explore the climate-migration relationship in rural Burkina Faso and Senegal. We construct four threshold-based climate measures to investigate the effect of heat waves, cold snaps, droughts and excessive precipitation on the likelihood of household-level international outmigration. Results from multi-level logit models show that excessive precipitation increases international migration from Senegal while heat waves decrease international mobility in Burkina Faso, providing evidence for the climate inhibitor mechanism. Consistent with the agricultural pathway, interaction models and results from a geographically weighted regression (GWR) reveal a conditional effect of droughts on international outmigration from Senegal, which becomes stronger in areas with high levels of groundnut production. Moreover, climate change effects show a clear seasonal pattern, with the strongest effects appearing when heat waves overlap with the growing season and when excessive precipitation occurs prior to the growing season. PMID:28943813

International Climate Migration: Evidence for the Climate Inhibitor Mechanism and the Agricultural Pathway.

PubMed

Nawrotzki, Raphael J; Bakhtsiyarava, Maryia

2017-05-01

Research often assumes that, in rural areas of developing countries, adverse climatic conditions increase (climate driver mechanism) rather than reduce (climate inhibitor mechanism) migration, and that the impact of climate on migration is moderated by changes in agricultural productivity (agricultural pathway). Using representative census data in combination with high-resolution climate data derived from the novel Terra Populus system, we explore the climate-migration relationship in rural Burkina Faso and Senegal. We construct four threshold-based climate measures to investigate the effect of heat waves, cold snaps, droughts and excessive precipitation on the likelihood of household-level international outmigration. Results from multi-level logit models show that excessive precipitation increases international migration from Senegal while heat waves decrease international mobility in Burkina Faso, providing evidence for the climate inhibitor mechanism. Consistent with the agricultural pathway, interaction models and results from a geographically weighted regression (GWR) reveal a conditional effect of droughts on international outmigration from Senegal, which becomes stronger in areas with high levels of groundnut production. Moreover, climate change effects show a clear seasonal pattern, with the strongest effects appearing when heat waves overlap with the growing season and when excessive precipitation occurs prior to the growing season.

Entrepreneurship and Adolescents

ERIC Educational Resources Information Center

Santana Vega, Lidia E.; González-Morales, Olga; Feliciano García, Luis

2016-01-01

This work studied the entrepreneurial aspirations of 3,987 adolescents regarding self-employment and the influence of gender, age, nationality, type of school, location of the school, educational level and performance. The Logit model is used to analyze the data. The results indicate that the pupils' aspirations to be self-employed increase in the…

Freight Demand Characteristics and Mode Choice: An Analysis of the Results of Modeling with Disaggregate Revealed Preference Data

DOT National Transportation Integrated Search

1999-12-01

This paper analyzes the freight demand characteristics that drive modal choice by means of a large scale, national, disaggregate revealed preference database for shippers in France in 1988, using a nested logit. Particular attention is given to priva...

Multidimensional Computerized Adaptive Testing for Indonesia Junior High School Biology

ERIC Educational Resources Information Center

Kuo, Bor-Chen; Daud, Muslem; Yang, Chih-Wei

2015-01-01

This paper describes a curriculum-based multidimensional computerized adaptive test that was developed for Indonesia junior high school Biology. In adherence to the Indonesian curriculum of different Biology dimensions, 300 items was constructed, and then tested to 2238 students. A multidimensional random coefficients multinomial logit model was…

The Impact of Nontraditional Training on the Occupational Attainment of Women.

ERIC Educational Resources Information Center

Streker-Seeborg, Irmtraud; And Others

1984-01-01

Using a logit model of occupational attainment, researchers found that economically disadvantaged women who received nontraditional training were much less likely to be employed in male-dominated occupations and received lower hourly wages. Direct labor market discrimination seems to be responsible for the inhibited occupational attainment of…

Using Neural Networks to Predict MBA Student Success

ERIC Educational Resources Information Center

Naik, Bijayananda; Ragothaman, Srinivasan

2004-01-01

Predicting MBA student performance for admission decisions is crucial for educational institutions. This paper evaluates the ability of three different models--neural networks, logit, and probit to predict MBA student performance in graduate programs. The neural network technique was used to classify applicants into successful and marginal student…

Predicting Faculty Membership--Application of Student Choice Logit Model

ERIC Educational Resources Information Center

Kopanidis, Foula Zografina; Shaw, Michael John

2017-01-01

Purpose: Educational institutions are caught between increasing their offer rates and attracting and retaining those prospective students who are most suited to course completion. The purpose of this paper is to demonstrate the influence of demographic and psychological constructs on students' preferences when choosing to study in a particular…

Multifactor analysis and simulation of the surface runoff and soil infiltration at different slope gradients

NASA Astrophysics Data System (ADS)

Huang, J.; Kang, Q.; Yang, J. X.; Jin, P. W.

2017-08-01

The surface runoff and soil infiltration exert significant influence on soil erosion. The effects of slope gradient/length (SG/SL), individual rainfall amount/intensity (IRA/IRI), vegetation cover (VC) and antecedent soil moisture (ASM) on the runoff depth (RD) and soil infiltration (INF) were evaluated in a series of natural rainfall experiments in the South of China. RD is found to correlate positively with IRA, IRI, and ASM factors and negatively with SG and VC. RD decreased followed by its increase with SG and ASM, it increased with a further decrease with SL, exhibited a linear growth with IRA and IRI, and exponential drop with VC. Meanwhile, INF exhibits a positive correlation with SL, IRA and IRI and VC, and a negative one with SG and ASM. INF was going up and then down with SG, linearly rising with SL, IRA and IRI, increasing by a logit function with VC, and linearly falling with ASM. The VC level above 60% can effectively lower the surface runoff and significantly enhance soil infiltration. Two RD and INF prediction models, accounting for the above six factors, were constructed using the multiple nonlinear regression method. The verification of those models disclosed a high Nash-Sutcliffe coefficient and low root-mean-square error, demonstrating good predictability of both models.

Distributional changes in the western Burrowing Owl (Athene cunicularia hypugaea) in North America from 1967 to 2008

USGS Publications Warehouse

Macias-Duarte, Alberto; Conway, Courtney J.

2015-01-01

The quantification of shifts in bird distributions in response to climate change provides an opportunity to gain a deeper understanding of the processes that influence species persistence. We used data from the North American Breeding Bird Survey (BBS) to document changes in the distributional limits of the western Burrowing Owl (Athene cunicularia hypugaea) from 1967 to 2008. We used logistic regression to model presence probability (p) as a function of longitude, latitude, and year. We modeled a linear trend in logit(p) through time with slope and intercept modeled as a double Fourier series of longitude and latitude. We found that the western Burrowing Owl has experienced an intriguing southward shift in the northern half of its breeding range, contrary to what is predicted by most species niche models and what has been observed for many other species in North America. The breeding range of the Burrowing Owl has been shrinking near its northern, western, and eastern edges. Our model detected the population declines that were observed in California and eastern Washington, in locations where maps based on route-specific estimating equations had predicted significant population increases. We suggest that the northern boundary of the breeding distribution of the western Burrowing Owl has contracted southward and the southern boundary of the species' breeding distribution has expanded southward into areas of northern Mexico that were formerly used only by wintering migrants.

Time-varying mixed logit model for vehicle merging behavior in work zone merging areas.

PubMed

Weng, Jinxian; Du, Gang; Li, Dan; Yu, Yao

2018-08-01

This study aims to develop a time-varying mixed logit model for the vehicle merging behavior in work zone merging areas during the merging implementation period from the time of starting a merging maneuver to that of completing the maneuver. From the safety perspective, vehicle crash probability and severity between the merging vehicle and its surrounding vehicles are regarded as major factors influencing vehicle merging decisions. Model results show that the model with the use of vehicle crash risk probability and severity could provide higher prediction accuracy than previous models with the use of vehicle speeds and gap sizes. It is found that lead vehicle type, through lead vehicle type, through lag vehicle type, crash probability of the merging vehicle with respect to the through lag vehicle, crash severities of the merging vehicle with respect to the through lead and lag vehicles could exhibit time-varying effects on the merging behavior. One important finding is that the merging vehicle could become more and more aggressive in order to complete the merging maneuver as quickly as possible over the elapsed time, even if it has high vehicle crash risk with respect to the through lead and lag vehicles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Exploratory Analysis of Survey Data for Understanding Adoption of Novel Aerospace Systems

NASA Astrophysics Data System (ADS)

Reddy, Lauren M.

In order to meet the increasing demand for manned and unmanned flight, the air transportation system must constantly evolve. As new technologies or operational procedures are conceived, we must determine their effect on humans in the system. In this research, we introduce a strategy to assess how individuals or organizations would respond to a novel aerospace system. We employ the most appropriate and sophisticated exploratory analysis techniques on the survey data to generate insight and identify significant variables. We employ three different methods for eliciting views from individuals or organizations who are affected by a system: an opinion survey, a stated preference survey, and structured interviews. We conduct an opinion survey of both the general public and stakeholders in the unmanned aircraft industry to assess their knowledge, attitude, and practices regarding unmanned aircraft. We complete a statistical analysis of the multiple-choice questions using multinomial logit and multivariate probit models and conduct qualitative analysis on free-text questions. We next present a stated preference survey of the general public on the use of an unmanned aircraft package delivery service. We complete a statistical analysis of the questions using multinomial logit, ordered probit, linear regression, and negative binomial models. Finally, we discuss structured interviews conducted on stakeholders from ANSPs and airlines operating in the North Atlantic. We describe how these groups may choose to adopt a new technology (space-based ADS-B) or operational procedure (in-trail procedures). We discuss similarities and differences between the stakeholders groups, the benefits and costs of in-trail procedures and space-based ADS-B as reported by the stakeholders, and interdependencies between the groups interviewed. To demonstrate the value of the data we generated, we explore how the findings from the surveys can be used to better characterize uncertainty in the cost-benefit analysis of aerospace systems. We demonstrate how the findings from the opinion and stated preference surveys can be infused into the cost-benefit analysis of an unmanned aircraft delivery system. We also demonstrate how to apply the findings from the interviews to characterize uncertainty in the estimation of the benefits of space-based ADS-B.

Plasma myelin basic protein assay using Gilford enzyme immunoassay cuvettes.

PubMed

Groome, N P

1981-10-01

The assay of myelin basic protein in body fluids has potential clinical importance as a routine indicator of demyelination. Preliminary details of a competitive enzyme immunoassay for this protein have previously been published by the author (Groome, N. P. (1980) J. Neurochem. 35, 1409-1417). The present paper now describes the adaptation of this assay for use on human plasma and various aspects of routine data processing. A commercially available cuvette system was found to have advantages over microtitre plates but required a permuted arrangement of sample replicates for consistent results. For dose interpolation, the standard curve could be fitted to a three parameter non-linear equation by regression analysis or linearised by the logit/log transformation.

College binge drinking: deviant versus mainstream behavior.

PubMed

Leppel, Karen

2006-01-01

College binge drinking is examined from the perspectives of two cultures. The traditional culture views binging as deviant; the second culture promotes it. In this context, logit regression is used to explore the effects of various factors, including student employment and parental education. Employed students are less likely to binge than are students who are not employed. Also, students whose mother is a college graduate, but whose father is not, are more likely to binge than other students. The prescriptions for reducing binge drinking are different when the behavior is perceived as mainstream rather than deviant. The research calls for the development of a process for promoting cultural change in an environment of continually changing student leadership.

[Optimization of diagnosis indicator selection and inspection plan by 3.0T MRI in breast cancer].

PubMed

Jiang, Zhongbiao; Wang, Yunhua; He, Zhong; Zhang, Lejun; Zheng, Kai

2013-08-01

To optimize 3.0T MRI diagnosis indicator in breast cancer and to select the best MRI scan program. Totally 45 patients with breast cancers were collected, and another 35 patients with benign breast tumor served as the control group. All patients underwent 3.0T MRI, including T1- weighted imaging (T1WI), fat suppression of the T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), 1H magnetic resonance spectroscopy (1H-MRS) and dynamic contrast enhanced (DCE) sequence. With operation pathology results as the gold standard in the diagnosis of breast diseases, the pathological results of benign and malignant served as dependent variables, and the diagnostic indicators of MRI were taken as independent variables. We put all the indicators of MRI examination under Logistic regression analysis, established the Logistic model, and optimized the diagnosis indicators of MRI examination to further improve MRI scan of breast cancer. By Logistic regression analysis, some indicators were selected in the equation, including the edge feature of the tumor, the time-signal intensity curve (TIC) type and the apparent diffusion coefficient (ADC) value when b=500 s/mm2. The regression equation was Logit (P)=-21.936+20.478X6+3.267X7+ 21.488X3. Valuable indicators in the diagnosis of breast cancer are the edge feature of the tumor, the TIC type and the ADC value when b=500 s/mm2. Combining conventional MRI scan, DWI and dynamic enhanced MRI is a better examination program, while MRS is the complementary program when diagnosis is difficult.

Prevalence of abortion and stillbirth in a beef cattle system in Southeastern Mexico.

PubMed

Segura-Correa, José C; Segura-Correa, Victor M

2009-12-01

Prenatal mortality is an important cause of production losses in the livestock industry. This study estimates the prevalences of abortion and stillbirth in a beef cattle system and determines the significance of some risk factors, in the tropics of Mexico. Data were obtained from a Zebu cattle herd and their crosses with Bos taurus breeds, in Yucatan, Mexico. The logit of the probability of an abortion or stillbirth was modeled using binary logistic regression. The risk factors tested were: year of abortion (or calving), season of abortion (or calving), parity number and dam breed group. The effect of twins on stillbirth was tested using Fisher exact test. Of the 4175 calvings studied 49 were abortions (1.17%). Significant factors in the logistic regression analysis for abortions were season of abortion and parity number. The risk of abortion was lower in the dry seasons compared to the rainy and windy seasons (P = 0.009). The risk of abortion was higher in second parity cows followed by the third and first parity cows, as compared to older cows (P = 0.015). Of the 4126 births, 87 were stillbirths (2.11%). Significant factors in the logistic regression analysis for stillbirth were year of calving (P = 0.0001) and parity number (P < 0.001). The risk of stillbirth in first parity cows was 2.6 times that of old cows. Of the total births, 15 were twins (0.36%) of which 7 were born dead calves. Herd owners must focus on the significant risk factors under their control to reduce the prevalence of prenatal mortality.

Cigarette smoking and cutaneous damage in systemic lupus erythematosus.

PubMed

Turchin, Irina; Bernatsky, Sasha; Clarke, Ann E; St-Pierre, Yvan; Pineau, Christian A

2009-12-01

To evaluate the association between cigarette smoking and cutaneous damage in systemic lupus erythematosus (SLE). Our study was performed in SLE clinic registry cohort patients, all of whom fulfilled revised American College of Rheumatology criteria for SLE; patients are followed prospectively with annual assessments that include collection of demographic variables, smoking history, disease activity (SLE Disease Activity Index version 2000, SLEDAI-2K), medications, and damage scores (Systemic Lupus International Collaborating Clinics/ACR Damage Index). Cumulative cutaneous damage scores were used for the primary analyses. Logistic and logit regression models were performed to examine potential associations between current smoking and cutaneous damage, controlling for age, sex, race, lupus disease duration, antimalarial or immunosuppressant use, and anti-DNA and anti-SSA antibody status. Of our sample (N = 276), 92% were women and 73.7% were Caucasian; the mean age was 45.1 years, mean disease duration 13.5 years, and 17.5% were current smokers. In the regression analyses, current cigarette smoking was associated with total cutaneous damage (OR 2.73, 95% CI 1.10, 6.81) and with scarring (OR 4.70, 95 CI 1.04, 21.2). In additional analyses, current smoking was also associated with active lupus rash (OR 6.18, 95% CI 1.63, 23.3). Current cigarette smoking may be associated with cutaneous damage and active lupus rash in SLE, suggesting another reason to emphasize smoking cessation in patients with SLE.

An econometric analysis of changes in arable land utilization using multinomial logit model in Pinggu district, Beijing, China.

PubMed

Xu, Yueqing; McNamara, Paul; Wu, Yanfang; Dong, Yue

2013-10-15

Arable land in China has been decreasing as a result of rapid population growth and economic development as well as urban expansion, especially in developed regions around cities where quality farmland quickly disappears. This paper analyzed changes in arable land utilization during 1993-2008 in the Pinggu district, Beijing, China, developed a multinomial logit (MNL) model to determine spatial driving factors influencing arable land-use change, and simulated arable land transition probabilities. Land-use maps, as well as social-economic and geographical data were used in the study. The results indicated that arable land decreased significantly between 1993 and 2008. Lost arable land shifted into orchard, forestland, settlement, and transportation land. Significant differences existed for arable land transitions among different landform areas. Slope, elevation, population density, urbanization rate, distance to settlements, and distance to roadways were strong drivers influencing arable land transition to other uses. The MNL model was proved effective for predicting transition probabilities in land use from arable land to other land-use types, thus can be used for scenario analysis to develop land-use policies and land-management measures in this metropolitan area. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impacts of geographical locations and sociocultural traits on the Vietnamese entrepreneurship.

PubMed

Vuong, Quan Hoang

2016-01-01

This paper presents new results obtained from investigating the data from a 2015 Vietnamese entrepreneurs' survey, containing 3071 observations. Evidence from the estimations using multinomial logits was found to support relationships between several sociocultural factors and entrepreneurship-related performance or traits. Specifically, those relationships include: (a) Active participation in entrepreneurs' social networks and reported value of creativity; (b) CSR-willingness and reported entrepreneurs' perseverance; (c) Transforming of sociocultural values and entrepreneurs' decisiveness; and, (d) Lessons learned from others' failures and perceived chance of success. Using geographical locations as the control variate, evaluations of the baseline-category logits models indicate their varying effects on the outcomes when combined with the sociocultural factors that are found to be statistically significant. Empirical probabilities that give further detail about behavioral patterns are provided; and toward the end, the paper offers some conclusions with some striking insights and useful explanations on the Vietnamese entrepreneurship processes.

Median infectious dose (ID₅₀) of porcine reproductive and respiratory syndrome virus isolate MN-184 via aerosol exposure.

PubMed

Cutler, Timothy D; Wang, Chong; Hoff, Steven J; Kittawornrat, Apisit; Zimmerman, Jeffrey J

2011-08-05

The median infectious dose (ID(50)) of porcine reproductive and respiratory syndrome (PRRS) virus isolate MN-184 was determined for aerosol exposure. In 7 replicates, 3-week-old pigs (n=58) respired 10l of airborne PRRS virus from a dynamic aerosol toroid (DAT) maintained at -4°C. Thereafter, pigs were housed in isolation and monitored for evidence of infection. Infection occurred at virus concentrations too low to quantify by microinfectivity assays. Therefore, exposure dose was determined using two indirect methods ("calculated" and "theoretical"). "Calculated" virus dose was derived from the concentration of rhodamine B monitored over the exposure sequence. "Theoretical" virus dose was based on the continuous stirred-tank reactor model. The ID(50) estimate was modeled on the proportion of pigs that became infected using the probit and logit link functions for both "calculated" and "theoretical" exposure doses. Based on "calculated" doses, the probit and logit ID(50) estimates were 1 × 10(-0.13)TCID(50) and 1 × 10(-0.14)TCID(50), respectively. Based on "theoretical" doses, the probit and logit ID(50) were 1 × 10(0.26)TCID(50) and 1 × 10(0.24)TCID(50), respectively. For each point estimate, the 95% confidence interval included the other three point estimates. The results indicated that MN-184 was far more infectious than PRRS virus isolate VR-2332, the only other PRRS virus isolate for which ID(50) has been estimated for airborne exposure. Since aerosol ID(50) estimates are available for only these two isolates, it is uncertain whether one or both of these isolates represent the normal range of PRRS virus infectivity by this route. Copyright © 2011 Elsevier B.V. All rights reserved.

Forest amenities and location choice in the Southwest

Treesearch

Michael S. Hand; Jennifer A. Thacher; Daniel R. McCollum; Robert P. Berrens

2008-01-01

Locations with natural characteristics, such as forests, are thought to be attractive residential locations. This proposition is tested in the Southwest United States, composed of Arizona and New Mexico. This paper presents a conditional logit model of location choice estimated with household observations from the U.S. Census, geographic information system (GIS) data,...

Minimum Wages and Teenagers' Enrollment--Employment Outcomes: A Multinominal Logit Model.

ERIC Educational Resources Information Center

Ehrenberg, Ronald G.; Marcus, Alan J.

1982-01-01

This paper tests the hypothesis that the effect of minimum wage legislation on teenagers' education decisions is asymmetrical across family income classes, with the legislation inducing children from low-income families to reduce their levels of schooling and children from higher-income families to increase their educational attainment. (Author)

Does race matter in landowners' participation in conservation incentive programs?

Treesearch

Jianbang Gan; Okwuldili O. Onianwa; John Schelhas; Gerald C. Wheelock; Mark R. Dubois

2005-01-01

This study investigated and compared the participation behavior of white and minority small landowners in Alabama in eight conservation incentive programs. Using nonparametric tests and logit modeling, we found both similarities and differences in participation behavior between these two landowner groups. Both white and minority landowners tended not to participate in...

The Sex Difference in Depression across 29 Countries

ERIC Educational Resources Information Center

Hopcroft, Rosemary L.; Bradley, Dana Burr

2007-01-01

The sex difference in depression is well documented in westernized, developed societies, although there has been little quantitative cross-cultural research on the topic. In this study, we use multilevel logit models to examine sex differences in depression across 29 countries using data from the World Values Survey. We find that in no country are…

A panel multinomial logit analysis of elderly living arrangements: evidence from Aging In Manitoba longitudinal data, Canada.

PubMed

Sarma, Sisira; Simpson, Wayne

2007-12-01

Utilizing a unique longitudinal survey linked with home care use data, this paper analyzes the determinants of elderly living arrangements in Manitoba, Canada using a random effects multinomial logit model that accounts for unobserved individual heterogeneity. Because current home ownership is potentially endogenous in a living arrangements choice model, we use prior home ownership as an instrument. We also use prior home care use as an instrument for home care and use a random coefficient framework to account for unobserved health status. After controlling for relevant socio-demographic factors and accounting for unobserved individual heterogeneity, we find that home care and home ownership reduce the probability of living in a nursing home. Consistent with previous studies, we find that age is a strong predictor of nursing home entry. We also find that married people, those who have lived longer in the same community, and those who are healthy are more likely to live independently and less likely to be institutionalized or to cohabit with individuals other than their spouse.

How uncertain is the future of electric vehicle market: Results from Monte Carlo simulations using a nested logit model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Changzheng; Oak Ridge National Lab.; Lin, Zhenhong

Plug-in electric vehicles (PEVs) are widely regarded as an important component of the technology portfolio designed to accomplish policy goals in sustainability and energy security. However, the market acceptance of PEVs in the future remains largely uncertain from today's perspective. By integrating a consumer choice model based on nested multinomial logit and Monte Carlo simulation, this study analyzes the uncertainty of PEV market penetration using Monte Carlo simulation. Results suggest that the future market for PEVs is highly uncertain and there is a substantial risk of low penetration in the early and midterm market. Top factors contributing to market sharemore » variability are price sensitivities, energy cost, range limitation, and charging availability. The results also illustrate the potential effect of public policies in promoting PEVs through investment in battery technology and infrastructure deployment. Here, continued improvement of battery technologies and deployment of charging infrastructure alone do not necessarily reduce the spread of market share distributions, but may shift distributions toward right, i.e., increase the probability of having great market success.« less

A Multilevel Logit Estimation on the Determinants of Utilization of Preventive Health Care and Healthy Lifestyle Practice in China

PubMed Central

Fan, Lida; Liu, Jianye; Habibov, Nazim N

2015-01-01

The purpose of this study is to provide policy implications by estimating the individual and community level determinants of preventive health-care utilization in China based upon data from the China Health and Nutrition Survey. Two different frameworks, a human capital model and a psychological-behavioral model, are tested using a multilevel logit estimation. The results demonstrate different patterns for medical and nonmedical preventive activities. There is a strong correlation between having medical insurance and utilizing preventive health services. For the usage of medical-related preventive health care (MP), age, gender, education, urban residence, and medical insurance are strong predictors. High income did not provide much of an increase in the usage level of MP, but the lack of income was a huge obstacle for low-income people to overcome. Community variation in number of facilities accounted for about one third of the total variation in the utilization of MP. The utilization of MP in China remains dependent upon the individual's social-economic conditions. PMID:26688776

How uncertain is the future of electric vehicle market: Results from Monte Carlo simulations using a nested logit model

DOE PAGES

Liu, Changzheng; Oak Ridge National Lab.; Lin, Zhenhong; ...

2016-12-08

Plug-in electric vehicles (PEVs) are widely regarded as an important component of the technology portfolio designed to accomplish policy goals in sustainability and energy security. However, the market acceptance of PEVs in the future remains largely uncertain from today's perspective. By integrating a consumer choice model based on nested multinomial logit and Monte Carlo simulation, this study analyzes the uncertainty of PEV market penetration using Monte Carlo simulation. Results suggest that the future market for PEVs is highly uncertain and there is a substantial risk of low penetration in the early and midterm market. Top factors contributing to market sharemore » variability are price sensitivities, energy cost, range limitation, and charging availability. The results also illustrate the potential effect of public policies in promoting PEVs through investment in battery technology and infrastructure deployment. Here, continued improvement of battery technologies and deployment of charging infrastructure alone do not necessarily reduce the spread of market share distributions, but may shift distributions toward right, i.e., increase the probability of having great market success.« less

Gender, Alcohol Consumption Patterns, and Engagement in Sexually Intimate Behaviors Among Adolescents and Young Adults in Nha Trang, Viet Nam

PubMed Central

Kaljee, Linda M.; Green, Mackenzie S.; Zhan, Min; Riel, Rosemary; Lerdboon, Porntip; Lostutter, Ty W.; Tho, Le Huu; Van Luong, Vo; Minh, Truong Tan

2010-01-01

A randomly selected cross-sectional survey was conducted with 880 youth (16 to 24 years) in Nha Trang City to assess relationships between alcohol consumption and sexual behaviors. A timeline followback method was employed. Chi-square, generalized logit modeling and logistic regression analyses were performed. Of the sample, 78.2% male and 56.1% female respondents ever consumed alcohol. Males reporting sexual behaviors (vaginal, anal, oral sex) had a significantly higher calculated peak BAC of 0.151 compared to 0.082 for males reporting no sexual intimacy (p < .0001). Females reporting sexual behaviors had a peak BAC of 0.072 compared to 0.027 for those reporting no sexual intimacy (p = .016). Fifty percent of (33/66) males and 30.4% (7/23) females report event specific drinking and engagement in sexual behaviors. Males reporting 11+ drinks in 30 days had more sexual partners than those reporting 1 to 10 drinks (p = .037). Data suggest different physical and psychosocial mediators between alcohol consumption and sexual behaviors by gender. PMID:21373363

Statin initiation by GPs in WA--a structured vignette study.

PubMed

Stafford, Leanne; Harmer, Nichola; Dhaliwal, Satvinder; Jiwa, Moyez

2009-09-01

Statins are recommended for all patients with known coronary heart disease. This pilot study investigated statin initiation by a Western Australian general practitioner cohort and the influence of prescriber and patient characteristics on prescribing. A structured vignette questionnaire was posted to members of the Fremantle GP Network. Respondents indicated their prescribing decisions for nine hypothetical patients who had recently suffered a myocardial infarction. Data analysis utilised logistic regression analyses and a generalised linear model with a logit link function. Fifty-five GPs responded (16.0% response rate). In over 20% of cases a statin was not prescribed. Male (OR 4.71; 95% CI: 1.24-17.87) and GPs with fewer years in practice (4.50; 1.21-16.77) were more likely to prescribe appropriately. Younger patients (2.21; 1.38-3.53), and those with diabetes (1.74; 1.09-2.76) or hypercholesterolaemia (4.81; 2.88-8.03) were more likely to receive therapy. Prescribing practices failed to comply with current guidelines in a significant number of cases. Further research to confirm these findings is warranted.

Racial/Ethnic Disparities in Hypertension Prevalence: Reconsidering the Role of Chronic Stress

PubMed Central

Lee, Hedwig; Morenoff, Jeffrey; House, James S.; Williams, David R.

2014-01-01

Objectives. We investigated the association between anticipatory stress, also known as racism-related vigilance, and hypertension prevalence in Black, Hispanic, and White adults. Methods. We used data from the Chicago Community Adult Health Study, a population-representative sample of adults (n = 3105) surveyed in 2001 to 2003, to regress hypertension prevalence on the interaction between race/ethnicity and vigilance in logit models. Results. Blacks reported the highest vigilance levels. For Blacks, each unit increase in vigilance (range = 0–12) was associated with a 4% increase in the odds of hypertension (odds ratio [OR] = 1.04; 95% confidence interval [CI] = 1.00, 1.09). Hispanics showed a similar but nonsignificant association (OR = 1.05; 95% CI = 0.99, 1.12), and Whites showed no association (OR = 0.95; 95% CI = 0.87, 1.03). Conclusions. Vigilance may represent an important and unique source of chronic stress that contributes to the well-documented higher prevalence of hypertension among Blacks than Whites; it is a possible contributor to hypertension among Hispanics but not Whites. PMID:24228644

Gendered health inequalities in mental well-being? The Nordic countries in a comparative perspective.

PubMed

Olafsdottir, Sigrun

2017-03-01

The aims of this study were to: (a) compare gender differences in mental well-being in the Nordic countries with gender differences in 28 other countries around the world; and (b) evaluate whether gender differences in the Nordic countries remain when other social and lifestyle factors are taken into account. Data were obtained from 32 countries around the world that participated in the 2011 health module of the International Social Survey Programme. Ordered logit regression models were used to evaluate whether gender differences remained significant when other social and lifestyle factors were considered. Gender differences in mental well-being in the Nordic countries are not particularly small and the four countries do not cluster together. The gender differences remain when other social and lifestyle factors are taken into account. There appears to be a similar Nordic health paradox for mental well-being outcomes as for physical health outcomes. Although there may be multiple reasons for this, continued gender equality, including sex segregation in the labour market and gendered expectations, are considered to play a part.

Improved Estimates of the Benefits of Breastfeeding Using Sibling Comparisons to Reduce Selection Bias

PubMed Central

Evenhouse, Eirik; Reilly, Siobhan

2005-01-01

Objective Better measurement of the health and cognitive benefits of breastfeeding by using sibling comparisons to reduce sample selection bias. Data We use data on the breastfeeding history, physical and emotional health, academic performance, cognitive ability, and demographic characteristics of 16,903 adolescents from the first (1994) wave of the National Longitudinal Study of Adolescent Health. The sample includes 2,734 sibling pairs. Study Design We examine the relationship between breastfeeding history and 15 indicators of physical health, emotional health, and cognitive ability, using ordinary least squares and logit regression. For each indicator, we estimate, in addition to the usual between-family model, a within-family model to see whether differences in siblings' outcomes are associated with differences in the siblings' breastfeeding histories. Principal Findings Nearly all of the correlations found in the between-family model become statistically insignificant in the within-family model. The notable exception is a persistent positive correlation between breastfeeding and cognitive ability. These findings hold whether breastfeeding is measured in terms of duration or as a Yes/No variable. Conclusions This study provides persuasive evidence of a causal connection between breastfeeding and intelligence. However, it also suggests that nonexperimental studies of breastfeeding overstate some of its other long-term benefits, even if controls are included for race, ethnicity, income, and education. PMID:16336548

Forest resources, government policy, and investment location decisions of the forest products industry in the southern United States

Treesearch

Changyou Sun; Daowei Zhang

2010-01-01

In this article, the results of an initial attempt to estimate the effects of state attributes on plant location and investment expenditure were presented for the forest products industry in the southern United States. A conditional logit model was used to analyze new plant births, and a time-series cross-section model to assess the total capital expenditure....

Valuing air quality impacts using stated choice analysis: trading off visibility against morbidity effects.

PubMed

Rizzi, Luis Ignacio; Maza, Cristóbal De La; Cifuentes, Luis Abdón; Gómez, Jorge

2014-12-15

Direct valuation of air quality has as a drawback; that estimated willingness to pay figures cannot be apportioned to the several environmental goods affected by air quality, such as mortality and morbidity effects, visibility, outdoor recreation, among others. To address this issue, we implemented a survey in Santiago de Chile to identify component values of confounded environmental services by means of a choice experiment. We designed a survey where two environmental goods, a morbidity health endpoint and improved visibility, had to be jointly traded off against each other and against money in a unified framework. The health endpoint is a respiratory illness that results in an emergency room visit with a probability of hospitalization being required for appropriate treatment. Visibility is described as an aesthetic effect related to the number of days per year of high visibility. Modeling comprises both a logit model with covariates and a mixed-logit model. The results suggest that the health endpoint midpoint value is in a range from USD 2,800 to USD 13,000, mainly depending on the model and age stratum. The mid point value of an extra day of high visibility per year ranges from USD 281,000 to USD 379,000. Copyright © 2014 Elsevier Ltd. All rights reserved.

The MDI Method as a Generalization of Logit, Probit and Hendry Analyses in Marketing.

DTIC Science & Technology

1980-04-01

model involves nothing more than fitting a normal distribution function ( Hanushek and Jackson (1977)). For a given value of x, the probit model...preference shifts within the soft drink category. --For applications of probit models relevant for marketing, see Hausman and Wise (1978) and Hanushek and...Marketing Research" JMR XIV, Feb. (1977). Hanushek , E.A., and J.E. Jackson, Statistical Methods for Social Scientists. Academic Press, New York (1977

Determinants of Health Insurance Coverage among People Aged 45 and over in China: Who Buys Public, Private and Multiple Insurance

PubMed Central

Jin, Yinzi; Hou, Zhiyuan; Zhang, Donglan

2016-01-01

Background China is reforming and restructuring its health insurance system to achieve the goal of universal coverage. This study aims to understand the determinants of public, private and multiple insurance coverage among people of retirement-age in China. Methods We used data from the China Health and Retirement Longitudinal Survey 2011 and 2013, a nationally representative survey of Chinese people aged 45 and over. Multinomial logit regression was performed to identify the determinants of public, private and multiple health insurance coverage. We also conducted logit regression to examine the association between public insurance coverage and demand for private insurance. Results In 2013, 94.5% of this population had at least one type of public insurance, and 12.2% purchased private insurance. In general, we found that rural residents were less likely to be uninsured (Relative Risk Ratio (RRR) = 0.40, 95% Confidence Interval (CI): 0.34–0.47) and were less likely to buy private insurance (RRR = 0.22, 95% CI: 0.16–0.31). But rural-to-urban migrants were more likely to be uninsured (RRR = 1.39, 95% CI: 1.24–1.57). Public health insurance coverage may crowd out private insurance market (Odds Ratio = 0.55, 95% CI: 0.48–0.63), particularly among enrollees of Urban Resident Basic Medical Insurance. There exists a huge socioeconomic disparity in both public and private insurance coverage. Conclusion The migrants, the poor and the vulnerable remained in the edge of the system. The growing private insurance market did not provide sufficient financial protection and did not cover the people with the greatest need. To achieve universal coverage and reduce socioeconomic disparity, China should integrate the urban and rural public insurance schemes across regions and remove the barriers for the middle-income and low-income to access private insurance. PMID:27564320

Are regional variations in activity of dispatcher-assisted cardiopulmonary resuscitation associated with out-of-hospital cardiac arrests outcomes? A nation-wide population-based cohort study.

PubMed

Nishi, Taiki; Kamikura, Takahisa; Funada, Akira; Myojo, Yasuhiro; Ishida, Tetsuya; Inaba, Hideo

2016-01-01

Dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) impacts the rates of bystander CPR (BCPR) and survival after out-of-hospital cardiac arrests (OHCAs). This study aimed to elucidate whether regional variations in indexes for BCPR and emergency medical service (EMS) may be associated with OHCA outcomes. We conducted a population-based observational study involving 157,093 bystander-witnessed, resuscitation-attempted OHCAs without physician involvement between 2007 and 2011. For each index of BCPR and EMS, we classified the 47 prefectures into the following three groups: advanced, intermediate, and developing regions. Nominal logit analysis followed by multivariable logistic regression including OHCA backgrounds was employed to examine the association between neurologically favourable 1-month survival, and regional classifications based on BCPR- and EMS-related indexes. Logit analysis including all regional classifications revealed that the number of BLS training course participants per population or bystander's own performance of BCPR without DA-CPR was not associated with the survival. Multivariable logistic regression including the OHCA backgrounds known to be associated with survival (BCPR provision, arrest aetiology, initial rhythm, patient age, time intervals of witness-to-call and call-to-arrival at patient), the following regional classifications based on DA-CPR but not on EMS were associated with survival: sensitivity of DA-CPR [adjusted odds ratio (95% confidence intervals) for advanced region; those for intermediate region, with developing region as reference, 1.277 (1.131-1.441); 1.162 (1.058-1.277)]; the proportion of bystanders to follow DA-CPR [1.749 (1.554-1.967); 1.280 (1.188-1.380)]. Good outcomes of bystander-witnessed OHCAs correlate with regions having higher sensitivity of DA-CPR and larger proportion of bystanders to follow DA-CPR. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Identifying Measurement Disturbance Effects Using Rasch Item Fit Statistics and the Logit Residual Index.

ERIC Educational Resources Information Center

Mount, Robert E.; Schumacker, Randall E.

1998-01-01

A Monte Carlo study was conducted using simulated dichotomous data to determine the effects of guessing on Rasch item fit statistics and the Logit Residual Index. Results indicate that no significant differences were found between the mean Rasch item fit statistics for each distribution type as the probability of guessing the correct answer…

Applying additive logistic regression to data derived from sensors monitoring behavioral and physiological characteristics of dairy cows to detect lameness.

PubMed

Kamphuis, C; Frank, E; Burke, J K; Verkerk, G A; Jago, J G

2013-01-01

The hypothesis was that sensors currently available on farm that monitor behavioral and physiological characteristics have potential for the detection of lameness in dairy cows. This was tested by applying additive logistic regression to variables derived from sensor data. Data were collected between November 2010 and June 2012 on 5 commercial pasture-based dairy farms. Sensor data from weigh scales (liveweight), pedometers (activity), and milk meters (milking order, unadjusted and adjusted milk yield in the first 2 min of milking, total milk yield, and milking duration) were collected at every milking from 4,904 cows. Lameness events were recorded by farmers who were trained in detecting lameness before the study commenced. A total of 318 lameness events affecting 292 cows were available for statistical analyses. For each lameness event, the lame cow's sensor data for a time period of 14 d before observation date were randomly matched by farm and date to 10 healthy cows (i.e., cows that were not lame and had no other health event recorded for the matched time period). Sensor data relating to the 14-d time periods were used for developing univariable (using one source of sensor data) and multivariable (using multiple sources of sensor data) models. Model development involved the use of additive logistic regression by applying the LogitBoost algorithm with a regression tree as base learner. The model's output was a probability estimate for lameness, given the sensor data collected during the 14-d time period. Models were validated using leave-one-farm-out cross-validation and, as a result of this validation, each cow in the data set (318 lame and 3,180 nonlame cows) received a probability estimate for lameness. Based on the area under the curve (AUC), results indicated that univariable models had low predictive potential, with the highest AUC values found for liveweight (AUC=0.66), activity (AUC=0.60), and milking order (AUC=0.65). Combining these 3 sensors improved AUC to 0.74. Detection performance of this combined model varied between farms but it consistently and significantly outperformed univariable models across farms at a fixed specificity of 80%. Still, detection performance was not high enough to be implemented in practice on large, pasture-based dairy farms. Future research may improve performance by developing variables based on sensor data of liveweight, activity, and milking order, but that better describe changes in sensor data patterns when cows go lame. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Analysis of crash proportion by vehicle type at traffic analysis zone level: A mixed fractional split multinomial logit modeling approach with spatial effects.

PubMed

Lee, Jaeyoung; Yasmin, Shamsunnahar; Eluru, Naveen; Abdel-Aty, Mohamed; Cai, Qing

2018-02-01

In traffic safety literature, crash frequency variables are analyzed using univariate count models or multivariate count models. In this study, we propose an alternative approach to modeling multiple crash frequency dependent variables. Instead of modeling the frequency of crashes we propose to analyze the proportion of crashes by vehicle type. A flexible mixed multinomial logit fractional split model is employed for analyzing the proportions of crashes by vehicle type at the macro-level. In this model, the proportion allocated to an alternative is probabilistically determined based on the alternative propensity as well as the propensity of all other alternatives. Thus, exogenous variables directly affect all alternatives. The approach is well suited to accommodate for large number of alternatives without a sizable increase in computational burden. The model was estimated using crash data at Traffic Analysis Zone (TAZ) level from Florida. The modeling results clearly illustrate the applicability of the proposed framework for crash proportion analysis. Further, the Excess Predicted Proportion (EPP)-a screening performance measure analogous to Highway Safety Manual (HSM), Excess Predicted Average Crash Frequency is proposed for hot zone identification. Using EPP, a statewide screening exercise by the various vehicle types considered in our analysis was undertaken. The screening results revealed that the spatial pattern of hot zones is substantially different across the various vehicle types considered. Copyright © 2017 Elsevier Ltd. All rights reserved.

Random preferences towards bioenergy environmental externalities: a case study of woody biomass based electricity in the Southern United States

Treesearch

Andres Susaeta; Pankaj Lal; Janaki Alavalapati; Evan Mercer

2011-01-01

This paper contrasts alternate methodological approaches of investigating public preferences, the random parameter logit (RPL) where tastes and preferences of respondents are assumed to be heterogeneous and the conditional logit (CL) approach where tastes and preferences remain fixed for individuals. We conducted a choice experiment to assess preferences for woody...

Exploring Factors Related to Young Children's Word-Meaning Derivations during Read-Alouds

ERIC Educational Resources Information Center

Christ, Tanya; Wang, X. Christine; Chiu, Ming Ming

2017-01-01

This study explores how child and text clues were related to 31 kindergarteners' word-meaning derivation outcomes for 372 words presented in books read aloud to children. Data were analyzed using a multilevel, cross-classification, ordered logit model. Children showed no word-meaning derivation 40% of the time, indicating a need for instruction.…

Using Multidimensional Rasch Analysis to Validate the Chinese Version of the Motivated Strategies for Learning Questionnaire (MSLQ-CV)

ERIC Educational Resources Information Center

Lee, John Chi-Kin; Zhang, Zhonghua; Yin, Hongbiao

2010-01-01

This article used the multidimensional random coefficients multinomial logit model to examine the construct validity and detect the substantial differential item functioning (DIF) of the Chinese version of motivated strategies for learning questionnaire (MSLQ-CV). A total of 1,354 Hong Kong junior high school students were administered the…

Does Education Affect Happiness? Evidence for Spain

ERIC Educational Resources Information Center

Cunado, Juncal; de Gracia, Fernando Perez

2012-01-01

In this paper we study the impact of education on happiness in Spain using individual-level data from the European Social Survey, by means of estimating Ordinal Logit Models. We find both direct and indirect effects of education on happiness. First, we find an indirect effect of education on happiness through income and labour status. That is, we…

Building social capital in forest communities: Analysis of New Mexico's Collaborative Forest Restoration Program

Treesearch

Tyler Prante; Jennifer A. Thacher; Daniel W. McCollum; Robert P. Berrens

2007-01-01

In part because of its emphasis on building social capital, the Collaborative Forest Restoration Program (CFRP) in New Mexico represents a unique experiment in public lands management. This study uses logit probability modeling to investigate what factors determined CFRP funding, which totaled $26 million between 2001 and 2006. Results reveal program preferences for...

Estimating a family forest landowner's likelihood of posting against trespass

Treesearch

Stephanie A. Snyder; Michael A. Kilgore; Steven J. Taff; Joseph M. Schertz

2008-01-01

Hunters and other recreators face challenges to gain access to private forestland in the United States because of an increasing number of landowners posting their land. A landowners' decision to post their land is influenced by a variety of factors, including landowner characteristics, hunter behavior, and parcel attributes. We used a logit model to help...

A Multinomial Logit Approach to Estimating Regional Inventories by Product Class

Treesearch

Lawrence Teeter; Xiaoping Zhou

1998-01-01

Current timber inventory projections generally lack information on inventory by product classes. Most models available for inventory projection and linked to supply analyses are limited to projecting aggregate softwood and hardwood. The objective of this research is to develop a methodology to distribute the volume on each FIA survey plot to product classes and...

Adoption of Agri-Environmental Measures by Organic Farmers: The Role of Interpersonal Communication

ERIC Educational Resources Information Center

Unay Gailhard, Ilkay; Bavorová, Miroslava; Pirscher, Frauke

2015-01-01

Purpose: The purpose of this study is to investigate the impact of interpersonal communication on the adoption of agri-environmental measures (AEM) by organic farmers in Germany. Methodology: The study used the logit model to predict the probability of adoption behaviour, and Social Network Analysis (SNA) was conducted to analyse the question of…

Statistical Models for the Analysis of Zero-Inflated Pain Intensity Numeric Rating Scale Data.

PubMed

Goulet, Joseph L; Buta, Eugenia; Bathulapalli, Harini; Gueorguieva, Ralitza; Brandt, Cynthia A

2017-03-01

Pain intensity is often measured in clinical and research settings using the 0 to 10 numeric rating scale (NRS). NRS scores are recorded as discrete values, and in some samples they may display a high proportion of zeroes and a right-skewed distribution. Despite this, statistical methods for normally distributed data are frequently used in the analysis of NRS data. We present results from an observational cross-sectional study examining the association of NRS scores with patient characteristics using data collected from a large cohort of 18,935 veterans in Department of Veterans Affairs care diagnosed with a potentially painful musculoskeletal disorder. The mean (variance) NRS pain was 3.0 (7.5), and 34% of patients reported no pain (NRS = 0). We compared the following statistical models for analyzing NRS scores: linear regression, generalized linear models (Poisson and negative binomial), zero-inflated and hurdle models for data with an excess of zeroes, and a cumulative logit model for ordinal data. We examined model fit, interpretability of results, and whether conclusions about the predictor effects changed across models. In this study, models that accommodate zero inflation provided a better fit than the other models. These models should be considered for the analysis of NRS data with a large proportion of zeroes. We examined and analyzed pain data from a large cohort of veterans with musculoskeletal disorders. We found that many reported no current pain on the NRS on the diagnosis date. We present several alternative statistical methods for the analysis of pain intensity data with a large proportion of zeroes. Published by Elsevier Inc.

Predictors of functional vision changes after cataract surgery: the PROVISION study.

PubMed

Chaudhary, Varun; Popovic, Marko; Holmes, Julie; Robinson, Tammy; Mak, Michael; Mohaghegh P, S Mohammad; Eino, Dalia; Mann, Keith; Kobetz, Lawrence; Gusenbauer, Kaela; Barbosa, Joshua

2016-08-01

To ascertain whether time-to-treatment, sex, age, preoperative functional vision scores, education, and ocular comorbidities predict change in functional vision pre- to postoperatively in patients receiving cataract surgery. Prospective cohort study. Three hundred and forty-three cataract patients at the Hamilton Regional Eye Institute. Participants 18 years or older scheduled to undergo cataract surgery completed the Catquest-9SF functional vision questionnaire on the day of their surgery and were mailed a survey 2-3 months postoperatively. Multivariate linear regression was used to determine the ability of predictors to explain variability in functional vision change between questionnaire administrations. One hundred and sixty-six patients completed both baseline and follow-up questionnaires. Mean age of the cohort was 73.8 ± 8.1 years. Most patients were female (59.6%), had cataract surgery performed for the first time (66.9%), and had spent a mean time of 20.3 ± 20.7 weeks waiting for surgery. Functional vision improved in 83.7% of patients. The mean baseline Catquest-9SF score was the only significant predictor of functional vision improvement (adjusted R(2) = 0.47; F1,159 = 144.6; p < 0.001). Controlling for other variables, functional vision improved by 0.74 logits when mean baseline survey score increased by 1 logit. In most patients, functional vision improved after cataract surgery. Mean baseline Catquest-9SF score was a moderate predictor of the observed improvement. Copyright © 2016 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Real-time Mainshock Forecast by Statistical Discrimination of Foreshock Clusters

NASA Astrophysics Data System (ADS)

Nomura, S.; Ogata, Y.

2016-12-01

Foreshock discremination is one of the most effective ways for short-time forecast of large main shocks. Though many large earthquakes accompany their foreshocks, discreminating them from enormous small earthquakes is difficult and only probabilistic evaluation from their spatio-temporal features and magnitude evolution may be available. Logistic regression is the statistical learning method best suited to such binary pattern recognition problems where estimates of a-posteriori probability of class membership are required. Statistical learning methods can keep learning discreminating features from updating catalog and give probabilistic recognition of forecast in real time. We estimated a non-linear function of foreshock proportion by smooth spline bases and evaluate the possibility of foreshocks by the logit function. In this study, we classified foreshocks from earthquake catalog by the Japan Meteorological Agency by single-link clustering methods and learned spatial and temporal features of foreshocks by the probability density ratio estimation. We use the epicentral locations, time spans and difference in magnitudes for learning and forecasting. Magnitudes of main shocks are also predicted our method by incorporating b-values into our method. We discuss the spatial pattern of foreshocks from the classifier composed by our model. We also implement a back test to validate predictive performance of the model by this catalog.

Determinants of Anemia and Hemoglobin Concentration in Haitian School-Aged Children

PubMed Central

Iannotti, Lora L.; Delnatus, Jacques R.; Odom, Audrey R.; Eaton, Jacob C.; Griggs, Jennifer J.; Brown, Sarah; Wolff, Patricia B.

2015-01-01

Anemia diminishes oxygen transport in the body, resulting in potentially irreversible growth and developmental consequences for children. Limited evidence for determinants of anemia exists for school-aged children. We conducted a cluster randomized controlled trial in Haiti from 2012 to 2013 to test the efficacy of a fortified school snack. Children (N = 1,047) aged 3–13 years were followed longitudinally at three time points for hemoglobin (Hb) concentrations, anthropometry, and bioelectrical impedance measures. Dietary intakes, infectious disease morbidities, and socioeconomic and demographic factors were collected at baseline and endline. Longitudinal regression modeling with generalized least squares and logit models with random effects identified anemia risk factors beyond the intervention effect. At baseline, 70.6% of children were anemic and 2.6% were severely anemic. Stunting increased the odds of developing anemia (adjusted odds ratio [OR]: 1.48, 95% confidence interval [CI]: 1.05–2.08) and severe anemia (adjusted OR: 2.47, 95% CI: 1.30–4.71). Parent-reported vitamin A supplementation and deworming were positively associated with Hb concentrations, whereas fever and poultry ownership showed a negative relationship with Hb concentration and increased odds of severe anemia, respectively. Further research should explore the full spectrum of anemia etiologies in school children, including genetic causes. PMID:26350448

Is religion the forgotten variable in maternal and child health? Evidence from Zimbabwe.

PubMed

Ha, Wei; Salama, Peter; Gwavuya, Stanley; Kanjala, Chifundo

2014-10-01

The Apostolic faith, a rapidly growing and increasingly influential force in Zimbabwe, has received attention in the literature due to its potential role in shaping its followers' attitudes and behaviours towards health. Existing literature, however, has only examined small cross-section samples from a few confined survey sites or has failed to adequately control for the many factors that may mediate the effects of religion. This paper examines the effects of the Apostolic faith on the usage of maternal health and child immunization services in Zimbabwe. It is based on a nationally representative sample from the 2009 Multi-Indicator Monitoring Survey and employs the established Andersen model on access to health services. Well controlled multivariate logit regression models derived from these data show that an affiliation with the Apostolic faith is a substantial and significant risk factor in reducing the utilization of both maternal and child health services. Moreover, even when the services were least costly and readily available and when gaps along other social and economic factors were limited, as in the case of Bacillus Calmette-Guérin vaccination and one visit to antenatal care, women and children from Apostolic faith families still fared significantly worse than others in accessing them. Copyright © 2014 Elsevier Ltd. All rights reserved.

Prioritizing school intramural and interscholastic programs based on observed physical activity.

PubMed

Bocarro, Jason N; Kanters, Michael A; Edwards, Michael B; Casper, Jonathan M; McKenzie, Thomas L

2014-01-01

To examine which school sports engage children in more physical activity. Observational, cross-sectional study examining differences between intramural (IM) and interscholastic (IS) sports. Athletic facilities at two schools with IM sports and two schools with IS sports in Wake County, North Carolina. Middle-school children (N = 6735). Percentage of children observed in sedentary, moderate, and vigorous activity assessed by the System for Observation Play and Leisure Among Youth (SOPLAY). Energy expenditure and physical activity intensity were also estimated by using MET values. T-tests; generalized linear model using cumulative logit link function. IM sports had higher MET values than IS sports (t = -3.69, p < .001), and IM sports ranked in four of the top five sports in terms of average MET values. Regression models found a significant interaction between school sport delivery model and gender, with boys significantly less physically active in IS programs than boys in IM programs (B = -.447, p < .001) but more physically active (B = .359, p <.001) than girls in IM sports. Regardless of sport type, IM sports generated more physical activity than IS sports among boys but not girls. Soccer, basketball, and track, regardless of school delivery approach, provide the highest physical activity levels. Results suggest that school administrators consider reassessing their programs to more efficiently use diminishing resources to increase students' physical activity levels.

Decision-theoretic approach to data acquisition for transit operations planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ritchie, S.G.

The most costly element of transportation planning and modeling activities in the past has usually been that of data acquisition. This is even truer today when the unit costs of data collection are increasing rapidly and at the same time budgets are severely limited by continuing policies of fiscal austerity in the public sector. The overall objectives of this research were to improve the decisions and decision-making capabilities of transit operators or planners in short-range transit planning, and to improve the quality and cost-effectiveness of associated route or corridor-level data collection and service monitoring activities. A new approach was presentedmore » for sequentially updating the parameters of both simple and multiple linear regression models with stochastic regressors, and for determining the expected value of sample information and expected net gain of sampling for associated sample designs. A new approach was also presented for estimating and updating (both spatially and temporally) the parameters of multinomial logit discrete choice models, and for determining associated optimal sample designs for attribute-based and choice-based sampling methods. The approach provides an effective framework for addressing the issue of optimal sampling method and sample size, which to date have been largely unresolved. The application of these methodologies and the feasibility of the decision-theoretic approach was illustrated with a hypothetical case study example.« less

Why Did People Move During the Great Recession?: The Role of Economics in Migration Decisions

PubMed Central

Levy, Brian L.; Mouw, Ted; Daniel Perez, Anthony

2017-01-01

Labor migration offers an important mechanism to reallocate workers when there are regional differences in employment conditions. Whereas conventional wisdom suggests migration rates should increase during recessions as workers move out of areas that are hit hardest, initial evidence suggested that overall migration rates declined during the Great Recession, despite large regional differences in unemployment and growth rates. In this paper, we use data from the American Community Survey to analyze internal migration trends before and during the economic downturn. First, we find only a modest decline in the odds of adults leaving distressed labor market areas during the recession, which may result in part from challenges related to the housing price crash. Second, we estimate conditional logit models of destination choice for individuals who migrate across labor market areas and find a substantial effect of economic factors such as labor demand, unemployment, and housing values. We also estimate latent class conditional logit models that test whether there is heterogeneity in preferences for destination characteristics among migrants. Over all, the latent class models suggest that roughly equal percentages of migrants were motivated by economic factors before and during the recession. We conclude that fears of dramatic declines in labor migration seem to be unsubstantiated. PMID:28547003

Why Did People Move During the Great Recession?: The Role of Economics in Migration Decisions.

PubMed

Levy, Brian L; Mouw, Ted; Daniel Perez, Anthony

2017-04-01

Labor migration offers an important mechanism to reallocate workers when there are regional differences in employment conditions. Whereas conventional wisdom suggests migration rates should increase during recessions as workers move out of areas that are hit hardest, initial evidence suggested that overall migration rates declined during the Great Recession, despite large regional differences in unemployment and growth rates. In this paper, we use data from the American Community Survey to analyze internal migration trends before and during the economic downturn. First, we find only a modest decline in the odds of adults leaving distressed labor market areas during the recession, which may result in part from challenges related to the housing price crash. Second, we estimate conditional logit models of destination choice for individuals who migrate across labor market areas and find a substantial effect of economic factors such as labor demand, unemployment, and housing values. We also estimate latent class conditional logit models that test whether there is heterogeneity in preferences for destination characteristics among migrants. Over all, the latent class models suggest that roughly equal percentages of migrants were motivated by economic factors before and during the recession. We conclude that fears of dramatic declines in labor migration seem to be unsubstantiated.

Age and pedestrian injury severity in motor-vehicle crashes: a heteroskedastic logit analysis.

PubMed

Kim, Joon-Ki; Ulfarsson, Gudmundur F; Shankar, Venkataraman N; Kim, Sungyop

2008-09-01

This research explores the injury severity of pedestrians in motor-vehicle crashes. It is hypothesized that the variance of unobserved pedestrian characteristics increases with age. In response, a heteroskedastic generalized extreme value model is used. The analysis links explanatory factors with four injury outcomes: fatal, incapacitating, non-incapacitating, and possible or no injury. Police-reported crash data between 1997 and 2000 from North Carolina, USA, are used. The results show that pedestrian age induces heteroskedasticity which affects the probability of fatal injury. The effect grows more pronounced with increasing age past 65. The heteroskedastic model provides a better fit than the multinomial logit model. Notable factors increasing the probability of fatal pedestrian injury: increasing pedestrian age, male driver, intoxicated driver (2.7 times greater probability of fatality), traffic sign, commercial area, darkness with or without streetlights (2-4 times greater probability of fatality), sport-utility vehicle, truck, freeway, two-way divided roadway, speeding-involved, off roadway, motorist turning or backing, both driver and pedestrian at fault, and pedestrian only at fault. Conversely, the probability of a fatal injury decreased: with increasing driver age, during the PM traffic peak, with traffic signal control, in inclement weather, on a curved roadway, at a crosswalk, and when walking along roadway.

Airline Choice for Domestic Flights in Sao Paulo Metropolitan Area: An Application of the Conditional Logit Model

NASA Technical Reports Server (NTRS)

Moreno, Marcelo Baena

2006-01-01

Using the conditional (multinomial) LOGIT model, this paper addresses airline choice in the S o Paulo Metropolitan Area. There are two airports in this region, where two, three or even four airlines compete for passengers flying to an array of domestic destinations. The airline choice is believed to be a result of the tradeoff passengers face among flight cost, flight frequency and airline performance. It was found that the lowest fare better explains airline choice than the highest fare, whereas direct flight frequencies give better explanation to airline choice than indirect (connections and stops) and total (direct plus indirect) ones. Out of 15 variables tested, the lowest fare was the variable that best explained airline choice. However, its signal was counterintuitive (positive) possibly because the cheapest airline was offering few flights, so passengers overwhelmingly failed to choose the cheapest airline. The model specification most adjusted to the data considered the lowest fare, direct flight frequency in the travel day and period (morning or afternoon peak) and airline age. Passengers departing from S o Paulo-Guarulhos International Airport (GRU) airport make their airline choice in terms of cost whereas those from Sao Paulo-Congonhas Airport (CGH) airport do not. Finally, senior passengers place more importance on airline age than junior passengers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooker, A.; Gonder, J.; Lopp, S.

The Automotive Deployment Option Projection Tool (ADOPT) is a light-duty vehicle consumer choice and stock model supported by the U.S. Department of Energy’s Vehicle Technologies Office. It estimates technology improvement impacts on U.S. light-duty vehicles sales, petroleum use, and greenhouse gas emissions. ADOPT uses techniques from the multinomial logit method and the mixed logit method estimate sales. Specifically, it estimates sales based on the weighted value of key attributes including vehicle price, fuel cost, acceleration, range and usable volume. The average importance of several attributes changes nonlinearly across its range and changes with income. For several attributes, a distribution ofmore » importance around the average value is used to represent consumer heterogeneity. The majority of existing vehicle makes, models, and trims are included to fully represent the market. The Corporate Average Fuel Economy regulations are enforced. The sales feed into the ADOPT stock model. It captures key aspects for summing petroleum use and greenhouse gas emissions This includes capturing the change in vehicle miles traveled by vehicle age, the creation of new model options based on the success of existing vehicles, new vehicle option introduction rate limits, and survival rates by vehicle age. ADOPT has been extensively validated with historical sales data. It matches in key dimensions including sales by fuel economy, acceleration, price, vehicle size class, and powertrain across multiple years. A graphical user interface provides easy and efficient use. It manages the inputs, simulation, and results.« less

Economic Analysis of Job-Related Attributes in Undergraduate Students' Initial Job Selection

ERIC Educational Resources Information Center

Jin, Yanhong H.; Mjelde, James W.; Litzenberg, Kerry K.

2014-01-01

Economic tradeoffs students place on location, salary, distances to natural resource amenities, size of the city where the job is located, and commuting times for their first college graduate job are estimated using a mixed logit model for a sample of Texas A&M University students. The Midwest is the least preferred area having a mean salary…

Elasticity of Demand for Tuition Fees at an Institution of Higher Education

ERIC Educational Resources Information Center

Langelett, George; Chang, Kuo-Liang; Ola' Akinfenwa, Samson; Jorgensen, Nicholas; Bhattarai, Kopila

2015-01-01

Using a conjoint survey of 161 students at South Dakota State University (SDSU), we mapped a probability-of-enrolment curve for SDSU students, consistent with demand theory. A quasi-demand curve was created from the conditional-logit model. This study shows that along with the price of tuition fees, distance from home, availability of majors, and…

Ethnic and Gender Differences in Science Graduation at Selective Colleges with Implications for Admission Policy and College Choice

ERIC Educational Resources Information Center

Smyth, Frederick L.; McArdle, John J.

2004-01-01

Using Bowen and Bok's data from 23 selective colleges, we fit multilevel logit models to test two hypotheses with implications for affirmative action and group differences in attainment of science, math, or engineering (SME) degrees. Hypothesis 1, that differences in precollege academic preparation will explain later SME graduation disparities,…

Exploring the Effects of Financial Aid on the Gap in Student Dropout Risks by Income Level

ERIC Educational Resources Information Center

Chen, Rong; DesJardins, Stephen L.

2008-01-01

Using national survey data and discrete-time logit modeling, this research seeks to understand whether student aid mediates the relationship between parental income and student dropout behavior. Our analysis confirms that there is a gap in dropout rates for low-income students compared with their upper income peers, and suggests that some types of…

How School Choice Is Framed by Parental Preferences and Family Characteristics: A Study of Western Area, Sierra Leone

ERIC Educational Resources Information Center

Dixon, Pauline; Humble, Steve

2017-01-01

This research set out to investigate how, in a post-conflict area, parental preferences and household characteristics affect school choice for their children. A multinomial logit is used to model the relationship between education preferences and the selection of schools for 954 households in Freetown and neighboring districts, Western Area,…

Cyclists' red-light running behaviours: an examination of risk-taking, opportunistic, and law-obeying behaviours.

PubMed

Pai, Chih-Wei; Jou, Rong-Chang

2014-01-01

Literature has suggested that bicyclists' red-light violations (RLVs) tend not to cause accidents although RLV is a frequent and typical bicyclist's behaviour. High association between bicyclist RLVs and accidents were, however, revealed in Taiwan. The current research explores bicyclists' RLVs by classifying crossing behaviours into three distinct manners: risk-taking, opportunistic, and law-obeying. Other variables, as well as bicyclists' crossing behaviours, were captured through the use of video cameras that were installed at selected intersections in Taoyuan County, Taiwan. Considering the unobserved heterogeneity, this research develops a mixed logit model of bicyclists' three distinct crossing behaviours. Several variables (pupils in uniform, speed limit with 60km/h) appear to have heterogeneous effects, lending support to the use of mixed logit models in bicyclist RLV research. Several factors were found to significantly increase the likelihood of bicyclists' risky behaviours, most notably: intersections with short red-light duration, T/Y intersections, when riders were pupils in uniform, when riders were riding electric bicycles, when riders were unhelmeted. Implications of the research findings, and the concluding remarks, are finally provided. Copyright © 2013 Elsevier Ltd. All rights reserved.

Diversity-induced resonance in the response to social norms

NASA Astrophysics Data System (ADS)

Tessone, Claudio J.; Sánchez, Angel; Schweitzer, Frank

2013-02-01

In this paper we focus on diversity-induced resonance, which was recently found in bistable, excitable, and other physical systems. We study the appearance of this phenomenon in a purely economic model of cooperating and defecting agents. An agent's contribution to a public good is seen as a social norm, so defecting agents face a social pressure, which decreases if free riding becomes widespread. In this model, diversity among agents naturally appears because of the different sensitivities towards the social norm. We study the evolution of cooperation as a response to the social norm (i) for the replicator dynamics and (ii) for the logit dynamics by means of numerical simulations. Diversity-induced resonance is observed as a maximum in the response of agents to changes in the social norm as a function of the degree of heterogeneity in the population. We provide an analytical, mean-field approach for the logit dynamics and find very good agreement with the simulations. From a socioeconomic perspective, our results show that, counterintuitively, diversity in the individual sensitivity to social norms may result in a society that better follows such norms as a whole, even if part of the population is less prone to follow them.

Community forestry as perceived by local people around Cross River National Park, Nigeria.

PubMed

Ezebilo, Eugene E

2012-01-01

The prior identification of local people's preferences for conservation-development projects will help gear nature-conservation strategies toward the needs of different groups of local people. This will help policy-makers in designing a more acceptable and effective conservation strategy. This article reports a study of local perceptions of a community forestry project that aims to help improve the design as well as local acceptance of the project. The data originated from personal interviews conducted in communities around Okwangwo Division of the Cross River National Park in southeast Nigeria and were analysed using ordered logit and binary logit models. The results showed that >50% of the respondents were satisfied with the community forestry project. The respondents' perceptions were mainly influenced by education, age, gender, and willingness to contribute money to tourism as well as the contributions of cocoa, banana, and afang (Gnetum africanum) to the respondents' income. The results from this study have important implications for nature conservation in Nigeria and potentially other conservation contexts across the developing world.

Community Forestry as Perceived by Local People Around Cross River National Park, Nigeria

NASA Astrophysics Data System (ADS)

Ezebilo, Eugene E.

2012-01-01

The prior identification of local people's preferences for conservation-development projects will help gear nature-conservation strategies toward the needs of different groups of local people. This will help policy-makers in designing a more acceptable and effective conservation strategy. This article reports a study of local perceptions of a community forestry project that aims to help improve the design as well as local acceptance of the project. The data originated from personal interviews conducted in communities around Okwangwo Division of the Cross River National Park in southeast Nigeria and were analysed using ordered logit and binary logit models. The results showed that >50% of the respondents were satisfied with the community forestry project. The respondents' perceptions were mainly influenced by education, age, gender, and willingness to contribute money to tourism as well as the contributions of cocoa, banana, and afang ( Gnetum africanum) to the respondents' income. The results from this study have important implications for nature conservation in Nigeria and potentially other conservation contexts across the developing world.

Comparing performances of logistic regression and neural networks for predicting melatonin excretion patterns in the rat exposed to ELF magnetic fields.

PubMed

Jahandideh, Samad; Abdolmaleki, Parviz; Movahedi, Mohammad Mehdi

2010-02-01

Various studies have been reported on the bioeffects of magnetic field exposure; however, no consensus or guideline is available for experimental designs relating to exposure conditions as yet. In this study, logistic regression (LR) and artificial neural networks (ANNs) were used in order to analyze and predict the melatonin excretion patterns in the rat exposed to extremely low frequency magnetic fields (ELF-MF). Subsequently, on a database containing 33 experiments, performances of LR and ANNs were compared through resubstitution and jackknife tests. Predictor variables were more effective parameters and included frequency, polarization, exposure duration, and strength of magnetic fields. Also, five performance measures including accuracy, sensitivity, specificity, Matthew's Correlation Coefficient (MCC) and normalized percentage, better than random (S) were used to evaluate the performance of models. The LR as a conventional model obtained poor prediction performance. Nonetheless, LR distinguished the duration of magnetic fields as a statistically significant parameter. Also, horizontal polarization of magnetic fields with the highest logit coefficient (or parameter estimate) with negative sign was found to be the strongest indicator for experimental designs relating to exposure conditions. This means that each experiment with horizontal polarization of magnetic fields has a higher probability to result in "not changed melatonin level" pattern. On the other hand, ANNs, a more powerful model which has not been introduced in predicting melatonin excretion patterns in the rat exposed to ELF-MF, showed high performance measure values and higher reliability, especially obtaining 0.55 value of MCC through jackknife tests. Obtained results showed that such predictor models are promising and may play a useful role in defining guidelines for experimental designs relating to exposure conditions. In conclusion, analysis of the bioelectromagnetic data could result in finding a relationship between electromagnetic fields and different biological processes. (c) 2009 Wiley-Liss, Inc.

Association of Rotating Night Shift Work with BMI and Abdominal Obesity among Nurses and Midwives.

PubMed

Peplonska, Beata; Bukowska, Agnieszka; Sobala, Wojciech

2015-01-01

Mounting epidemiological evidence suggests that night shift work may contribute to the etiology of increased body weight. The present study aimed to examine association between rotating night shift work and body mass index (BMI), and abdominal adiposity respectively among nurses and midwives. A cross-sectional study was conducted among 724 female nurses and midwives, aged 40-60 years (354 rotating night shift and 370 daytime workers) in Łódź, Poland, between 2008 and 2011. Information about occupational history and potential confounders was collected during personal interviews. Anthropometric measurements of body weight, height, waist (WC) and hip (HC) circumference were made, and body mass index (BMI), waist to hip ratio (WHR) and waist to height ratio (WHtR) were calculated. GLM regression models and multinomial logit regression models were fitted to explore the association between night shift work and anthropometric parameters, with adjustment for age, body silhouette at age 20, current smoking status, packyears, marital status, and menopausal hormone therapy use. Cumulative night shift work showed significant associations with BMI, WC, HC and WHtR, with BMI increasing by 0.477 kg/m2 per 1000 night duties and by 0.432 kg/m2 per 10000 night shift hours, WC increasing respectively by 1.089 cm and 0.99 cm, and HC by 0.72 cm and WHtR by 0.007 cm for both metrics. Both current and cumulative night work was associated with obesity (BMI≥30kg/m2), with OR=3.9 (95%CI:1.5-9.9), in women reporting eight or more night shifts per month. The results of the study support the previously reported relations between night shift work and development of obesity.

Association of Rotating Night Shift Work with BMI and Abdominal Obesity among Nurses and Midwives

PubMed Central

Peplonska, Beata; Bukowska, Agnieszka; Sobala, Wojciech

2015-01-01

Background Mounting epidemiological evidence suggests that night shift work may contribute to the etiology of increased body weight. The present study aimed to examine association between rotating night shift work and body mass index (BMI), and abdominal adiposity respectively among nurses and midwives. Methods A cross-sectional study was conducted among 724 female nurses and midwives, aged 40-60 years (354 rotating night shift and 370 daytime workers) in Łódź, Poland, between 2008 and 2011. Information about occupational history and potential confounders was collected during personal interviews. Anthropometric measurements of body weight, height, waist (WC) and hip (HC) circumference were made, and body mass index (BMI), waist to hip ratio (WHR) and waist to height ratio (WHtR) were calculated. GLM regression models and multinomial logit regression models were fitted to explore the association between night shift work and anthropometric parameters, with adjustment for age, body silhouette at age 20, current smoking status, packyears, marital status, and menopausal hormone therapy use. Results Cumulative night shift work showed significant associations with BMI, WC, HC and WHtR, with BMI increasing by 0.477 kg/m2 per 1000 night duties and by 0.432 kg/m2 per 10000 night shift hours, WC increasing respectively by 1.089 cm and 0.99 cm, and HC by 0.72 cm and WHtR by 0.007 cm for both metrics. Both current and cumulative night work was associated with obesity (BMI≥30kg/m2), with OR=3.9 (95%CI:1.5-9.9), in women reporting eight or more night shifts per month. Conclusion The results of the study support the previously reported relations between night shift work and development of obesity. PMID:26196859

A generalized nonlinear model-based mixed multinomial logit approach for crash data analysis.

PubMed

Zeng, Ziqiang; Zhu, Wenbo; Ke, Ruimin; Ash, John; Wang, Yinhai; Xu, Jiuping; Xu, Xinxin

2017-02-01

The mixed multinomial logit (MNL) approach, which can account for unobserved heterogeneity, is a promising unordered model that has been employed in analyzing the effect of factors contributing to crash severity. However, its basic assumption of using a linear function to explore the relationship between the probability of crash severity and its contributing factors can be violated in reality. This paper develops a generalized nonlinear model-based mixed MNL approach which is capable of capturing non-monotonic relationships by developing nonlinear predictors for the contributing factors in the context of unobserved heterogeneity. The crash data on seven Interstate freeways in Washington between January 2011 and December 2014 are collected to develop the nonlinear predictors in the model. Thirteen contributing factors in terms of traffic characteristics, roadway geometric characteristics, and weather conditions are identified to have significant mixed (fixed or random) effects on the crash density in three crash severity levels: fatal, injury, and property damage only. The proposed model is compared with the standard mixed MNL model. The comparison results suggest a slight superiority of the new approach in terms of model fit measured by the Akaike Information Criterion (12.06 percent decrease) and Bayesian Information Criterion (9.11 percent decrease). The predicted crash densities for all three levels of crash severities of the new approach are also closer (on average) to the observations than the ones predicted by the standard mixed MNL model. Finally, the significance and impacts of the contributing factors are analyzed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Meta-analysis of prediction model performance across multiple studies: Which scale helps ensure between-study normality for the C-statistic and calibration measures?

PubMed

Snell, Kym Ie; Ensor, Joie; Debray, Thomas Pa; Moons, Karel Gm; Riley, Richard D

2017-01-01

If individual participant data are available from multiple studies or clusters, then a prediction model can be externally validated multiple times. This allows the model's discrimination and calibration performance to be examined across different settings. Random-effects meta-analysis can then be used to quantify overall (average) performance and heterogeneity in performance. This typically assumes a normal distribution of 'true' performance across studies. We conducted a simulation study to examine this normality assumption for various performance measures relating to a logistic regression prediction model. We simulated data across multiple studies with varying degrees of variability in baseline risk or predictor effects and then evaluated the shape of the between-study distribution in the C-statistic, calibration slope, calibration-in-the-large, and E/O statistic, and possible transformations thereof. We found that a normal between-study distribution was usually reasonable for the calibration slope and calibration-in-the-large; however, the distributions of the C-statistic and E/O were often skewed across studies, particularly in settings with large variability in the predictor effects. Normality was vastly improved when using the logit transformation for the C-statistic and the log transformation for E/O, and therefore we recommend these scales to be used for meta-analysis. An illustrated example is given using a random-effects meta-analysis of the performance of QRISK2 across 25 general practices.

Macro-level vulnerable road users crash analysis: A Bayesian joint modeling approach of frequency and proportion.

PubMed

Cai, Qing; Abdel-Aty, Mohamed; Lee, Jaeyoung

2017-10-01

This study aims at contributing to the literature on pedestrian and bicyclist safety by building on the conventional count regression models to explore exogenous factors affecting pedestrian and bicyclist crashes at the macroscopic level. In the traditional count models, effects of exogenous factors on non-motorist crashes were investigated directly. However, the vulnerable road users' crashes are collisions between vehicles and non-motorists. Thus, the exogenous factors can affect the non-motorist crashes through the non-motorists and vehicle drivers. To accommodate for the potentially different impact of exogenous factors we convert the non-motorist crash counts as the product of total crash counts and proportion of non-motorist crashes and formulate a joint model of the negative binomial (NB) model and the logit model to deal with the two parts, respectively. The formulated joint model is estimated using non-motorist crash data based on the Traffic Analysis Districts (TADs) in Florida. Meanwhile, the traditional NB model is also estimated and compared with the joint model. The result indicates that the joint model provides better data fit and can identify more significant variables. Subsequently, a novel joint screening method is suggested based on the proposed model to identify hot zones for non-motorist crashes. The hot zones of non-motorist crashes are identified and divided into three types: hot zones with more dangerous driving environment only, hot zones with more hazardous walking and cycling conditions only, and hot zones with both. It is expected that the joint model and screening method can help decision makers, transportation officials, and community planners to make more efficient treatments to proactively improve pedestrian and bicyclist safety. Published by Elsevier Ltd.

The effect of consumers’ perception to the satisfaction of use of traditional medicines in Medan

NASA Astrophysics Data System (ADS)

Siregar, R. S.; Supriana, T.; Haryanti, S.

2018-02-01

Consumption of chemical medicines fluctuated in 2009-2014, whereas the consumption of solid traditional medicine increased in 2009-2014. The purpose of this study is to analyse the influence of consumers’s perception on the consumption of traditional medicinal plants. The data was analysed by using a binomial logit regression analysis. It is found that the consumers’s perceptions affect customer satisfaction simultaneously are the health benefits variable, quality of traditional medicine variable, price of traditional medicine and available product; the health benefits variable and quality of traditional medicine variable partially have significant effects to customers’s satisfaction simultaneously satisfaction partially; the health benefit variable and quality of traditional medicine is found to have a marginal effect of 7% and 4%, respectively.

Disentangling WTP per QALY data: different analytical approaches, different answers.

PubMed

Gyrd-Hansen, Dorte; Kjaer, Trine

2012-03-01

A large random sample of the Danish general population was asked to value health improvements by way of both the time trade-off elicitation technique and willingness-to-pay (WTP) using contingent valuation methods. The data demonstrate a high degree of heterogeneity across respondents in their relative valuations on the two scales. This has implications for data analysis. We show that the estimates of WTP per QALY are highly sensitive to the analytical strategy. For both open-ended and dichotomous choice data we demonstrate that choice of aggregated approach (ratios of means) or disaggregated approach (means of ratios) affects estimates markedly as does the interpretation of the constant term (which allows for disproportionality across the two scales) in the regression analyses. We propose that future research should focus on why some respondents are unwilling to trade on the time trade-off scale, on how to interpret the constant value in the regression analyses, and on how best to capture the heterogeneity in preference structures when applying mixed multinomial logit. Copyright © 2011 John Wiley & Sons, Ltd.

Widowed Mothers’ Coresidence With Adult Children

PubMed Central

2014-01-01

Objectives. Coresidence is one way that middle-aged offspring assist vulnerable, aging parents. This study investigated which characteristics of widowed mothers and adult children predict coresidence. When coresidence occurred, the analysis explored how individual children’s characteristics were associated with their coresidence with the mother. Method. Survey data from adults 53–54 years old in 1993 (N = 2,324) and a random sibling reported about their living situation, other siblings, and their mother, median age 80. Results. Logistic regressions revealed that mothers in poor health, who were older, and who had a daughter were more likely to live with a child. Among coresiding families, results from discrete choice conditional logit models showed that widowed mothers were more likely to live with an unmarried son than an unmarried daughter. Married children were less likely to coreside than unmarried children, but married daughters were more likely than married sons to coreside. Past receipt of financial help from parents was not associated with coresidence. Coresidence was more likely for those with a close relationship with the mother. Discussion. The discussion considers coresidence as an intergenerational transfer and its importance for the contemporary aging society. Data are needed on characteristics of all offspring to test theories about parent–child relationships. PMID:24013798

The cycle of victimization: The relationship between childhood maltreatment and adolescent peer victimization.

PubMed

Benedini, Kristen M; Fagan, Abigail A; Gibson, Chris L

2016-09-01

Child maltreatment has been demonstrated to have many short- and long-term harmful consequences for victims, but whether or not child abuse is associated with an increased risk of peer victimization during adolescence is unclear. This study analyzed prospective data from 831 children and parents participating in the Longitudinal Studies on Child Abuse and Neglect (LONGSCAN) to investigate the relationships between child physical and sexual abuse and adolescent victimization by peers, as well as the potential for gender to moderate these relationships. Results from ordinal logit regression models indicated that children who were physically abused prior to age 12, based on official reports, parent reports, and child reports, had a greater risk of experiencing more intimidation and physical assault by peers at age 16. Having a history of sexual abuse predicted more physical assault but not intimidation. There was no evidence that gender moderated these relationships; in all cases, the relationship between abuse and revictimization was similar for boys and girls. The findings emphasize the need to provide victims of abuse with assistance to help prevent a cycle of victimization. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stay or Migrate? An Empirical Study of the Relationship between Place of Work, Place of Study and Birthplace

ERIC Educational Resources Information Center

Liping, Ma; Kunfeng, Pan

2014-01-01

Based on a 2009 national survey on college graduate employment in China, this article analyzes the relationship of college graduates' place of work to their birthplace and where they attend college, using a conditional logit model. The findings indicate that graduates tend to stay to work in their birthplaces or places of study, controlling for…

An analysis of factors affecting participation behavior of limited resource farmers in agricultural cost-share programs in Alabama

Treesearch

Okwudili Onianwa; Gerald Wheelock; Buddhi Gyawali; Jianbang Gan; Mark Dubois; John Schelhas

2004-01-01

This study examines factors that affect the participation behavior of limited resource farmers in agricultural cost-share programs in Alabama. The data were generated from a survey administered to a sample of limited resource farm operators. A binary logit model was employed to analyze the data. Results indicate that college education, age, gross sales, ratio of owned...

A mixed logit model of homeowner preferences for wildfire hazard reduction

Treesearch

Thomas P. Holmes; John Loomis; Armando González-Cabán

2009-01-01

People living in the wildland-urban interface (WUI) are at greater risk of suffering major losses of property and life from wildfires. Over the past several decades the prevailing view has been that wildfire risk in rural areas was exogenous to the activities of homeowners. In response to catastrophic fires in the WUI over the past few years, recent approaches to fire...

A Mixed Logit Model of Homeowner Preferences for Wildfire Hazard Reduction

Treesearch

Thomas P. Holmes; John Loomis; Armando Gonzalez-Caban

2010-01-01

People living in the wildland-urban interface (WUI) are at greater risk of suffering major losses of property and life from wildfires. Over the past several decades the prevailing view has been that wildfire risk in rural areas was exogenous to the activities of homeowners. In response to catastrophic fires in the WUI over the past few years, recent approaches to fire...

Minority households’ willingness to pay for public and private wildfire risk reduction in Florida

Treesearch

Armando González-Cabán; José J. Sánchez

2017-01-01

The purpose of this work is to estimate willingness to pay (WTP) for minority (African-American and Hispanic) homeowners in Florida for private and public wildfire risk-reduction programs and also to test for differences in response between the two groups. A random parameter logit and latent class model allowed us to determine if there is a difference in wildfire...

Life Satisfaction among Turkish and Moroccan Immigrants in the Netherlands: The Role of Absolute and Relative Income

ERIC Educational Resources Information Center

Gokdemir, Ozge; Dumludag, Devrim

2012-01-01

In this paper we investigate the role of several socio-economic and non-economic factors such as absolute and relative income, education and religion to explain the differences of happiness levels of Turkish and Moroccan Immigrants in the Netherlands by using ordered logit model. We focus on members of the Moroccan and Turkish communities, as…

Single toxin dose-response models revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demidenko, Eugene, E-mail: eugened@dartmouth.edu

The goal of this paper is to offer a rigorous analysis of the sigmoid shape single toxin dose-response relationship. The toxin efficacy function is introduced and four special points, including maximum toxin efficacy and inflection points, on the dose-response curve are defined. The special points define three phases of the toxin effect on mortality: (1) toxin concentrations smaller than the first inflection point or (2) larger then the second inflection point imply low mortality rate, and (3) concentrations between the first and the second inflection points imply high mortality rate. Probabilistic interpretation and mathematical analysis for each of the fourmore » models, Hill, logit, probit, and Weibull is provided. Two general model extensions are introduced: (1) the multi-target hit model that accounts for the existence of several vital receptors affected by the toxin, and (2) model with a nonzero mortality at zero concentration to account for natural mortality. Special attention is given to statistical estimation in the framework of the generalized linear model with the binomial dependent variable as the mortality count in each experiment, contrary to the widespread nonlinear regression treating the mortality rate as continuous variable. The models are illustrated using standard EPA Daphnia acute (48 h) toxicity tests with mortality as a function of NiCl or CuSO{sub 4} toxin. - Highlights: • The paper offers a rigorous study of a sigmoid dose-response relationship. • The concentration with highest mortality rate is rigorously defined. • A table with four special points for five morality curves is presented. • Two new sigmoid dose-response models have been introduced. • The generalized linear model is advocated for estimation of sigmoid dose-response relationship.« less

Sexual orientation, social capital and daily tobacco smoking: a population-based study.

PubMed

Lindström, Martin; Axelsson, Jakob; Modén, Birgit; Rosvall, Maria

2014-06-06

Studies have suggested poorer health in the homosexual and bisexual groups compared to heterosexuals. Tobacco smoking, which is a health-related behavior associated with psychosocial stress, may be one explanation behind such health differences. Social capital, i.e. the generalized trust in other people and social participation/social networks which decreases the costs of social interaction, has been suggested to affect health through psychosocial pathways and through norms connected with health related behaviours, The aim of this study is to investigate the association between sexual orientation and daily tobacco smoking, taking social capital into account and analyzing the attenuation of the logit after the introduction of social participation, trust and their combination in the models. In 2008 a cross-sectional public health survey was conducted in southern Sweden with a postal questionnaire with 28,198 participants aged 18-80 (55% participation rate). This study was restricted to 24,348 participants without internally missing values on all included variables. Associations between sexual orientation and tobacco smoking were analyzed with logistic regression analysis. Overall, 11.9% of the men and 14.8% of the women were daily tobacco smokers. Higher and almost unaltered odds ratios of daily smoking compared to heterosexuals were observed for bisexual men and women, and for homosexual men throughout the analyses. The odds ratios of daily smoking among homosexual women were not significant. Only for the "other" sexual orientation group the odds ratios of daily smoking were reduced to not significant levels among both men and women, with a corresponding 54% attenuation of the logit in the "other" group among men and 31.5% among women after the inclusion of social participation and trust. In addition, only the "other" sexual orientation group had higher odds ratios of low participation than heterosexuals. Bisexual men and women and homosexual men, but not homosexual women, are daily smokers to a higher extent than heterosexuals. Only for the "other" sexual orientation group the odds ratios of daily smoking were reduced to not significant levels after adjustments for covariates including trust and social participation.

The impacts of health, education, family planning and electrification programs on fertility, mortality and child schooling in East Java, Indonesia.

PubMed

Wirakartakusumah, M D

1988-06-01

This paper examines the effects of public health, family planning, education, electrification, and water supply programs on fertility, child mortality, and school enrollment decisions of rural households in East Java, Indonesia. The theoretical model assumes that parents maximize a utility function, subject to 1) a budget constraint that equates income with expenditures on children (including schooling and health inputs), and 2) a production function that relates health inputs to child survival possibilities. Public programs affect prices of contraceptives, schooling and health inputs, and environmental conditions that in turn affect child survival. Data are taken from the 1980 East Java Population Survey, the Socio-economic Survey, and the Detailed Village Census. The final sample consists of 3170 rural households with married women of childbearing age. Ordinary least squares and logit regressions of recent fertility, child mortality, and school enrollment on program and household variables yielded the following findings. 1) The presence of maternal and child health clinics reduced fertility but not mortality. 2) The presence of public health centers strongly reduced mortality but not fertility. 3) The presence of contraceptive distribution centers had no effect on fertility. 4) School attendance rates were influenced positively by the availability of primary and secondary schools. 5) Health and family planning programs had no effects on schooling. 6) The availability of public latrines reduced fertility and mortality. 7) The water supply variable did not affect the dependent variables when ordinary least squares techniques were applied but had statistically significant impact when logit methods were used. 8) Electricity supply had little effect on the dependent variables. 9) The mother's schooling had a strong positive correlation with children's schooling but no effect on fertility or mortality. 10) Household expenditures were related positively to school attendance and negatively to mortality. 11) There was little or no interaction between household variables and presence of government programs. 12) Subprovincial area measures of service availability appeared more appropriate for public health and family planning services, while village-level measures appeared more appropriate for schooling.

Getting the right balance? A mixed logit analysis of the relationship between UK training doctors’ characteristics and their specialties using the 2013 National Training Survey

PubMed Central

Chalkley, Martin

2017-01-01

Objective To analyse how training doctors’ demographic and socioeconomic characteristics vary according to the specialty that they are training for. Design Descriptive statistics and mixed logistic regression analysis of cross-sectional survey data to quantify evidence of systematic relationships between doctors’ characteristics and their specialty. Setting Doctors in training in the United Kingdom in 2013. Participants 27 530 doctors in training but not in their foundation year who responded to the National Training Survey 2013. Main outcome measures Mixed logit regression estimates and the corresponding odds ratios (calculated separately for all doctors in training and a subsample comprising those educated in the UK), relating gender, age, ethnicity, place of studies, socioeconomic background and parental education to the probability of training for a particular specialty. Results Being female and being white British increase the chances of being in general practice with respect to any other specialty, while coming from a better-off socioeconomic background and having parents with tertiary education have the opposite effect. Mixed results are found for age and place of studies. For example, the difference between men and women is greatest for surgical specialties for which a man is 12.121 times more likely to be training to a surgical specialty (relative to general practice) than a woman (p-value<0.01). Doctors who attended an independent school which is proxy for doctor’s socioeconomic background are 1.789 and 1.413 times more likely to be training for surgical or medical specialties (relative to general practice) than those who attended a state school (p-value<0.01). Conclusions There are systematic and substantial differences between specialties in respect of training doctors’ gender, ethnicity, age and socioeconomic background. The persistent underrepresentation in some specialties of women, minority ethnic groups and of those coming from disadvantaged backgrounds will impact on the representativeness of the profession into the future. Further research is needed to understand how the processes of selection and the self-selection of applicants into specialties gives rise to these observed differences. PMID:28801397

Mediators of the Association of Major Depressive Syndrome and Anxiety Syndrome with Postpartum Smoking Relapse

PubMed Central

Correa-Fernández, Virmarie; Ji, Lingyun; Castro, Yessenia; Heppner, Whitney L.; Vidrine, Jennifer Irvin; Costello, Tracy J.; Mullen, Patricia Dolan; Cofta-Woerpel, Ludmila; Velasquez, Mary M.; Greisinger, Anthony; Cinciripini, Paul M.; Wetter, David W.

2012-01-01

Objective Based on conceptual models of addiction and affect regulation, this study examined the mechanisms linking current major depressive syndrome (MDS) and anxiety syndrome (AS) to postpartum smoking relapse. Method Data were collected in a randomized clinical trial from 251 women who quit smoking during pregnancy. Simple and multiple mediation models of the relations of MDS and AS with postpartum relapse were examined using linear regression, continuation ratio logit models, and a Bootstrapping procedure to test the indirect effects. Results Both MDS and AS significantly predicted postpartum smoking relapse. After adjusting for MDS, AS significantly predicted relapse. However, after adjusting for AS, MDS no longer predicted relapse. Situationally-based self-efficacy, expectancies of controlling negative affect by means other than smoking, and various dimensions of primary and secondary tobacco dependence individually mediated the effect of both MDS and AS on relapse. In multiple mediation models, self-efficacy in negative/affective situations significantly mediated the effect of MDS and AS on relapse. Conclusion The findings underscore the negative impact of depression and anxiety on postpartum smoking relapse, and suggest that the effects of MDS on postpartum relapse may be largely explained by comorbid AS. The current investigation provided mixed support for affect regulation models of addiction. Cognitive and tobacco dependence-related aspects of negative and positive reinforcement significantly mediated the relationship of depression and anxiety with relapse, while affect and stress did not. The findings emphasize the unique role of low agency with respect to abstaining from smoking in negative affective situations as a key predictor of postpartum smoking relapse. PMID:22390410

Mediators of the association of major depressive syndrome and anxiety syndrome with postpartum smoking relapse.

PubMed

Correa-Fernández, Virmarie; Ji, Lingyun; Castro, Yessenia; Heppner, Whitney L; Vidrine, Jennifer Irvin; Costello, Tracy J; Mullen, Patricia Dolan; Cofta-Woerpel, Ludmila; Velasquez, Mary M; Greisinger, Anthony; Cinciripini, Paul M; Wetter, David W

2012-08-01

Based on conceptual models of addiction and affect regulation, this study examined the mechanisms linking current major depressive syndrome (MDS) and anxiety syndrome (AS) to postpartum smoking relapse. Data were collected in a randomized clinical trial from 251 women who quit smoking during pregnancy. Simple and multiple mediation models of the relations of MDS and AS with postpartum relapse were examined using linear regression, continuation ratio logit models, and a bootstrapping procedure to test the indirect effects. Both MDS and AS significantly predicted postpartum smoking relapse. After adjusting for MDS, AS significantly predicted relapse. However, after adjusting for AS, MDS no longer predicted relapse. Situationally based self-efficacy, expectancies of controlling negative affect by means other than smoking, and various dimensions of primary and secondary tobacco dependence individually mediated the effect of both MDS and AS on relapse. In multiple mediation models, self-efficacy in negative/affective situations significantly mediated the effect of MDS and AS on relapse. The findings underscore the negative impact of depression and anxiety on postpartum smoking relapse and suggest that the effects of MDS on postpartum relapse may be largely explained by comorbid AS. The current investigation provided mixed support for affect regulation models of addiction. Cognitive and tobacco dependence-related aspects of negative and positive reinforcement significantly mediated the relationship of depression and anxiety with relapse, whereas affect and stress did not. The findings emphasize the unique role of low agency with respect to abstaining from smoking in negative affective situations as a key predictor of postpartum smoking relapse. © 2012 American Psychological Association

Examining driver behavior at the onset of yellow in a traffic simulator environment: Comparisons between random parameters and latent class logit models.

PubMed

Savolainen, Peter T

2016-11-01

This study involves an examination of driver behavior at the onset of a yellow signal indication. Behavioral data were obtained from a driving simulator study that was conducted through the National Advanced Driving Simulator (NADS) laboratory at the University of Iowa. These data were drawn from a series of events during which study participants drove through a series of intersections where the traffic signals changed from the green to yellow phase. The resulting dataset provides potential insights into how driver behavior is affected by distracted driving through an experimental design that alternated handheld, headset, and hands-free cell phone use with "normal" baseline driving events. The results of the study show that male drivers ages 18-45 were more likely to stop. Participants were also more likely to stop as they became more familiar with the simulator environment. Cell phone use was found to some influence on driver behavior in this setting, though the effects varied significantly across individuals. The study also demonstrates two methodological approaches for dealing with unobserved heterogeneity across drivers. These include random parameters and latent class logit models, each of which analyze the data as a panel. The results show each method to provide significantly better fit than a pooled, fixed parameter model. Differences in terms of the context of these two approaches are discussed, providing important insights as to the differences between these modeling frameworks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimating wetland vegetation abundance from Landsat-8 operational land imager imagery: a comparison between linear spectral mixture analysis and multinomial logit modeling methods

NASA Astrophysics Data System (ADS)

Zhang, Min; Gong, Zhaoning; Zhao, Wenji; Pu, Ruiliang; Liu, Ke

2016-01-01

Mapping vegetation abundance by using remote sensing data is an efficient means for detecting changes of an eco-environment. With Landsat-8 operational land imager (OLI) imagery acquired on July 31, 2013, both linear spectral mixture analysis (LSMA) and multinomial logit model (MNLM) methods were applied to estimate and assess the vegetation abundance in the Wild Duck Lake Wetland in Beijing, China. To improve mapping vegetation abundance and increase the number of endmembers in spectral mixture analysis, normalized difference vegetation index was extracted from OLI imagery along with the seven reflective bands of OLI data for estimating the vegetation abundance. Five endmembers were selected, which include terrestrial plants, aquatic plants, bare soil, high albedo, and low albedo. The vegetation abundance mapping results from Landsat OLI data were finally evaluated by utilizing a WorldView-2 multispectral imagery. Similar spatial patterns of vegetation abundance produced by both fully constrained LSMA algorithm and MNLM methods were observed: higher vegetation abundance levels were distributed in agricultural and riparian areas while lower levels in urban/built-up areas. The experimental results also indicate that the MNLM model outperformed the LSMA algorithm with smaller root mean square error (0.0152 versus 0.0252) and higher coefficient of determination (0.7856 versus 0.7214) as the MNLM model could handle the nonlinear reflection phenomenon better than the LSMA with mixed pixels.

Them That's Got: How Tie Formation in Partnership Networks Gives High Schools Differential Access to Social Capital

ERIC Educational Resources Information Center

Bridwell-Mitchell, E. N.

2017-01-01

School partnerships are important sources of school social capital. Schools may have unequal access to social capital due to the pattern of relationships in the school-partner network. Using data on school resource needs, sociometric measures, and a set of multilevel logit models, the results of a study of 211 New York City public high schools and…

Predictors of Place of Death for Seniors in Ontario: A Population-Based Cohort Analysis

ERIC Educational Resources Information Center

Motiwala, Sanober S.; Croxford, Ruth; Guerriere, Denise N.; Coyte, Peter C.

2006-01-01

Place of death was determined for all 58,689 seniors (age greater than or equal to 66 years) in Ontario who died during fiscal year 2001/2002. The relationship of place of death to medical and socio-demographic characteristics was examined using a multinomial logit model. Half (49.2 %) of these individuals died in hospital, 30.5 per cent died in a…

Factors influencing spatial pattern in tropical forest clearance and stand age: Implications for carbon storage and species diversity.

Treesearch

E. H. Helmer; Thomas J. Brandeis; Ariel E. Lugo; Todd Kennaway

2008-01-01

Little is known about the tropical forests that undergo clearing as urban/built-up and other developed lands spread. This study uses remote sensing-based maps of Puerto Rico, multinomial logit models and forest inventory data to explain patterns of forest age and the age of forests cleared for land development and assess their implications for forest carbon storage and...

Adoption of health information technologies by physicians for clinical practice: The Andalusian case.

PubMed

Villalba-Mora, Elena; Casas, Isabel; Lupiañez-Villanueva, Francisco; Maghiros, Ioannis

2015-07-01

We investigated the level of adoption of Health Information Technologies (HIT) services, and the factors that influence this, amongst specialised and primary care physicians; in Andalusia, Spain. We analysed the physicians' responses to an online survey. First, we performed a statistical descriptive analysis of the data; thereafter, a principal component analysis; and finally an order logit model to explain the effect of the use in the adoption and to analyse which are the existing barriers. The principal component analysis revealed three main uses of Health Information Technologies: Electronic Health Records (EHR), ePrescription and patient management and telemedicine services. Results from an ordered logit model showed that the frequency of use of HIT is associated with the physicians' perceived usefulness. Lack of financing appeared as a common barrier to the adoption of the three types of services. For ePrescription and patient management, the physician's lack of skills is still a barrier. In the case of telemedicine services, lack of security and lack of interest amongst professionals are the existing barriers. EHR functionalities are fully adopted, in terms of perceived usefulness. EPrescription and patient management are almost fully adopted, while telemedicine is in an early stage of adoption. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The combined effect of age and basal follicle-stimulating hormone on the cost of a live birth at assisted reproductive technology.

PubMed

Henne, Melinda B; Stegmann, Barbara J; Neithardt, Adrienne B; Catherino, William H; Armstrong, Alicia Y; Kao, Tzu-Cheg; Segars, James H

2008-01-01

To predict the cost of a delivery following assisted reproductive technologies (ART). Cost analysis based on retrospective chart analysis. University-based ART program. Women aged >or=26 and

The effect of three-tier formulary adoption on medication continuation and spending among elderly retirees.

PubMed

Huskamp, Haiden A; Deverka, Patricia A; Landrum, Mary Beth; Epstein, Robert S; McGuigan, Kimberly A

2007-10-01

To assess the effect of three-tier formulary adoption on medication continuation and spending among elderly members of retiree health plans. Pharmacy claims and enrollment data on elderly members of four retiree plans that adopted a three-tier formulary over the period July 1999 through December 2002 and two comparison plans that maintained a two-tier formulary during this period. We used a quasi-experimental design to compare the experience of enrollees in intervention and comparison plans. We used propensity score methods to match intervention and comparison users of each drug class and plan. We estimated repeated measures regression models for each class/plan combination for medication continuation and monthly plan, enrollee, and total spending. We estimated logit models of the probability of nonpersistent use, medication discontinuation, and medication changes. We used pharmacy claims to create person-level drug utilization and spending files for the year before and year after three-tier adoption. Three-tier formulary adoption resulted in shifting of costs from plan to enrollee, with relatively small effects on medication continuation. Although implementation had little effect on continuation on average, a small minority of patients were more likely to have gaps in use and discontinue use relative to comparison patients. Moderate cost sharing increases from three-tier formulary adoption had little effect on medication continuation among elderly enrolled in retiree health plans with relatively generous drug coverage.

US Food assistance programs and trends in children's weight.

PubMed

Ver Ploeg, Michele; Mancino, Lisa; Lin, Biing-Hwan; Guthrie, Joanne

2008-01-01

OBJECTIVES. High rates of overweight and obesity among low-income children have led some to question whether participation in US domestic food assistance programs contributes to this health problem. We use multiple years of data to examine trends in children's body weight and participation in the Food Stamp Program (FSP) or Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Specifically, we assess whether a consistent relationship between program participation and body weight exists over time. METHODS. Data from multiple waves of the National Health and Nutrition Examination Surveys (NHANES) are used to examine the relationship between children's body weight and food assistance programs between 1976 and 2002. Linear regression models are used to estimate BMI and logit models are used to predict the probabilities of at-risk of overweight and overweight. Food assistance program participants (either FSP or WIC participants depending on age) are compared with income eligible non-participants and higher income children. RESULTS. Results show no systematic relationship over time between FSP participation and weight status for school-aged children (age 5-17). For children aged 2-4, no differences in weight status between WIC participants and eligible non-participants were found. However, recent data show some differences between WIC participants and higher income children. CONCLUSIONS. Our analysis does not find evidence of a consistent relationship between childhood obesity and participation in the FSP or WIC programs.

Modeling with the logistic regression of the growth/no growth interface of Saccharomyces cerevisiae in relation to 2 antimicrobial terpenes (citral and linalool), pH, and a(w).

PubMed

Tabanelli, Giulia; Montanari, Chiara; Patrignani, Francesca; Siroli, Lorenzo; Lanciotti, Rosalba; Gardini, Fausto

2014-03-01

The antimicrobial effects of 2 terpenes (citral and linalool) on a Saccharomyces cerevisiae strain isolated from spoiled soft drink have been evaluated, alone or in combination, in relation to pH and aw using in vitro assays. The obtained data were fitted with the logit model to find the growth/no growth boundary regions of the 2 terpenes, focusing the attention on the type of interaction exerted by citral and linalool. In particular, the results showed an increase of citral antimicrobial effect in growth media characterized by low aw value, as well as a higher linalool antimicrobial effect in media at low pH. Moreover, the interactive effects of the 2 terpenes were exploited. The results obtained with the model were validated in an independent experiment. The knowledge of the interactions of essential oil molecules with enhanced antimicrobial activity, in relation to some of the most important chemicophysical variables, can have important industrial applications, since these substances are able to assure the desired antimicrobial effect without negatively modifying the product flavor profile. The effects of the main chemicophysical parameters (such as aw and pH) on the antimicrobial activity of bioactive terpenes are necessary for the definition of an industrially applicable preservation strategy based on the use of essential oils as natural antimicrobials aimed to prolong shelf life of food products. © 2014 Institute of Food Technologists®

Preference elicitation approach for measuring the willingness to pay for liver cancer treatment in Korea.

PubMed

Cho, Donghun; Jo, Changik

2015-09-01

The Korean government has expanded the coverage of the national insurance scheme for four major diseases: cancers, cardiovascular diseases, cerebrovascular diseases, and rare diseases. This policy may have a detrimental effect on the budget of the national health insurance agency. Like taxes, national insurance premiums are levied on the basis of the income or wealth of the insured. Using a preference elicitation method, we attempted to estimate how much people are willing to pay for insurance premiums that would expand their coverage for liver cancer treatment. We calculated the marginal willingness to pay (MWTP) through the marginal rate of substitution between the two attributes of the insurance premium and the total annual treatment cost by adopting conditional logit and mixed logit models. The effects of various other terms that could interact with socioeconomic status were also estimated, such as gender, income level, educational attainment, age, employment status, and marital status. The estimated MWTP values of the monthly insurance premium for liver cancer treatment range from 4,130 KRW to 9,090 KRW.

Antimicrobial Activity of Aroma Compounds against Saccharomyces cerevisiae and Improvement of Microbiological Stability of Soft Drinks as Assessed by Logistic Regression▿

PubMed Central

Belletti, Nicoletta; Kamdem, Sylvain Sado; Patrignani, Francesca; Lanciotti, Rosalba; Covelli, Alessandro; Gardini, Fausto

2007-01-01

The combined effects of a mild heat treatment (55°C) and the presence of three aroma compounds [citron essential oil, citral, and (E)-2-hexenal] on the spoilage of noncarbonated beverages inoculated with different amounts of a Saccharomyces cerevisiae strain were evaluated. The results, expressed as growth/no growth, were elaborated using a logistic regression in order to assess the probability of beverage spoilage as a function of thermal treatment length, concentration of flavoring agents, and yeast inoculum. The logit models obtained for the three substances were extremely precise. The thermal treatment alone, even if prolonged for 20 min, was not able to prevent yeast growth. However, the presence of increasing concentrations of aroma compounds improved the stability of the products. The inhibiting effect of the compounds was enhanced by a prolonged thermal treatment. In fact, it influenced the vapor pressure of the molecules, which can easily interact within microbial membranes when they are in gaseous form. (E)-2-Hexenal showed a threshold level, related to initial inoculum and thermal treatment length, over which yeast growth was rapidly inhibited. Concentrations over 100 ppm of citral and thermal treatment longer than 16 min allowed a 90% probability of stability for bottles inoculated with 105 CFU/bottle. Citron gave the most interesting responses: beverages with 500 ppm of essential oil needed only 3 min of treatment to prevent yeast growth. In this framework, the logistic regression proved to be an important tool to study alternative hurdle strategies for the stabilization of noncarbonated beverages. PMID:17616627

Incorporating detection probability into northern Great Plains pronghorn population estimates

USGS Publications Warehouse

Jacques, Christopher N.; Jenks, Jonathan A.; Grovenburg, Troy W.; Klaver, Robert W.; DePerno, Christopher S.

2014-01-01

Pronghorn (Antilocapra americana) abundances commonly are estimated using fixed-wing surveys, but these estimates are likely to be negatively biased because of violations of key assumptions underpinning line-transect methodology. Reducing bias and improving precision of abundance estimates through use of detection probability and mark-resight models may allow for more responsive pronghorn management actions. Given their potential application in population estimation, we evaluated detection probability and mark-resight models for use in estimating pronghorn population abundance. We used logistic regression to quantify probabilities that detecting pronghorn might be influenced by group size, animal activity, percent vegetation, cover type, and topography. We estimated pronghorn population size by study area and year using mixed logit-normal mark-resight (MLNM) models. Pronghorn detection probability increased with group size, animal activity, and percent vegetation; overall detection probability was 0.639 (95% CI = 0.612–0.667) with 396 of 620 pronghorn groups detected. Despite model selection uncertainty, the best detection probability models were 44% (range = 8–79%) and 180% (range = 139–217%) greater than traditional pronghorn population estimates. Similarly, the best MLNM models were 28% (range = 3–58%) and 147% (range = 124–180%) greater than traditional population estimates. Detection probability of pronghorn was not constant but depended on both intrinsic and extrinsic factors. When pronghorn detection probability is a function of animal group size, animal activity, landscape complexity, and percent vegetation, traditional aerial survey techniques will result in biased pronghorn abundance estimates. Standardizing survey conditions, increasing resighting occasions, or accounting for variation in individual heterogeneity in mark-resight models will increase the accuracy and precision of pronghorn population estimates.

Perceived Race-Based Discrimination, Employment Status, and Job Stress in a National Sample of Black Women: Implications for Health Outcomes

PubMed Central

Mays, Vickie M.; Coleman, Lerita M.; Jackson, James S.

2013-01-01

Previous research has not systematically examined the relationship of perceived race-based discriminations to labor force participation or job related stresses–problems experienced by Black women. The present study investigated the relative contributions of perceived race-based discriminations and sociodemographic characteristics to employment status and job stress in a national probability sample (the National Survey of Black Americans; J. S. Jackson, 1991) of Black women in the United States. Logit and polychotomous logistic regression analyses revealed that Black women’s current employment status was best explained by sociodemographic measures. In contrast, the combination of perceived discrimination and sociodemographics differentially affects patterns of employment status and perceived job stress in the work environment of Black women. Implications of these findings for the health of African American women are discussed. PMID:9547054

Household's willingness to pay for heterogeneous attributes of drinking water quality and services improvement: an application of choice experiment

NASA Astrophysics Data System (ADS)

Dauda, Suleiman Alhaji; Yacob, Mohd Rusli; Radam, Alias

2015-09-01

The service of providing good quality of drinking water can greatly improve the lives of the community and maintain a normal health standard. For a large number of population in the world, specifically in the developing countries, the availability of safe water for daily sustenance is none. Damaturu is the capital of Yobe State, Nigeria. It hosts a population of more than two hundred thousand, yet only 45 % of the households are connected to the network of Yobe State Water Corporation's pipe borne water services; this has led people to source for water from any available source and thus, exposed them to the danger of contracting waterborne diseases. In order to address the problem, Yobe State Government has embarked on the construction of a water treatment plant with a capacity and facility to improve the water quality and connect the town with water services network. The objectives of this study are to assess the households' demand preferences of the heterogeneous water attributes in Damaturu, and to estimate their marginal willingness to pay, using mixed logit model in comparison with conditional logit model. A survey of 300 households randomly sampled indicated that higher education greatly influenced the households' WTP decisions. The most significant variable from both of the models is TWQ, which is MRS that rates the water quality from the level of satisfactory to very good. 219 % in simple model is CLM, while 126 % is for the interaction model. As for MLM, 685 % is for the simple model and 572 % is for the interaction model. Estimate of MLM has more explanatory powers than CLM. Essentially, this finding can help the government in designing cost-effective management and efficient tariff structure.

Estimating preferences for local public services using migration data.

PubMed

Dahlberg, Matz; Eklöf, Matias; Fredriksson, Peter; Jofre-Monseny, Jordi

2012-01-01

Using Swedish micro data, the paper examines the impact of local public services on community choice. The choice of community is modelled as a choice between a discrete set of alternatives. It is found that, given taxes, high spending on child care attracts migrants. Less conclusive results are obtained with respect to the role of spending on education and elderly care. High local taxes deter migrants. Relaxing the independence of the irrelevant alternatives assumption, by estimating a mixed logit model, has a significant impact on the results.

Ready-to-use supplementary food increases fat mass and BMI in Haitian school-aged children.

PubMed

Iannotti, Lora L; Henretty, Nicole M; Delnatus, Jacques Raymond; Previl, Windy; Stehl, Tom; Vorkoper, Susan; Bodden, Jaime; Maust, Amanda; Smidt, Rachel; Nash, Marilyn L; Tamimie, Courtney A; Owen, Bridget C; Wolff, Patricia B

2015-04-01

In Haiti and other countries, large-scale investments in school feeding programs have been made with marginal evidence of nutrition outcomes. We aimed to examine the effectiveness of a fortified ready-to-use supplementary food (RUSF), Mamba, on reduced anemia and improved body composition in school-aged children compared to an unfortified cereal bar, Tablet Yo, and control groups. A cluster, randomized trial with children ages 3-13 y (n = 1167) was conducted in the north of Haiti. Six schools were matched and randomized to the control group, Tablet Yo group (42 g, 165 kcal), or Mamba group (50 g, 260 kcal, and >75% of the RDA for critical micronutrients). Children in the supplementation groups received the snack daily for 100 d, and all were followed longitudinally for hemoglobin concentrations, anthropometry, and bioelectrical impedance measures: baseline (December 2012), midline (March 2013), and endline (June 2013). Parent surveys were conducted at baseline and endline to examine secondary outcomes of morbidities and dietary intakes. Longitudinal regression modeling using generalized least squares and logit with random effects tested the main effects. At baseline,14.0% of children were stunted, 14.5% underweight, 9.1% thin, and 73% anemic. Fat mass percentage (mean ± SD) was 8.1% ± 4.3% for boys and 12.5% ± 4.4% for girls. In longitudinal modeling, Mamba supplementation increased body mass index z score (regression coefficient ± SEE) 0.25 ± 0.06, fat mass 0.45 ± 0.14 kg, and percentage fat mass 1.28% ± 0.27% compared with control at each time point (P < 0.001). Among boys, Mamba increased fat mass (regression coefficient ± SEE) 0.73 ± 0.19 kg and fat-free mass 0.62 ± 0.34 kg compared with control (P < 0.001). Mamba reduced the odds of developing anemia by 28% compared to control (adjusted OR: 0.72; 95% CI: 0.57, 0.91; P < 0.001). No treatment effect was found for hemoglobin concentration. To our knowledge, this is the first study to give evidence of body composition effects from an RUSF in school-aged children. © 2015 American Society for Nutrition.

Modeling pedestrian gap crossing index under mixed traffic condition.

PubMed

Naser, Mohamed M; Zulkiple, Adnan; Al Bargi, Walid A; Khalifa, Nasradeen A; Daniel, Basil David

2017-12-01

There are a variety of challenges faced by pedestrians when they walk along and attempt to cross a road, as the most recorded accidents occur during this time. Pedestrians of all types, including both sexes with numerous aging groups, are always subjected to risk and are characterized as the most exposed road users. The increased demand for better traffic management strategies to reduce the risks at intersections, improve quality traffic management, traffic volume, and longer cycle time has further increased concerns over the past decade. This paper aims to develop a sustainable pedestrian gap crossing index model based on traffic flow density. It focusses on the gaps accepted by pedestrians and their decision for street crossing, where (Log-Gap) logarithm of accepted gaps was used to optimize the result of a model for gap crossing behavior. Through a review of extant literature, 15 influential variables were extracted for further empirical analysis. Subsequently, data from the observation at an uncontrolled mid-block in Jalan Ampang in Kuala Lumpur, Malaysia was gathered and Multiple Linear Regression (MLR) and Binary Logit Model (BLM) techniques were employed to analyze the results. From the results, different pedestrian behavioral characteristics were considered for a minimum gap size model, out of which only a few (four) variables could explain the pedestrian road crossing behavior while the remaining variables have an insignificant effect. Among the different variables, age, rolling gap, vehicle type, and crossing were the most influential variables. The study concludes that pedestrians' decision to cross the street depends on the pedestrian age, rolling gap, vehicle type, and size of traffic gap before crossing. The inferences from these models will be useful to increase pedestrian safety and performance evaluation of uncontrolled midblock road crossings in developing countries. Copyright © 2017 National Safety Council and Elsevier Ltd. All rights reserved.

An innovative statistical approach for analysing non-continuous variables in environmental monitoring: assessing temporal trends of TBT pollution.

PubMed

Santos, José António; Galante-Oliveira, Susana; Barroso, Carlos

2011-03-01

The current work presents an innovative statistical approach to model ordinal variables in environmental monitoring studies. An ordinal variable has values that can only be compared as "less", "equal" or "greater" and it is not possible to have information about the size of the difference between two particular values. The example of ordinal variable under this study is the vas deferens sequence (VDS) used in imposex (superimposition of male sexual characters onto prosobranch females) field assessment programmes for monitoring tributyltin (TBT) pollution. The statistical methodology presented here is the ordered logit regression model. It assumes that the VDS is an ordinal variable whose values match up a process of imposex development that can be considered continuous in both biological and statistical senses and can be described by a latent non-observable continuous variable. This model was applied to the case study of Nucella lapillus imposex monitoring surveys conducted in the Portuguese coast between 2003 and 2008 to evaluate the temporal evolution of TBT pollution in this country. In order to produce more reliable conclusions, the proposed model includes covariates that may influence the imposex response besides TBT (e.g. the shell size). The model also provides an analysis of the environmental risk associated to TBT pollution by estimating the probability of the occurrence of females with VDS ≥ 2 in each year, according to OSPAR criteria. We consider that the proposed application of this statistical methodology has a great potential in environmental monitoring whenever there is the need to model variables that can only be assessed through an ordinal scale of values.

Quality of life of the most severely vision-impaired.

PubMed

Crewe, Julie M; Morlet, Nigel; Morgan, William H; Spilsbury, Katrina; Mukhtar, Aqif; Clark, Antony; Ng, Jonathon Q; Crowley, Margaret; Semmens, James B

2011-01-01

To explore the interaction between vision impairment, perceived quality of life loss and willingness to trade remaining life for vision gain. Community-based cross-sectional study. Legally blind or severely vision-impaired people selected randomly from the Association for the Blind of Western Australia register. Individuals were examined by consultant ophthalmologists and completed the Impact of Vision Impairment profile quality of life assessment and a Time Trade-Off evaluation. Vision-related utility values were calculated. The results were analysed using univariate and multivariate regression methods. IVI Rasch Logits and TTO utility values (TTO UV). 156 people volunteered to contribute to the study. The median age was 80 (19-97) years, and 56% were female. Being legally blind (logMAR > 1) (95% CI 1.1 to 5.2, P = 0.003), clinically depressed (95% CI -11.2 to -1.8, P = 0.007) or more than 40 years of age (95% CI 0.9 to 8.1, P = 0.015) significantly lowered overall impact of vision impairment scores. The emotional domain of impact of vision impairment was associated with willingness to trade part of remaining life. A 5-Logit increase in impact of vision impairment emotional score resulted in a 21% (95% CI 10 to 31) decrease in the odds of being likely to trade life for sight. The Australian definition of blindness compared with World Health Organisation or USA best separates those with perceived loss and appears useful in identifying vision loss-related morbidity. These results suggest that emotional health and lack of depression are important determinants for quality and value of life. © 2011 The Authors. Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists.

A Comparison between Discrimination Indices and Item-Response Theory Using the Rasch Model in a Clinical Course Written Examination of a Medical School.

PubMed

Park, Jong Cook; Kim, Kwang Sig

2012-03-01

The reliability of test is determined by each items' characteristics. Item analysis is achieved by classical test theory and item response theory. The purpose of the study was to compare the discrimination indices with item response theory using the Rasch model. Thirty-one 4th-year medical school students participated in the clinical course written examination, which included 22 A-type items and 3 R-type items. Point biserial correlation coefficient (C(pbs)) was compared to method of extreme group (D), biserial correlation coefficient (C(bs)), item-total correlation coefficient (C(it)), and corrected item-total correlation coeffcient (C(cit)). Rasch model was applied to estimate item difficulty and examinee's ability and to calculate item fit statistics using joint maximum likelihood. Explanatory power (r2) of Cpbs is decreased in the following order: C(cit) (1.00), C(it) (0.99), C(bs) (0.94), and D (0.45). The ranges of difficulty logit and standard error and ability logit and standard error were -0.82 to 0.80 and 0.37 to 0.76, -3.69 to 3.19 and 0.45 to 1.03, respectively. Item 9 and 23 have outfit > or =1.3. Student 1, 5, 7, 18, 26, 30, and 32 have fit > or =1.3. C(pbs), C(cit), and C(it) are good discrimination parameters. Rasch model can estimate item difficulty parameter and examinee's ability parameter with standard error. The fit statistics can identify bad items and unpredictable examinee's responses.

Linkage Analysis of Urine Arsenic Species Patterns in the Strong Heart Family Study

PubMed Central

Gribble, Matthew O.; Voruganti, Venkata Saroja; Cole, Shelley A.; Haack, Karin; Balakrishnan, Poojitha; Laston, Sandra L.; Tellez-Plaza, Maria; Francesconi, Kevin A.; Goessler, Walter; Umans, Jason G.; Thomas, Duncan C.; Gilliland, Frank; North, Kari E.; Franceschini, Nora; Navas-Acien, Ana

2015-01-01

Arsenic toxicokinetics are important for disease risks in exposed populations, but genetic determinants are not fully understood. We examined urine arsenic species patterns measured by HPLC-ICPMS among 2189 Strong Heart Study participants 18 years of age and older with data on ∼400 genome-wide microsatellite markers spaced ∼10 cM and arsenic speciation (683 participants from Arizona, 684 from Oklahoma, and 822 from North and South Dakota). We logit-transformed % arsenic species (% inorganic arsenic, %MMA, and %DMA) and also conducted principal component analyses of the logit % arsenic species. We used inverse-normalized residuals from multivariable-adjusted polygenic heritability analysis for multipoint variance components linkage analysis. We also examined the contribution of polymorphisms in the arsenic metabolism gene AS3MT via conditional linkage analysis. We localized a quantitative trait locus (QTL) on chromosome 10 (LOD 4.12 for %MMA, 4.65 for %DMA, and 4.84 for the first principal component of logit % arsenic species). This peak was partially but not fully explained by measured AS3MT variants. We also localized a QTL for the second principal component of logit % arsenic species on chromosome 5 (LOD 4.21) that was not evident from considering % arsenic species individually. Some other loci were suggestive or significant for 1 geographical area but not overall across all areas, indicating possible locus heterogeneity. This genome-wide linkage scan suggests genetic determinants of arsenic toxicokinetics to be identified by future fine-mapping, and illustrates the utility of principal component analysis as a novel approach that considers % arsenic species jointly. PMID:26209557

Effects of messages emphasizing environmental determinants of obesity on intentions to engage in diet and exercise behaviors.

PubMed

Niederdeppe, Jeff; Roh, Sungjong; Shapiro, Michael A; Kim, Hye Kyung

2013-12-12

Reducing rates of obesity will require interventions that influence both individual decisions and environmental factors through changes in public policy. Previous work indicates that messages emphasizing environmental determinants increases support for public policies, but some suspect this strategy may undermine motivation to engage in diet and exercise. Study 1 involved 485 adults recruited from a shopping mall in New York. Study 2 involved 718 adult members of a Web-based national panel of US adults. Respondents in both studies were randomly assigned to read a story that emphasized environmental determinants of health or a control condition. The stories varied in the extent to which they described the story character as taking personal responsibility for weight management. Logistic regression and ordered logit models were used to test for differences in intentions to engage in diet and exercise behaviors based on which story the participant read. Analyses were also performed separately by participants' weight status. In both studies, messages that acknowledged personal responsibility while emphasizing environmental causes of obesity increased intentions to engage in healthy behavior for at least 1 weight status group. Emphasizing factors outside of personal control appears to enhance rather than undermine motivations to engage in healthy diet and exercise behavior.

Chronic pain and health care spending: an analysis of longitudinal data from the Medical Expenditure Panel Survey.

PubMed

Stockbridge, Erica L; Suzuki, Sumihiro; Pagán, José A

2015-06-01

To estimate average incremental health care expenditures associated with chronic pain by health care service category, expanding on prior research that focused on specific pain conditions instead of general pain, excluded low levels of pain, or did not incorporate pain duration. Medical Expenditure Panel Survey (MEPS) data (2008-2011; N = 26,671). Differences in annual expenditures for adults at different levels of pain that interferes with normal work, as measured by the SF-12, were estimated using recycled predictions from two-part logit-generalized linear regression models. "A little bit" of chronic pain-related interference was associated with a $2,498 increase in total adjusted expenditures over no pain interference (p < .0001) and a $1,008 increase over nonchronic pain interference (p = .0001). Moderate and severe chronic pain-related interference was associated with a $3,707 and $5,804 increase in expenditures over no pain interference and a $2,218 and $4,315 increase over nonchronic interference, respectively (p < .0001). Expenditure increases were most pronounced for inpatient and hospital outpatient expenditures compared to other types of health care expenditures. Chronic pain limitations are associated with higher health care expenditures. Results underscore the substantial cost of pain to the health care system. © Health Research and Educational Trust.

How children with special health care needs affect the employment decisions of low-income parents.

PubMed

Loprest, Pamela; Davidoff, Amy

2004-09-01

To better understand the impact of having a child with special health care needs (CSHCN), on low-income parents' employment decisions. Using data from the 1999 and 2000 National Health Interview Survey (NHIS), we estimate multivariate statistical regressions (logit and tobit models) to estimate the relationship between having a CSHCN and the likelihood of employment and hours of employment for a sample-of low-income single parents. Controlling for differences in demographic and family characteristics, we find no significant association between having a CSHCN and the probability of work or the number of hours worked among low-income single-parent families. Separate analysis of different dimensions of special health care needs shows that parents of children with activity limitations are significantly less likely to work and work fewer hours. This result does not hold true for the group of children defined based on elevated or special service use, or for the group of children with specific chronic conditions. These results indicate that only a specific subset of children with special needs present difficulties for low-income parents' work. This suggests that policies to help low-income single parents of children with disabilities move into work should target this specific subset of children with special health care needs.

The Effect of Mystery Shopper Reports on Age Verification for Tobacco Purchases

PubMed Central

KREVOR, BRAD S.; PONICKI, WILLIAM R.; GRUBE, JOEL W.; DeJONG, WILLIAM

2011-01-01

Mystery shops (MS) involving attempted tobacco purchases by young buyers have been employed to monitor retail stores’ performance in refusing underage sales. Anecdotal evidence suggests that MS visits with immediate feedback to store personnel can improve age verification. This study investigated the impact of monthly and twice-monthly MS reports on age verification. Forty-five Walgreens stores were each visited 20 times by mystery shoppers. The stores were randomly assigned to one of three conditions. Control group stores received no feedback, whereas two treatment groups received feedback communications every visit (twice monthly) or every second visit (monthly) after baseline. Logit regression models tested whether each treatment group improved verification rates relative to the control group. Post-baseline verification rates were higher in both treatment groups than in the control group, but only the stores receiving monthly communications had a significantly greater improvement than control group stores. Verification rates increased significantly during the study period for all three groups, with delayed improvement among control group stores. Communication between managers regarding the MS program may account for the delayed age-verification improvements observed in the control group stores. Encouraging inter-store communication might extend the benefits of MS programs beyond those stores that receive this intervention. PMID:21541874

Nutritional causes of anemia in Mexican children under 5 years. Results from the 2006 National Health and Nutrition Survey.

PubMed

De la Cruz-Góngora, Vanessa; Villalpando, Salvador; Rebollar, Rosario; Shamah-Levy, Teresa; Méndez-Gómez Humarán, Ignacio

2012-01-01

To describe the frequency and severity of anemia and the nutritional variables associated to hemoglobin levels (Hb) in children <5 years of age. We studied 981 children measuring hemoglobin and serum concentrations of ferritin, soluble transferrin receptors (sTfR), C-reactive protein (CRP), zinc, iron, copper, magnesium, folate and vitamin B12. Ordinal logit or multiple regression models were constructed to assess the risk for anemia and the associations among nutritional variables. The overall prevalence of anemia was 20.6%, of which 14% were mild cases and 6.38% moderate. Anemia was associated with iron deficiency (ID) in 42.17% of the cases, whereas ID coexisted with either folate or vitamin B12 deficiency in 9%. Only 2% of cases of anemia were associated with either folate or vitamin B12 deficiencies. CRP (coef: 0.17 g/dl) and third tertile of s-copper (coef: -0.85 g/dl) were associated to unexplained anemia (p<0.05). ID is the main cause of anemia in children <5 y. Folate and vitamin B12 concentrations were associated with anemia. CRP was associated to unexplained anemia. However, vitamin A deficiency, which is associated with anemia, was not studied.

Stability and change in fertility preferences among young women in Malawi.

PubMed

Sennott, Christie; Yeatman, Sara

2012-03-01

Although studies have demonstrated change in fertility preferences over time, there is a lack of definitive knowledge about the level and direction of change among individuals, especially young and unmarried women. Furthermore, little is known about the factors associated with changes in fertility preferences over time. The analysis uses the first five waves of data from a longitudinal study of a random sample of women aged 15-25 in southern Malawi. The data were collected four months apart over an 18-month period, between June 2009 and December 2010. Multinomial logit regression models were used to calculate relative risk ratios and identify associations between four categories of life events-reproductive, relationship, health and economic-and shifts in fertility timing preferences. In each four-month period, more than half of the women reported changes in the desired timing of their next birth, and delays and accelerations in timing desires were common. Several life events, including having a child, entering a serious relationship and changes in household finances were associated with changes in the level and direction of fertility preference. Shifts in fertility timing preferences often occur in response to changes in life circumstances. Understanding the reasons for these shifts may aid family planning providers in meeting women's contraceptive needs.

Effects of Messages Emphasizing Environmental Determinants of Obesity on Intentions to Engage in Diet and Exercise Behaviors

PubMed Central

Roh, Sungjong; Shapiro, Michael A.; Kim, Hye Kyung

2013-01-01

Introduction Reducing rates of obesity will require interventions that influence both individual decisions and environmental factors through changes in public policy. Previous work indicates that messages emphasizing environmental determinants increases support for public policies, but some suspect this strategy may undermine motivation to engage in diet and exercise. Methods Study 1 involved 485 adults recruited from a shopping mall in New York. Study 2 involved 718 adult members of a Web-based national panel of US adults. Respondents in both studies were randomly assigned to read a story that emphasized environmental determinants of health or a control condition. The stories varied in the extent to which they described the story character as taking personal responsibility for weight management. Logistic regression and ordered logit models were used to test for differences in intentions to engage in diet and exercise behaviors based on which story the participant read. Analyses were also performed separately by participants’ weight status. Results In both studies, messages that acknowledged personal responsibility while emphasizing environmental causes of obesity increased intentions to engage in healthy behavior for at least 1 weight status group. Conclusion Emphasizing factors outside of personal control appears to enhance rather than undermine motivations to engage in healthy diet and exercise behavior. PMID:24331282

[Socio-demographic and health factors associated with the institutionalization of dependent people].

PubMed

Ayuso Gutiérrez, Mercedes; Pozo Rubio, Raúl Del; Escribano Sotos, Francisco

2010-01-01

The analysis of the effect that different variables have in the probability that dependent people are institutionalized is a topic scantily studied in Spain. The aim of the work is to analyze as certain socio-demographic and health factors can influence probability of dependent person living in a residence. A cross-section study has been conducted from a representative sample of the dependent population in Cuenca (Spain) in February, 2009. We have obtained information for people with level II and III of dependence. A binary logit regression model has been estimated to identify those factors related to the institutionalization of dependent people. People with ages between 65-74 years old are six times more likely to be institutionalized than younger people (< 65 years old); this probability increases sixteen times for those individuals with ages equal or higher than 95 years. The probability of institutionalization of people who live in an urban area is three times the probability of people who live in a rural area. People who need pharmacological, psychotherapy or rehabilitation treatments have between two and four times more probability of being institutionalized that those who do not need those. Age, marital status, place of residence, cardiovascular and musculoskeletal diseases and four times of medical treatment are the principal variables associated with the institutionalization of dependent people.

The effect of mystery shopper reports on age verification for tobacco purchases.

PubMed

Krevor, Brad S; Ponicki, William R; Grube, Joel W; DeJong, William

2011-09-01

Mystery shops involving attempted tobacco purchases by young buyers have been implemented in order to monitor retail stores' performance in refusing underage sales. Anecdotal evidence suggests that mystery shop visits with immediate feedback to store personnel can improve age verification. This study investigated the effect of monthly and twice-monthly mystery shop reports on age verification. Mystery shoppers visited 45 Walgreens stores 20 times. The stores were randomly assigned to 1 of 3 conditions. Control group stores received no feedback, whereas 2 treatment groups received feedback communications on every visit (twice monthly) or on every second visit (monthly) after baseline. Logit regression models tested whether each treatment group improved verification rates relative to the control group. Postbaseline verification rates were higher in both treatment groups than in the control group, but only the stores receiving monthly communications had a significantly greater improvement compared with the control group stores. Verification rates increased significantly during the study period for all 3 groups, with delayed improvement among control group stores. Communication between managers regarding the mystery shop program may account for the delayed age-verification improvements observed in the control group stores. Encouraging interstore communication might extend the benefits of mystery shop programs beyond those stores that receive this intervention. Copyright © Taylor & Francis Group, LLC

Modal split model considering carpool mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyles, R.W.

1979-03-01

Modal split remains a primary concern of transportation planners as the state-of-the art has developed from diversion curves to behavioral models. The approach taken here is to formulate the mode-choice decision for the work trip as a linear combination of real and perceived characteristics of the modes considered. The logit formulation is used with three modes being considered: two automobile modes (drive-alone and carpool) and a public transit mode (bus). The final model provides insight into which factors are important in travel decisions among these three modes and the importance of examining traveler's perceptions of the differences among modes relativemore » to actual measurable differences.« less

A Framework for the Analysis of the Reserve Officer Augmentation Process in the United States Marine Corps

DTIC Science & Technology

1987-12-01

occupation group, category (i.e., strength, loss, etc.), years of commissioned service (YCS), grade, occupation, source of commission, education, sex ...OF MCORP OUTPUT OCCUPATION GROUP: All CAT: Strength YCS: 01 - 09 GRADE: All Unrestricted Officers OCCUPATION: All SOURCE: All EDUCATION: All SEX : All...source of commission, sex , MOS, GCT, and other pertinent variables such as the performance index. A Probit or Logit model could be utilized. The variables

The economic value of stream restoration

NASA Astrophysics Data System (ADS)

Collins, Alan; Rosenberger, Randy; Fletcher, Jerald

2005-02-01

The economic value of restoring Deckers Creek in Monongalia and Preston counties of West Virginia was determined from mail, Internet, and personal contact surveys. Multiattribute, choice experiments were conducted and nested logit models were estimated to derive the economic values of full restoration for three attributes of this creek: aquatic life, swimming, and scenic quality. Their relative economic values were that aquatic life > scenic quality ≈ swimming. These economic values imply that respondents had the highest value for aquatic life when fully restoring Deckers Creek to a sustainable fishery rather than a "put and take" fishery that cannot sustain fish populations. The welfare improvement estimates for full restoration of all three attributes ranged between 12 and 16 per month per household. Potential stream users (anglers) had the largest welfare gain from restoration, while nonangler respondents had the lowest. When these estimates were aggregated up to the entire watershed population, the benefit from restoration of Deckers Creek was estimated to be about $1.9 million annually. This benefit does not account for any economic values from partial stream restoration. On the basis of log likelihood tests of the nested logit models, two subsamples of the survey population (the general population and stream users) were found to be from the same population. Thus restoration choices by stream users may be representative of the watershed population, although the sample size of stream users was small in this research.

Sociodemographic and health-lifestyle determinants of obesity risks in Malaysia.

PubMed

Tan, Andrew K G; Dunn, Richard A; Samad, Mohamed Ismail Abdul; Feisul, Mustapha Idzwan

2011-04-01

The purpose of this study was to examine the sociodemographic and health-lifestyle factors that affect the likelihood of obesity among Malaysians. Data were obtained from the Malaysian Non-Communicable Disease Surveillance-1. The cross-sectional population-based survey consisted of 2447 observations, with an obesity prevalence rate of 17.2%. Based on logit regression analysis, the results suggest that obesity risks in Malaysia are affected by gender, education level, family history, health conditions, smoking status, and ethnic backgrounds. Specifically, Malaysians more likely to be obese are females (5.3%), lower educated (0.9%), those with history of family illnesses (4.8%), and nonsmokers (6.4%). However, Chinese (9.3%) and other (5.5%) ethnic groups are less likely to be obese when compared with Malays. Based on these results, several policy implications are discussed vis-à-vis obesity risks in Malaysia.

The demand for statin: the effect of copay on utilization and compliance.

PubMed

Thiebaud, Patrick; Patel, Bimal V; Nichol, Michael B

2008-01-01

Increasing drug costs in the US have prompted employers and insurers alike to turn to higher drug copays for cost containment. The effect of rising copays on compliance with statins (HMG-CoA reductase inhibitors) treatment has received surprisingly little attention in the applied literature. This paper uses pharmacy claims data from a commercially insured adult population to determine the effect of copay change on compliance at the individual level. Fixed effect logit and Poisson regressions estimate the effect of copays on monthly likelihood of high compliance and average monthly days of supply respectively. Higher copays reduce compliance among statin users, with less compliant patients responding more strongly to copay change than compliant patients. These results suggest that specific financial incentives given to less compliant patients could improve compliance with statin treatment at a relatively low cost. Copyright (c) 2007 John Wiley & Sons, Ltd.

Empowerment and physical violence throughout women's reproductive life in Mexico.

PubMed

Castro, Roberto; Casique, Irene; Brindis, Claire D

2008-06-01

This article analyzes intimate partner violence (IPV) against women aged 15 to 21, 30 to 34, and 45 to 49, based on the 2003 National Survey on the Dynamics of Household Relationships (in Spanish, ENDIREH) in Mexico. The authors examined the degree of women's empowerment and autonomy in relation to their partners. Logit regression analyses showed that variables significantly associated with physical violence varied between the three age groups, suggesting that women followed specific trajectories throughout their reproductive lives. Some dimensions of empowerment reduced the risk of violence (women's ability to decide whether to work, when to have sexual relations, and the extent of their partners' participation in household chores). Other dimensions (women's decision making regarding reproductive matters) increased such risk. Thus, access to resources meant to empower women did not automatically decrease the risk of violence. The authors recommend specific interventions tailored to each age group, aimed at breaking the cycle of violence.

An Empirical Bayes Approach to Spatial Analysis

NASA Technical Reports Server (NTRS)

Morris, C. N.; Kostal, H.

1983-01-01

Multi-channel LANDSAT data are collected in several passes over agricultural areas during the growing season. How empirical Bayes modeling can be used to develop crop identification and discrimination techniques that account for spatial correlation in such data is considered. The approach models the unobservable parameters and the data separately, hoping to take advantage of the fact that the bulk of spatial correlation lies in the parameter process. The problem is then framed in terms of estimating posterior probabilities of crop types for each spatial area. Some empirical Bayes spatial estimation methods are used to estimate the logits of these probabilities.

Estimating child mortality and modelling its age pattern for India.

PubMed

Roy, S G

1989-06-01

"Using data [for India] on proportions of children dead...estimates of infant and child mortality are...obtained by Sullivan and Trussell modifications of [the] Brass basic method. The estimate of child survivorship function derived after logit smoothing appears to be more reliable than that obtained by the Census Actuary. The age pattern of childhood mortality is suitably modelled by [a] Weibull function defining the probability of surviving from birth to a specified age and involving two parameters of level and shape. A recently developed linearization procedure based on [a] graphical approach is adopted for estimating the parameters of the function." excerpt

Factors associated with the frequency of monitoring of liver enzymes, renal function and lipid laboratory markers among individuals initiating combination antiretroviral therapy: a cohort study.

PubMed

Gillis, Jennifer; Bayoumi, Ahmed M; Burchell, Ann N; Cooper, Curtis; Klein, Marina B; Loutfy, Mona; Machouf, Nima; Montaner, Julio Sg; Tsoukas, Chris; Hogg, Robert S; Raboud, Janet

2015-10-26

As the average age of the HIV-positive population increases, there is increasing need to monitor patients for the development of comorbidities as well as for drug toxicities. We examined factors associated with the frequency of measurement of liver enzymes, renal function tests, and lipid levels among participants of the Canadian Observational Cohort (CANOC) collaboration which follows people who initiated HIV antiretroviral therapy in 2000 or later. We used zero-inflated negative binomial regression models to examine the associations of demographic and clinical characteristics with the rates of measurement during follow-up. Generalized estimating equations with a logit link were used to examine factors associated with gaps of 12 months or more between measurements. Electronic laboratory data were available for 3940 of 7718 CANOC participants. The median duration of electronic follow-up was 3.5 years. The median (interquartile) rates of tests per year were 2.76 (1.60, 3.73), 2.55 (1.44, 3.38) and 1.42 (0.50, 2.52) for liver, renal and lipid parameters, respectively. In multivariable zero-inflated negative binomial regression models, individuals infected through injection drug use (IDU) were significantly less likely to have any measurements. Among participants with at least one measurement, rates of measurement of liver, renal and lipid tests were significantly lower for younger individuals and Aboriginal Peoples. Hepatitis C co-infected individuals with a history of IDU had lower rates of measurement and were at greater risk of having 12 month gaps between measurements. Hepatitis C co-infected participants infected through IDU were at increased risk of gaps in testing, despite publicly funded health care and increased risk of comorbid conditions. This should be taken into consideration in analyses examining factors associated with outcomes based on laboratory parameters.

Self-reported functional, communicative, and critical health literacy on foodborne diseases in Accra, Ghana.

PubMed

Gupta, Sangeeta; Tutu, Raymond Asare; Boateng, John; Busingye, Janice Desire; Elavarthi, Sathya

2018-01-01

Although substantial progress has been made in reducing total mortality resulting from foodborne diseases, diarrheal illness are still the second most common illnesses among children. In Ghana, foodborne diseases have consistently been among the top 20 causes of outpatient illness over the last couple of decades. This study, therefore, examines health literacy on foodborne diseases and the relative effects of health literacy on self-rated health. Foodborne diseases are major causes of morbidity and mortality globally. A mixed-method approach was used for this study. A survey questionnaire and an in-depth interview guideline were administered to samples of 401 and 30 individuals, respectively. We undertook reliability and validity analyses. ANOVA and chi-square tests were undertaken to assess bivariate association between health literacy and demographic variables as well as health status. Ordinal logistic regression models were used to examine the relative effects of health literacy on self-rated health status controlling for individual characteristics. The instrument was internally consistent (Cronbach alpha = 0.744) and valid. On health literacy, 40% of the respondents reported not to require help when they are given information on foodborne diseases to read by a doctor, nurse, or pharmacist. Approximately 60% of respondents need help with completing or filling out hospital documents. Educational level was found to be positively related to functional health literacy. Ordinal logit regression models showed that health literacy is a predictor of self-rated health after controlling for demographic variables. Functional literacy is relatively low in the community. There is a positive association between educational level and functional health literacy. The study has also demonstrated the direct positive relationship between health literacy and health status controlling for covariates. Subsequent studies will need to examine multiple level dimensions of health literacy with direct link between specific foodborne diseases and health literacy.

Estimating a Preference-Based Index from the Clinical Outcomes in Routine Evaluation–Outcome Measure (CORE-OM)

PubMed Central

Brazier, John E.; Rowen, Donna; Barkham, Michael

2013-01-01

Background. The Clinical Outcomes in Routine Evaluation–Outcome Measure (CORE-OM) is used to evaluate the effectiveness of psychological therapies in people with common mental disorders. The objective of this study was to estimate a preference-based index for this population using CORE-6D, a health state classification system derived from the CORE-OM consisting of a 5-item emotional component and a physical item, and to demonstrate a novel method for generating states that are not orthogonal. Methods. Rasch analysis was used to identify 11 emotional health states from CORE-6D that were frequently observed in the study population and are, thus, plausible (in contrast, conventional statistical design might generate implausible states). Combined with the 3 response levels of the physical item of CORE-6D, they generate 33 plausible health states, 18 of which were selected for valuation. A valuation survey of 220 members of the public in South Yorkshire, United Kingdom, was undertaken using the time tradeoff (TTO) method. Regression analysis was subsequently used to predict values for all possible states described by CORE-6D. Results. A number of multivariate regression models were built to predict values for the 33 health states of CORE-6D, using the Rasch logit value of the emotional state and the response level of the physical item as independent variables. A cubic model with high predictive value (adjusted R2 = 0.990) was selected to predict TTO values for all 729 CORE-6D health states. Conclusion. The CORE-6D preference-based index will enable the assessment of cost-effectiveness of interventions for people with common mental disorders using existing and prospective CORE-OM data sets. The new method for generating states may be useful for other instruments with highly correlated dimensions. PMID:23178639

Adoption and Diffusion of Evidence-Based Addiction Medications in Substance Abuse Treatment

PubMed Central

Heinrich, Carolyn J; Cummings, Grant R

2014-01-01

ObjectiveTo examine the roles of facility-and state-level factors in treatment facilities’ adoption and diffusion of pharmaceutical agents used in addiction treatment. Data SourcesSecondary data from the National Survey of Substance Abuse Treatment Services (N-SSATS), Substance Abuse and Mental Health Services Administration (SAMHSA), Centers for Medicare and Medicaid Services, Alcohol Policy Information System, and Kaiser Family Foundation. Study DesignWe estimate ordered logit and multinomial logit models to examine the relationship of state and treatment facility characteristics to the adoption and diffusion of three pharmaceutical agents over 4 years when each was at a different stage of adoption or diffusion. Data CollectionN-SSATS data with facility codes, obtained directly from SAMHSA, were linked by state identifiers to the other publicly available, secondary data. Principal FindingsThe analysis confirms the importance of awareness and exposure to the adoption behavior of others, dissemination of information about the feasibility and effectiveness of innovations, geographical clustering, and licensing and accreditation in legitimizing facilities’ adoption and continued use of pharmacotherapies in addiction treatment. ConclusionsPolicy and administrative levers exist to increase the availability of pharmaceutical technologies and their continued use by substance abuse treatment facilities. PMID:23855719

The Effect of Three-Tier Formulary Adoption on Medication Continuation and Spending among Elderly Retirees

PubMed Central

Huskamp, Haiden A; Deverka, Patricia A; Landrum, Mary Beth; Epstein, Robert S; McGuigan, Kimberly A

2007-01-01

Objective To assess the effect of three-tier formulary adoption on medication continuation and spending among elderly members of retiree health plans. Data Sources Pharmacy claims and enrollment data on elderly members of four retiree plans that adopted a three-tier formulary over the period July 1999 through December 2002 and two comparison plans that maintained a two-tier formulary during this period. Study Design We used a quasi-experimental design to compare the experience of enrollees in intervention and comparison plans. We used propensity score methods to match intervention and comparison users of each drug class and plan. We estimated repeated measures regression models for each class/plan combination for medication continuation and monthly plan, enrollee, and total spending. We estimated logit models of the probability of nonpersistent use, medication discontinuation, and medication changes. Data Collection/Extraction Methods We used pharmacy claims to create person-level drug utilization and spending files for the year before and year after three-tier adoption. Principal Findings Three-tier formulary adoption resulted in shifting of costs from plan to enrollee, with relatively small effects on medication continuation. Although implementation had little effect on continuation on average, a small minority of patients were more likely to have gaps in use and discontinue use relative to comparison patients. Conclusions Moderate cost sharing increases from three-tier formulary adoption had little effect on medication continuation among elderly enrolled in retiree health plans with relatively generous drug coverage. PMID:17850526

Centre-level variation in behaviour and the predictors of behaviour in 5-year-old children with non-syndromic unilateral cleft lip: The Cleft Care UK study. Part 5.

PubMed

Waylen, A; Mahmoud, O; Wills, A K; Sell, D; Sandy, J R; Ness, A R

2017-06-01

The aims of this study were to describe child behavioural and psychosocial outcomes associated with appearance and speech in the Cleft Care UK (CCUK) study. We also wanted to explore centre-level variation in child outcomes and investigate individual predictors of such outcomes. Two hundred and sixty-eight five-year-old children with non-syndromic unilateral cleft lip and palate (UCLP) recruited to CCUK. Parents completed the Strengths and Difficulties questionnaire (SDQ) and reported their own perceptions of the child's self-confidence. Child facial appearance and symmetry were assessed using photographs, and intelligibility of speech was derived from audio-visual speech recordings. Centre-level variation in behavioural and psychosocial outcomes was examined using hierarchical models, and associations with clinical outcomes were examined using logit regression models. Children with UCLP had a higher hyperactive difficulty score than the general population. For boys, the average score was 4.5 vs 4.1 (P=.03), and for girls, the average score was 3.8 vs 3.1 (P=.008). There was no evidence of centre-level variation for behaviour or parental perceptions of the child's self-confidence. There is no evidence of associations between self-confidence and SDQ scores and either facial appearance or behaviour. Children born with UCLP have higher levels of behaviour problems than the general population. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Preparing Teachers to Use GIS: The Impact of a Hybrid Professional Development Program on Teachers' Use of GIS

NASA Astrophysics Data System (ADS)

Moore, Steven; Haviland, Don; Moore, William; Tran, Michael

2016-12-01

This article reports the findings of a 3-year study of a hybrid professional development program designed to prepare science and mathematics teachers to implement GIS in their classrooms. The study was conducted as part of the CoastLines Innovative Technology Experiences for Students and Teachers project funded by the National Science Foundation. Three cohorts of teachers participated in the program, with each participant receiving 40 h of synchronous online instruction and 80 h of in-person instruction and support over an 8-month period. Data from surveys of participants both before and after the program were analyzed using correlation, ordinary least squares, and ordered logit regression analyses. The analyses revealed increases in the self-reported frequency of GIS use and enhanced feelings of preparation, competence, community, and comfort with respect to using GIS for instruction. A composite index of all impact variables was positively influenced as well. The statistical analyses found a strong relationship between self-reported feelings of preparation and use of GIS. Some support was found for the idea that feelings of competence, community, and comfort were related to the teachers' sense of preparation. The findings suggest that a robust hybrid model of teacher professional development can prepare teachers to use GIS in their classrooms. More research is needed to understand how hybrid models influence the sociopsychological and other dimensions that support teachers' feelings of preparation to implement GIS.

Incorporating real-time traffic and weather data to explore road accident likelihood and severity in urban arterials.

PubMed

Theofilatos, Athanasios

2017-06-01

The effective treatment of road accidents and thus the enhancement of road safety is a major concern to societies due to the losses in human lives and the economic and social costs. The investigation of road accident likelihood and severity by utilizing real-time traffic and weather data has recently received significant attention by researchers. However, collected data mainly stem from freeways and expressways. Consequently, the aim of the present paper is to add to the current knowledge by investigating accident likelihood and severity by exploiting real-time traffic and weather data collected from urban arterials in Athens, Greece. Random Forests (RF) are firstly applied for preliminary analysis purposes. More specifically, it is aimed to rank candidate variables according to their relevant importance and provide a first insight on the potential significant variables. Then, Bayesian logistic regression as well finite mixture and mixed effects logit models are applied to further explore factors associated with accident likelihood and severity respectively. Regarding accident likelihood, the Bayesian logistic regression showed that variations in traffic significantly influence accident occurrence. On the other hand, accident severity analysis revealed a generally mixed influence of traffic variations on accident severity, although international literature states that traffic variations increase severity. Lastly, weather parameters did not find to have a direct influence on accident likelihood or severity. The study added to the current knowledge by incorporating real-time traffic and weather data from urban arterials to investigate accident occurrence and accident severity mechanisms. The identification of risk factors can lead to the development of effective traffic management strategies to reduce accident occurrence and severity of injuries in urban arterials. Copyright © 2017 Elsevier Ltd and National Safety Council. All rights reserved.

The Impact of Income and Taxation in a Price-Tiered Cigarette Market - findings from the ITC Bangladesh Surveys.

PubMed

Huq, Iftekharul; Nargis, Nigar; Lkhagvasuren, Damba; Hussain, Akm Ghulam; Fong, Geoffrey T

2018-04-25

Taxing tobacco is among the most effective measures of tobacco control. However, in a tiered market structure where multiple tiers of taxes coexist, the anticipated impact of tobacco taxes on consumption is complex. This paper investigates changing smoking behaviour in lieu of changing prices and changing income. The objective of the paper is to evaluate the effectiveness of change in prices (through taxes) and change in income in a price-tiered cigarette market. A panel dataset from the International Tobacco Control Bangladesh surveys is used for analysis. For preliminary analysis transition matrices are developed. Next, probit and multinomial logit regression models are used to identify the effects of changes in prices and changes in income along with other control variables. Transition matrices show significant movement of smokers across price tiers from one wave to another. Regression results show that higher income raises the probability to up-trade and decreases the probability to down-trade. Results also show that higher prices raises the probability to up-trade and reduces the probability to down-trade. Although not significant, there exists a negative relationship between the probability to down-trade and the probability to intend to quit. It is evident from the results that a price-tiered market provides smokers more opportunities to accommodate their smoking behaviour when faced with price and income change. Therefore, tiered structure of the tax system should be replaced with uniform taxes. Moreover, overall cigarette taxes need to be raised to an extent so that it off-sets any positive effects of income growth. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Levels and patterns of physical activity and sedentary time among superdiverse adolescents in East London: a cross-sectional study.

PubMed

Curry, Whitney B; Dagkas, Symeon; Wilson, Marcia

2017-06-01

Little is known about the physical activity (PA) and sedentary time (ST) habits of adolescents from superdiverse communities in the UK. The objectives of this study are to examine and report the patterns of PA/ST among adolescents in East London living in superdiverse communities, to identify opportunities/barriers to PA and inform policy/practice. A total of 1260 young people (aged 11-13 years) from seven secondary schools in East London completed a questionnaire on PA/ST over the past seven days as part of the Newham's Every Child a Sports Person (NECaSP) intervention. Socio-demographic and anthropometric data were obtained. Significance tests were conducted to determine differences between socio-demographic and anthropometric predictors and PA/ST. Multinomial logit regression was used to explore the effects of ethnicity, sex, and body mass index (BMI) on PA levels. Males were significantly more likely to engage in PA at least five times during school in the past week (U = 5.07, z = -11.76, p < .05). Obese participants were less likely to report engaging in PA five times in the past week (U = 4.11, z =-1.17, p < .05). Black Caribbean girls (U = 5.08, z = -1.92, p < .05) were significantly more likely to report engaging in no activity. Multinomial logit regression analyses revealed that girls with higher BMI were less likely to engage in PA at least four times after school in the last week than boys (b = .11, Wald X 2 (1) = 9.81, p < .01). Walking (36.4%), jogging/running (29.9%), and football (28%) were the most frequently reported activities. Engaging girls in PA during and after school is important and making sports clubs and activities available and attractive to this target group may help increase engagement in PA and reduce ST. Findings support the need for more sex-specific and culturally responsive pedagogy in schools with curricula that respects diversity and individuality and has meaning and value amongst superdiverse young people. Finally, we need to extend current work presented and provide substantial evidence of the ways young people from minority ethnic groups process and act on the public health policy and the ways they understand and enact PA.

Getting the right balance? A mixed logit analysis of the relationship between UK training doctors' characteristics and their specialties using the 2013 National Training Survey.

PubMed

Rodriguez Santana, Idaira; Chalkley, Martin

2017-08-11

To analyse how training doctors' demographic and socioeconomic characteristics vary according to the specialty that they are training for. Descriptive statistics and mixed logistic regression analysis of cross-sectional survey data to quantify evidence of systematic relationships between doctors' characteristics and their specialty. Doctors in training in the United Kingdom in 2013. 27 530 doctors in training but not in their foundation year who responded to the National Training Survey 2013. Mixed logit regression estimates and the corresponding odds ratios (calculated separately for all doctors in training and a subsample comprising those educated in the UK), relating gender, age, ethnicity, place of studies, socioeconomic background and parental education to the probability of training for a particular specialty. Being female and being white British increase the chances of being in general practice with respect to any other specialty, while coming from a better-off socioeconomic background and having parents with tertiary education have the opposite effect. Mixed results are found for age and place of studies. For example, the difference between men and women is greatest for surgical specialties for which a man is 12.121 times more likely to be training to a surgical specialty (relative to general practice) than a woman (p-value<0.01). Doctors who attended an independent school which is proxy for doctor's socioeconomic background are 1.789 and 1.413 times more likely to be training for surgical or medical specialties (relative to general practice) than those who attended a state school (p-value<0.01). There are systematic and substantial differences between specialties in respect of training doctors' gender, ethnicity, age and socioeconomic background. The persistent underrepresentation in some specialties of women, minority ethnic groups and of those coming from disadvantaged backgrounds will impact on the representativeness of the profession into the future. Further research is needed to understand how the processes of selection and the self-selection of applicants into specialties gives rise to these observed differences. © 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.

Item Banking Enables Stand-Alone Measurement of Driving Ability.

PubMed

Khadka, Jyoti; Fenwick, Eva K; Lamoureux, Ecosse L; Pesudovs, Konrad

2016-12-01

To explore whether large item sets, as used in item banking, enable important latent traits, such as driving, to form stand-alone measures. The 88-item activity limitation (AL) domain of the glaucoma module of the Eye-tem Bank was interviewer-administered to patients with glaucoma. Rasch analysis was used to calibrate all items in AL domain on the same interval-level scale and test its psychometric properties. Based on Rasch dimensionality metrics, the AL scale was separated into subscales. These subscales underwent separate Rasch analyses to test whether they could form stand-alone measures. Independence of these measures was tested with Bland and Altman (B&A) Limit of Agreement (LOA). The AL scale was completed by 293 patients (median age, 71 years). It demonstrated excellent precision (3.12). However, Rasch analysis dimensionality metrics indicated that the domain arguably had other dimensions which were driving, luminance, and reading. Once separated, the remaining AL items, driving and luminance subscales, were unidimensional and had excellent precision of 4.25, 2.94, and 2.22, respectively. The reading subscale showed poor precision (1.66), so it was not examined further. The luminance subscale demonstrated excellent agreement (mean bias, 0.2 logit; 95% LOA, -2.2 to 3.3 logit); however, the driving subscale demonstrated poor agreement (mean bias, 1.1 logit; 95% LOA, -4.8 to 7.0 logit) with the AL scale. These findings indicate that driving items in the AL domain of the glaucoma module were perceived and responded to differently from the other AL items, but the reading and luminance items were not. Therefore, item banking enables stand-alone measurement of driving ability in glaucoma.

Absence of a moderating effect of parent health literacy on Early Head Start enrollment and dental use.

PubMed

Burgette, Jacqueline M; Preisser, John S; Weinberger, Morris; King, Rebecca S; Lee, Jessica Y; Rozier, R Gary

2018-04-16

To examine the moderating effect of parents' health literacy (HL) on the effectiveness of North Carolina Early Head Start (EHS) in improving children's dental use. Parents of 479 children enrolled in EHS and 699 Medicaid-matched parent-child dyads were interviewed at baseline when children were approximately 10 months old and 24 months later. We used in-person computer-assisted, structured interviews to collect information on sociodemographic characteristics, dental use, and administer the Short Assessment of Health Literacy - Spanish and English (SAHL-S&E). This quasi-experimental study tested whether the interaction effect between EHS and parents' HL was associated with dental use. Logit (any use) and marginalized zero-inflated negative binomial count models (number of dental visits) included random effects to account for clustering and controlled for baseline dental use, dental need, survey language, and a propensity score covariate. Nineteen percent of parents in EHS had low literacy compared to 12 percent of parents in the non-EHS group (P < 0.01). The interaction term between EHS and parent's HL was not significant in the adjusted logit model (ratio of aORs 0.98, 95 percent CI: 0.43-2.20) or the adjusted count model (ratio of aRRs 0.88, 95 percent CI: 0.72-1.09). Parents in EHS had a higher prevalence of low HL compared to non-EHS parents. Parents' HL did not moderate the relationship between EHS and child dental use, suggesting that EHS results in similar improvements in dental use regardless of parent's HL levels. © 2018 American Association of Public Health Dentistry.

Effects of truck traffic on crash injury severity on rural highways in Wyoming using Bayesian binary logit models.

PubMed

Ahmed, Mohamed M; Franke, Rebecca; Ksaibati, Khaled; Shinstine, Debbie S

2018-08-01

Roadway safety is an integral part of a functioning infrastructure. A major use of the highway system is the transport of goods. The United States has experienced constant growth in the amount of freight transported by truck in the last few years. Wyoming is experiencing a large increase in truck traffic on its local and county roads due to an increase in oil and gas production. This study explores the involvement of heavy trucks in crashes and their significance as a predictor of crash severity and addresses the effect that large truck traffic is having on the safety of roadways for various road classifications. Studies have been done on the factors involved in and the causation of heavy truck crashes, but none address the causation and effect of roadway classifications on truck crashes. Binary Logit Models (BLM) with Bayesian inferences were utilized to classify heavy truck involvement in severe and non-severe crashes using ten years (2002-2011) of historical crash data in the State of Wyoming. From the final main effects model, various interactions proved to be significant in predicting the severity of crashes and varied depending on the roadway classification. The results indicated the odds of a severe crash increase to 2.3 and 4.5 times when a heavy truck is involved on state and interstate highways respectively. The severity of crashes is significantly increased when road conditions were not clear, icy, and during snowy weather conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Investigating burden of informal caregivers in England, Finland and Greece: an analysis with the short form of the Burden Scale for Family Caregivers (BSFC-s).

PubMed

Konerding, Uwe; Bowen, Tom; Forte, Paul; Karampli, Eleftheria; Malmström, Tomi; Pavi, Elpida; Torkki, Paulus; Graessel, Elmar

2018-02-01

The burden of informal caregivers might show itself in different ways in different cultures. Understanding these differences is important for developing culture-specific measures aimed at alleviating caregiver burden. Hitherto, no findings regarding such cultural differences between different European countries were available. In this paper, differences between English, Finnish and Greek informal caregivers of people with dementia are investigated. A secondary analysis was performed with data from 36 English, 42 Finnish and 46 Greek caregivers obtained with the short form of the Burden Scale for Family Caregivers (BSFC-s). The probabilities of endorsing the BSFC-s items were investigated by computing a logit model with items and countries as categorical factors. Statistically significant deviation of data from this model was taken as evidence for country-specific response patterns. The two-factorial logit model explains the responses to the items quite well (McFadden's pseudo-R-square: 0.77). There are, however, also statistically significant deviations (p < 0.05). English caregivers have a stronger tendency to endorse items addressing impairments in individual well-being; Finnish caregivers have a stronger tendency to endorse items addressing the conflict between the demands resulting from care and demands resulting from the remaining social life and Greek caregivers have a stronger tendency to endorse items addressing impairments in physical health. Caregiver burden shows itself differently in English, Finnish and Greek caregivers. Accordingly, measures for alleviating caregiver burden in these three countries should address different aspects of the caregivers' lives.

An agent-based model for queue formation of powered two-wheelers in heterogeneous traffic

NASA Astrophysics Data System (ADS)

Lee, Tzu-Chang; Wong, K. I.

2016-11-01

This paper presents an agent-based model (ABM) for simulating the queue formation of powered two-wheelers (PTWs) in heterogeneous traffic at a signalized intersection. The main novelty is that the proposed interaction rule describing the position choice behavior of PTWs when queuing in heterogeneous traffic can capture the stochastic nature of the decision making process. The interaction rule is formulated as a multinomial logit model, which is calibrated by using a microscopic traffic trajectory dataset obtained from video footage. The ABM is validated against the survey data for the vehicular trajectory patterns, queuing patterns, queue lengths, and discharge rates. The results demonstrate that the proposed model is capable of replicating the observed queue formation process for heterogeneous traffic.

A MELD-based model to determine risk of mortality among patients with acute variceal bleeding.

PubMed

Reverter, Enric; Tandon, Puneeta; Augustin, Salvador; Turon, Fanny; Casu, Stefania; Bastiampillai, Ravin; Keough, Adam; Llop, Elba; González, Antonio; Seijo, Susana; Berzigotti, Annalisa; Ma, Mang; Genescà, Joan; Bosch, Jaume; García-Pagán, Joan Carles; Abraldes, Juan G

2014-02-01

Patients with cirrhosis with acute variceal bleeding (AVB) have high mortality rates (15%-20%). Previously described models are seldom used to determine prognoses of these patients, partially because they have not been validated externally and because they include subjective variables, such as bleeding during endoscopy and Child-Pugh score, which are evaluated inconsistently. We aimed to improve determination of risk for patients with AVB. We analyzed data collected from 178 patients with cirrhosis (Child-Pugh scores of A, B, and C: 15%, 57%, and 28%, respectively) and esophageal AVB who received standard therapy from 2007 through 2010. We tested the performance (discrimination and calibration) of previously described models, including the model for end-stage liver disease (MELD), and developed a new MELD calibration to predict the mortality of patients within 6 weeks of presentation with AVB. MELD-based predictions were validated in cohorts of patients from Canada (n = 240) and Spain (n = 221). Among study subjects, the 6-week mortality rate was 16%. MELD was the best model in terms of discrimination; it was recalibrated to predict the 6-week mortality rate with logistic regression (logit, -5.312 + 0.207 • MELD; bootstrapped R(2), 0.3295). MELD values of 19 or greater predicted 20% or greater mortality, whereas MELD scores less than 11 predicted less than 5% mortality. The model performed well for patients from Canada at all risk levels. In the Spanish validation set, in which all patients were treated with banding ligation, MELD predictions were accurate up to the 20% risk threshold. We developed a MELD-based model that accurately predicts mortality among patients with AVB, based on objective variables available at admission. This model could be useful to evaluate the efficacy of new therapies and stratify patients in randomized trials. Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.

Analysis of Salmonella sp bacterial contamination on Vannamei Shrimp using binary logit model approach

NASA Astrophysics Data System (ADS)

Oktaviana, P. P.; Fithriasari, K.

2018-04-01

Mostly Indonesian citizen consume vannamei shrimp as their food. Vannamei shrimp also is one of Indonesian exports comodities mainstay. Vannamei shrimp in the ponds and markets could be contaminated by Salmonella sp bacteria. This bacteria will endanger human health. Salmonella sp bacterial contamination on vannamei shrimp could be affected by many factors. This study is intended to identify what factors that supposedly influence the Salmonella sp bacterial contamination on vannamei shrimp. The researchers used the testing result of Salmonella sp bacterial contamination on vannamei shrimp as response variable. This response variable has two categories: 0 = if testing result indicate that there is no Salmonella sp on vannamei shrimp; 1 = if testing result indicate that there is Salmonella sp on vannamei shrimp. There are four factors that supposedly influence the Salmonella sp bacterial contamination on vannamei shrimp, which are the testing result of Salmonella sp bacterial contamination on farmer hand swab; the subdistrict of vannamei shrimp ponds; the fish processing unit supplied by; and the pond are in hectare. This four factors used as predictor variables. The analysis used is Binary Logit Model Approach according to the response variable that has two categories. The analysis result indicates that the factors or predictor variables which is significantly affect the Salmonella sp bacterial contamination on vannamei shrimp are the testing result of Salmonella sp bacterial contamination on farmer hand swab and the subdistrict of vannamei shrimp ponds.

Utilization of infertility services: how much does money matter?

PubMed

Farley Ordovensky Staniec, J; Webb, Natalie J

2007-06-01

To estimate the effects of financial access and other individual characteristics on the likelihood that a woman pursues infertility treatment and the choice of treatment type. The 1995 National Survey of Family Growth. We use a binomial logit model to estimate the effects of financial access and individual characteristics on the likelihood that a woman pursues infertility treatment. We then use a multinomial logit model to estimate the differential effects of these variables across treatment types. This study analyzes the subset of 1,210 women who meet the definition of infertile or subfecund from the 1995 National Survey of Family Growth. We find that income, insurance coverage, age, and parity (number of previous births) all significantly affect the probability of seeking infertility treatment; however, the effect of these variables on choice of treatment type varies significantly. Neither income nor insurance influences the probability of seeking advice, a relatively low cost, low yield treatment. At the other end of the spectrum, the choice to pursue assisted reproductive technologies (ARTs)-a much more expensive but potentially more productive option-is highly influenced by income, but merely having private insurance has no significant effect. In the middle of the spectrum are treatment options such as testing, surgery, and medications, for which "financial access" increases their probability of selection. Our results illustrate that for the sample of infertile of subfecund women of childbearing age studied, and considering their options, financial access to infertility treatment does matter.

Treatment preferences of originator versus biosimilar drugs in Crohn's disease; discrete choice experiment among gastroenterologists.

PubMed

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

2016-01-01

To explore preferences of gastroenterologists for biosimilar drugs in Crohn's disease. Discrete choice experiment was carried out involving 51 Hungarian gastroenterologists in May 2014. The following attributes were used to describe hypothetical choice sets: 1) type of the treatment (biosimilar/originator), 2) severity of disease, 3) availability of continuous medicine supply, 4) frequency of the efficacy check-ups. Multinomial logit model was used to differentiate between three attitude types: 1) always opting for the originator, 2) willing to consider biosimilar for biological-naïve patients only, 3) willing to consider biosimilar treatment for both types of patients. Conditional logit model was used to estimate the probabilities of choosing a given profile. Men, senior consultants, working in inflammatory bowel disease center and treating more patients were more likely willing to consider biosimilar for biological-naïve patients only. Treatment type (originator/biosimilar) was the most important determinant of choice for patients already treated with biologicals, and the availability of continuous medicine supply in case of biological-naïve patients. The probabilities of choosing the biosimilar with all the benefits offered over the originator under current reimbursement conditions are 89% versus 11% for new patients, and 44% versus 56% for patients already treated with biological. For gastroenterologist, the continuous medical supply would be one of the major benefits of biosimilars. However, benefits offered in the scenarios do not compensate for the change from the originator to the biosimilar treatment of patients already treated with biologicals.

Use of collateral information to improve LANDSAT classification accuracies

NASA Technical Reports Server (NTRS)

Strahler, A. H. (Principal Investigator)

1981-01-01

Methods to improve LANDSAT classification accuracies were investigated including: (1) the use of prior probabilities in maximum likelihood classification as a methodology to integrate discrete collateral data with continuously measured image density variables; (2) the use of the logit classifier as an alternative to multivariate normal classification that permits mixing both continuous and categorical variables in a single model and fits empirical distributions of observations more closely than the multivariate normal density function; and (3) the use of collateral data in a geographic information system as exercised to model a desired output information layer as a function of input layers of raster format collateral and image data base layers.

Relationships between training load, injury, and fitness in sub-elite collision sport athletes.

PubMed

Gabbett, Tim J; Domrow, Nathan

2007-11-01

The purpose of this study was to develop statistical models that estimate the influence of training load on training injury and physical fitness in collision sport athletes. The incidence of training injuries was studied in 183 rugby league players over two competitive seasons. Participants were assessed for height, body mass, skinfold thickness, vertical jump, 10-m, 20-m and 40-m sprint time, agility, and estimated maximal aerobic power in the off-season, pre-season, mid-season, and end-season. Training load and injury data were summarised into pre-season, early-competition, and late-competition training phases. Individual training load, fitness, and injury data were modelled using a logistic regression model with a binomial distribution and logit link function, while team training load and injury data were modelled using a linear regression model. While physical fitness improved with training, there was no association (P=0.16-0.99) between training load and changes in physical fitness during any of the training phases. However, increases in training load during the early-competition training phase decreased (P= 0.04) agility performance. A relationship (P= 0.01-0.04) was observed between the log of training load and odds of injury during each training phase, resulting in a 1.50 - 2.85 increase in the odds of injury for each arbitrary unit increase in training load. Furthermore, during the pre-season training phase there was a relationship (P= 0.01) between training load and injury incidence within the training load range of 155 and 590 arbitrary units. During the early and late-competition training phases, increases in training load of 175-620 arbitrary units and 145-410 arbitrary units, respectively, resulted in no further increase in injury incidence. These findings demonstrate that increases in training load, particularly during the pre-season training phase, increase the odds of injury in collision sport athletes. However, while increases in training load from 175 to 620 arbitrary units during the early-competition training phase result in no further increase in injury incidence, marked reductions in agility performances can occur. These findings suggest that reductions in training load during the early-competition training phase can reduce the odds of injury without compromising agility performances in collision sport athletes.

Serum and urine metabolomics study reveals a distinct diagnostic model for cancer cachexia

PubMed Central

Yang, Quan‐Jun; Zhao, Jiang‐Rong; Hao, Juan; Li, Bin; Huo, Yan; Han, Yong‐Long; Wan, Li‐Li; Li, Jie; Huang, Jinlu; Lu, Jin

2017-01-01

Abstract Background Cachexia is a multifactorial metabolic syndrome with high morbidity and mortality in patients with advanced cancer. The diagnosis of cancer cachexia depends on objective measures of clinical symptoms and a history of weight loss, which lag behind disease progression and have limited utility for the early diagnosis of cancer cachexia. In this study, we performed a nuclear magnetic resonance‐based metabolomics analysis to reveal the metabolic profile of cancer cachexia and establish a diagnostic model. Methods Eighty‐four cancer cachexia patients, 33 pre‐cachectic patients, 105 weight‐stable cancer patients, and 74 healthy controls were included in the training and validation sets. Comparative analysis was used to elucidate the distinct metabolites of cancer cachexia, while metabolic pathway analysis was employed to elucidate reprogramming pathways. Random forest, logistic regression, and receiver operating characteristic analyses were used to select and validate the biomarker metabolites and establish a diagnostic model. Results Forty‐six cancer cachexia patients, 22 pre‐cachectic patients, 68 weight‐stable cancer patients, and 48 healthy controls were included in the training set, and 38 cancer cachexia patients, 11 pre‐cachectic patients, 37 weight‐stable cancer patients, and 26 healthy controls were included in the validation set. All four groups were age‐matched and sex‐matched in the training set. Metabolomics analysis showed a clear separation of the four groups. Overall, 45 metabolites and 18 metabolic pathways were associated with cancer cachexia. Using random forest analysis, 15 of these metabolites were identified as highly discriminating between disease states. Logistic regression and receiver operating characteristic analyses were used to create a distinct diagnostic model with an area under the curve of 0.991 based on three metabolites. The diagnostic equation was Logit(P) = −400.53 – 481.88 × log(Carnosine) −239.02 × log(Leucine) + 383.92 × log(Phenyl acetate), and the result showed 94.64% accuracy in the validation set. Conclusions This metabolomics study revealed a distinct metabolic profile of cancer cachexia and established and validated a diagnostic model. This research provided a feasible diagnostic tool for identifying at‐risk populations through the detection of serum metabolites. PMID:29152916

Occupant Perceptions and a Health Outcome in Retail Stores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Mingjie; Kim, Yang-Seon; Srebric, Jelena

Indoor Environmental Quality (IEQ) in commercial buildings, such as retail stores, can affect employee satisfaction, productivity, and health. This study administered an IEQ survey to retail employees and found correlations between measured IEQ parameters and the survey responses. The survey included 611 employees in 14 retail stores located in Pennsylvania (climate zone 5A) and Texas (climate zone 2A). The survey questionnaire featured ratings of different aspects of IEQ, including thermal comfort, lighting and noise level, indoor smells, overall cleanness, and environmental quality. Simultaneously with the survey, on-site physical measurements were taken to collect data of relative humidity levels, air exchangemore » rates, dry bulb temperatures, and contaminant concentrations. This data was analyzed using multinomial logit regression with independent variables being the measured IEQ parameters, employees’ gender, and age. This study found that employee perception of stuffy smells is related to formaldehyde and PM10 concentrations. Furthermore, the survey also asked the employees to report an annual frequency of common colds as a health indicator. The regression analysis showed that the cold frequency statistically correlates with the measured air exchange rates, outdoor temperatures, and indoor PM concentrations. Overall, the air exchange rate is the most influential parameter on the employee perception of the overall environmental quality and self-reported health outcome.« less

Health disparities among immigrant and non-immigrant elders: the association of acculturation and education.

PubMed

Lum, Terry Y; Vanderaa, Julianne P

2010-10-01

Guided by the theories of human capital and acculturation, this study investigated the association of immigrant status among older people with their physical and mental health outcomes, health services utilization, and health insurance coverage. Specifically, it examined the interactive effects of immigrant status, education, acculturation, race, and ethnicity on these dependent variables. The study used a national representation sample of 7,345 older Americans from the first wave of the Asset and Health Dynamic of the Oldest Old study (AHEAD) survey. We used both logistic regression and ordered logit regression for our multivariate analyses. The findings are as follows: (1) immigrant status was negatively associated with level of depression, number of IADL difficulties, and on types of health insurance coverage. Immigrant status had a significant relationship only with the utilization of outpatient surgery, but not on other health services utilization. (2) There were significant interactive effects of race and ethnicity and immigrant status on these dependent variables. The findings support the existence of double jeopardy among those who are simultaneously an immigrant and a member of a racial and ethnic minority group in the United States. (3) Acculturation has strong associations with health insurance coverage and with number of difficulties with IADL.

Interrelationships Between Receiver/Relative Operating Characteristics Display, Binomial, Logit, and Bayes' Rule Probability of Detection Methodologies

NASA Technical Reports Server (NTRS)

Generazio, Edward R.

2014-01-01

Unknown risks are introduced into failure critical systems when probability of detection (POD) capabilities are accepted without a complete understanding of the statistical method applied and the interpretation of the statistical results. The presence of this risk in the nondestructive evaluation (NDE) community is revealed in common statements about POD. These statements are often interpreted in a variety of ways and therefore, the very existence of the statements identifies the need for a more comprehensive understanding of POD methodologies. Statistical methodologies have data requirements to be met, procedures to be followed, and requirements for validation or demonstration of adequacy of the POD estimates. Risks are further enhanced due to the wide range of statistical methodologies used for determining the POD capability. Receiver/Relative Operating Characteristics (ROC) Display, simple binomial, logistic regression, and Bayes' rule POD methodologies are widely used in determining POD capability. This work focuses on Hit-Miss data to reveal the framework of the interrelationships between Receiver/Relative Operating Characteristics Display, simple binomial, logistic regression, and Bayes' Rule methodologies as they are applied to POD. Knowledge of these interrelationships leads to an intuitive and global understanding of the statistical data, procedural and validation requirements for establishing credible POD estimates.

Food insufficiency and food insecurity as risk factors for physical disability among Palestinian refugees in Lebanon: Evidence from an observational study.

PubMed

Salti, Nisreen; Ghattas, Hala

2016-10-01

Potential interactions between malnutrition and disability are increasingly recognized, and both are important global health issues. Causal effects working from nutrition to disability and from disability back to nutrition present an empirical challenge to measuring either of these effects. However, disability affects nutrition whatever the cause of disability, whereas nutrition is likelier to affect disease-related disability than war- or work-related disability. This paper investigates the association of food insufficiency with the risk of physical disability. Data on disability by cause allow us to address the difficulty of reverse causality. Multinomial logit regressions of disability by cause on food insufficiency are run using survey data from 2010 on 2575 Palestinian refugee households in Lebanon. Controls include household sociodemographic, health and economic characteristics. Regressions of food insufficiency on disability by cause are also run. Disability has a significant coefficient in regressions of food insufficiency, whatever the cause of disability; but in regressions of disability on food insufficiency, food insufficiency is significant only for disease-related disability (log odds of disease-related disability .78 higher, p = .008). The difference in the results by cause of disability is evidence of a significant association between food insufficiency and disease-related disability, net of any reverse effect from disability to food access. The association between disease-related disability and food insufficiency is statistically significant suggesting that even taking into account feedback from disability to nutrition, nutrition is an effective level of intervention to avert the poverty-disability trap resulting from the impoverishing effect of disability. Copyright © 2016 Elsevier Inc. All rights reserved.

A multiclass vehicular dynamic traffic flow model for main roads and dedicated lanes/roads of multimodal transport network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sossoe, K.S., E-mail: kwami.sossoe@irt-systemx.fr; Lebacque, J-P., E-mail: jean-patrick.lebacque@ifsttar.fr

2015-03-10

We present in this paper a model of vehicular traffic flow for a multimodal transportation road network. We introduce the notion of class of vehicles to refer to vehicles of different transport modes. Our model describes the traffic on highways (which may contain several lanes) and network transit for pubic transportation. The model is drafted with Eulerian and Lagrangian coordinates and uses a Logit model to describe the traffic assignment of our multiclass vehicular flow description on shared roads. The paper also discusses traffic streams on dedicated lanes for specific class of vehicles with event-based traffic laws. An Euler-Lagrangian-remap schememore » is introduced to numerically approximate the model’s flow equations.« less

Impact of socioeconomic status and medical conditions on health and healthcare utilization among aging Ghanaians.

PubMed

Saeed, Bashiru Ii; Xicang, Zhao; Yawson, Alfred Edwin; Nguah, Samuel Blay; Nsowah-Nuamah, Nicholas N N

2015-03-20

This study attempts to examine the impact of socioeconomic and medical conditions in health and healthcare utilization among older adults in Ghana. Five separate models with varying input variables were estimated for each response variable. Data (Wave 1 data) were drawn from the World Health Organization Global Ageing and Adult Health (SAGE) conducted during 2007-2008 and included a total of 4770 respondents aged 50+ and 803 aged 18-49 in Ghana. Ordered logits was estimated for self-rated health, and binary logits for functional limitation and healthcare utilization. Our results show that the study provides enough grounds for further research on the interplay between socioeconomic and medical conditions on one hand and the health of the aged on the other. Controlling for socioeconomic status substantially contributes significantly to utilization. Also, aged women experience worse health than men, as shown by functioning assessment, self-rated health, chronic conditions and functional limitations. Women have higher rates of healthcare utilization, as shown by significantly higher rates of hospitalization and outpatient encounters. Expansion of the national health insurance scheme to cover the entire older population--for those in both formal and informal employments--is likely to garner increased access and improved health states for the older population.

Chronic Pain and Health Care Spending: An Analysis of Longitudinal Data from the Medical Expenditure Panel Survey

PubMed Central

Stockbridge, Erica L; Suzuki, Sumihiro; Pagán, José A

2015-01-01

Objective To estimate average incremental health care expenditures associated with chronic pain by health care service category, expanding on prior research that focused on specific pain conditions instead of general pain, excluded low levels of pain, or did not incorporate pain duration. Data Source Medical Expenditure Panel Survey (MEPS) data (2008–2011; N = 26,671). Study Design Differences in annual expenditures for adults at different levels of pain that interferes with normal work, as measured by the SF-12, were estimated using recycled predictions from two-part logit-generalized linear regression models. Principal Findings “A little bit” of chronic pain-related interference was associated with a $2,498 increase in total adjusted expenditures over no pain interference (p < .0001) and a $1,008 increase over nonchronic pain interference (p = .0001). Moderate and severe chronic pain-related interference was associated with a $3,707 and $5,804 increase in expenditures over no pain interference and a $2,218 and $4,315 increase over nonchronic interference, respectively (p < .0001). Expenditure increases were most pronounced for inpatient and hospital outpatient expenditures compared to other types of health care expenditures. Conclusions Chronic pain limitations are associated with higher health care expenditures. Results underscore the substantial cost of pain to the health care system. PMID:25424348

Older Persons' Evaluations of Health Care: The Effects of Medical Skepticism and Worry about Health

PubMed Central

Borders, Tyrone F; Rohrer, James E; Xu, K Tom; Smith, David R

2004-01-01

Objective To describe how skepticism about medical care and other individual differences, including worry about health status, are associated with evaluations of health care among the noninstitutionalized elderly. Data Sources/Study Setting Data were collected through a survey of approximately 5,000 community-dwelling elders (aged 65 and older) in a southwestern region of the United States. Study Design Global evaluations of health care were measured with two items from the Consumer Assessment of Health Plans Study (CAHPS) instrument, an overall care rating (OCR) and a personal doctor rating (PDR). Multivariate ordered logit regression models were tested to examine how medical skepticism and other factors were associated with ratings of 0–7, 8–9, and 10. Principal Findings Consumers who were skeptical of prescription drugs relative to home remedies, who held attitudes that they understand their health better than most doctors, and who worried about their health had worse OCR and PDR. Those who held attitudes that individual behavior determines how soon one gets better when sick had better PDR and OCR. Conclusions Health policymakers, managers, and providers may need to consider the degree to which they should attempt to satisfy skeptical consumers, many of whom may never rate their care highly. Alternatively, they may need to target skeptical consumers with educational efforts explaining the benefits of medical care. PMID:14965076

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

PubMed

Hofman, Robine; de Bekker-Grob, Esther W; Raat, Hein; Helmerhorst, Theo J M; van Ballegooijen, Marjolein; Korfage, Ida J

2014-05-15

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. 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. 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%. 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.

[Stigma, discrimination and HIV/AIDS in the Brazilian context, 1998 and 2005].

PubMed

Garcia, Sandra; Koyama, Mitti Ayako Hara

2008-06-01

To identify discriminatory attitudes in two moments of the Brazilian HIV/AIDS epidemic, as well as the occurrence of possible changes. The Intention of Discrimination Index was obtained by scoring 1 for discriminatory situations or 0, when the opposite was the case. Intention of discrimination ranges were established by means of the clustering technique, and made compatible between the 1998 and 2005 surveys. Mean comparisons, chi-square test and ordered logit adjusted regression models were used to verify association between the index and socio-demographic variables. Between the 1998 and 2005 surveys, there was a statistically significant reduction in the proportion of people who answered "yes" to anti-HIV test's being mandatory in the following cases: admission for employment, before getting married, when joining the military service, drug users, foreigners entering the country, sex professionals, and for all the people. To have lower level of education, to be female, to live in the North/Northeast regions of Brazil, and to be aged over 45 years are factors associated with higher intention of discrimination level. The growth of intention of discrimination shows that information about ways of AIDS transmission and non-transmission still needs to be better planned and promoted, especially among populations that have lower level of education, live in the North/Northeast regions, are female and aged over 45 years.

Thal Amyloid Stages Do Not Significantly Impact the Correlation Between Neuropathological Change and Cognition in the Alzheimer Disease Continuum.

PubMed

Serrano-Pozo, Alberto; Qian, Jing; Muzikansky, Alona; Monsell, Sarah E; Montine, Thomas J; Frosch, Matthew P; Betensky, Rebecca A; Hyman, Bradley T

2016-06-01

The 2012 neuropathological criteria for the diagnosis of Alzheimer disease (AD) summarize the extent of AD neuropathological change with an ABC score, which is a composite of the Thal stage of amyloid deposition (A), the Braak stage of neurofibrillary tangles (NFTs) (B), and the CERAD neuritic plaque score (C). NFTs and neuritic plaques are well-established contributors to cognitive impairment, but whether the Thal amyloid stage independently predicts antemortem cognition remains unknown. We used the National Alzheimer's Coordinating Center autopsy data set to build adjacent-categories logit regression models with CDR-SOB and Mini-Mental State Examination (MMSE) scores as cognitive outcome variables. Increasing CERAD scores were independently associated with higher CDR-SOB scores, whereas increasing Braak NFT stages predicted both higher CDR-SOB and lower MMSE scores. Increasing Thal amyloid stages were not significantly independently associated with either outcome measure. Increasing ABC scores predicted higher CDR-SOB and lower MMSE scores. These results raise the possibility that Thal amyloid stages do not substantially contribute to predicting antemortem cognition compared to CERAD neuritic plaque scores and Braak NFT stages, and suggest that the diffuse amyloid deposits participating in the assignment of Thal amyloid stages are neutral with respect to clinically detectable cognitive and functional changes. © 2016 American Association of Neuropathologists, Inc. All rights reserved.

Migrant female head porters' enrolment in and utilisation and renewal of the National Health Insurance Scheme in Kumasi, Ghana.

PubMed

Boateng, Simon; Amoako, Prince; Poku, Adjoa Afriyie; Baabereyir, Anthony; Gyasi, Razak Mohammed

2017-01-01

As a social protection policy, Ghana's National Health Insurance Scheme (NHIS) aims to improve access to healthcare, especially for the vulnerable. Migrant female head porters ( kayayoo ), who are part of the informal economic workforce, are underscored as an ethnic minority and vulnerable group in Ghana. This study aimed to analyse the factors associated with enrolment in and renewal and utilisation of the NHIS among migrant female head porters in the Kumasi Metropolis. We purposively sampled 392 migrant female head porters in the Kejetia, Asafo and Bantama markets. We used a binary logit regression model to estimate associations among baseline characteristics, convenience and benefit factors and enrolment in and renewal and utilisation of the NHIS. Age and income significantly increased the probability of NHIS enrolment, renewal and utilisation. Long waiting times at NHIS offices significantly reduced the likelihood of renewal, while provision of drugs highly significantly increased the tendency for migrant female head porters to enrol in, renew and use the NHIS. Consulting and surgery also significantly increased renewal and utilisation of the NHIS. Political commitment is imperative for effective implementation of the decentralisation policy of the NHIS through the National Health Insurance Authority in Kumasi. We argue that retail offices should be well equipped with logistic facilities to ensure convenience in NHIS initial enrolment and renewal processes by citizenry, and by vulnerable groups in particular.

Evolutionary games combining two or three pair coordinations on a square lattice

NASA Astrophysics Data System (ADS)

Király, Balázs; Szabó, György

2017-10-01

We study multiagent logit-rule-driven evolutionary games on a square lattice whose pair interactions are composed of a maximal number of nonoverlapping elementary coordination games describing Ising-type interactions between just two of the available strategies. Using Monte Carlo simulations we investigate the macroscopic noise-level-dependent behavior of the two- and three-pair games and the critical properties of the continuous phase transtitions these systems exhibit. The four-strategy game is shown to be equivalent to a system that consists of two independent and identical Ising models.

Evolutionary games combining two or three pair coordinations on a square lattice.

PubMed

Király, Balázs; Szabó, György

2017-10-01

We study multiagent logit-rule-driven evolutionary games on a square lattice whose pair interactions are composed of a maximal number of nonoverlapping elementary coordination games describing Ising-type interactions between just two of the available strategies. Using Monte Carlo simulations we investigate the macroscopic noise-level-dependent behavior of the two- and three-pair games and the critical properties of the continuous phase transtitions these systems exhibit. The four-strategy game is shown to be equivalent to a system that consists of two independent and identical Ising models.

Decennial Life Tables for the White Population of the United States, 1790-1900.

PubMed

Hacker, J David

2010-04-01

This article constructs new life tables for the white population of the United States in each decade between 1790 and 1900. Drawing from several recent studies, it suggests best estimates of life expectancy at age 20 for each decade. These estimates are fitted to new standards derived from the 1900-02 rural and 1900-02 overall DRA life tables using a two-parameter logit model with fixed slope. The resulting decennial life tables more accurately represent sex-and age-specific mortality rates while capturing known mortality trends.

Reliability measures in item response theory: manifest versus latent correlation functions.

PubMed

Milanzi, Elasma; Molenberghs, Geert; Alonso, Ariel; Verbeke, Geert; De Boeck, Paul

2015-02-01

For item response theory (IRT) models, which belong to the class of generalized linear or non-linear mixed models, reliability at the scale of observed scores (i.e., manifest correlation) is more difficult to calculate than latent correlation based reliability, but usually of greater scientific interest. This is not least because it cannot be calculated explicitly when the logit link is used in conjunction with normal random effects. As such, approximations such as Fisher's information coefficient, Cronbach's α, or the latent correlation are calculated, allegedly because it is easy to do so. Cronbach's α has well-known and serious drawbacks, Fisher's information is not meaningful under certain circumstances, and there is an important but often overlooked difference between latent and manifest correlations. Here, manifest correlation refers to correlation between observed scores, while latent correlation refers to correlation between scores at the latent (e.g., logit or probit) scale. Thus, using one in place of the other can lead to erroneous conclusions. Taylor series based reliability measures, which are based on manifest correlation functions, are derived and a careful comparison of reliability measures based on latent correlations, Fisher's information, and exact reliability is carried out. The latent correlations are virtually always considerably higher than their manifest counterparts, Fisher's information measure shows no coherent behaviour (it is even negative in some cases), while the newly introduced Taylor series based approximations reflect the exact reliability very closely. Comparisons among the various types of correlations, for various IRT models, are made using algebraic expressions, Monte Carlo simulations, and data analysis. Given the light computational burden and the performance of Taylor series based reliability measures, their use is recommended. © 2014 The British Psychological Society.

Migrant integration policies and health inequalities in Europe.

PubMed

Giannoni, Margherita; Franzini, Luisa; Masiero, Giuliano

2016-06-01

Research on socio-economic determinants of migrant health inequalities has produced a large body of evidence. There is lack of evidence on the influence of structural factors on lives of fragile groups, frequently exposed to health inequalities. The role of poor socio-economic status and country level structural factors, such as migrant integration policies, in explaining migrant health inequalities is unclear. The objective of this paper is to examine the role of migrant socio-economic status and the impact of migrant integration policies on health inequalities during the recent economic crisis in Europe. Using the 2012 wave of Eurostat EU-SILC data for a set of 23 European countries, we estimate multilevel mixed-effects ordered logit models for self-assessed poor health (SAH) and self-reported limiting long-standing illnesses (LLS), and multilevel mixed-effects logit models for self-reported chronic illness (SC). We estimate two-level models with individuals nested within countries, allowing for both individual socio-economic determinants of health and country-level characteristics (healthy life years expectancy, proportion of health care expenditure over the GDP, and problems in migrant integration policies, derived from the Migrant Integration Policy Index (MIPEX). Being a non-European citizen or born outside Europe does not increase the odds of reporting poor health conditions, in accordance with the "healthy migrant effect". However, the country context in terms of problems in migrant integration policies influences negatively all of the three measures of health (self-reported health status, limiting long-standing illnesses, and self-reported chronic illness) in foreign people living in European countries, and partially offsets the "healthy migrant effect". Policies for migrant integration can reduce migrant health disparities.

How bicycle level of traffic stress correlate with reported cyclist accidents injury severities: A geospatial and mixed logit analysis.

PubMed

Chen, Chen; Anderson, Jason C; Wang, Haizhong; Wang, Yinhai; Vogt, Rachel; Hernandez, Salvador

2017-11-01

Transportation agencies need efficient methods to determine how to reduce bicycle accidents while promoting cycling activities and prioritizing safety improvement investments. Many studies have used standalone methods, such as level of traffic stress (LTS) and bicycle level of service (BLOS), to better understand bicycle mode share and network connectivity for a region. However, in most cases, other studies rely on crash severity models to explain what variables contribute to the severity of bicycle related crashes. This research uniquely correlates bicycle LTS with reported bicycle crash locations for four cities in New Hampshire through geospatial mapping. LTS measurements and crash locations are compared visually using a GIS framework. Next, a bicycle injury severity model, that incorporates LTS measurements, is created through a mixed logit modeling framework. Results of the visual analysis show some geospatial correlation between higher LTS roads and "Injury" type bicycle crashes. It was determined, statistically, that LTS has an effect on the severity level of bicycle crashes and high LTS can have varying effects on severity outcome. However, it is recommended that further analyses be conducted to better understand the statistical significance and effect of LTS on injury severity. As such, this research will validate the use of LTS as a proxy for safety risk regardless of the recorded bicycle crash history. This research will help identify the clustering patterns of bicycle crashes on high-risk corridors and, therefore, assist with bicycle route planning and policy making. This paper also suggests low-cost countermeasures or treatments that can be implemented to address high-risk areas. Specifically, with the goal of providing safer routes for cyclists, such countermeasures or treatments have the potential to substantially reduce the number of fatalities and severe injuries. Published by Elsevier Ltd.

A global goodness-of-fit test for receiver operating characteristic curve analysis via the bootstrap method.

PubMed

Zou, Kelly H; Resnic, Frederic S; Talos, Ion-Florin; Goldberg-Zimring, Daniel; Bhagwat, Jui G; Haker, Steven J; Kikinis, Ron; Jolesz, Ferenc A; Ohno-Machado, Lucila

2005-10-01

Medical classification accuracy studies often yield continuous data based on predictive models for treatment outcomes. A popular method for evaluating the performance of diagnostic tests is the receiver operating characteristic (ROC) curve analysis. The main objective was to develop a global statistical hypothesis test for assessing the goodness-of-fit (GOF) for parametric ROC curves via the bootstrap. A simple log (or logit) and a more flexible Box-Cox normality transformations were applied to untransformed or transformed data from two clinical studies to predict complications following percutaneous coronary interventions (PCIs) and for image-guided neurosurgical resection results predicted by tumor volume, respectively. We compared a non-parametric with a parametric binormal estimate of the underlying ROC curve. To construct such a GOF test, we used the non-parametric and parametric areas under the curve (AUCs) as the metrics, with a resulting p value reported. In the interventional cardiology example, logit and Box-Cox transformations of the predictive probabilities led to satisfactory AUCs (AUC=0.888; p=0.78, and AUC=0.888; p=0.73, respectively), while in the brain tumor resection example, log and Box-Cox transformations of the tumor size also led to satisfactory AUCs (AUC=0.898; p=0.61, and AUC=0.899; p=0.42, respectively). In contrast, significant departures from GOF were observed without applying any transformation prior to assuming a binormal model (AUC=0.766; p=0.004, and AUC=0.831; p=0.03), respectively. In both studies the p values suggested that transformations were important to consider before applying any binormal model to estimate the AUC. Our analyses also demonstrated and confirmed the predictive values of different classifiers for determining the interventional complications following PCIs and resection outcomes in image-guided neurosurgery.

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

What Do Patients Want from Otolaryngologists? A Discrete Choice Experiment.

PubMed

Naunheim, Matthew R; Rathi, Vinay K; Naunheim, Margaret L; Alkire, Blake C; Lam, Allen C; Song, Phillip C; Shrime, Mark G

2017-10-01

Objectives Patient preferences are crucial for the delivery of patient-centered care. Discrete choice experiments (DCEs) are an emerging quantitative methodology used for understanding these preferences. In this study, we employed DCE techniques to understand the preferences of patients presenting for an ear, nose, and throat clinic visit. Study Design DCE. Setting Decision science laboratory. Methods A DCE survey of 5 attributes-wait time, physician experience, physician personality, utilization of visit time, and cost/copayment-was constructed with structured qualitative interviews with patients. The DCE was administered to participants from the general population, who chose among hypothetical scenarios that varied across these attributes. A conditional logit model was used to determine relative attribute importance, with a separate logit model for determining subject effects. Results A total of 161 participants were included. Cost/copayment had the greatest impact on decision making (importance, 32.2%), followed by wait time and physician experience (26.5% and 24.7%, respectively). Physician personality mattered least (4.7%), although all attributes were significantly correlated to decision making. Participants preferred doctors who spent more time performing physical examination than listening or explaining. Participants were willing to pay $52 extra to avoid a 4-week delay in appointment time; $87 extra for a physician with 10 years of experience (vs 0 years); and $9 extra for a caring, friendly, and compassionate doctor (vs formal, efficient, and business-like). Conclusion DCEs allow for powerful economic analyses that may help physicians understand patient preferences. Our model showed that cost is an important factor to patients and that patients are willing to pay extra for timely appointments, experience, and thorough physical examination.

Developmental Idealism, Body Weight and Shape, and Marriage Entry in Transitional China.

PubMed

Xu, Hongwei

2016-04-01

New trends toward later and less marriage are emerging in post-reform China. Previous research has examined the changing individual-level socioeconomic and demographic characteristics shaping marriage entry in Chinese adults. Employing a cultural model known as developmental idealism (DI), this study argues that a new worldview specifying an ideal body type has become popular in the West and that this new worldview has been exported to China. This new part of the DI package is likely stratified by gender, has a stronger impact on women than on men, and has likely penetrated urban areas more than rural areas. Drawing on the 1991-2009 longitudinal data from the China Health and Nutrition Survey, this study employs discrete-time logit models to estimate the relationships between various body types and transition to first marriage in Chinese young adults 18-30 years old. Body weight status and body shape are measured by body mass index (BMI) and waist-to-hip ratio (WHR), respectively, and further divided into categories of underweight, normal, and obese. Regression results indicate that larger values of BMI and WHR were associated with delayed entry into first marriage in urban women, whereas being overweight or obese was associated with accelerated transition to first marriage in rural men. Not only were these associations statistically significant, but their strengths were substantively remarkable. Findings from this study suggest that both body weight and body shape have important implications for marital success, independent of individual-level socioeconomic and demographic characteristics, and contribute to evolving gender and rural-urban disparities, as China is undergoing a rapid nutrition transition.

Infection of foxes by Echinococcocus multilocularis in urban and suburban areas of Nancy, France: influence of feeding habits and environment.

PubMed

Robardet, E; Giraudoux, P; Caillot, C; Boue, F; Cliquet, F; Augot, D; Barrat, J

2008-03-01

This study evaluated the impact of biological and environmental factors on the infection of red foxes (Vulpes vulpes) by Echinococcus multilocularis in an endemic area of north-east France. From January 2004 to April 2006, 127 foxes were examined for E. multilocularis and their stomach contents analysed. The effect of year, season, age, sex and urbanisation level on E. multilocularis presence was estimated using a General Linear Model (GLM) with logit link, (i.e. logistic regression). Urbanisation level was the only influencing factor, with a decreasing gradient from rural [54%, CI 95% (40-68)] to peri-urban [31%, CI 95% (15-52)] and urban area [4%, CI 95% (0.7-15)]. The consumption of Arvicola terrestris and Microtus sp., grassland species, the main presumed intermediate hosts of E. multilocularis, was studied by the same approach. The two species were consumed less in the urban area and more in autumn than in spring. Anthropogenic food consumption was linked to urbanisation and to age. The frequency of anthropogenic food consumption decreased in the rural area. A global model explaining the presence of E. multilocularis and including urbanisation level and diet was then elaborated. Independently of urbanisation, there was a suggestion of less E. multilocularis infection with anthropogenic food consumption. Red foxes consuming Microtus sp. and A. terrestris had higher worm burden than those that did not. The results suggest that the decreasing gradient observed from rural to urban area is linked to behaviour and feeding habits.

The influence of the WIC food package changes on the retail food environment in New Orleans.

PubMed

Rose, Donald; O'Malley, Keelia; Dunaway, Lauren Futrell; Bodor, J Nicholas

2014-01-01

To examine the effect of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food package changes on availability of healthy foods in small stores. Pre-post comparison group design with repeat in-store observations. New Orleans. Small stores (n = 102; 77% of total) were visited in 2009. Of these, 91% were observed again in 2010, including both WIC (n = 27) and non-WIC (n = 66) stores. The 2009 WIC food package changes to include healthier foods. Change in store availability of fruits, vegetables, lower-fat milks, whole wheat bread, and brown rice. Change in number of varieties and shelf length of fruits and vegetables. Difference-in-differences analysis using logit models for change in availability and regression models for change in number of varieties or shelf length. The WIC stores were more likely to improve availability of lower-fat milks than non-WIC stores (adjusted odds ratio, 5.0, 95% confidence interval, 1.2-21.0). An even greater relative improvement was seen with whole grains. The WIC stores showed a relative increase in number of varieties of fresh fruits (0.9 ± 0.3; P < .01) and shelf length of vegetables (1.2 ± 0.4 meters; P < .01). Results suggest that WIC changes improved the availability of healthy foods in small stores in New Orleans. Similar changes throughout the country could have a significant impact on neighborhood food environments. Copyright © 2014 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

Using choice-based conjoint to determine the relative importance of dental benefit plan attributes.

PubMed

Cunningham, M A; Gaeth, G J; Juang, C; Chakraborty, G

1999-05-01

The purpose of this study was to use conjoint analysis to determine the importance of specific dental benefit plan features for University of Iowa (UI) staff and to build a model to predict enrollment. From a random sample of 2000 UI staff, 40 percent responded (N = 773). The survey instrument was developed using seven attributes (five dental benefit plan features and two facility characteristics) each offered at three levels (e.g., premium = $20, $15, $10/month). Pilot testing was used to find a realistic range of plan options. Twenty-seven hypothetical dental benefit plans were developed using fractional factorial combinations of the three levels for each of the seven attributes. For all of the hypothetical plans, dental care was to be provided in the UI predoctoral dental clinic. Plan profiles were arranged four per page by combining the existing plan with three hypothetical plans, for a total of nine pages. Respondents' task was to select one plan from each set of four. A regression-like statistical model (Multinomial Logit) was used to estimate importance of each attribute and each attribute level. Relative importance (and coefficients) for each of the seven attributes are as follows: maximum annual benefit (.98), orthodontic coverage (.72), routine restorative (.70), major restorative (.67), time to complete treatment (.61), clinic hours of operation (.47), premium (.18). For each attribute, relative importance of each of three levels will also be presented. These coefficients for each level are used to predict enrollment for plans with specific combinations of the dental benefit plan features.

Fear of walking outdoors. A multilevel ecologic analysis of crime and disorder.

PubMed

Roman, Caterina G; Chalfin, Aaron

2008-04-01

Although a number of studies have tested ecologic models that postulate relationships among social networks, the built environment, and active living, few neighborhood-based studies have considered the role of crime and violence. This study investigates the degree to which individual-level demographic characteristics and neighborhood-level physical and social characteristics are associated with increased fear of crime. Data were analyzed in 2007 from a 2005 survey of 901 randomly selected individuals living in 55 neighborhoods in Washington DC. Multilevel ordered logit regression was used to examine associations between individual-level and neighborhood-level characteristics and how often fear of crime prevents a respondent from walking outdoors. Age and female gender were associated with an increase in fear; the percentage of a resident's life spent in the same neighborhood was associated with a decrease in fear. Results of cross-level interactions showed that at the neighborhood level, women were more fearful than men in neighborhoods without violence, but that the difference in fear between men and women shrinks as neighborhood violence increases. Collective efficacy was found to increase fear among black respondents and had no effect on fear among nonblack respondents. If the study of neighborhoods and active living is to progress and contribute to both etiologic understanding and policy formation, it is essential that theoretical and empirical models consider the impact of violence and fear on walking. Efforts to increase active living in urban neighborhoods that do not account for the impact of crime and fear may fall short of their intended outcomes.

Developmental Idealism, Body Weight and Shape, and Marriage Entry in Transitional China

PubMed Central

Xu, Hongwei

2016-01-01

New trends toward later and less marriage are emerging in post-reform China. Previous research has examined the changing individual-level socioeconomic and demographic characteristics shaping marriage entry in Chinese adults. Employing a cultural model known as developmental idealism (DI), this study argues that a new worldview specifying an ideal body type has become popular in the West and that this new worldview has been exported to China. This new part of the DI package is likely stratified by gender, has a stronger impact on women than on men, and has likely penetrated urban areas more than rural areas. Drawing on the 1991-2009 longitudinal data from the China Health and Nutrition Survey, this study employs discrete-time logit models to estimate the relationships between various body types and transition to first marriage in Chinese young adults 18-30 years old. Body weight status and body shape are measured by body mass index (BMI) and waist-to-hip ratio (WHR), respectively, and further divided into categories of underweight, normal, and obese. Regression results indicate that larger values of BMI and WHR were associated with delayed entry into first marriage in urban women, whereas being overweight or obese was associated with accelerated transition to first marriage in rural men. Not only were these associations statistically significant, but their strengths were substantively remarkable. Findings from this study suggest that both body weight and body shape have important implications for marital success, independent of individual-level socioeconomic and demographic characteristics, and contribute to evolving gender and rural-urban disparities, as China is undergoing a rapid nutrition transition. PMID:27909585

The development and application of an injury prediction model for noncontact, soft-tissue injuries in elite collision sport athletes.

PubMed

Gabbett, Tim J

2010-10-01

Limited information exists on the training dose-response relationship in elite collision sport athletes. In addition, no study has developed an injury prediction model for collision sport athletes. The purpose of this study was to develop an injury prediction model for noncontact, soft-tissue injuries in elite collision sport athletes. Ninety-one professional rugby league players participated in this 4-year prospective study. This study was conducted in 2 phases. Firstly, training load and injury data were prospectively recorded over 2 competitive seasons in elite collision sport athletes. Training load and injury data were modeled using a logistic regression model with a binomial distribution (injury vs. no injury) and logit link function. Secondly, training load and injury data were prospectively recorded over a further 2 competitive seasons in the same cohort of elite collision sport athletes. An injury prediction model based on planned and actual training loads was developed and implemented to determine if noncontact, soft-tissue injuries could be predicted and therefore prevented in elite collision sport athletes. Players were 50-80% likely to sustain a preseason injury within the training load range of 3,000-5,000 units. These training load 'thresholds' were considerably reduced (1,700-3,000 units) in the late-competition phase of the season. A total of 159 noncontact, soft-tissue injuries were sustained over the latter 2 seasons. The percentage of true positive predictions was 62.3% (n = 121), whereas the total number of false positive and false negative predictions was 20 and 18, respectively. Players that exceeded the training load threshold were 70 times more likely to test positive for noncontact, soft-tissue injury, whereas players that did not exceed the training load threshold were injured 1/10 as often. These findings provide information on the training dose-response relationship and a scientific method of monitoring and regulating training load in elite collision sport athletes.

Influence of Immunology Knowledge on Healthcare and Healthy Lifestyle.

PubMed

Abu Kassim, Noor Lide; Saleh Huddin, Afiqah Binti; Daoud, Jamal Ibrahim; Rahman, Mohammad Tariqur

2016-01-01

Completing a course in Immunology is expected to improve health care knowledge (HCK), which in turn is anticipated to influence a healthy lifestyle (HLS), controlled use of health care services (HCS) and an awareness of emerging health care concerns (HCC). This cross-sectional study was designed to determine whether these interrelationships are empirically supported. Participants involved in this study were government servants from two ministries in Malaysia (n = 356) and university students from a local university (n = 147). Participants were selected using the non-random purposive sampling method. Data were collected using a self-developed questionnaire, which had been validated in a pilot study involving similar subjects. The questionnaire items were analyzed using Rasch analysis, SPSS version 21 and AMOS version 22. Results have shown that participants who followed a course in Immunology (CoI) had a higher primary HCK (Mean = 0.69 logit, SD = 1.29 logits) compared with those who had not (Mean = -0.27logit, SD = 1.26 logits). Overall, there were significant correlations among the HLS, the awareness of emerging HCC, and the controlled use of HCS (p <0.001). However, no significant correlations were observed between primary HCK and the other variables. However, significant positive correlation was observed between primary HCK and controlled use of HCS for the group without CoI. Path analysis showed that the awareness of emerging HCC exerted a positive influence on controlled use of HCS (β = 0.156, p < .001) and on HLS (β = 0.224, p < .001). These findings suggest that having CoI helps increase primary HCK which influences controlled use of HCS but does not necessarily influence HLS. Hence, introducing Immunology at various levels of education and increasing the public awareness of emerging HCC might help to improve population health en masse. In addition, further investigations on the factors affecting HLS is required to provide a better understanding on the relationship between primary HCK and HLS.

Determining Barriers to Use of Edible School Gardens in Illinois.

PubMed

Loftus, Lucy; Spaulding, Aslihan D; Steffen, Richard; Kopsell, Dave; Nnakwe, Nweze

2017-01-01

The objective of this study was to gather data regarding the awareness, perceived benefits, interest in, and barriers to establishment of edible school gardens in Illinois public schools. Setting/Design: This study used an online survey design. Participants included Illinois public elementary school principals and superintendents. Region and community population, current edible garden use, perception (Likert scale) of garden benefits, interest in establishment of a school edible garden, and barriers to establishment of a school edible garden were the variables of interest. Logit regression and Kruskal-Wallis with follow-up where p < 0.05 were performed. Elementary school principals and superintendents are aware of gardens and their potential benefits to students, but many barriers exist that make their use challenging. Funding, staff and volunteer support, and class time were identified as the major barriers. Region affected likelihood of garden use, and community population size also affected the odds of having an edible school garden. Data suggest that edible garden use would increase with provision of resources and organization of dedicated supporters.

The effects of mandatory health insurance on equity in access to outpatient care in Indonesia.

PubMed

Hidayat, Budi; Thabrany, Hasbullah; Dong, Hengjin; Sauerborn, Rainer

2004-09-01

This paper examines the effects of mandatory health insurance on access and equity in access to public and private outpatient care in Indonesia. Data from the second round of the 1997 Indonesian Family Life Survey were used. We adopted the concentration index as a measure of equity, and this was calculated from actual data and from predicted probability of outpatient-care use saved from a multinomial logit regression. The study found that a mandatory insurance scheme for civil servants (Askes) had a strongly positive impact on access to public outpatient care, while a mandatory insurance scheme for private employees (Jamsostek) had a positive impact on access to both public and private outpatient care. The greatest effects of Jamsostek were observed amongst poor beneficiaries. A substantial increase in access will be gained by expanding insurance to the whole population. However, neither Askes nor Jamsostek had a positive impact on equity. Policy implications are discussed.

HMO penetration and quality of care: the case of breast cancer.

PubMed

Decker, S L; Hempstead, K

1999-01-01

In theory, health maintenance organizations (HMOs) receiving a fixed payment rate per enrolled member have an incentive to coordinate services and emphasize prevention and early detection of disease in order to minimize costs of care. This article tests whether higher HMO penetration rates across counties in the United States and across time improve the use of mammography services, the chance of early rather than late detection of breast cancer, and ultimately improve breast cancer survival. We use two data sets to test the effect of HMO penetration on use of breast cancer services and on breast cancer health outcomes for women aged 55 to 64 years. These data sources are matched with county-level data on HMO penetration and other market variables from the Bureau of Health Profession's Area Resource File. Results of logit regression show evidence that HMO penetration positively affects the probability of recent mammography receipt. However, we do not find a statistically significant relationship between HMO penetration and either stage of diagnosis or breast cancer survival.

Predicting subscriber dissatisfaction and improving retention in the wireless telecommunications industry.

PubMed

Mozer, M C; Wolniewicz, R; Grimes, D B; Johnson, E; Kaushansky, H

2000-01-01

Competition in the wireless telecommunications industry is fierce. To maintain profitability, wireless carriers must control churn, which is the loss of subscribers who switch from one carrier to another.We explore techniques from statistical machine learning to predict churn and, based on these predictions, to determine what incentives should be offered to subscribers to improve retention and maximize profitability to the carrier. The techniques include logit regression, decision trees, neural networks, and boosting. Our experiments are based on a database of nearly 47,000 U.S. domestic subscribers and includes information about their usage, billing, credit, application, and complaint history. Our experiments show that under a wide variety of assumptions concerning the cost of intervention and the retention rate resulting from intervention, using predictive techniques to identify potential churners and offering incentives can yield significant savings to a carrier. We also show the importance of a data representation crafted by domain experts. Finally, we report on a real-world test of the techniques that validate our simulation experiments.

Alcohol and Other Drug Use in Middle School: The Interplay of Gender, Peer Victimization, and Supportive Social Relationships

PubMed Central

Wormington, Stephanie V.; Anderson, Kristen G.; Tomlinson, Kristin L.; Brown, Sandra A.

2015-01-01

The current study examined the impact of supportive social relationships (i.e., teacher support, adult support, school relatedness) and peer victimization on middle school students’ substance use. Over 3,000 middle school students reported on alcohol, cigarette, and marijuana use, supportive social relationships, and instances in which they were the victim of aggressive behavior. Mixed-effects logit regression analyses revealed complementary patterns of results across types of substances. Students who perceived high levels of social support were less likely to report alcohol and drug use initiation, particularly at low levels of peer victimization. Gender moderated the negative effect of peer victimization, with highly victimized boys most likely to report alcohol, cigarette, and marijuana use. Results indicated a complex interplay of social influences and moderating variables in predicting early onset alcohol and other drug use, one that researchers should consider when studying adolescents’ decisions to use alcohol and other drugs. PMID:26294803

Attitude towards the incorporation of the selective collection of biowaste in a municipal solid waste management system. A case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernad-Beltrán, D.; Simó, A.; Bovea, M.D., E-mail: bovea@uji.es

Highlights: • Attitude towards incorporating biowaste selective collection is analysed. • Willingness to participate and to pay in biowaste selective collection is obtained. • Socioeconomic aspects affecting WtParticipate and WtPay are identified. - Abstract: European waste legislation has been encouraging for years the incorporation of selective collection systems for the biowaste fraction. European countries are therefore incorporating it into their current municipal solid waste management (MSWM) systems. However, this incorporation involves changes in the current waste management habits of households. In this paper, the attitude of the public towards the incorporation of selective collection of biowaste into an existing MSWMmore » system in a Spanish municipality is analysed. A semi-structured telephone interview was used to obtain information regarding aspects such as: level of participation in current waste collection systems, willingness to participate in selective collection of biowaste, reasons and barriers that affect participation, willingness to pay for the incorporation of the selective collection of biowaste and the socioeconomic characteristics of citizens who are willing to participate and pay for selective collection of biowaste. The results showed that approximately 81% of the respondents were willing to participate in selective collection of biowaste. This percentage would increase until 89% if the Town Council provided specific waste bins and bags, since the main barrier to participate in the new selective collection system is the need to use specific waste bin and bags for the separation of biowaste. A logit response model was applied to estimate the average willingness to pay, obtaining an estimated mean of 7.5% on top of the current waste management annual tax. The relationship of willingness to participate and willingness to pay for the implementation of this new selective collection with the socioeconomic variables (age, gender, size of the household, work, education and income) was analysed. Chi-square independence tests and binary logistic regression was used for willingness to participate, not being obtained any significant relationship. Chi-square independence tests, ordinal logistic regression and ordinary linear regression was applied for willingness to pay, obtaining statistically significant relationship for most of the socioeconomic variables.« less

Patterns of Dupuytren disease in fingers: studying correlations with a multivariate ordinal logit model.

PubMed

Lanting, Rosanne; Nooraee, Nazanin; Werker, Paul M N; van den Heuvel, Edwin R

2014-09-01

Dupuytren disease affects fingers in a variable fashion. Knowledge about specific disease patterns (phenotype) based on location and severity of the disease is lacking. In this cross-sectional study, 344 primary affected hands with Dupuytren disease were physically examined. The Pearson correlation coefficient between the coexistence of Dupuytren disease in pairs of fingers was calculated, and agglomerative hierarchical clustering was applied to identify possible clusters of affected fingers. With a multivariate ordinal logit model, the authors studied the correlation on severity, taking into account age and sex, and tested hypotheses on independence between groups of fingers. The ring finger was most frequently affected by Dupuytren disease, and contractures were seen in 15.1 percent of affected rays. The severity of thumb and index finger, middle and ring fingers, and middle and little fingers was significantly correlated. Occurrences in pairs of fingers were highest in the middle and ring fingers and lowest in the thumb and index finger. Correlation between the ring and little fingers and a correlation between fingers from the ulnar and radial sides could not be demonstrated. Rays on the ulnar side of the hand are predominantly affected. The middle finger is substantially correlated with other fingers on the ulnar side, and the thumb and index finger are correlated; however, there was no evidence that the ulnar side and the radial side were correlated in any way, which suggests that occurrence on one side of the hand does not predict Dupuytren disease on the other side of the hand. Risk, III.

Quality of life of patients from rural and urban areas in Poland with head and neck cancer treated with radiotherapy. A study of the influence of selected socio-demographic factors.

PubMed

Depta, Adam; Jewczak, Maciej; Skura-Madziała, Anna

2017-10-01

The quality of life (QoL) experienced by cancer patients depends both on their state of health and on sociodemographic factors. Tumours in the head and neck region have a particularly adverse effect on patients psychologically and on their social functioning. The study involved 121 patients receiving radiotherapy treatment for head and neck cancers. They included 72 urban and 49 rural residents. QoL was assessed using the questionnaires EORTC-QLQ-C30 and QLQ-H&N35. The data were analysed using statistical methods: a χ 2 test for independence and a multinomial logit model. The evaluation of QoL showed a strong, statistically significant, positive dependence on state of health, and a weak dependence on sociodemographic factors and place of residence. Evaluations of financial situation and living conditions were similar for rural and urban residents. Patients from urban areas had the greatest anxiety about deterioration of their state of health. Rural respondents were more often anxious about a worsening of their financial situation, and expressed a fear of loneliness. Studying the QoL of patients with head and neck cancer provides information concerning the areas in which the disease inhibits their lives, and the extent to which it does so. It indicates conditions for the adaptation of treatment and care methods in the healthcare system which might improve the QoL of such patients. A multinomial logit model identifies the factors determining the patients' health assessment and defines the probable values of such assessment.

The two faces of enhancing utilization of health-care services: determinants of patient initiation and retention in rural Burkina Faso.

PubMed Central

Mugisha, Frederick; Bocar, Kouyate; Dong, Hengjin; Chepng'eno, Gloria; Sauerborn, Rainer

2004-01-01

OBJECTIVE: To explore the factors that determine whether a patient will initiate treatment within a system of health-care services, and the factors that determine whether the patient will be retained in the chosen system, in Nouna, rural Burkina Faso. METHODS: The data used were pooled from four rounds of a household survey conducted in Nouna, rural Burkina Faso. The ongoing demographic surveillance system provided a sampling framework for this survey in which 800 households were sampled using a two-stage cluster sampling procedure. More than one treatment episode was observed for a single episode of illness per patient. The multinomial logit model was used to explore the determinants of patient initiation to systems of modern, traditional and home treatment, and a binary logit model was used to explore the determinants of patient retention within the chosen health-care provider system. FINDINGS: The results suggest that the determinants of patient initiation and their subsequent retention are different. Household income, education, urban residence and expected competency of the provider are positive predictors of initiation, but not of retention, for modern health-care services. Only perceived quality of care positively predicted retention in modern health-care services. CONCLUSION: Interventions focusing on patient initiation and patient retention are likely to be different. Policies directed at enhancing initiation for modern health-care services would primarily focus on reducing financial barriers, while those directed at increasing retention would primarily focus on attributes that improve the perceived quality of care. PMID:15375446

Activity interference and noise annoyance

NASA Astrophysics Data System (ADS)

Hall, F. L.; Taylor, S. M.; Birnie, S. E.

1985-11-01

Debate continues over differences in the dose-response functions used to predict the annoyance at different sources of transportation noise. This debate reflects the lack of an accepted model of noise annoyance in residential communities. In this paper a model is proposed which is focussed on activity interference as a central component mediating the relationship between noise exposure and annoyance. This model represents a departure from earlier models in two important respects. First, single event noise levels (e.g., maximum levels, sound exposure level) constitute the noise exposure variables in place of long-term energy equivalent measures (e.g., 24-hour Leq or Ldn). Second, the relationships within the model are expressed as probabilistic rather than deterministic equations. The model has been tested by using acoustical and social survey data collected at 57 sites in the Toronto region exposed to aircraft, road traffic or train noise. Logit analysis was used to estimate two sets of equations. The first predicts the probability of activity interference as a function of event noise level. Four types of interference are included: indoor speech, outdoor speech, difficulty getting to sleep and awakening. The second set predicts the probability of annoyance as a function of the combination of activity interferences. From the first set of equations, it was possible to estimate a function for indoor speech interference only. In this case, the maximum event level was the strongest predictor. The lack of significant results for the other types of interference is explained by the limitations of the data. The same function predicts indoor speech interference for all three sources—road, rail and aircraft noise. The results for the second set of equations show strong relationships between activity interference and the probability of annoyance. Again, the parameters of the logit equations are similar for the three sources. A trial application of the model predicts a higher probability of annoyance for aircraft than for road traffic situations with the same 24-hour Leq. This result suggests that the model may account for previously reported source differences in annoyance.

Rasch measurement: the Arm Activity measure (ArmA) passive function sub-scale.

PubMed

Ashford, Stephen; Siegert, Richard J; Alexandrescu, Roxana

2016-01-01

To evaluate the conformity of the Arm Activity measure (ArmA) passive function sub-scale to the Rasch model. A consecutive cohort of patients (n = 92) undergoing rehabilitation, including upper limb rehabilitation and spasticity management, at two specialist rehabilitation units were included. Rasch analysis was used to examine scaling and conformity to the model. Responses were analysed using Rasch unidimensional measurement models (RUMM 2030). The following aspects were considered: overall model and individual item fit statistics and fit residuals, internal reliability, item response threshold ordering, item bias, local dependency and unidimensionality. ArmA contains both active and passive function sub-scales, but in this analysis only the passive function sub-scale was considered. Four of the seven items in the ArmA passive function sub-scale initially had disordered thresholds. These items were rescored to four response options, which resulted in ordered thresholds for all items. Once the items with disordered thresholds had been rescored, item bias was not identified for age, global disability level or diagnosis, but with a small difference in difficulty between males and females for one item of the scale. Local dependency was not observed and the unidimensionality of the sub-scale was supported and good fit to the Rasch model was identified. The person separation index (PSI) was 0.95 indicating that the scale is able to reliably differentiate at least two groups of patients. The ArmA passive function sub-scale was shown in this evaluation to conform to the Rasch model once disordered thresholds had been addressed. Using the logit scores produced by the Rasch model it was possible to convert this back to the original scale range. Implications for Rehabilitation The ArmA passive function sub-scale was shown, in this evaluation, to conform to the Rasch model once disordered thresholds had been addressed and therefore to be a clinically applicable and potentially useful hierarchical measure. Using Rasch logit scores it has be possible to convert back to the original ordinal scale range and provide an indication of real change to enable evaluation of clinical outcome of importance to patients and clinicians.

Dutch Tariff for the Five-Level Version of EQ-5D.

PubMed

M Versteegh, Matthijs; M Vermeulen, Karin; M A A Evers, Silvia; de Wit, G Ardine; Prenger, Rilana; A Stolk, Elly

2016-06-01

In 2009, a new version of the EuroQol five-dimensional questionnaire (EQ-5D) was introduced with five rather than three answer levels per dimension. This instrument is known as the EQ-5D-5L. To make the EQ-5D-5L suitable for use in economic evaluations, societal values need to be attached to all 3125 health states. To derive a Dutch tariff for the EQ-5D-5L. Health state values were elicited during face-to-face interviews in a general population sample stratified for age, sex, and education, using composite time trade-off (cTTO) and a discrete choice experiment (DCE). Data were modeled using ordinary least squares and tobit regression (for cTTO) and a multinomial conditional logit model (for DCE). Model performance was evaluated on the basis of internal consistency, parsimony, goodness of fit, handling of left-censored values, and theoretical considerations. A representative sample (N = 1003) of the Dutch population participated in the valuation study. Data of 979 and 992 respondents were included in the analysis of the cTTO and the DCE, respectively. The cTTO data were left-censored at -1. The tobit model was considered the preferred model for the tariff on the basis of its handling of the censored nature of the data, which was confirmed through comparison with the DCE data. The predicted values for the EQ-5D-5L ranged from -0.446 to 1. This study established a Dutch tariff for the EQ-5D-5L on the basis of cTTO. The values represent the preferences of the Dutch population. The tariff can be used to estimate the impact of health care interventions on quality of life, for example, in context of economic evaluations. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Jointly modeling longitudinal proportional data and survival times with an application to the quality of life data in a breast cancer trial.

PubMed

Song, Hui; Peng, Yingwei; Tu, Dongsheng

2017-04-01

Motivated by the joint analysis of longitudinal quality of life data and recurrence free survival times from a cancer clinical trial, we present in this paper two approaches to jointly model the longitudinal proportional measurements, which are confined in a finite interval, and survival data. Both approaches assume a proportional hazards model for the survival times. For the longitudinal component, the first approach applies the classical linear mixed model to logit transformed responses, while the second approach directly models the responses using a simplex distribution. A semiparametric method based on a penalized joint likelihood generated by the Laplace approximation is derived to fit the joint model defined by the second approach. The proposed procedures are evaluated in a simulation study and applied to the analysis of breast cancer data motivated this research.

Therapy preferences of patients with lung and colon cancer: a discrete choice experiment.

PubMed

Schmidt, Katharina; Damm, Kathrin; Vogel, Arndt; Golpon, Heiko; Manns, Michael P; Welte, Tobias; Graf von der Schulenburg, J-Matthias

2017-01-01

There is increasing interest in studies that examine patient preferences to measure health-related outcomes. Understanding patients' preferences can improve the treatment process and is particularly relevant for oncology. In this study, we aimed to identify the subgroup-specific treatment preferences of German patients with lung cancer (LC) or colorectal cancer (CRC). Six discrete choice experiment (DCE) attributes were established on the basis of a systematic literature review and qualitative interviews. The DCE analyses comprised generalized linear mixed-effects model and latent class mixed logit model. The study cohort comprised 310 patients (194 with LC, 108 with CRC, 8 with both types of cancer) with a median age of 63 (SD =10.66) years. The generalized linear mixed-effects model showed a significant ( P <0.05) degree of association for all of the tested attributes. "Strongly increased life expectancy" was the attribute given the greatest weight by all patient groups. Using latent class mixed logit model analysis, we identified three classes of patients. Patients who were better informed tended to prefer a more balanced relationship between length and health-related quality of life (HRQoL) than those who were less informed. Class 2 (LC patients with low HRQoL who had undergone surgery) gave a very strong weighting to increased length of life. We deduced from Class 3 patients that those with a relatively good life expectancy (CRC compared with LC) gave a greater weight to moderate effects on HRQoL than to a longer life. Overall survival was the most important attribute of therapy for patients with LC or CRC. Differences in treatment preferences between subgroups should be considered in regard to treatment and development of guidelines. Patients' preferences were not affected by sex or age, but were affected by the cancer type, HRQoL, surgery status, and the main source of information on the disease.

Integrating geographic information systems and remote sensing with spatial econometric and mixed logit models for environmental valuation

NASA Astrophysics Data System (ADS)

Wells, Aaron Raymond

This research focuses on the Emory and Obed Watersheds in the Cumberland Plateau in Central Tennessee and the Lower Hatchie River Watershed in West Tennessee. A framework based on market and nonmarket valuation techniques was used to empirically estimate economic values for environmental amenities and negative externalities in these areas. The specific techniques employed include a variation of hedonic pricing and discrete choice conjoint analysis (i.e., choice modeling), in addition to geographic information systems (GIS) and remote sensing. Microeconomic models of agent behavior, including random utility theory and profit maximization, provide the principal theoretical foundation linking valuation techniques and econometric models. The generalized method of moments estimator for a first-order spatial autoregressive function and mixed logit models are the principal econometric methods applied within the framework. The dissertation is subdivided into three separate chapters written in a manuscript format. The first chapter provides the necessary theoretical and mathematical conditions that must be satisfied in order for a forest amenity enhancement program to be implemented. These conditions include utility, value, and profit maximization. The second chapter evaluates the effect of forest land cover and information about future land use change on respondent preferences and willingness to pay for alternative hypothetical forest amenity enhancement options. Land use change information and the amount of forest land cover significantly influenced respondent preferences, choices, and stated willingness to pay. Hicksian welfare estimates for proposed enhancement options ranged from 57.42 to 25.53, depending on the policy specification, information level, and econometric model. The third chapter presents economic values for negative externalities associated with channelization that affect the productivity and overall market value of forested wetlands. Results of robust, generalized moments estimation of a double logarithmic first-order spatial autoregressive error model (inverse distance weights with spatial dependence up to 1500m) indicate that the implicit cost of damages to forested wetlands caused by channelization equaled -$5,438 ha-1. Collectively, the results of this dissertation provide economic measures of the damages to and benefits of environmental assets, help private landowners and policy makers identify the amenity attributes preferred by the public, and improve the management of natural resources.

Application of rrm as behavior mode choice on modelling transportation

NASA Astrophysics Data System (ADS)

Surbakti, M. S.; Sadullah, A. F.

2018-03-01

Transportation mode selection, the first step in transportation planning process, is probably one of the most important planning elements. The development of models that can explain the preference of passengers regarding their chosen mode of public transport option will contribute to the improvement and development of existing public transport. Logit models have been widely used to determine the mode choice models in which the alternative are different transport modes. Random Regret Minimization (RRM) theory is a theory developed from the behavior to choose (choice behavior) in a state of uncertainty. During its development, the theory was used in various disciplines, such as marketing, micro economy, psychology, management, and transportation. This article aims to show the use of RRM in various modes of selection, from the results of various studies that have been conducted both in north sumatera and western Java.

Journal of Air Transportation, Volume 11, No. 2

NASA Technical Reports Server (NTRS)

Bowen, Brent (Editor); Kabashkin, Igor (Editor); Gudmundsson, Sveinn Vidar (Editor); EspiritoSanto, Jr. Respicio (Editor)

2006-01-01

The following topics were covered: How Do Airlines Perceive That Strategic Alliances Affect Their Individual Branding?; Airline Choice for Domestic Flights in Sao Paulo Metropolitan Area: An Application of the Conditional Logit Model; Consequences of Feeder Delays for the Success of A380 Operations; Inside the Mechanics of Network Development: How Competition and Strategy Reorganize European Air Traffic; The Opportunities and Threats of Turning Airports into Hubs; Another Approach to Enhance Airline Safety: Using System Safety Tools; A Simulation Based Approach for Contingency Planning for Aircraft Turnaround Activities in Airline Hubs; and The Council on Aviation Accreditation: Part One- Historical Foundation.

Willingness to pay for midwife-endorsed product: An Australian best-worst study.

PubMed

Lahtinen, Ville; Rundle-Thiele, Sharyn; Adamsen, Jannie Mia

2016-01-01

This article examined the impact of midwife endorsement on stated choice preferences in one of the highest volume baby care product categories, diapers. An online survey was conducted testing 12 alternatives of which six were midwife endorsed. A total of 215 responses were analyzed using best-worst and multinomial logit modeling. Results indicate that package size, price, and brand are more sensitive predictors of stated choice preferences than midwife endorsement. Respondents were willing to pay 2.3% more for a diaper that was endorsed by midwives. These findings suggest that midwife endorsement should be pursued by health marketers.

Parent-Child Communication and Marijuana Initiation: Evidence Using Discrete-Time Survival Analysis

PubMed Central

Nonnemaker, James M.; Silber-Ashley, Olivia; Farrelly, Matthew C.; Dench, Daniel

2012-01-01

This study supplements existing literature on the relationship between parent-child communication and adolescent drug use by exploring whether parental and/or adolescent recall of specific drug-related conversations differentially impact youth's likelihood of initiating marijuana use. Using discrete-time survival analysis, we estimated the hazard of marijuana initiation using a logit model to obtain an estimate of the relative risk of initiation. Our results suggest that parent-child communication about drug use is either not protective (no effect) or—in the case of youth reports of communication—potentially harmful (leading to increased likelihood of marijuana initiation). PMID:22958867

Decennial Life Tables for the White Population of the United States, 1790–19001

PubMed Central

Hacker, J. David

2010-01-01

This article constructs new life tables for the white population of the United States in each decade between 1790 and 1900. Drawing from several recent studies, it suggests best estimates of life expectancy at age 20 for each decade. These estimates are fitted to new standards derived from the 1900–02 rural and 1900–02 overall DRA life tables using a two-parameter logit model with fixed slope. The resulting decennial life tables more accurately represent sex-and age-specific mortality rates while capturing known mortality trends. PMID:20563225

Main Determinants of Catastrophic Health Expenditures: A Bayesian Logit Approach on Iranian Household Survey Data (2010)

PubMed Central

Fazaeli, Ali Akbar; Ghaderi, Hossein; Fazaeli, Amir Abbas; Lotfi, Farhad; Salehi, Masoud; Mehrara, Mohsen

2015-01-01

Background: During recent decades, increase in both health care expenditures and improvement of the awareness as well as health expectations have created some problems with regard to finance healthcare expenditures so that the issue of health financing by households has been determined as a major challenge in health sector. According to the definition by the World Health Organization, catastrophic health expenditure is considered if financial contribution for health service is more than 40% of income remaining after subsistence needs have been met. Objectives: The purpose of our study was determination of Main factors on catastrophic health expenditures in Iranian households. Patients and Methods: In this study, using an econometrics Bayesian logit model, determinants of the appearance of catastrophic health expenditure based on household budget data collected in 2010 were evaluated. Results: Among Iranian households, the following groups were more likely to encounter with unsustainable health expenditures: rural households, households with the numbers of the elderly more than 65 years, illiterate householders, unemployed householders, households with some unemployed persons, households in upper rank and households with larger equivalent household size were higher than the average of community could significantly predict catastrophic health expenditures. Conclusions: About 2.1% of households were faced with catastrophic health expenditures in 2010. Thus, the implemented policies could not make considerable and significant change in improving justice in financing in health systems. PMID:25946936

Main determinants of catastrophic health expenditures: a Bayesian logit approach on Iranian household survey data (2010).

PubMed

Fazaeli, Ali Akbar; Ghaderi, Hossein; Abbas Fazaeli, Amir; Lotfi, Farhad; Salehi, Masoud; Mehrara, Mohsen

2015-01-26

During recent decades, increase in both health care expenditures and improvement of the awareness as well as health expectations have created some problems with regard to finance healthcare expenditures so that the issue of health financing by households has been determined as a major challenge in health sector. According to the definition by the World Health Organization, catastrophic health expenditure is considered if financial contribution for health service is more than 40% of income remaining after subsistence needs have been met. The purpose of our study was determination of Main factors on catastrophic health expenditures in Iranian households. In this study, using an econometrics Bayesian logit model, determinants of the appearance of catastrophic health expenditure based on household budget data collected in 2010 were evaluated. Among Iranian households, the following groups were more likely to encounter with unsustainable health expenditures: rural households, households with the numbers of the elderly more than 65 years, illiterate householders, unemployed householders, households with some unemployed persons, households in upper rank and households with larger equivalent household size were higher than the average of community could significantly predict catastrophic health expenditures. About 2.1% of households were faced with catastrophic health expenditures in 2010. Thus, the implemented policies could not make considerable and significant change in improving justice in financing in health systems.

The associations between self-reported sleep duration and adolescent health outcomes: what is the role of time spent on Internet use?

PubMed

Do, Young Kyung; Shin, Eunhae; Bautista, Mary Ann; Foo, Kelvin

2013-02-01

This study aimed to examine the associations of self-reported sleep duration with adolescent health outcomes, taking into account time spent on Internet use. We used data from the 2008-2009 Korea Youth Behavioral Risk Factor Survey, a cross-sectional online survey of middle and high school students aged 13-18years in South Korea (N=136,589) to examine the associations of self-reported sleep duration with four mental and physical health measures, e.g. self-report of depressive symptoms, suicidal ideation, weight status, and self-rated health. The binary logit and generalized ordered logit models controlled for time spent on Internet use for non-study purposes and other factors. Shorter self-reported sleep duration was associated with a higher likelihood of reporting depressive symptoms, suicidal ideation, and overweight or obese status, and a lower likelihood of reporting better self-rated health, even after accounting for time spent on Internet use. Excessive Internet use was found to be an independent risk factor for these outcomes. Among in-school adolescents in South Korea, shorter sleep duration and excessive Internet use are independently and additively associated with multiple indicators of adverse health status. Excessive Internet use may have not only direct adverse health consequences, but also have indirect negative effects through sleep deprivation. Copyright © 2012 Elsevier B.V. All rights reserved.

The impact of weight misperception on health-related quality of life in Korean adults (KNHANES 2007–2014): a community-based cross-sectional study

PubMed Central

Park, Susan; Lee, Sejin; Hwang, Jinseub; Kwon, Jin-Won

2017-01-01

Background/objectives Weight perception, especially misperception, might affect health-related quality of life (HRQoL); however, related research is scarce and results remain equivocal. We examined the association between HRQoL and weight misperception by comparing obesity level as measured by body mass index (BMI) and weight perception in Korean adults. Methods Study subjects were 43 883 adults aged 19 years or older from cycles IV (2007–2009), V (2010–2012) and VI (2013–2014) of the Korean National Health and Nutrition Examination Survey. Multiple regression analyses comprising both logit and tobit models were conducted to evaluate the independent effect of obesity level as measured by BMI, weight perception and weight misperception on HRQoL after adjusting for demographics, socioeconomic status and number of chronic diseases. We also performed multiple regressions to explore the association between weight misperception and HRQoL stratified by BMI status. Results Obesity level as measured by BMI and weight perception were independently associated with low HRQoL in both separate and combined analyses. Weight misperception, including underestimation and overestimation, had a significantly negative impact on HRQoL. In subgroup analysis, subjects with BMI ranges from normal to overweight who misperceived their weight also had a high risk of low HRQoL. Overestimation of weight among obese subjects associated with low HRQoL, whereas underestimation of weight showed no significant association. Conclusions Both obesity level as measured by BMI and perceiving weight as fat were significant risk factors for low HRQoL. Subjects who incorrectly perceived their weight relative to their BMI status were more likely to report impaired HRQoL, particularly subjects with BMI in the normal to overweight range. Based on these findings, we recommend political and clinical efforts to better inform individuals about healthy weight status and promote accurate weight perception. PMID:28645975

Religion, contraception, and method choice of married women in Ghana.

PubMed

Gyimah, Stephen Obeng; Adjei, Jones K; Takyi, Baffour K

2012-12-01

Using pooled data from the 1998 and 2003 Demographic and Health Surveys, this paper investigates the association between religion and contraceptive behavior of married women in Ghana. Guided by the particularized theology and characteristics hypotheses, multinomial logit and complementary log-log models are used to explore denominational differences in contraceptive adoption among currently married women and assess whether the differences could be explained through other characteristics. We found that while there were no differences between women of different Christian faiths, non-Christian women (Muslim and Traditional) were significantly more likely to have never used contraception compared with Christian women. Similar observations were made on current use of contraception, although the differences were greatly reduced in the multivariate models.

Willingness to pay for cattle and buffalo insurance: an analysis of dairy farmers in central India.

PubMed

Khan, Mohd Ameer; Chander, Mahesh; Bardhan, Dwaipayan

2013-02-01

In India, insurance market especially in agricultural sector is usually underdeveloped. The idea of livestock insurance emerged in India before three decades, yet, it has not operated in a significant way till date. It is well noted that livestock insurance scheme is the relevant strategy in managing different risks related to livestock farming but very little attention has been paid to address the livestock insurance needs of the dairy farmers. This study, therefore, addresses the basic question that how many people and to what extent they are willing to pay for livestock insurance and determine the main factors which influence insurance participation of dairy farmers. The data was collected from Gorakhpur district of Uttar Pradesh in India with a sample survey of 120 cattle and buffalo farmers. For eliciting willingness to pay, a contingent valuation scenario was presented to dairy animal owners in the group of five to six. A logit discrete binary regression model was used to know the factors influencing adoption of livestock insurance. The results suggest that most of the farmers were willing to participate in cattle and buffalo insurance. The amount of premium varies across different breeds of dairy animals. The low level of education of many dairy farmers have negatively influenced the decision to purchase livestock insurance. Farmers having more experience in rearing dairy animals are more likely to be willing to pay for cattle and buffalo insurance.

Energy and women's economic empowerment: Rethinking the benefits of improved cookstove use in rural India

NASA Astrophysics Data System (ADS)

Seaward, James Nicholas

International development organizations have recently ramped up efforts to promote the use of improved cookstoves (ICS) in developing countries, aiming to reduce the harmful environmental and public health impacts of the burning of biomass for cooking and heating. I hypothesize that ICS use also has additional benefits---economic and social benefits---that can contribute to women's economic empowerment in the developing world. To explore the relationship between ICS use and women's economic empowerment, I use Ordinary Least Squares and Logit models based on data from the India Human Development Survey (IHDS) to analyze differences between women living in households that use ICS and those living in homes that use traditional cookstoves. My regression results reveal that ICS use has a statistically significant and negative effect on the amount of time women and girls spend on fuel collection and a statistically significant and positive effect on the likelihood of women's participation in side businesses, but does not have a statistically significant effect on the likelihood of lost productivity. My analysis shows promise that in addition to health and environmental benefits, fuel-efficient cooking technologies can also have social and economic impacts that are especially beneficial to women. It is my hope that the analysis provided in this paper will be used to further the dialogue about the importance of women's access to modern energy services in the fight to improve women's living standards in the developing world.

Investigating the disparities in cervical cancer screening among Namibian women.

PubMed

Kangmennaang, Joseph; Thogarapalli, Nandini; Mkandawire, Paul; Luginaah, Isaac

2015-08-01

We examined the influence of knowledge and information, health care access and different socio-economic variables on women's decision to screen for cervical cancer using a nationally representative dataset. We use hierarchical binary logit regression models to explore the determinants of screening for cervical cancer among women who reported hearing about cervical cancer. This enabled us to include the effect of unobserved heterogeneity at the cluster level that may affect screening behaviors. Among women who have heard about cervical cancer (N=6542), only 39% of them did undergo screening with a mean age of 33 years. The univariate results reveal that women who are educated, insured, can afford money needed for treatment and reported distance not a barrier to accessing healthcare were more likely to screen. Our multivariate results indicate that insured women (OR=1.89, p=0.001) and women who had access to information through education and contact with a health worker (OR=1.41, p=0.001) were more likely to undertake screening compared to uninsured women and those with no contact with a health personnel, after controlling for relevant variables. The adoption of a universal health insurance scheme that ensures equity in access to health care and extension of public health information targeting women in rural communities especially within the Caprivi region may be needed for a large scale increase in cervical cancer screening in Namibia. Copyright © 2015 Elsevier Inc. All rights reserved.

The gender gap in self-rated health and education in Spain. A multilevel analysis.

PubMed

Pinillos-Franco, Sara; García-Prieto, Carmen

2017-01-01

Women tend to report poorer self-rated health than men. It is also well established that education has a positive effect on health. However, the issue of how the benefits of education on health differ between men and women has not received enough attention and the few existing studies which do focus on the subject do not draw a clear conclusion. Therefore, this study aims to analyse whether the positive influence of educational attainment on health is higher for women and whether education helps to overcome the gender gap in self-rated health. We analyse cross-sectional data from the 2012 European Union statistics on income and living conditions. We use a logit regression model with odds ratios and a multilevel perspective to carry out a study which includes several individual and contextual control variables. We focused our study on the working population in Spain aged between 25 and 65. The final sample considered is composed of 14,120 subjects: 7,653 men and 6,467 women. There is a gender gap in self-rated health only for the less educated. This gap is not statistically significant among more highly educated individuals. Attaining a high level of education has the same positive effect on both women's and men's self-rated health. Although we did not find gender disparities when considering the effect of education on health, we show that women's health is poorer among the less educated, mainly due to labour precariousness and household conditions.

Determinants of Skilled Delivery Assistance in a Rural Population: Findings from an HDSS Site of Rural West Bengal, India.

PubMed

Ghosh, Saswata; Siddiqui, Md Zakaria; Barik, Anamitra; Bhaumik, Sunil

2015-11-01

This study examines the determinants of utilisation of skilled birth attendants (SBAs) amongst 2886 rural women in the state of West Bengal, India, using data from a survey of 2012-2013 conducted by the Birbhum Health and Demographic Surveillance System. Multilevel logit regression models were estimated and qualitative investigations conducted to understand the determinants of utilisation of SBAs in rural West Bengal. Among women who delivered their last child during the 3 years preceding the survey, 69.1 % of deliveries were assisted by SBAs, while 30.9 % were home deliveries without any SBA assistance. Multivariate analysis revealed that apart from socio-demographic and economic factors (such as household affluence, women's education, birth order, uptake of comprehensive ANC check-ups, advice regarding danger signs of pregnancy and household's socio-religious affiliation), supply side factors, such as availability of skilled birth attendants in the village and all-weather roads, have significant effect on seeking skilled assistance. Our findings also show that unobserved factors at village level independently influence uptake of SBA-assisted delivery. The present findings emphasise that both demand and supply side intervention strategies are essential prerequisites to enhance skilled birth attendance. Ample communication is observed at the individual level, but improving community level outreach and advocacy activities could generate further demand. SBAs can be better integrated by accommodating the socio-religious needs of local communities, such as providing female doctors and doctors with similar socio-religious backgrounds.

Health care barriers, racism, and intersectionality in Australia.

PubMed

Bastos, João L; Harnois, Catherine E; Paradies, Yin C

2018-02-01

While racism has been shown to negatively affect health care quality, little is known about the extent to which racial discrimination works with and through gender, class, and sexuality to predict barriers to health care (e.g., perceived difficulty accessing health services). Additionally, most existing studies focus on racial disparities in the U.S. context, with few examining marginalized groups in other countries. To address these knowledge gaps, we analyze data from the 2014 Australian General Social Survey, a nationally representative survey of individuals aged 15 and older living in 12,932 private dwellings. Following an intersectional perspective, we estimate a series of multivariable logit regression models to assess three hypotheses: racial discrimination will be positively associated with perceived barriers to health care (H1); the effect of perceived racial discrimination will be particularly severe for women, sexual minorities, and low socio-economic status individuals (H2); and, in addition to racial discrimination, other forms of perceived discrimination will negatively impact perceived barriers to health care (H3). Findings show that perceptions of racial discrimination are significantly associated with perceived barriers to health care, though this relationship is not significantly stronger for low status groups. In addition, our analyses reveal that perceived racism and other forms of discrimination combine to predict perceived barriers to health care. Taken together, these results speak to the benefits of an intersectional approach for examining racial inequalities in perceived access to health care. Copyright © 2017 Elsevier Ltd. All rights reserved.

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 Ehrmann

2018-01-01

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. Survey mailed to occupational therapists working in home care and community-dwelling elderly or disabled persons. A sample (N=714) of home-based occupational therapists (n=241), elderly persons from a bank of research participants (n=226), and adults with physical disabilities recruited through community organizations (n=247). Not applicable. The dependent variable was whether the referral scenario was prioritized or not in each question. The results were analyzed through logistic regression using conditional logit models. Prioritization preferences differed between groups (P<.001). Occupational therapists most strongly prioritized people who had a few falls (odds ratio vs no falls, 48.7), whereas elderly people and adults with disabilities most strongly prioritized people who were unable to enter and exit the home (odds ratio vs no difficulty entering and exiting the home, 30.8 for elderly people and 16.8 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 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

End-of-Life Care Planning in Accountable Care Organizations: Associations with Organizational Characteristics and Capabilities.

PubMed

Ahluwalia, Sangeeta C; Harris, Benjamin J; Lewis, Valerie A; Colla, Carrie H

2018-06-01

To measure the extent to which accountable care organizations (ACOs) have adopted end-of-life (EOL) care planning processes and characterize those ACOs that have established processes related to EOL. This study uses data from three waves (2012-2015) of the National Survey of ACOs. Respondents were 397 ACOs participating in Medicare, Medicaid, and commercial ACO contracts. This is a cross-sectional survey study using multivariate ordered logit regression models. We measured the extent to which the ACO had adopted EOL care planning processes as well as organizational characteristics, including care management, utilization management, health informatics, and shared decision-making capabilities, palliative care, and patient-centered medical home experience. Twenty-one percent of ACOs had few or no EOL care planning processes, 60 percent had some processes, and 19.6 percent had advanced processes. ACOs with a hospital in their system (OR: 3.07; p = .01), and ACOs with advanced care management (OR: 1.43; p = .02), utilization management (OR: 1.58, p = .00), and shared decision-making capabilities (OR: 16.3, p = .000) were more likely to have EOL care planning processes than those with no hospital or few to no capabilities. There remains considerable room for today's ACOs to increase uptake of EOL care planning, possibly by leveraging existing care management, utilization management, and shared decision-making processes. © Health Research and Educational Trust.

Profiles of innovators in a semi-arid smallholder agricultural environment in south west Zimbabwe

NASA Astrophysics Data System (ADS)

Mutsvangwa-Sammie, Eness P.; Manzungu, Emmanuel; Siziba, Shephard

2017-08-01

Innovations are regarded as critical to improving the efficiency, productivity and effectiveness of African agriculture. However, few efforts have been directed at understanding 'agricultural innovators', especially among smallholder farmers in sub-Saharan Africa who face low agricultural productivity and widespread food insecurity. This paper investigates the profile of innovators from a local perspective in a semi-arid smallholder farming area in south-west Zimbabwe. The paper is based on data collected from key informant interviews and a household questionnaire survey administered to 239 households from Gwanda and Insiza districts between 2013 and 2014. Qualities or attributes of an innovator (which constitute the profile of an innovator) identified by key informants included: resource endowment; social networks; education; and enthusiasm (passionate and hardworking). The attributes were used in a logit regression model to estimate the probability of the 239 households exhibiting the attributes of an innovator. Social networks and resource endowment, as depicted by amount of land cultivated, were found to significantly influence the probability of an individual being an innovator. Interestingly, the common attributes of education or belonging to an innovation platform used by extension and development agents, were found not to influence the probability of one being an innovator. The paper concludes that understanding local perceptions of innovators, which is based on appreciation of the socio-economic and biophysical circumstances, should be used to identify a 'basket' of context specific innovations that have potential to address the diverse needs of rural households farming households.

Development and internal validation of a side-specific, multiparametric magnetic resonance imaging-based nomogram for the prediction of extracapsular extension of prostate cancer.

PubMed

Martini, Alberto; Gupta, Akriti; Lewis, Sara C; Cumarasamy, Shivaram; Haines, Kenneth G; Briganti, Alberto; Montorsi, Francesco; Tewari, Ashutosh K

2018-04-19

To develop a nomogram for predicting side-specific extracapsular extension (ECE) for planning nerve-sparing radical prostatectomy. We retrospectively analysed data from 561 patients who underwent robot-assisted radical prostatectomy between February 2014 and October 2015. To develop a side-specific predictive model, we considered the prostatic lobes separately. Four variables were included: prostate-specific antigen; highest ipsilateral biopsy Gleason grade; highest ipsilateral percentage core involvement; and ECE on multiparametric magnetic resonance imaging (mpMRI). A multivariable logistic regression analysis was fitted to predict side-specific ECE. A nomogram was built based on the coefficients of the logit function. Internal validation was performed using 'leave-one-out' cross-validation. Calibration was graphically investigated. The decision curve analysis was used to evaluate the net clinical benefit. The study population consisted of 829 side-specific cases, after excluding negative biopsy observations (n = 293). ECE was reported on mpMRI and final pathology in 115 (14%) and 142 (17.1%) cases, respectively. Among these, mpMRI was able to predict ECE correctly in 57 (40.1%) cases. All variables in the model except highest percentage core involvement were predictors of ECE (all P ≤ 0.006). All variables were considered for inclusion in the nomogram. After internal validation, the area under the curve was 82.11%. The model demonstrated excellent calibration and improved clinical risk prediction, especially when compared with relying on mpMRI prediction of ECE alone. When retrospectively applying the nomogram-derived probability, using a 20% threshold for performing nerve-sparing, nine out of 14 positive surgical margins (PSMs) at the site of ECE resulted above the threshold. We developed an easy-to-use model for the prediction of side-specific ECE, and hope it serves as a tool for planning nerve-sparing radical prostatectomy and in the reduction of PSM in future series. © 2018 The Authors BJU International © 2018 BJU International Published by John Wiley & Sons Ltd.

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 service delivery not yet available in policy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electric system restructuring and system reliability

NASA Astrophysics Data System (ADS)

Horiuchi, Catherine Miller

In 1996 the California legislature passed AB 1890, explicitly defining economic benefits and detailing specific mechanisms for initiating a partial restructuring the state's electric system. Critics have since sought re-regulation and proponents have asked for patience as the new institutions and markets take shape. Other states' electric system restructuring activities have been tempered by real and perceived problems in the California model. This study examines the reduced regulatory controls and new constraints introduced in California's limited restructuring model using utility and regulatory agency records from the 1990's to investigate effects of new institutions and practices on system reliability for the state's five largest public and private utilities. Logit and negative binomial regressions indicate negative impact from the California model of restructuring on system reliability as measured by customer interruptions. Time series analysis of outage data could not predict the wholesale power market collapse and the subsequent rolling blackouts in early 2001; inclusion of near-outage reliability disturbances---load shedding and energy emergencies---provided a measure of forewarning. Analysis of system disruptions, generation capacity and demand, and the role of purchased power challenge conventional wisdom on the causality of Californian's power problems. The quantitative analysis was supplemented by a targeted survey of electric system restructuring participants. Findings suggest each utility and the organization controlling the state's electric grid provided protection from power outages comparable to pre-restructuring operations through 2000; however, this reliability has come at an inflated cost, resulting in reduced system purchases and decreased marginal protection. The historic margin of operating safety has fully eroded, increasing mandatory load shedding and emergency declarations for voluntary and mandatory conservation. Proposed remedies focused on state-funded contracts and government-managed power authorities may not help, as the findings suggest pricing models, market uncertainty, interjurisdictional conflict and an inability to respond to market perturbations are more significant contributors to reduced regional generation availability than the particular contract mechanisms and funding sources used for power purchases.

Age affects severity of venous gas emboli on decompression from 14.7 to 4.3 psia

NASA Technical Reports Server (NTRS)

Conkin, Johnny; Powell, Michael R.; Gernhardt, Michael L.

2003-01-01

INTRODUCTION: Variables that define who we are, such as age, weight and fitness level influence the risk of decompression sickness (DCS) and venous gas emboli (VGE) from diving and aviation decompressions. We focus on age since astronauts that perform space walks are approximately 10 yr older than our test subjects. Our null hypothesis is that age is not statistically associated with the VGE outcomes from decompression to 4.3 psia. METHODS: Our data are from 7 different NASA tests where 188 men and 50 women performed light exercise at 4.3 psia for planned exposures no less than 4 h. Prebreathe (PB) time on 100% oxygen ranged from 150-270 min, including ascent time, with exercise of different intensity and length being performed during the PB in four of the seven tests with 150 min of PB. Subjects were monitored for VGE in the pulmonary artery using a Doppler ultrasound bubble detector for a 4-min period every 12 min. There were six design variables; the presence or absence of lower body adynamia and five PB variables; plus five concomitant variables on physical characteristics: age, weight height, body mass index, and gender that were available for logistic regression (LR). We used LR models for the probability of DCS and VGE, and multinomial logit (ML) models for the probability of Spencer VGE Grades 0-IV at exposure times of 61, 95, 131, 183 min, and for the entire exposure. RESULTS: Age was significantly associated with VGE in both the LR and ML models, so we reject the null hypothesis. Lower body adynamia was significant for all responses. CONCLUSIONS: Our selection of tests produced a wide range of the explanatory variables, but only age, lower body adynamia, height, and total PB time was helpful in various combinations to model the probability of DCS and VGE.

Overweight and obesity in India: policy issues from an exploratory multi-level analysis.

PubMed

Siddiqui, Md Zakaria; Donato, Ronald

2016-06-01

This article analyses a nationally representative household dataset-the National Family Health Survey (NFHS-3) conducted in 2005 to 2006-to examine factors influencing the prevalence of overweight/obesity in India. The dataset was disaggregated into four sub-population groups-urban and rural females and males-and multi-level logit regression models were used to estimate the impact of particular covariates on the likelihood of overweight/obesity. The multi-level modelling approach aimed to identify individual and macro-level contextual factors influencing this health outcome. In contrast to most studies on low-income developing countries, the findings reveal that education for females beyond a particular level of educational attainment exhibits a negative relationship with the likelihood of overweight/obesity. This relationship was not observed for males. Muslim females and all Sikh sub-populations have a higher likelihood of overweight/obesity suggesting the importance of socio-cultural influences. The results also show that the relationship between wealth and the probability of overweight/obesity is stronger for males than females highlighting the differential impact of increasing socio-economic status on gender. Multi-level analysis reveals that states exerted an independent influence on the likelihood of overweight/obesity beyond individual-level covariates, reflecting the importance of spatially related contextual factors on overweight/obesity. While this study does not disentangle macro-level 'obesogenic' environmental factors from socio-cultural network influences, the results highlight the need to refrain from adopting a 'one size fits all' policy approach in addressing the overweight/obesity epidemic facing India. Instead, policy implementation requires a more nuanced and targeted approach to incorporate the growing recognition of socio-cultural and spatial contextual factors impacting on healthy behaviours. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Understanding the role of violence as a social determinant of preterm birth.

PubMed

Masho, Saba W; Cha, Susan; Chapman, Derek A; Chelmow, David

2017-02-01

Preterm birth is one of the leading causes of infant morbidity and mortality. Although major strides have been made in identifying risk factors for preterm birth, the complexities between social and individual risk factors are not well understood. This study examines the association between neighborhood youth violence and preterm birth. A 10-year live birth registry data set (2004 through 2013) from Richmond, VA, a mid-sized, racially diverse city, was analyzed (N = 27,519). Data were geocoded and merged with census tract and police report data. Gestational age at birth was classified as <32 weeks, 32-36 weeks, and term ≥37 weeks. Using police report data, youth violence rates were calculated for each census tract area and categorized into quartiles. Hierarchical models were examined fitting multilevel logistic regression models incorporating randomly distributed census tract-specific intercepts assuming a binary distribution and a logit link function. Nearly a fifth of all births occurred in areas with the highest quartiles of violence. After adjusting for maternal age, race/ethnicity, education, paternal presence, parity, adequacy of prenatal care, pregnancy complications, history of preterm birth, insurance, and tobacco, alcohol, and drug use, census tracts with the highest level of violence had 38% higher odds of very preterm births (adjusted odds ratio, 1.38; 95% confidence interval, 1.06-1.80), than census tracts with the lowest level of violence. There is an association between high rate of youth violence and very preterm birth. Findings from this study may help inform future research to develop targeted interventions aimed at reducing community violence and very preterm birth in vulnerable populations. Copyright © 2016 Elsevier Inc. All rights reserved.

Quality of life of patients from rural and urban areas in Poland with head and neck cancer treated with radiotherapy. A study of the influence of selected socio-demographic factors

PubMed Central

Jewczak, Maciej; Skura-Madziała, Anna

2017-01-01

Introduction The quality of life (QoL) experienced by cancer patients depends both on their state of health and on sociodemographic factors. Tumours in the head and neck region have a particularly adverse effect on patients psychologically and on their social functioning. Material and methods The study involved 121 patients receiving radiotherapy treatment for head and neck cancers. They included 72 urban and 49 rural residents. QoL was assessed using the questionnaires EORTC-QLQ-C30 and QLQ-H&N35. The data were analysed using statistical methods: a χ2 test for independence and a multinomial logit model. Results The evaluation of QoL showed a strong, statistically significant, positive dependence on state of health, and a weak dependence on sociodemographic factors and place of residence. Evaluations of financial situation and living conditions were similar for rural and urban residents. Patients from urban areas had the greatest anxiety about deterioration of their state of health. Rural respondents were more often anxious about a worsening of their financial situation, and expressed a fear of loneliness. Conclusions Studying the QoL of patients with head and neck cancer provides information concerning the areas in which the disease inhibits their lives, and the extent to which it does so. It indicates conditions for the adaptation of treatment and care methods in the healthcare system which might improve the QoL of such patients. A multinomial logit model identifies the factors determining the patients’ health assessment and defines the probable values of such assessment. PMID:29181080

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.

Vision and Quality of Life Index: validation of the Indian version using Rasch analysis.

PubMed

Gothwal, Vijaya K; Bagga, Deepak K

2013-07-18

A multi-attribute utility instrument (MAUI) consists of a descriptive system in which the items and responses seek information about a concept of the universe of health-related quality of life (QoL), and responses to these items then are weighted and combined to produce the index. To our knowledge, the 6-item Vision and Quality of Life Index (VisQoL) is the only available vision-related MAUI, developed and validated in Australia, specifically for visually impaired (VI) populations. To our knowledge, the psychometric properties of the VisQoL have not yet been investigated in an Indian VI sample; this was the aim of our study. The Indian VisQoL was administered to 349 VI adults face-to-face by a trained interviewer at the Vision Rehabilitation Centres of a tertiary eye care facility, South India. Rasch analysis was used to assess the psychometric properties. Rescoring was necessary for all except one item before ordered thresholds were obtained. All items fit the Rasch model and unidimensionality was confirmed. Person separation was acceptable (2.01), indicating that the instrument can discriminate among three strata of participants" vision-related QoL (VRQoL). The VisQoL items were targeted substantially to the participants" VRQoL (-0.69 logits). One item ("ability to have friendships") demonstrated large differential item functioning by work status; working participants reported the item to be more difficult (-1.13 logits) relative to other items when compared to the nonworking participants. The 6-item Indian VisQoL satisfies unidimensional Rasch model expectations in VI patients. Disordering of response categories was evident; replication is required before a common rescoring option should be considered.

Patients' Preferences Related to Benefits, Risks, and Formulations of Schizophrenia Treatment.

PubMed

Levitan, Bennett; Markowitz, Michael; Mohamed, Ateesha F; Johnson, F Reed; Alphs, Larry; Citrome, Leslie; Bridges, John F P

2015-07-01

The objective of this study was to quantify patients' preferences related to benefits and risks of antipsychotic treatments for schizophrenia and to assess the relative importance of treatment attributes and adherence. Treatment-related preferences among U.S. residents with a self-reported physician diagnosis of schizophrenia were assessed via a discrete-choice experiment. Patients chose between competing hypothetical scenarios characterized by improvements in positive symptoms, negative symptoms, and social functioning; incidence of weight gain, extrapyramidal symptoms (EPS), hyperprolactinemia, and hyperglycemia; and medication formulation. Preferences were estimated by using a random-parameters logit model, and the impact of adherence was estimated with conditional logit models. The final sample consisted of 271 patients. Complete improvement in positive symptoms was the most preferred outcome (relative importance score of 10.0), followed by elimination of hyperglycemia (3.6, 95% confidence interval [CI]=2.6-4.6), improvement in negative symptoms (3.0, CI=1.6-4.3), reduced weight gain (2.6, CI=1.2-4.0), avoidance of hyperprolactinemia (1.7, CI=.9-2.6), improved social functioning (1.5, CI=.4-2.5), and avoidance of EPS (1.0, CI=.3-1.8). Patients judged a daily pill superior to monthly injections (p<.01) and monthly injections superior to injections every three months (p<.01) for adherent patients and monthly injections superior to a daily pill for nonadherent patients (p=.01). Persons who self-identified as having schizophrenia judged improvement in positive symptoms as the most important treatment benefit. Hyperglycemia was identified as the most important adverse event. Patients judged oral formulations to be better than monthly injections for adherent patients and monthly injections to be a better choice for nonadherent patients.

Validation of Catquest-9SF-A Visual Disability Instrument to Evaluate Patient Function After Corneal Transplantation.

PubMed

Claesson, Margareta; Armitage, W John; Byström, Berit; Montan, Per; Samolov, Branka; Stenvi, Ulf; Lundström, Mats

2017-09-01

Catquest-9SF is a 9-item visual disability questionnaire developed for evaluating patient-reported outcome measures after cataract surgery. The aim of this study was to use Rasch analysis to determine the responsiveness of Catquest-9SF for corneal transplant patients. Patients who underwent corneal transplantation primarily to improve vision were included. One group (n = 199) completed the Catquest-9SF questionnaire before corneal transplantation and a second independent group (n = 199) completed the questionnaire 2 years after surgery. All patients were recorded in the Swedish Cornea Registry, which provided clinical and demographic data for the study. Winsteps software v.3.91.0 (Winsteps.com, Beaverton, OR) was used to assess the fit of the Catquest-9SF data to the Rasch model. Rasch analysis showed that Catquest-9SF applied to corneal transplant patients was unidimensional (infit range, 0.73-1.32; outfit range, 0.81-1.35), and therefore, measured a single underlying construct (visual disability). The Rasch model explained 68.5% of raw variance. The response categories of the 9-item questionnaire were ordered, and the category thresholds were well defined. Item difficulty matched the level of patients' ability (0.36 logit difference between the means). Precision in terms of person separation (3.09) and person reliability (0.91) was good. Differential item functioning was notable for only 1 item (satisfaction with vision), which had a differential item functioning contrast of 1.08 logit. Rasch analysis showed that Catquest-9SF is a valid instrument for measuring visual disability in patients who have undergone corneal transplantation primarily to improve vision.

Racial Differences in Receipt of Chlamydia Testing Among Medicaid-Insured Women in 2013.

PubMed

Patel, Chirag G; Chesson, Harrell W; Tao, Guoyu

2016-03-01

To estimate the percentage of young, sexually active Medicaid-insured women who were tested for chlamydia by age, race/ethnicity, and history of sexually transmitted disease (STD) diagnosis. We used the medical diagnostic and procedural codes from Truven Health MarketScan Medicaid claims data from 10 states in 2012 and 2013 to estimate the rates of chlamydia testing in 2013 and previous STD diagnosis (diagnosed in 2012) among Medicaid-insured women aged 15-25 years who were sexually active in 2013. We also used a logit model to assess the association between chlamydia testing and women's age, race/ethnicity, and previous STD diagnosis. Overall, among approximately 261,000 Medicaid-insured women aged 15-25 years in 2013 who were classified as sexually active, 50.2% were tested for chlamydia in 2013. The chlamydia testing rate was 45.6% for white women and 57.5% for black women. The chlamydia testing rate was 63.5% for women diagnosed as having an STD in 2012 and 46.8% for women not diagnosed as having an STD in 2012. The chlamydia testing rate was significantly (P < 0.05) associated with previous STD diagnosis, age, and race/ethnicity in our logit model. Higher chlamydia testing rates among black women can be explained in part by higher rates of previous STD diagnoses. Our finding that black women have the highest chlamydia testing rates is encouraging, as improved access to STD prevention services among racial/ethnic minorities can help to reduce racial/ethnic disparities in STDs. However, chlamydia screening remains an underused preventive health service for young women of all racial and ethnic groups.

Measurement of faculty anesthesiologists' quality of clinical supervision has greater reliability when controlling for the leniency of the rating anesthesia resident: a retrospective cohort study.

PubMed

Dexter, Franklin; Ledolter, Johannes; Hindman, Bradley J

2017-06-01

Our department monitors the quality of anesthesiologists' clinical supervision and provides each anesthesiologist with periodic feedback. We hypothesized that greater differentiation among anesthesiologists' supervision scores could be obtained by adjusting for leniency of the rating resident. From July 1, 2013 to December 31, 2015, our department has utilized the de Oliveira Filho unidimensional nine-item supervision scale to assess the quality of clinical supervision provided by faculty as rated by residents. We examined all 13,664 ratings of the 97 anesthesiologists (ratees) by the 65 residents (raters). Testing for internal consistency among answers to questions (large Cronbach's alpha > 0.90) was performed to rule out that one or two questions accounted for leniency. Mixed-effects logistic regression was used to compare ratees while controlling for rater leniency vs using Student t tests without rater leniency. The mean supervision scale score was calculated for each combination of the 65 raters and nine questions. The Cronbach's alpha was very large (0.977). The mean score was calculated for each of the 3,421 observed combinations of resident and anesthesiologist. The logits of the percentage of scores equal to the maximum value of 4.00 were normally distributed (residents, P = 0.24; anesthesiologists, P = 0.50). There were 20/97 anesthesiologists identified as significant outliers (13 with below average supervision scores and seven with better than average) using the mixed-effects logistic regression with rater leniency entered as a fixed effect but not by Student's t test. In contrast, there were three of 97 anesthesiologists identified as outliers (all three above average) using Student's t tests but not by logistic regression with leniency. The 20 vs 3 was significant (P < 0.001). Use of logistic regression with leniency results in greater detection of anesthesiologists with significantly better (or worse) clinical supervision scores than use of Student's t tests (i.e., without adjustment for rater leniency).

Writing and overwriting short-term memory

PubMed Central

Killeen, Peter R.

2008-01-01

An integrative account of short-term memory is based on data from pigeons trained to report the majority color in a sequence of lights. Performance showed strong recency effects, was invariant over changes in the interstimulus interval, and improved with increases in the intertrial interval. A compound model of binomial variance around geometrically decreasing memory described the data; a logit transformation rendered it isomorphic with other memory models. The model was generalized for variance in the parameters, where it was shown that averaging exponential and power functions from individuals or items with different decay rates generates new functions that are hyperbolic in time and in log time, respectively. The compound model provides a unified treatment of both the accrual and the dissipation of memory and is consistent with data from various experiments, including the choose-short bias in delayed recall, multielement stimuli, and Rubin and Wenzel’s (1996) meta-analyses of forgetting. PMID:11340865

TU-H-CAMPUS-JeP1-02: Fully Automatic Verification of Automatically Contoured Normal Tissues in the Head and Neck

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCarroll, R; UT Health Science Center, Graduate School of Biomedical Sciences, Houston, TX; Beadle, B

Purpose: To investigate and validate the use of an independent deformable-based contouring algorithm for automatic verification of auto-contoured structures in the head and neck towards fully automated treatment planning. Methods: Two independent automatic contouring algorithms [(1) Eclipse’s Smart Segmentation followed by pixel-wise majority voting, (2) an in-house multi-atlas based method] were used to create contours of 6 normal structures of 10 head-and-neck patients. After rating by a radiation oncologist, the higher performing algorithm was selected as the primary contouring method, the other used for automatic verification of the primary. To determine the ability of the verification algorithm to detect incorrectmore » contours, contours from the primary method were shifted from 0.5 to 2cm. Using a logit model the structure-specific minimum detectable shift was identified. The models were then applied to a set of twenty different patients and the sensitivity and specificity of the models verified. Results: Per physician rating, the multi-atlas method (4.8/5 point scale, with 3 rated as generally acceptable for planning purposes) was selected as primary and the Eclipse-based method (3.5/5) for verification. Mean distance to agreement and true positive rate were selected as covariates in an optimized logit model. These models, when applied to a group of twenty different patients, indicated that shifts could be detected at 0.5cm (brain), 0.75cm (mandible, cord), 1cm (brainstem, cochlea), or 1.25cm (parotid), with sensitivity and specificity greater than 0.95. If sensitivity and specificity constraints are reduced to 0.9, detectable shifts of mandible and brainstem were reduced by 0.25cm. These shifts represent additional safety margins which might be considered if auto-contours are used for automatic treatment planning without physician review. Conclusion: Automatically contoured structures can be automatically verified. This fully automated process could be used to flag auto-contours for special review or used with safety margins in a fully automatic treatment planning system.« less

How to determine an optimal threshold to classify real-time crash-prone traffic conditions?

PubMed

Yang, Kui; Yu, Rongjie; Wang, Xuesong; Quddus, Mohammed; Xue, Lifang

2018-08-01

One of the proactive approaches in reducing traffic crashes is to identify hazardous traffic conditions that may lead to a traffic crash, known as real-time crash prediction. Threshold selection is one of the essential steps of real-time crash prediction. And it provides the cut-off point for the posterior probability which is used to separate potential crash warnings against normal traffic conditions, after the outcome of the probability of a crash occurring given a specific traffic condition on the basis of crash risk evaluation models. There is however a dearth of research that focuses on how to effectively determine an optimal threshold. And only when discussing the predictive performance of the models, a few studies utilized subjective methods to choose the threshold. The subjective methods cannot automatically identify the optimal thresholds in different traffic and weather conditions in real application. Thus, a theoretical method to select the threshold value is necessary for the sake of avoiding subjective judgments. The purpose of this study is to provide a theoretical method for automatically identifying the optimal threshold. Considering the random effects of variable factors across all roadway segments, the mixed logit model was utilized to develop the crash risk evaluation model and further evaluate the crash risk. Cross-entropy, between-class variance and other theories were employed and investigated to empirically identify the optimal threshold. And K-fold cross-validation was used to validate the performance of proposed threshold selection methods with the help of several evaluation criteria. The results indicate that (i) the mixed logit model can obtain a good performance; (ii) the classification performance of the threshold selected by the minimum cross-entropy method outperforms the other methods according to the criteria. This method can be well-behaved to automatically identify thresholds in crash prediction, by minimizing the cross entropy between the original dataset with continuous probability of a crash occurring and the binarized dataset after using the thresholds to separate potential crash warnings against normal traffic conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Associating crash avoidance maneuvers with driver attributes and accident characteristics: a mixed logit model approach.

PubMed

Kaplan, Sigal; Prato, Carlo Giacomo

2012-01-01

The current study focuses on the propensity of drivers to engage in crash avoidance maneuvers in relation to driver attributes, critical events, crash characteristics, vehicles involved, road characteristics, and environmental conditions. The importance of avoidance maneuvers derives from the key role of proactive and state-aware road users within the concept of sustainable safety systems, as well as from the key role of effective corrective maneuvers in the success of automated in-vehicle warning and driver assistance systems. The analysis is conducted by means of a mixed logit model that represents the selection among 5 emergency lateral and speed control maneuvers (i.e., "no avoidance maneuvers," "braking," "steering," "braking and steering," and "other maneuvers) while accommodating correlations across maneuvers and heteroscedasticity. Data for the analysis were retrieved from the General Estimates System (GES) crash database for the year 2009 by considering drivers for which crash avoidance maneuvers are known. The results show that (1) the nature of the critical event that made the crash imminent greatly influences the choice of crash avoidance maneuvers, (2) women and elderly have a relatively lower propensity to conduct crash avoidance maneuvers, (3) drowsiness and fatigue have a greater negative marginal effect on the tendency to engage in crash avoidance maneuvers than alcohol and drug consumption, (4) difficult road conditions increase the propensity to perform crash avoidance maneuvers, and (5) visual obstruction and artificial illumination decrease the probability to carry out crash avoidance maneuvers. The results emphasize the need for public awareness campaigns to promote safe driving style for senior drivers and warning about the risks of driving under fatigue and distraction being comparable to the risks of driving under the influence of alcohol and drugs. Moreover, the results suggest the need to educate drivers about hazard perception, designing a forgiving infrastructure within a sustainable safety systems, and rethinking in-vehicle collision warning systems. Future research should address the effectiveness of crash avoidance maneuvers and joint modeling of maneuver selection and crash severity.

Correlates of Leisure-Time Physical Activity Participation Among Latino Children and Adolescents with Acanthosis Nigricans.

PubMed

Wen, Ming; Su, Dejun

2015-10-01

Little is known about leisure-time physical activity (LTPA) correlates in high-risk youth prone to obesity, insulin resistance, and associated morbidities. This study examined LTPA correlates among Latino youth identified with acanthosis nigricans (AN), a skin condition typically caused by metabolic impairment. Data were collected on 305 AN-positive Latino youth of ages 5-15 and one of their biological parents in 2012 from Texas. Ordinal logit regression was performed to analyze the data. Five health and behavioral LTPA correlates were identified, including child time spent in TV watching or videogame playing (OR of highest quartile vs. lowest quartile = 0.45; p = 0.01), child fair/poor health (OR 0.42; p = 0.01), parent obesity (OR 0.63; p = 0.06), parent daily physical exercise for more than 30 min (OR 2.20; p < 0.01), and parent housework time (OR 0.76; p < 0.05). Parent socioeconomic status was insignificant. For at-risk Latino youth, physical activity intervention strategies should take both behavioral and health factors into account.

Business cycles, hypertension and cardiovascular disease: evidence from the Icelandic economic collapse.

PubMed

Asgeirsdottir, Tinna Laufey; Olafsdottir, Thorhildur; Ragnarsdottir, Dagny Osk

2014-08-01

Business cycles affect people's lives. A growing literature examines their effect on health outcomes. The available studies on the relationship between ambient economic conditions and cardiovascular health show mixed results. They are furthermore limited in their outcome measures, focusing mostly on mortality. We examined the relationship between economic conditions and cardiovascular disease and hypertension, using the Icelandic economic collapse of 2008. Logit regression analyses are used to examine the relationship between economic conditions and the probability of reporting a cardiovascular disease or hypertension. We furthermore investigated potential mediators of this relationship. The data used come from a health and lifestyle survey carried out by the Public Health Institute of Iceland in 2007 and 2009. The crisis was positively related to hypertension in males but no statistically significant relationship was found for females. The mediation analyses indicated partial mediation through changes in working hours and stress level, but negligible mediation through changes in income. The male hypertension was, however, suppressed by concurrent changes in smoking and body weight. Only examining mortality effects of society-wide economic conditions may understate the overall effect on cardiovascular health.

Causal explanations for class inequality in health--an empirical analysis.

PubMed

Lundberg, O

1991-01-01

One of the most important issues for research on social class inequalities in health are the causes behind such differences. So far, the debate on class inequalities in health has mainly been centred around hypotheses on artefactual and selectional processes. Although most contributors to this branch of research have argued in favour of causal explanations, these have gained very little systematic scrutiny. In this article, several possible causal factors are singled out for empirical testing. The effect of these factors on class differences in physical and mental illness is studied by means of logit regressions. On the basis of these analyses, it is shown that physical working conditions are the prime source of class inequality in physical illness, although economic hardship during upbringing and health related behaviours also contribute. For class inequality in mental illness these three factors plus weak social network are important. In sum, a large part of the class differences in physical as well as mental illness can be understood as a result of systematic differences between classes in living conditions, primarily differences in working conditions.

Parent-child communication and marijuana initiation: evidence using discrete-time survival analysis.

PubMed

Nonnemaker, James M; Silber-Ashley, Olivia; Farrelly, Matthew C; Dench, Daniel

2012-12-01

This study supplements existing literature on the relationship between parent-child communication and adolescent drug use by exploring whether parental and/or adolescent recall of specific drug-related conversations differentially impact youth's likelihood of initiating marijuana use. Using discrete-time survival analysis, we estimated the hazard of marijuana initiation using a logit model to obtain an estimate of the relative risk of initiation. Our results suggest that parent-child communication about drug use is either not protective (no effect) or - in the case of youth reports of communication - potentially harmful (leading to increased likelihood of marijuana initiation). Copyright © 2012 Elsevier Ltd. All rights reserved.

Choice of contracts in the British National Health Service: an empirical study.

PubMed

Chalkley, Martin; McVicar, Duncan

2008-09-01

Following major reforms of the British National Health Service (NHS) in 1990, the roles of purchasing and providing health services were separated, with the relationship between purchasers and providers governed by contracts. Using a mixed multinomial logit analysis, we show how this policy shift led to a selection of contracts that is consistent with the predictions of a simple model, based on contract theory, in which the characteristics of the health services being purchased and of the contracting parties influence the choice of contract form. The paper thus provides evidence in support of the practical relevance of theory in understanding health care market reform.

The impact of macroeconomic conditions on obesity in Canada.

PubMed

Latif, Ehsan

2014-06-01

The paper used longitudinal Canadian data from the National Population Health Survey to estimate the impact of macroeconomic conditions measured by provincial unemployment rate on individual obesity and BMI. To control for individual-specific unobserved heterogeneity, the study utilized the conditional fixed effect logit and fixed effects models. The study found that unemployment rate had a significant positive impact on the probability of being severely obese. The study also found that unemployment rate significantly increased BMI. However, the study did not find any significant impact of unemployment rate on the probability of being overweight or obese. Copyright © 2013 John Wiley & Sons, Ltd.

The Influence of Consumer Goals and Marketing Activities on Product Bundling

NASA Astrophysics Data System (ADS)

Haijun, Wang

Upon entering a store, consumers are faced with the questions of whether to buy, what to buy, and how much to buy. Consumers include products from different categories in their decision process. Product categories can be related in different ways. Product bundling is a process that involves the choice of at least two non-substitutable items. In this research, the consumers' explicit product bundling activity at the point of sale is focused. We focuses on the retailers' perspective and therefore leaves out consumers' brand choice decisions, concentrating on purchase incidence and quantity. At the base of the current model of the exist researches, we integrate behavioural choice analysis and predictive choice modelling through the underlying behavioural models, called random utility maximization (RUM) models. The methodological contribution of this research lies therein to combine a nested logit choice model with a latent variable factor model. We point out several limitations for both theory and practice at the end.

Forecasting the impact of transport improvements on commuting and residential choice

NASA Astrophysics Data System (ADS)

Elhorst, J. Paul; Oosterhaven, Jan

2006-03-01

This paper develops a probabilistic, competing-destinations, assignment model that predicts changes in the spatial pattern of the working population as a result of transport improvements. The choice of residence is explained by a new non-parametric model, which represents an alternative to the popular multinominal logit model. Travel times between zones are approximated by a normal distribution function with different mean and variance for each pair of zones, whereas previous models only use average travel times. The model’s forecast error of the spatial distribution of the Dutch working population is 7% when tested on 1998 base-year data. To incorporate endogenous changes in its causal variables, an almost ideal demand system is estimated to explain the choice of transport mode, and a new economic geography inter-industry model (RAEM) is estimated to explain the spatial distribution of employment. In the application, the model is used to forecast the impact of six mutually exclusive Dutch core-periphery railway proposals in the projection year 2020.

Stability of Mixed-Strategy-Based Iterative Logit Quantal Response Dynamics in Game Theory

PubMed Central

Zhuang, Qian; Di, Zengru; Wu, Jinshan

2014-01-01

Using the Logit quantal response form as the response function in each step, the original definition of static quantal response equilibrium (QRE) is extended into an iterative evolution process. QREs remain as the fixed points of the dynamic process. However, depending on whether such fixed points are the long-term solutions of the dynamic process, they can be classified into stable (SQREs) and unstable (USQREs) equilibriums. This extension resembles the extension from static Nash equilibriums (NEs) to evolutionary stable solutions in the framework of evolutionary game theory. The relation between SQREs and other solution concepts of games, including NEs and QREs, is discussed. Using experimental data from other published papers, we perform a preliminary comparison between SQREs, NEs, QREs and the observed behavioral outcomes of those experiments. For certain games, we determine that SQREs have better predictive power than QREs and NEs. PMID:25157502

Virtualized healthcare delivery: understanding users and their usage patterns of online medical consultations.

PubMed

Jung, Changmi; Padman, Rema

2014-12-01

Virtualization of healthcare delivery via patient portals has facilitated the increasing interest in online medical consultations due to its benefits such as improved convenience and flexibility, lower cost, and time savings. Despite this growing interest, adoption by both consumers and providers has been slow, and little is known about users and their usage and adoption patterns. To learn characteristics of online healthcare consumers and understand their patterns of adoption and usage of online clinical consultation services (or eVisits delivered via the portal) such as adoption time for portal users, whether adoption hazard changes over time, and what factors influence patients to become early/late adopters. Using online medical consultation records between April 1, 2009 and May 31, 2010 from four ambulatory practices affiliated with a major healthcare provider, we conduct simple descriptive analysis to understand the users of online clinical consults and their usage patterns. Multilevel Logit regression is employed to measure the effect of patient and primary care provider characteristics on the likelihood of eVisit adoption by the patient, and survival analysis and Ordered Logit regression are applied to study eVisit adoption patterns that delineate elements describing early or late adopters. On average, eVisit adopters are younger and predominantly female. Their primary care providers participate in the eVisit service, highlighting the importance of physician's role in encouraging patients to utilize the service. Patients who are familiar with the patient portal are more likely to use the service, as are patients with more complex health issues. Younger and female patients have higher adoption hazard, but gender does not affect the decision of adopting early vs. late. These adopters also access the patient portal more frequently before adoption, indicating that they are potentially more involved in managing their health. The majority of eVisits are submitted during business hours, with female physicians responding faster (from submission to reply), on average. This study addresses virtualization of primary care delivery via patient portals and online clinical consultations and examines factors that distinguish eVisit adopters from patient portal users. Among many delineating characteristics, it is particularly significant that familiarity with the patient portal service and participation of primary care provider are found to be key elements that motivate patients to become an eVisit user and early/late adopter. These findings can be used by provider organizations to design and implement strategies to improve uptake of online medical consultations to complement traditional office visits. Offering such alternative channels of care delivery may potentially improve access, efficiency and outcomes for both patients and providers alike. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Applying crash data to injury claims - an investigation of determinant factors in severe motor vehicle accidents.

PubMed

Shannon, Darren; Murphy, Finbarr; Mullins, Martin; Eggert, Julian

2018-04-01

An extensive number of research studies have attempted to capture the factors that influence the severity of vehicle impacts. The high number of risks facing all traffic participants has led to a gradual increase in sophisticated data collection schemes linking crash characteristics to subsequent severity measures. This study serves as a departure from previous research by relating injuries suffered in road traffic accidents to expected trauma compensation payouts and deriving a quantitative cost function. Data from the National Highway Traffic Safety Administration's (NHTSA) Crash Injury Research (CIREN) database for the years 2005-2014 is combined with the Book of Quantum, an Irish governmental document that offers guidelines on the appropriate compensation to be awarded for injuries sustained in accidents. A multiple linear regression is carried out to identify the crash factors that significantly influence expected compensation costs and compared to ordered and multinomial logit models. The model offers encouraging results given the inherent variation expected in vehicular incidents and the subjectivity influencing compensation payout judgments, attaining an adjusted-R 2 fit of 20.6% when uninfluential factors are removed. It is found that relative speed at time of impact and dark conditions increase the expected costs, while rear-end incidents, incident sustained in van-based trucks and incidents sustained while turning result in lower expected compensations. The number of airbags available in the vehicle is also a significant factor. The scalar-outcome approach used in this research offers an alternative methodology to the discrete-outcome models that dominate traffic safety analyses. The results also raise queries on the future development of claims reserving (capital allocations earmarked for future expected claims payments) as advanced driver assistant systems (ADASs) seek to eradicate the most frequent types of crash factors upon which insurance mathematics base their assumptions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Assessing rear-end crash potential in urban locations based on vehicle-by-vehicle interactions, geometric characteristics and operational conditions.

PubMed

Dimitriou, Loukas; Stylianou, Katerina; Abdel-Aty, Mohamed A

2018-03-01

Rear-end crashes are one of the most frequently occurring crash types, especially in urban networks. An understanding of the contributing factors and their significant association with rear-end crashes is of practical importance and will help in the development of effective countermeasures. The objective of this study is to assess rear-end crash potential at a microscopic level in an urban environment, by investigating vehicle-by-vehicle interactions. To do so, several traffic parameters at the individual vehicle level have been taken into consideration, for capturing car-following characteristics and vehicle interactions, and to investigate their effect on potential rear-end crashes. In this study rear-end crash potential was estimated based on stopping distance between two consecutive vehicles, and four rear-end crash potential cases were developed. The results indicated that 66.4% of the observations were estimated as rear-end crash potentials. It was also shown that rear-end crash potential was presented when traffic flow and speed standard deviation were higher. Also, locational characteristics such as lane of travel and location in the network were found to affect drivers' car following decisions and additionally, it was shown that speeds were lower and headways higher when Heavy Goods Vehicles lead. Finally, a model-based behavioral analysis based on Multinomial Logit regression was conducted to systematically identify the statistically significant variables in explaining rear-end risk potential. The modeling results highlighted the significance of the explanatory variables associated with rear-end crash potential, however it was shown that their effect varied among different model configurations. The outcome of the results can be of significant value for several purposes, such as real-time monitoring of risk potential, allocating enforcement units in urban networks and designing targeted proactive safety policies. Copyright © 2018 Elsevier Ltd. All rights reserved.

Variations in Mortality in Children Admitted with Pneumonia to Kenyan Hospitals

PubMed Central

Ayieko, Philip; Okiro, Emelda A.; Edwards, Tansy; Nyamai, Rachel; English, Mike

2012-01-01

Background The existing case fatality estimates of inpatient childhood pneumonia in developing countries are largely from periods preceding routine use of conjugate vaccines for infant immunization and such primary studies rarely explore hospital variations in mortality. We analysed case fatality rates of children admitted to nine Kenyan hospitals with pneumonia during the era of routine infant immunization with Hib conjugate vaccine to determine if significant variations exist between hospitals. Methods Pneumonia admissions and outcomes in paediatric wards are described using data collected over two time periods: a one-year period (2007–2008) in nine hospitals, and data from a 9.25-year period (1999-March 2008) in one of the participating hospitals. Hospital case fatality rates for inpatient pneumonia during 2007 to 2008 were modeled using a fixed effect binomial regression model with a logit link. Using an interrupted time series design, data from one hospital were analysed for trends in pneumonia mortality during the period between 1997 and March 2008. Results Overall, 195 (5.9%) children admitted to all 9 hospitals with pneumonia from March 2007 to March 2008 died in hospital. After adjusting for child’s sex, comorbidity, and hospital effect, mortality was significantly associated with child’s age (p<0.001) and pneumonia severity (p<0.001). There was evidence of significant variations in mortality between hospitals (LR χ2 = 52.19; p<0.001). Pneumonia mortality remained stable in the periods before (trend −0.03, 95% CI −0.1 to 0.02) and after Hib introduction (trend 0.04, 95% CI −0.04 to 0.11). Conclusions There are important variations in hospital-pneumonia case fatality in Kenya and these variations are not attributed to temporal changes. Such variations in mortality are not addressed by existing epidemiological models and need to be considered in allocating resources to improve child health. PMID:23139752

Measuring discrimination in South Korea: underestimating the prevalence of discriminatory experiences among female and less educated workers?

PubMed

Kim, Seung-Sup; Chung, Yeonseung; Subramanian, S V; Williams, David R

2012-01-01

To investigate the possibility that Koreans show different patterns in reporting discriminatory experiences based on their gender and education level, we analyzed the participants who answered "Not Applicable" for the questions of discriminatory experiences that they were eligible to answer. Discriminatory experiences in eight social situations were assessed using the 7(th) wave of Korean Labor and Income Panel Study. After restricting the study population to waged workers, a logistic regression model was constructed to predict the probability that an individual has experienced discrimination based on the observed covariates for each of eight situations, using the data of participants who answered either Yes or No. With the model fit, the predicted logit score of discrimination (PLSD) was obtained for participants who answered Not Applicable (NA), as well as for those who answered Yes or No. The mean PLSD of the NA group was compared with those of the Yes group and the No group after stratification by gender and education level using an ANOVA model. On the questions of discrimination in getting hired and receiving income, the PLSD of the NA group was significantly higher than that of the No group and was not different from that of Yes group for female and junior high or less educated workers, suggesting that their NA responses were more likely to mean that they have experienced discrimination. For male and college or more educated workers, the NA group had a PLSD similar to that for the No group and had a significantly higher PLSD than the Yes group, implying that their NA responses would mean they that they have not experienced discrimination. Our findings suggest that the responses of NA on the discrimination questionnaire may need different interpretation based on the respondents' gender and education level in South Korea.

Plausible role for CHW peer support groups in increasing care-seeking in an integrated community case management project in Rwanda: a mixed methods evaluation.

PubMed

Langston, Anne; Weiss, Jennifer; Landegger, Justine; Pullum, Thomas; Morrow, Melanie; Kabadege, Melene; Mugeni, Catherine; Sarriot, Eric

2014-08-01

The Kabeho Mwana project (2006-2011) supported the Rwanda Ministry of Health (MOH) in scaling up integrated community case management (iCCM) of childhood illness in 6 of Rwanda's 30 districts. The project trained and equipped community health workers (CHWs) according to national guidelines. In project districts, Kabeho Mwana staff also trained CHWs to conduct household-level health promotion and established supervision and reporting mechanisms through CHW peer support groups (PSGs) and quality improvement systems. The 2005 and 2010 Demographic and Health Surveys were re-analyzed to evaluate how project and non-project districts differed in terms of care-seeking for fever, diarrhea, and acute respiratory infection symptoms and related indicators. We developed a logit regression model, controlling for the timing of the first CHW training, with the district included as a fixed categorical effect. We also analyzed qualitative data from the final evaluation to examine factors that may have contributed to improved outcomes. While there was notable improvement in care-seeking across all districts, care-seeking from any provider for each of the 3 conditions, and for all 3 combined, increased significantly more in the project districts. CHWs contributed a larger percentage of consultations in project districts (27%) than in non-project districts (12%). Qualitative data suggested that the PSG model was a valuable sub-level of CHW organization associated with improved CHW performance, supervision, and social capital. The iCCM model implemented by Kabeho Mwana resulted in greater improvements in care-seeking than those seen in the rest of the country. Intensive monitoring, collaborative supervision, community mobilization, and CHW PSGs contributed to this success. The PSGs were a unique contribution of the project, playing a critical role in improving care-seeking in project districts. Effective implementation of iCCM should therefore include CHW management and social support mechanisms. Finally, re-analysis of national survey data improved evaluation findings by providing impact estimates.

Social influence, agent heterogeneity and the emergence of the urban informal sector

NASA Astrophysics Data System (ADS)

García-Díaz, César; Moreno-Monroy, Ana I.

2012-02-01

We develop an agent-based computational model in which the urban informal sector acts as a buffer where rural migrants can earn some income while queuing for higher paying modern-sector jobs. In the model, the informal sector emerges as a result of rural-urban migration decisions of heterogeneous agents subject to social influence in the form of neighboring effects of varying strengths. Besides using a multinomial logit choice model that allows for agent idiosyncrasy, explicit agent heterogeneity is introduced in the form of socio-demographic characteristics preferred by modern-sector employers. We find that different combinations of the strength of social influence and the socio-economic composition of the workforce lead to very different urbanization and urban informal sector shares. In particular, moderate levels of social influence and a large proportion of rural inhabitants with preferred socio-demographic characteristics are conducive to a higher urbanization rate and a larger informal sector.

Calibration and validation of the Physical Activity Barrier Scale for persons who are blind or visually impaired.

PubMed

Lee, Miyoung; Zhu, Weimo; Ackley-Holbrook, Elizabeth; Brower, Diana G; McMurray, Bryan

2014-07-01

It is critical to employ accurate measures when assessing physical activity (PA) barriers in any subpopulation, yet existing measures are not appropriate for persons with blindness or visual impairment (PBVI) due to a lack of validity or reliability evidence. To develop and calibrate a PA barrier scale for PBVI. An expert panel (n = 3) and 18 PBVI were recruited to establish content validity for a PA barriers subscale; 160 PBVI (96 females) completed the scale along with the Physical Activity Scale for Individuals with Physical Disabilities for calibration. To establish construct-related validity evidence, Confirmative factor analysis (CFA) and Rasch analysis were applied. To investigate internal consistency and reliability, Cronbach's alpha and the reliability coefficient (R) were employed, respectively. Following CFA and Rasch analyses, five items were eliminated due to misfits; reliability coefficients were unchanged upon deletion of these items. The barriers perceived by PBVI to have the most negative impact on PA included "lack of self-discipline" (logit = 1.40) and "lack of motivation" (logit = 1.27). "Too many stairs in the exercise facility" (logit = -1.49) was perceived to have the least impact. The newly-developed scale was found to be a valid and reliable tool for evaluating PA barriers in PBVI. To enhance promotion of health-producing levels of PA in PBVI, practitioners should consider applying this new tool as a precursor to programs aimed at improving PA participation in this group. Copyright © 2014 Elsevier Inc. All rights reserved.

Methodologies for Evaluating the Impact of Contraceptive Social Marketing Programs.

ERIC Educational Resources Information Center

Bertrand, Jane T.; And Others

1989-01-01

An overview of the evaluation issues associated with contraceptive social marketing programs is provided. Methodologies covered include survey techniques, cost-effectiveness analyses, retail audits of sales data, time series analysis, nested logit analysis, and discriminant analysis. (TJH)

Impact of First Eye versus Second Eye Cataract Surgery on Visual Function and Quality of Life.

PubMed

Shekhawat, Nakul S; Stock, Michael V; Baze, Elizabeth F; Daly, Mary K; Vollman, David E; Lawrence, Mary G; Chomsky, Amy S

2017-10-01

To compare the impact of first eye versus second eye cataract surgery on visual function and quality of life. Cohort study. A total of 328 patients undergoing separate first eye and second eye phacoemulsification cataract surgeries at 5 veterans affairs centers in the United States. Patients with previous ocular surgery, postoperative endophthalmitis, postoperative retinal detachment, reoperation within 30 days, dementia, anxiety disorder, hearing difficulty, or history of drug abuse were excluded. Patients received complete preoperative and postoperative ophthalmic examinations for first eye and second eye cataract surgeries. Best-corrected visual acuity (BCVA) was measured 30 to 90 days preoperatively and postoperatively. Patients completed the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ) 30 to 90 days preoperatively and postoperatively. The NEI-VFQ scores were calculated using a traditional subscale scoring algorithm and a Rasch-refined approach producing visual function and socioemotional subscale scores. Postoperative NEI-VFQ scores and improvement in NEI-VFQ scores comparing first eye versus second eye cataract surgery. Mean age was 70.4 years (±9.6 standard deviation [SD]). Compared with second eyes, first eyes had worse mean preoperative BCVA (0.55 vs. 0.36 logarithm of the minimum angle of resolution (logMAR), P < 0.001), greater mean BCVA improvement after surgery (-0.50 vs. -0.32 logMAR, P < 0.001), and slightly worse postoperative BCVA (0.06 vs. 0.03 logMAR, P = 0.039). Compared with first eye surgery, second eye surgery resulted in higher postoperative NEI-VFQ scores for nearly all traditional subscales (P < 0.001), visual function subscale (-3.85 vs. -2.91 logits, P < 0.001), and socioemotional subscale (-2.63 vs. -2.10 logits, P < 0.001). First eye surgery improved visual function scores more than second eye surgery (-2.99 vs. -2.67 logits, P = 0.021), but both first and second eye surgeries resulted in similar improvements in socioemotional scores (-1.62 vs. -1.51 logits, P = 0.255). Second eye cataract surgery improves visual function and quality of life well beyond levels achieved after first eye cataract surgery alone. For certain socioemotional aspects of quality of life, second eye cataract surgery results in comparable improvement to first eye cataract surgery. Copyright © 2017 American Academy of Ophthalmology. All rights reserved.

On-the-job moms: work and breastfeeding initiation and duration for a sample of low-income women.

PubMed

Kimbro, Rachel Tolbert

2006-01-01

As both employed and breastfeeding mothers increase, more women are facing the decision of whether and how to combine the behaviors. This paper examines three hypotheses for a sample of low-income women: 1) Mothers who expect to return to work after the birth of their baby will be less likely to initiate breastfeeding; 2) The timing of the return to work and quitting breastfeeding will coincide; 3) Mothers in professional jobs and Stay-at-Home (SAH) Moms will breastfeed for longer durations than mothers with other types of jobs. The Fragile Families and Child Wellbeing Study, a sample of mostly low-income, unmarried U.S. mothers, offers a unique opportunity to study this issue, as there is reason to believe that employment may impact breastfeeding differently for low-income women. Logistic regression determines the relationship between the expectation of work and breastfeeding initiation, and discrete-time logit models examine breastfeeding duration, the timing of the return to work, and occupation type. Expecting to work in the year after the baby's birth does not impact breastfeeding initiation. The timing of quitting breastfeeding and the return to work are closely and powerfully linked, and mothers in administrative and manual positions quit earlier than other women. Interestingly, women in service occupations do not differ in breastfeeding duration from SAH mothers or professionals. This research demonstrates that low-income women are having difficulty combining work and breastfeeding, which has important health implications for their infants, and that women working in administrative and manual occupations may face special constraints.

Freezing as a treatment to prevent the spread of Hypothenemus hampei (Coleoptera: Curculionidae), in coffee.

PubMed

Hollingsworth, Robert C; Jang, Eric B; Follett, Peter A

2013-04-01

Coffee berry borer, Hypothenemus hampei (Ferrari) is the most serious insect pest of coffee around the world. Although it is already present in most of the world's major coffee growing regions, it is important to delay further spread and to prevent reintroductions that might include hyperparasites or improve the genetic base of existing populations. Green coffee is shipped around the world for custom blending and roasting and such shipments carry the risk of spreading H. hampei. We used heavily infested coffee berries as a surrogate for green coffee to test the freezing tolerance of H. hampei. After freezing, all life stages of H. hampei were dissected from coffee berries and mortality was assessed. Counting all life stages, > 15,000 insects were measured in this study. A temperature of approximately -15 degrees C (range, -13.9 to -15.5) for 48 h provided 100% control of all life stages. A logit regression model predicted < or = 1 survivor in a million for treatments of -20 degrees C for 5 d or -15 degrees C for 6 d. A freezing treatment for green coffee might be more economical and acceptable compared with fumigation with methyl bromide, especially for small-scale and organic growers and millers in Hawaii who ship green coffee beans to other islands for custom roasting. Freezing treatments could also be used to kill H. hampei in coffee seeds before export with minimal effects on seed germination if coffee seeds are first dried to critical water content levels in accordance with published methods.

Valuing EQ-5D-5L health states 'in context' using a discrete choice experiment.

PubMed

Cole, Amanda; Shah, Koonal; Mulhern, Brendan; Feng, Yan; Devlin, Nancy

2018-05-01

In health state valuation studies, health states are typically presented as a series of sentences, each describing a health dimension and severity 'level'. Differences in the severity levels can be subtle, and confusion about which is 'worse' can lead to logically inconsistent valuation data. A solution could be to mimic the way patients self-report health, where the ordinal structure of levels is clear. We develop and test the feasibility of presenting EQ-5D-5L health states in the 'context' of the entire EQ-5D-5L descriptive system. An online two-arm discrete choice experiment was conducted in the UK (n = 993). Respondents were randomly allocated to a control (standard presentation) or 'context' arm. Each respondent completed 16 paired comparison tasks and feedback questions about the tasks. Differences across arms were assessed using regression analyses. Presenting health states 'in context' can significantly reduce the selection of logically dominated health states, particularly for labels 'severe' and 'extreme' (χ 2  = 46.02, p < 0.001). Preferences differ significantly between arms (likelihood ratio statistic = 42.00, p < 0.05). Comparing conditional logit modeling results, coefficients are ordered as expected for both arms, but the magnitude of decrements between levels is larger for the context arm. Health state presentation is a key consideration in the design of valuation studies. Presenting health states 'in context' affects valuation data and reduces logical inconsistencies. Our results could have implications for other valuation tasks such as time trade-off, and for the valuation of other preference-based measures.

Soccer Heading Is Associated with White Matter Microstructural and Cognitive Abnormalities

PubMed Central

Kim, Namhee; Zimmerman, Molly E.; Kim, Mimi; Stewart, Walter F.; Branch, Craig A.

2013-01-01

Purpose: To investigate the association of soccer heading with subclinical evidence of traumatic brain injury. Materials and Methods: With institutional review board approval and compliance with HIPAA guidelines, 37 amateur soccer players (mean age, 30.9 years; 78% [29] men, 22% [eight] women) gave written informed consent and completed a questionnaire to quantify heading in the prior 12 months and lifetime concussions. Diffusion-tensor magnetic resonance (MR) imaging at 3.0 T was performed (32 directions; b value, 800 sec/mm2; 2 × 2 × 2-mm voxels). Cognitive function was measured by using a computerized battery of tests. Voxelwise linear regression (heading vs fractional anisotropy [FA]) was applied to identify significant regional associations. FA at each location and cognition were tested for a nonlinear relationship to heading by using an inverse logit model that incorporated demographic covariates and history of concussion. Results: Participants had headed 32–5400 times (median, 432 times) over the previous year. Heading was associated with lower FA at three locations in temporo-occipital white matter with a threshold that varied according to location (885–1550 headings per year) (P < .00001). Lower levels of FA were also associated with poorer memory scores (P < .00001), with a threshold of 1800 headings per year. Lifetime concussion history and demographic features were not significantly associated with either FA or cognitive performance. Conclusion: Heading is associated with abnormal white matter microstructure and with poorer neurocognitive performance. This relationship is not explained by a history of concussion. © RSNA, 2013 PMID:23757503

Can a publicly funded home care system successfully allocate service based on perceived need rather than socioeconomic status? A Canadian experience.

PubMed

Laporte, Audrey; Croxford, Ruth; Coyte, Peter C

2007-03-01

The present quantitative study evaluates the degree to which socioeconomic status (SES), as opposed to perceived need, determines utilisation of publicly funded home care in Ontario, Canada. The Registered Persons Data Base of the Ontario Health Insurance Plan was used to identify the age, sex and place of residence for all Ontarians who had coverage for the complete calendar year 1998. Utilisation was characterised in two dimensions: (1) propensity - the probability that an individual received service, which was estimated using a multinomial logit equation; and (2) intensity - the amount of service received, conditional on receipt. Short- and long-term service intensity were modelled separately using ordinary least squares regression. Age, sex and co-morbidity were the best predictors (P < 0.0001) of whether or not an individual received publicly funded home care as well as how much care was received, with sicker individuals having increased utilisation. The propensity and intensity of service receipt increased with lower SES (P < 0.0001), and decreased with the proportion of recent immigrants in the region (P < 0.0001), after controlling for age, sex and co-morbidity. Although the allocation of publicly funded home care service was primarily based on perceived need rather than ability to pay, barriers to utilisation for those from areas with a high proportion of recent immigrants were identified. Future research is needed to assess whether the current mix and level of publicly funded resources are indeed sufficient to offset the added costs associated with the provision of high-quality home care.

Social and Environmental Factors Related to Boys' and Girls' Park-Based Physical Activity.

PubMed

Bocarro, Jason N; Floyd, Myron F; Smith, William R; Edwards, Michael B; Schultz, Courtney L; Baran, Perver; Moore, Robin A; Cosco, Nilda; Suau, Luis J

2015-06-18

Parks provide opportunities for physical activity for children. This study examined sex differences in correlates of park-based physical activity because differences may indicate that a standard environmental intervention to increase activity among children may not equally benefit boys and girls. The System for Observation Play and Recreation in Communities was used to measure physical activity among 2,712 children and adolescents in 20 neighborhood parks in Durham, North Carolina, in 2007. Sedentary activity, walking, vigorous park activity, and energy expenditure were the primary outcome variables. Hierarchical logit regression models of physical activity were estimated separately for boys and girls. Type of activity area and presence of other active children were positively associated with boys' and girls' physical activity, and presence of a parent was negatively associated. A significant interaction involving number of recreation facilities in combination with formal activities was positively associated with girls' activity. A significant interaction involving formal park activity and young boys (aged 0-5 y) was negatively associated with park-based physical activity. Activity area and social correlates of park-based physical activity were similar for boys and girls; findings for formal park programming, age, and number of facilities were mixed. Results show that girls' physical activity was more strongly affected by social effects (eg, presence of other active children) whereas boys' physical activity was more strongly influenced by the availability of park facilities. These results can inform park planning and design. Additional studies are necessary to clarify sex differences in correlates of park-based physical activity.

Social and Environmental Factors Related to Boys’ and Girls’ Park-Based Physical Activity

PubMed Central

Floyd, Myron F.; Smith, William R.; Edwards, Michael B.; Schultz, Courtney L.; Baran, Perver; Moore, Robin A.; Cosco, Nilda; Suau, Luis J.

2015-01-01

Introduction Parks provide opportunities for physical activity for children. This study examined sex differences in correlates of park-based physical activity because differences may indicate that a standard environmental intervention to increase activity among children may not equally benefit boys and girls. Methods The System for Observation Play and Recreation in Communities was used to measure physical activity among 2,712 children and adolescents in 20 neighborhood parks in Durham, North Carolina, in 2007. Sedentary activity, walking, vigorous park activity, and energy expenditure were the primary outcome variables. Hierarchical logit regression models of physical activity were estimated separately for boys and girls. Results Type of activity area and presence of other active children were positively associated with boys’ and girls’ physical activity, and presence of a parent was negatively associated. A significant interaction involving number of recreation facilities in combination with formal activities was positively associated with girls’ activity. A significant interaction involving formal park activity and young boys (aged 0–5 y) was negatively associated with park-based physical activity. Conclusion Activity area and social correlates of park-based physical activity were similar for boys and girls; findings for formal park programming, age, and number of facilities were mixed. Results show that girls’ physical activity was more strongly affected by social effects (eg, presence of other active children) whereas boys’ physical activity was more strongly influenced by the availability of park facilities. These results can inform park planning and design. Additional studies are necessary to clarify sex differences in correlates of park-based physical activity. PMID:26086610

Citizen Participation in Patient Prioritization Policy Decisions: An Empirical and Experimental Study on Patients' Characteristics

PubMed Central

Diederich, Adele; Swait, Joffre; Wirsik, Norman

2012-01-01

Health systems worldwide are grappling with the need to control costs to maintain system viability. With the combination of worsening economic conditions, an aging population and reductions in tax revenues, the pressures to make structural changes are expected to continue growing. Common cost control mechanisms, e.g. curtailment of patient access and treatment prioritization, are likely to be adversely viewed by citizens. It seems therefore wise to include them in the decision making processes that lead up to policy changes. In the context of a multilevel iterative mixed-method design a quantitative survey representative of the German population (N = 2031) was conducted to probe the acceptance of priority setting in medicine and to explore the practicability of direct public involvement. Here we focus on preferences for patients' characteristics (medical aspects, lifestyle and socio-economic status) as possible criteria for prioritizing medical services. A questionnaire with closed response options was fielded to gain insight into attitudes toward broad prioritization criteria of patient groups. Furthermore, a discrete choice experiment was used as a rigorous approach to investigate citizens' preferences toward specific criteria level in context of other criteria. Both the questionnaire and the discrete choice experiment were performed with the same sample. The citizens' own health and social situation are included as explanatory variables. Data were evaluated using corresponding analysis, contingency analysis, logistic regression and a multinomial exploded logit model. The results show that some medical criteria are highly accepted for prioritizing patients whereas socio-economic criteria are rejected. PMID:22590619

The stroke impairment assessment set: its internal consistency and predictive validity.

PubMed

Tsuji, T; Liu, M; Sonoda, S; Domen, K; Chino, N

2000-07-01

To study the scale quality and predictive validity of the Stroke Impairment Assessment Set (SIAS) developed for stroke outcome research. Rasch analysis of the SIAS; stepwise multiple regression analysis to predict discharge functional independence measure (FIM) raw scores from demographic data, the SIAS scores, and the admission FIM scores; cross-validation of the prediction rule. Tertiary rehabilitation center in Japan. One hundred ninety stroke inpatients for the study of the scale quality and the predictive validity; a second sample of 116 stroke inpatients for the cross-validation study. Mean square fit statistics to study the degree of fit to the unidimensional model; logits to express item difficulties; discharge FIM scores for the study of predictive validity. The degree of misfit was acceptable except for the shoulder range of motion (ROM), pain, visuospatial function, and speech items; and the SIAS items could be arranged on a common unidimensional scale. The difficulty patterns were identical at admission and at discharge except for the deep tendon reflexes, ROM, and pain items. They were also similar for the right- and left-sided brain lesion groups except for the speech and visuospatial items. For the prediction of the discharge FIM scores, the independent variables selected were age, the SIAS total scores, and the admission FIM scores; and the adjusted R2 was .64 (p < .0001). Stability of the predictive equation was confirmed in the cross-validation sample (R2 = .68, p < .001). The unidimensionality of the SIAS was confirmed, and the SIAS total scores proved useful for stroke outcome prediction.

Modelling self-assessed vulnerability to HIV and its associated factors in a HIV-burdened country.

PubMed

Fagbamigbe, A F; Lawal, A M; Idemudia, E S

2017-12-01

Globally, individuals' self-assessment of vulnerability to HIV infection is important to maintain safer sexual behaviour and reduce risky behaviours. However, determinants of self-perceived risk of HIV infection are not well documented and differ. We assessed the level of self-perceived vulnerability to HIV infection in Nigeria and also identified its risk factors. We explored a recent nationally representative data with self-reported vulnerability ('high', 'low' and 'no risk at all') to HIV infection as the outcome of interest. Data were weighted and association between the outcomes and the risk factors determined. We used simple ordered logit regression to model relationship between the outcome variable and risk factors, and controlled for the significant variables in multiple ordered logistic regression at 5% significance level. About 74% had good knowledge of HIV transmission and 6% had experienced STI recently. The likelihood of assessing oneself as having 'no risk at all' was 50% and for 'high chances' was 1.6%. Self-perceived high risk of HIV was higher among those who recently experienced STI (5.6%) than those who did not (1.7%), and also higher among those who recently engaged in transactional sex and had multiple sexual partners. The odds of good knowledge of HIV transmission on high self-perceived vulnerability to HIV was 19% higher than poor knowledge (OR = 1.19, 95% CI: 1.12-1.27). Also, respondents who recently had multiple sexual partners were 72% (OR = 1.72, 95% CI: 1.60-1.86) more likely to report self as having high risk. Younger respondents aged 14-19 years had higher odds of 41% (OR = 1.41, 95% CI: 1.29-1.55) to perceive self as having high vulnerability to HIV than older respondents. High vulnerability to HIV infection was reported among younger respondents, those with history of STIS and those who engage in multiple sexual relations. Despite high level of risky sexual behaviour and good knowledge of HIV transmission and prevention found in this study, self-perceived vulnerability to HIV generally is low. For the low perception found in this study to translate to low chance of HIV infection, there is need for all stakeholders to embark on risk reduction initiatives through sexual education that would minimise risky sexual practices and ensuring availability and affordability of HIV prevention methods.

Do political factors matter in explaining under- and overweight outcomes in developing countries?

PubMed Central

Fumagalli, Elena; Mentzakis, Emmanouil; Suhrcke, Marc

2013-01-01

We construct a rich dataset covering 47 developing countries over the years 1990–2007, combining several micro and macro level data sources to explore the link between political factors and body mass index (BMI). We implement a heteroskedastic generalized ordered logit model allowing for different covariate effects across the BMI distribution and accounting for the unequal BMI dispersion by geographical area. We find that systems with democratic qualities are more likely to reduce under-weight, but increase overweight/obesity, whereas effective political competition does entail double-benefits in the form of reducing both under-weight and obesity. Our results are robust to the introduction of country fixed effects. PMID:24795523

Value of arsenic-free drinking water to rural households in Bangladesh.

PubMed

Ahmad, Junaid; Goldar, Bishwanath; Misra, Smita

2005-01-01

Using contingent valuation survey data for about 2700 households in rural Bangladesh, and applying a multinomial logit model, the paper estimates the value of arsenic-free drinking water to the rural people. The estimates indicate that the rural people in arsenic-affected areas of Bangladesh place a low value on arsenic-free drinking water. It is about 10-14 percent of the amount they are willing to pay for piped water and only about 0.2-0.3 percent of the average household income. The implication of the result is that robust but costly arsenic reduction technologies such as activated alumina technology may find little social acceptance, unless heavily subsidized.

Rigorously testing multialternative decision field theory against random utility models.

PubMed

Berkowitsch, Nicolas A J; Scheibehenne, Benjamin; Rieskamp, Jörg

2014-06-01

Cognitive models of decision making aim to explain the process underlying observed choices. Here, we test a sequential sampling model of decision making, multialternative decision field theory (MDFT; Roe, Busemeyer, & Townsend, 2001), on empirical grounds and compare it against 2 established random utility models of choice: the probit and the logit model. Using a within-subject experimental design, participants in 2 studies repeatedly choose among sets of options (consumer products) described on several attributes. The results of Study 1 showed that all models predicted participants' choices equally well. In Study 2, in which the choice sets were explicitly designed to distinguish the models, MDFT had an advantage in predicting the observed choices. Study 2 further revealed the occurrence of multiple context effects within single participants, indicating an interdependent evaluation of choice options and correlations between different context effects. In sum, the results indicate that sequential sampling models can provide relevant insights into the cognitive process underlying preferential choices and thus can lead to better choice predictions. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Cycle frequency in standard Rock-Paper-Scissors games: Evidence from experimental economics

NASA Astrophysics Data System (ADS)

Xu, Bin; Zhou, Hai-Jun; Wang, Zhijian

2013-10-01

The Rock-Paper-Scissors (RPS) game is a widely used model system in game theory. Evolutionary game theory predicts the existence of persistent cycles in the evolutionary trajectories of the RPS game, but experimental evidence has remained to be rather weak. In this work, we performed laboratory experiments on the RPS game and analyzed the social-state evolutionary trajectories of twelve populations of N=6 players. We found strong evidence supporting the existence of persistent cycles. The mean cycling frequency was measured to be 0.029±0.009 period per experimental round. Our experimental observations can be quantitatively explained by a simple non-equilibrium model, namely the discrete-time logit dynamical process with a noise parameter. Our work therefore favors the evolutionary game theory over the classical game theory for describing the dynamical behavior of the RPS game.

Exclusive queueing model including the choice of service windows

NASA Astrophysics Data System (ADS)

Tanaka, Masahiro; Yanagisawa, Daichi; Nishinari, Katsuhiro

2018-01-01

In a queueing system involving multiple service windows, choice behavior is a significant concern. This paper incorporates the choice of service windows into a queueing model with a floor represented by discrete cells. We contrived a logit-based choice algorithm for agents considering the numbers of agents and the distances to all service windows. Simulations were conducted with various parameters of agent choice preference for these two elements and for different floor configurations, including the floor length and the number of service windows. We investigated the model from the viewpoint of transit times and entrance block rates. The influences of the parameters on these factors were surveyed in detail and we determined that there are optimum floor lengths that minimize the transit times. In addition, we observed that the transit times were determined almost entirely by the entrance block rates. The results of the presented model are relevant to understanding queueing systems including the choice of service windows and can be employed to optimize facility design and floor management.

Exploring the determinants of pedestrian-vehicle crash severity in New York City.

PubMed

Aziz, H M Abdul; Ukkusuri, Satish V; Hasan, Samiul

2013-01-01

Pedestrian-vehicle crashes remain a major concern in New York City due to high percentage of fatalities. This study develops random parameter logit models for explaining pedestrian injury severity levels of New York City accounting for unobserved heterogeneity in the population and across the boroughs. A log-likelihood ratio test for joint model suitability suggests that separate models for each of the boroughs should be estimated. Among many variables, road characteristics (e.g., number of lanes, grade, light condition, road surface, etc.), traffic attributes (e.g., presence of signal control, type of vehicle, etc.), and land use (e.g., parking facilities, commercial and industrial land use, etc.) are found to be statistically significant in the estimated model. The study also suggests that the set of counter measures should be different for different boroughs in the New York City and the priority ranks of countermeasures should be different as well. Copyright © 2012 Elsevier Ltd. All rights reserved.

Potential Influence of Metro on Bus: A Case Study

NASA Astrophysics Data System (ADS)

Selvakumar, M.; Abishek Reddy, M.; Sathish, V.; Venkatesh, R.

2018-03-01

A modal shift occurs when one mode of transport has a comparative advantage in a similar market over another. The present work concerns with the development of modal shift model for urban travel in Chennai, India. The modal shift model was calibrated using binary logit technique and validated using hold-out sample method. The validated model was used to predict the probability of shift in selected corridor. The recent introduction of metro rail in Chennai has lead to an increasing competition among public transport modes. To study the influence of metro on bus transport, a Stated Preference (SP) survey was conducted among express bus travellers. Using the SP survey data, a modal shift model was calibrated to estimate the plausible shift from bus to metro. Results indicate that variables like fare-difference, age, and income play an important role in the shift behaviour. When metro fare increases with respect to express bus fare, bus passengers are less willing to use metro and vice-versa.

Potential Influence of Metro on Bus: A Case Study

NASA Astrophysics Data System (ADS)

Selvakumar, M.; Abishek Reddy, M.; Sathish, V.; Venkatesh, R.

2018-06-01

A modal shift occurs when one mode of transport has a comparative advantage in a similar market over another. The present work concerns with the development of modal shift model for urban travel in Chennai, India. The modal shift model was calibrated using binary logit technique and validated using hold-out sample method. The validated model was used to predict the probability of shift in selected corridor. The recent introduction of metro rail in Chennai has lead to an increasing competition among public transport modes. To study the influence of metro on bus transport, a Stated Preference (SP) survey was conducted among express bus travellers. Using the SP survey data, a modal shift model was calibrated to estimate the plausible shift from bus to metro. Results indicate that variables like fare- difference, age, and income play an important role in the shift behaviour. When metro fare increases with respect to express bus fare, bus passengers are less willing to use metro and vice-versa.

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.

Experimental and statistical study on fracture boundary of non-irradiated Zircaloy-4 cladding tube under LOCA conditions

NASA Astrophysics Data System (ADS)

Narukawa, Takafumi; Yamaguchi, Akira; Jang, Sunghyon; Amaya, Masaki

2018-02-01

For estimating fracture probability of fuel cladding tube under loss-of-coolant accident conditions of light-water-reactors, laboratory-scale integral thermal shock tests were conducted on non-irradiated Zircaloy-4 cladding tube specimens. Then, the obtained binary data with respect to fracture or non-fracture of the cladding tube specimen were analyzed statistically. A method to obtain the fracture probability curve as a function of equivalent cladding reacted (ECR) was proposed using Bayesian inference for generalized linear models: probit, logit, and log-probit models. Then, model selection was performed in terms of physical characteristics and information criteria, a widely applicable information criterion and a widely applicable Bayesian information criterion. As a result, it was clarified that the log-probit model was the best among the three models to estimate the fracture probability in terms of the degree of prediction accuracy for both next data to be obtained and the true model. Using the log-probit model, it was shown that 20% ECR corresponded to a 5% probability level with a 95% confidence of fracture of the cladding tube specimens.

Multi-agent fare optimization model of two modes problem and its analysis based on edge of chaos

NASA Astrophysics Data System (ADS)

Li, Xue-yan; Li, Xue-mei; Li, Xue-wei; Qiu, He-ting

2017-03-01

This paper proposes a new framework of fare optimization & game model for studying the competition between two travel modes (high speed railway and civil aviation) in which passengers' group behavior is taken into consideration. The small-world network is introduced to construct the multi-agent model of passengers' travel mode choice. The cumulative prospect theory is adopted to depict passengers' bounded rationality, the heterogeneity of passengers' reference point is depicted using the idea of group emotion computing. The conceptions of "Langton parameter" and "evolution entropy" in the theory of "edge of chaos" are introduced to create passengers' "decision coefficient" and "evolution entropy of travel mode choice" which are used to quantify passengers' group behavior. The numerical simulation and the analysis of passengers' behavior show that (1) the new model inherits the features of traditional model well and the idea of self-organizing traffic flow evolution fully embodies passengers' bounded rationality, (2) compared with the traditional model (logit model), when passengers are in the "edge of chaos" state, the total profit of the transportation system is higher.

The effect of Saqez (Pistacia atlantica) ointment on the treatment of nipple fissure and nipple pain in breastfeeding women

PubMed Central

As’adi, Nayereh; Kariman, Nourossadat; Mojab, Faraz; Pourhoseingholi, Mohammad Amin

2017-01-01

Background Nipple fissure is a common problem in breastfeeding women, and the main reason for the early discontinuation of breastfeeding. Objective To determine the effect of Saqez (Pistacia atlantica) ointment on the treatment of nipple fissure and nipple pain in breastfeeding women. Methods This randomized clinical trial was conducted on 100 subjects admitted to the health centers in Tehran, Iran from mid-July to mid-November 2015. The subjects were randomly divided into two equal groups of 50 for the Saqez ointment group and the control group. The subjects were divided into the two groups through random allocation in Excel. The subjects were monitored on day 1, 3 and 7. Data were analyzed in SAS using the Cumulative Logit model and in SPSS-21 using Mann-Whitney, independent-samples t-test, the Chi square and Fisher’s exact test. Results No significant differences were observed between the two groups in terms of their demographic and fertility characteristics. The Cumulative Logit model showed that high levels of nipple fissure and pain were significantly less frequent in the Saqez group compared to the control group (p<0.001). There was about 83% reduction in the severity of fissure and 85 %in the severity of pain in the Saqez group compared to the control group (p<0.001). Conclusion Saqez ointment is more effective in the treatment of nipple fissures and pain than breast milk. As this study was done for the first time, judgment about the conclusive efficacy of Saqez ointment on the nipple fissure, needs further similar studies. Trial registration The trial was registered at the Iranian Registry of Clinical Trials (http://www.irct.ir) with the Irct ID: IRCT2015080723535N1. Funding The authors received no financial support for the research, authorship, and/or publication of this article. PMID:28979728

Contributing factors of crash injury severity at public highway-railroad grade crossings in the U.S.

PubMed

Haleem, Kirolos; Gan, Albert

2015-06-01

The Moving Ahead for Progress in the 21st Century (MAP-21) includes a separate program that supports safety improvements to reduce the number of fatalities and injuries at public highway-railroad grade crossings (HRGCs). This study identifies the significant factors affecting crash injury severity at public HRGCs in the United States. Crashes from 2009 through 2013 on 5,528 public HRGCs, extracted from the Federal Railroad Administration database, were used in the analysis. A comprehensive list of risk factors was explored. Examples include predictors related to geographic region of crash, geometry (e.g., area type and pavement marking type), railroad (e.g., warning device type and railroad class), traffic (e.g., train speed and vehicles annual average daily traffic "AADT"), highway user (e.g., driver age and gender), and environment (e.g., lighting and weather conditions). The study used the mixed logit model to better capture the complex highway user behavior at HRGCs. Female highway users were at higher risk of involvement in injuries and fatalities compared to males. Higher train speeds, very old drivers, open areas, concrete road surface types, and railroad equipment striking highway users before crash, were all found to increase the injury likelihood. On the other hand, young and middle-age drivers, non-passing of standing vehicles at HRGCs, industrial areas, and presence of warning bells were found to reduce injuries and fatalities. The mixed logit model succeeded in identifying contributing factors of crash severity at public HRGCs and potential countermeasures to reduce both fatalities and injuries are suggested. It is important to install warning bells at public HRGCs, especially at those with high number of injury and fatality crashes. Enforcement of traffic nearby HRGCs is necessary to prevent vehicles from overtaking of standing vehicles. Copyright © 2015 Elsevier Ltd. and National Safety Council. Published by Elsevier Ltd. All rights reserved.

Disability Measurement for Korean Community-Dwelling Adults With Stroke: Item-Level Psychometric Analysis of the Korean Longitudinal Study of Ageing

PubMed Central

2018-01-01

Objective To investigate the psychometric properties of the activities of daily living (ADL) instrument used in the analysis of Korean Longitudinal Study of Ageing (KLoSA) dataset. Methods A retrospective study was carried out involving 2006 KLoSA records of community-dwelling adults diagnosed with stroke. The ADL instrument used for the analysis of KLoSA included 17 items, which were analyzed using Rasch modeling to develop a robust outcome measure. The unidimensionality of the ADL instrument was examined based on confirmatory factor analysis with a one-factor model. Item-level psychometric analysis of the ADL instrument included fit statistics, internal consistency, precision, and the item difficulty hierarchy. Results The study sample included a total of 201 community-dwelling adults (1.5% of the Korean population with an age over 45 years; mean age=70.0 years, SD=9.7) having a history of stroke. The ADL instrument demonstrated unidimensional construct. Two misfit items, money management (mean square [MnSq]=1.56, standardized Z-statistics [ZSTD]=2.3) and phone use (MnSq=1.78, ZSTD=2.3) were removed from the analysis. The remaining 15 items demonstrated good item fit, high internal consistency (person reliability=0.91), and good precision (person strata=3.48). The instrument precisely estimated person measures within a wide range of theta (−4.75 logits < θ < 3.97 logits) and a reliability of 0.9, with a conceptual hierarchy of item difficulty. Conclusion The findings indicate that the 15 ADL items met Rasch expectations of unidimensionality and demonstrated good psychometric properties. It is proposed that the validated ADL instrument can be used as a primary outcome measure for assessing longitudinal disability trajectories in the Korean adult population and can be employed for comparative analysis of international disability across national aging studies. PMID:29765888

Are patients referred to rehabilitation diagnosed accurately?

PubMed

Tederko, Piotr; Krasuski, Marek; Nyka, Izabella; Mycielski, Jerzy; Tarnacka, Beata

2017-07-17

An accurate diagnosis of the leading health condition and comorbidities is a prerequisite for safe and effective rehabilitation. The problem of diagnostic errors in physical and rehabilitation medicine (PRM) has not been addressed sufficiently. The responsibility of a referring physician is to determine indications and contraindications for rehabilitation. To assess the rate of and risk factors for inaccurate referral diagnoses (RD) in patients referred to a rehabilitation facility. We hypothesized that inaccurate RD would be more common in patients 1) referred by non-PRM physicians; 2) waiting longer for the admission; 3) older patients. Retrospective observational study. 1000 randomly selected patients admitted between 2012 and 2016 to a day- rehabilitation center (DRC). University DRC specialized in musculoskeletal diseases. On admission all cases underwent clinical verification of RD. Inappropriateness regarding primary diagnoses and comorbidities were noted. Influence of several factors affecting probability of inaccurate RD was analyzed with multiple binary regression model applied to 6 categories of diseases. The rate of inaccurate RD was 25.2%. Higher frequency of inaccurate RD was noted among patients referred by non-PRM specialists (30.3% vs 17.3% in cases referred by PRM specialists). Application of logit regression showed highly significant influence of the specialty of a referring physician on the odds of inaccurate RD (joint Wald test ch2(6)=38.98, p- value=0.000), controlling for the influence of other variables. This may reflect a suboptimal knowledge of the rehabilitation process and a tendency to neglect of comorbidities by non-PRM specialists. The rate of inaccurate RD did not correlate with time between referral and admission (joint Wald test of all odds ratios equal to 1, chi2(6)=5.62, p-value=0.467), however, mean and median waiting times were relatively short (35.7 and 25 days respectively).A high risk of overlooked multimorbidity was revealed in elderly patients (all odds ratios for variable age significantly higher than 1). Hypotheses 1 and 3 were confirmed. Over 25% of patients referred to DRC had inaccurate RD. Risk factors for inaccurate RD include referral by a non-PRM specialist and elderly age. Verification of RD should be routinely introduced to PRM practice.

Anger and Desire for Retribution among Bereaved Parents.

ERIC Educational Resources Information Center

Drenovsky, Cynthia K.

1994-01-01

Logit results show suddenness of death contributes to likelihood parent will feel anger while anticipatory socialization to death or recency of death decreases odds of feeling anger toward child. All variables decrease likelihood parents will feel desire to punish someone for death of child. (BF)

Reviews Equipment: Data logger Book: Imagined Worlds Equipment: Mini data loggers Equipment: PICAXE-18M2 data logger Books: Engineering: A Very Short Introduction and To Engineer Is Human Book: Soap, Science, & Flat-Screen TVs Equipment: uLog and SensorLab Web Watch

NASA Astrophysics Data System (ADS)

2012-07-01

WE RECOMMEND Data logger Fourier NOVA LINK: data logging and analysis To Engineer is Human Engineering: essays and insights Soap, Science, & Flat-Screen TVs People, politics, business and science overlap uLog sensors and sensor adapter A new addition to the LogIT range offers simplicity and ease of use WORTH A LOOK Imagined Worlds Socio-scientific predictions for the future Mini light data logger and mini temperature data logger Small-scale equipment for schools SensorLab Plus LogIT's supporting software, with extra features HANDLE WITH CARE CAXE110P PICAXE-18M2 data logger Data logger 'on view' but disappoints Engineering: A Very Short Introduction A broad-brush treatment fails to satisfy WEB WATCH Two very different websites for students: advanced physics questions answered and a more general BBC science resource

Compensation of hospital-based physicians.

PubMed Central

Steinwald, B

1983-01-01

This study is concerned with methods of compensating hospital-based physicians (HBPs) in five medical specialties: anesthesiology, pathology, radiology, cardiology, and emergency medicine. Data on 2232 nonfederal, short-term general hospitals came from a mail questionnaire survey conducted in Fall 1979. The data indicate that numerous compensation methods exist but these methods, without much loss of precision, can be reduced to salary, percentage of department revenue, and fee-for-service. When HBPs are compensated by salary or percentage methods, most patient billing is conducted by the hospital. In contrast, most fee-for-service HBPs bill their patients directly. Determinants of HBP compensation methods are investigated via multinomial logit analysis. This analysis indicates that choice of HBP compensation methods are investigated via multinomial logit analysis. This analysis indicates that choice of HBP compensation methods is sensitive to a number of hospital characteristics and attributes of both the hospital and physicians' services markets. The empirical findings are discussed in light of past conceptual and empirical research on physician compensation, and current policy issues in the health services sector. PMID:6841112

People's Risk Recognition Preceding Evacuation and Its Role in Demand Modeling and Planning.

PubMed

Urata, Junji; Pel, Adam J

2018-05-01

Evacuation planning and management involves estimating the travel demand in the event that such action is required. This is usually done as a function of people's decision to evacuate, which we show is strongly linked to their risk awareness. We use an empirical data set, which shows tsunami evacuation behavior, to demonstrate that risk recognition is not synonymous with objective risk, but is instead determined by a combination of factors including risk education, information, and sociodemographics, and that it changes dynamically over time. Based on these findings, we formulate an ordered logit model to describe risk recognition combined with a latent class model to describe evacuation choices. Our proposed evacuation choice model along with a risk recognition class can evaluate quantitatively the influence of disaster mitigation measures, risk education, and risk information. The results obtained from the risk recognition model show that risk information has a greater impact in the sense that people recognize their high risk. The results of the evacuation choice model show that people who are unaware of their risk take a longer time to evacuate. © 2017 Society for Risk Analysis.

Benefits of Incentives for Breastfeeding and Smoking cessation in pregnancy (BIBS): a mixed-methods study to inform trial design.

PubMed

Morgan, Heather; Hoddinott, Pat; Thomson, Gill; Crossland, Nicola; Farrar, Shelley; Yi, Deokhee; Hislop, Jenni; Moran, Victoria Hall; MacLennan, Graeme; Dombrowski, Stephan U; Rothnie, Kieran; Stewart, Fiona; Bauld, Linda; Ludbrook, Anne; Dykes, Fiona; Sniehotta, Falko F; Tappin, David; Campbell, Marion

2015-04-01

Smoking in pregnancy and/or not breastfeeding have considerable negative health outcomes for mother and baby. To understand incentive mechanisms of action for smoking cessation in pregnancy and breastfeeding, develop a taxonomy and identify promising, acceptable and feasible interventions to inform trial design. Evidence syntheses, primary qualitative survey, and discrete choice experiment (DCE) research using multidisciplinary, mixed methods. Two mother-and-baby groups in disadvantaged areas collaborated throughout. UK. The qualitative study included 88 pregnant women/recent mothers/partners, 53 service providers, 24 experts/decision-makers and 63 conference attendees. The surveys included 1144 members of the general public and 497 health professionals. The DCE study included 320 women with a history of smoking. (1) Evidence syntheses: incentive effectiveness (including meta-analysis and effect size estimates), delivery processes, barriers to and facilitators of smoking cessation in pregnancy and/or breastfeeding, scoping review of incentives for lifestyle behaviours; (2) qualitative research: grounded theory to understand incentive mechanisms of action and a framework approach for trial design; (3) survey: multivariable ordered logit models; (4) DCE: conditional logit regression and the log-likelihood ratio test. Out of 1469 smoking cessation and 5408 breastfeeding multicomponent studies identified, 23 smoking cessation and 19 breastfeeding studies were included in the review. Vouchers contingent on biochemically proven smoking cessation in pregnancy were effective, with a relative risk of 2.58 (95% confidence interval 1.63 to 4.07) compared with non-contingent incentives for participation (four studies, 344 participants). Effects continued until 3 months post partum. Inconclusive effects were found for breastfeeding incentives compared with no/smaller incentives (13 studies) but provider commitment contracts for breastfeeding show promise. Intervention intensity is a possible confounder. The acceptability of seven promising incentives was mixed. Women (for vouchers) and those with a lower level of education (except for breastfeeding incentives) were more likely to disagree. Those aged ≤ 44 years and ethnic minority groups were more likely to agree. Agreement was greatest for a free breast pump and least for vouchers for breastfeeding. Universal incentives were preferred to those targeting low-income women. Initial daily text/telephone support, a quitting pal, vouchers for > £20.00 per month and values up to £80.00 increase the likelihood of smoking cessation. Doctors disagreed with provider incentives. A 'ladder' logic model emerged through data synthesis and had face validity with service users. It combined an incentive typology and behaviour change taxonomy. Autonomy and well-being matter. Personal difficulties, emotions, socialising and attitudes of others are challenges to climbing a metaphorical 'ladder' towards smoking cessation and breastfeeding. Incentive interventions provide opportunity 'rungs' to help, including regular skilled flexible support, a pal, setting goals, monitoring and outcome verification. Individually tailored and non-judgemental continuity of care can bolster women's capabilities to succeed. Rigid, prescriptive interventions placing the onus on women to behave 'healthily' risk them feeling pressurised and failing. To avoid 'losing face', women may disengage. Included studies were heterogeneous and of variable quality, limiting the assessment of incentive effectiveness. No cost-effectiveness data were reported. In surveys, selection bias and confounding are possible. The validity and utility of the ladder logic model requires evaluation with more diverse samples of the target population. Incentives provided with other tailored components show promise but reach is a concern. Formal evaluation is recommended. Collaborative service-user involvement is important. This study is registered as PROSPERO CRD42012001980. The National Institute for Health Research Health Technology Assessment programme.

Prevalence of virulence determinants and antimicrobial resistance among commensal Escherichia coli derived from dairy and beef cattle.

PubMed

Bok, Ewa; Mazurek, Justyna; Stosik, Michał; Wojciech, Magdalena; Baldy-Chudzik, Katarzyna

2015-01-19

Cattle is a reservoir of potentially pathogenic E. coli, bacteria that can represent a significant threat to public health, hence it is crucial to monitor the prevalence of the genetic determinants of virulence and antimicrobial resistance among the E. coli population. The aim of this study was the analysis of the phylogenetic structure, distribution of virulence factors (VFs) and prevalence of antimicrobial resistance among E. coli isolated from two groups of healthy cattle: 50 cows housed in the conventional barn (147 isolates) and 42 cows living on the ecological pasture (118 isolates). The phylogenetic analysis, identification of VFs and antimicrobial resistance genes were based on either multiplex or simplex PCR. The antimicrobial susceptibilities of E. coli were examined using the broth microdilution method. Two statistical approaches were used to analyse the results obtained for two groups of cattle. The relations between the dependent (VFs profiles, antibiotics) and the independent variables were described using the two models. The mixed logit model was used to characterise the prevalence of the analysed factors in the sets of isolates. The univariate logistic regression model was used to characterise the prevalence of these factors in particular animals. Given each model, the odds ratio (OR) and the 95% confidence interval for the population were estimated. The phylogroup B1 was predominant among isolates from beef cattle, while the phylogroups A, B1 and D occurred with equal frequency among isolates from dairy cattle. The frequency of VFs-positive isolates was significantly higher among isolates from beef cattle. E. coli from dairy cattle revealed significantly higher resistance to antibiotics. Some of the tested resistance genes were present among isolates from dairy cattle. Our study showed that the habitat and diet may affect the genetic diversity of commensal E. coli in the cattle. The results suggest that the ecological pasture habitat is related to the increased spreading rate of the VFs, while the barn habitat is characterised by the higher levels of antimicrobial resistance among E. coli.

Prevalence of Virulence Determinants and Antimicrobial Resistance among Commensal Escherichia coli Derived from Dairy and Beef Cattle

PubMed Central

Bok, Ewa; Mazurek, Justyna; Stosik, Michał; Wojciech, Magdalena; Baldy-Chudzik, Katarzyna

2015-01-01

Cattle is a reservoir of potentially pathogenic E. coli, bacteria that can represent a significant threat to public health, hence it is crucial to monitor the prevalence of the genetic determinants of virulence and antimicrobial resistance among the E. coli population. The aim of this study was the analysis of the phylogenetic structure, distribution of virulence factors (VFs) and prevalence of antimicrobial resistance among E. coli isolated from two groups of healthy cattle: 50 cows housed in the conventional barn (147 isolates) and 42 cows living on the ecological pasture (118 isolates). The phylogenetic analysis, identification of VFs and antimicrobial resistance genes were based on either multiplex or simplex PCR. The antimicrobial susceptibilities of E. coli were examined using the broth microdilution method. Two statistical approaches were used to analyse the results obtained for two groups of cattle. The relations between the dependent (VFs profiles, antibiotics) and the independent variables were described using the two models. The mixed logit model was used to characterise the prevalence of the analysed factors in the sets of isolates. The univariate logistic regression model was used to characterise the prevalence of these factors in particular animals. Given each model, the odds ratio (OR) and the 95% confidence interval for the population were estimated. The phylogroup B1 was predominant among isolates from beef cattle, while the phylogroups A, B1 and D occurred with equal frequency among isolates from dairy cattle. The frequency of VFs-positive isolates was significantly higher among isolates from beef cattle. E. coli from dairy cattle revealed significantly higher resistance to antibiotics. Some of the tested resistance genes were present among isolates from dairy cattle. Our study showed that the habitat and diet may affect the genetic diversity of commensal E. coli in the cattle. The results suggest that the ecological pasture habitat is related to the increased spreading rate of the VFs, while the barn habitat is characterised by the higher levels of antimicrobial resistance among E. coli. PMID:25607605

Palliative radiotherapy practice within Western European countries: impact of the radiotherapy financing system?

PubMed

Lievens, Y; Van den Bogaert, W; Rijnders, A; Kutcher, G; Kesteloot, K

2000-09-01

To analyze the reimbursement modalities for radiotherapy in the different Western European countries, as well as to investigate if these differences have an impact on the palliative radiotherapy practice for bone metastases. A questionnaire was sent to 565 radiotherapy centres included in the 1997 ESTRO directory. In this questionnaire the reimbursement strategy applied in the different centres was assessed, with respect to the use of a budget (departmental or hospital budget), case payment and/or fee-for-service reimbursement. The differences were analyzed according to country and to type and size of the radiotherapy centre. A total of 170 centres (86% of the responders) returned the questionnaire. Most frequent is budget reimbursement: some form of budget reimbursement is found in 69% of the centres, whereas 46% of the centres are partly reimbursed through fee-for-service and 35% through case payment. The larger the department, the more frequent the reimbursement through a budget or a case payment system and the less the importance of fee-for-service reimbursement (chi(2): P=0.0012; logit: P=0.0055). Whereas private centres are almost equally reimbursed by fee-for-service financing as by budget or case payment, radiotherapy departments in university hospitals receive the largest part of their financial resources through a budget or by case payment (83%) (chi(2): P=0.002; logit: P=0.0073). A correlation between the country and the radiotherapy reimbursement system was also demonstrated (P=0.002), radiotherapy centres in Spain, the Netherlands and the United Kingdom being almost entirely reimbursed through a budget and/or case payment and centres in Germany and Switzerland mostly through a fee-for-service system. In budget and case payment financing lower total number of fractions and lower total dose (chi(2): P=0.003; logit: P=0.0120) as well as less shielding blocks (chi(2): P=0.003; logit: P=0.0066) are used. A same tendency is found for the use of isodose calculations and field set-up, but without being statistically significant (P=0.264 and P=0.061 res.). The type of the centre and the reimbursement modality influence the fractionation regimen independently (P=0.0274). This is not the case for the centre size and the reimbursement, which were found to exert correlated effects on the fractionation schedule (P=0.1042). Reimbursement systems seem to influence radiotherapy practice. One should therefore aim to develop reimbursement criteria that pursue to deliver, not only the best qualitative, but also the most cost-effective treatments to the patients.

Managing scuba divers to meet ecological goals for coral reef conservation.

PubMed

Sorice, Michael G; Oh, Chi-Ok; Ditton, Robert B

2007-06-01

Marine protected areas increasingly are challenged to maintain or increase tourism benefits while adequately protecting resources. Although carrying capacity strategies can be used to cope with use-related impacts, there is little understanding of divers themselves, their management preferences, and how preferences relate to conservation goals. By using a stated preference choice modeling approach, we investigated the choices divers make in selecting diving trips to marine protected areas as defined by use level, access, level of supervision, fees, conservation education, and diving expectations. Logit models showed that divers preferred a more restrictive management scenario over the status quo. Divers favored reductions in the level of site use and increased levels of conservation education. Divers did not favor fees to access protected areas, having less access to the resource, or extensive supervision. Finally, divers were much more willing to accept increasingly restrictive management scenarios when they could expect to see increased marine life.

Factors impacting hunter access to private lands in southeast Minnesota

USGS Publications Warehouse

Walberg, Eric; Cornicelli, Louis; Fulton, David C.

2018-01-01

White-tailed deer (Odocoileus virginianus) have important socioeconomic and ecological impacts in the United States. Hunting is considered to be important for the effective management of deer and relies on access to privately owned lands. In 2013, we surveyed nonindustrial private landowners in southeast Minnesota and created two logit models to examine factors that impact landowners’ decision to (a) allow public hunting access and (b) post private property. Parcel characteristics were found to impact landowner decisions to allow hunting access, particularly the size of the property and whether it was posted. Hunting access to small properties was more likely to be restricted to family, friends, and neighbors (83%) compared to medium (74%) or large properties (60%). Hunter concerns (e.g., liability) and knowledge about deer management was significant in both models, suggesting there are opportunities to educate landowners about the importance of allowing public hunting access and available liability protections.

Customization in Prescribing for Bipolar Disorder

PubMed Central

Hodgkin, Dominic; Volpe-Vartanian, Joanna; Merrick, Elizabeth L.; Horgan, Constance M.; Nierenberg, Andrew A.; Frank, Richard G.; Lee, Sue

2011-01-01

For many disorders, patient heterogeneity requires physicians to customize their treatment to each patient’s needs. We test for the existence of customization in physicians’ prescribing for bipolar disorder, using data from a naturalistic clinical effectiveness trial of bipolar disorder treatment (STEP-BD), which did not constrain physician prescribing. Multinomial logit is used to model the physician’s choice among five combinations of drug classes. We find that our observed measure of the patient’s clinical status played only a limited role in the choice among drug class combinations, even for conditions such as mania that are expected to affect class choice. However, treatment of a patient with given characteristics differed widely depending on which physician was seen. The explanatory power of the model was low. There was variation within each physician’s prescribing, but the results do not suggest a high degree of customization in physicians’ prescribing, based on our measure of clinical status. PMID:21506194

Customization in prescribing for bipolar disorder.

PubMed

Hodgkin, Dominic; Volpe-Vartanian, Joanna; Merrick, Elizabeth L; Horgan, Constance M; Nierenberg, Andrew A; Frank, Richard G; Lee, Sue

2012-06-01

For many disorders, patient heterogeneity requires physicians to customize their treatment to each patient's needs. We test for the existence of customization in physicians' prescribing for bipolar disorder, using data from a naturalistic clinical effectiveness trial of bipolar disorder treatment (STEP-BD), which did not constrain physician prescribing. Multinomial logit is used to model the physician's choice among five combinations of drug classes. We find that our observed measure of the patient's clinical status played only a limited role in the choice among drug class combinations, even for conditions such as mania that are expected to affect class choice. However, treatment of a patient with given characteristics differed widely depending on which physician was seen. The explanatory power of the model was low. There was variation within each physician's prescribing, but the results do not suggest a high degree of customization in physicians' prescribing, based on our measure of clinical status. Copyright © 2011 John Wiley & Sons, Ltd.

SNAP Participants' Eating Patterns over the Benefit Month: A Time Use Perspective.

PubMed

Hamrick, Karen S; Andrews, Margaret

2016-01-01

Individuals receiving monthly benefits through the U.S. Supplemental Nutrition Assistance Program (SNAP) often fall short of food at the end of the month and some report feelings of hunger. To investigate this situation, we used time diaries from the 2006-08 American Time Use Survey and Eating & Health Module to identify the timing of days where respondents reported no eating occurrences. Analysis includes descriptive statistics, a logit model, and a simulated benefit month. We found that SNAP participants were increasingly more likely than nonparticipants to report a day with no eating occurrences over the benefit issuance cycle. This supports the view that there is a monthly cycle in food consumption associated with the SNAP monthly benefit issuance policy.

TRACING THE TIMING OF “CAREER” ACQUISITION IN A CONTEMPORARY YOUTH COHORT*

PubMed Central

Mortimer, Jeylan T.; Vuolo, Mike; Staff, Jeremy; Wakefield, Sara; Xie, Wanling

2008-01-01

Contemporary youth typically experience considerable floundering and uncertainty in their transition from school to work. This paper examines patterns of schooling and working during adolescence and the transition to adulthood that hasten or delay an important subjective marker of transition to adulthood: acquiring a job that is recognized as a “career.” We use Youth Development Study data, obtained from a prospective longitudinal study of 9th graders. Estimation of discrete-time logit models shows that adolescent work patterns during high school, as well as the cumulative investments they make in work and schooling in the years following, significantly influence this milestone. Time-varying predictors, including job characteristics and parenthood, also affect the process of movement into “careers”. PMID:18542713

Consumer preferences for food product quality attributes from Swedish agriculture.

PubMed

Carlsson, Fredrik; Frykblom, Peter; Lagerkvist, Carl Johan

2005-06-01

This paper employs a choice experiment to obtain consumer preferences and willingness to pay for food product quality attributes currently not available in Sweden. Data were obtained from a large mail survey and estimated with a random parameter logit model. We found evidence for intraproduct differences in consumer preferences for identical attributes, as well as interproduct discrepancies in ranking of attributes. Furthermore, we found evidence of a market failure relating to the potential use of genetically modified animal fodder. Finally, we found support for the idea that a cheap-talk script can alleviate problems of external validity of choice experiments. Our results are useful in forming product differentiation strategies within the food industry, as well as for the formation of food policy.

SNAP Participants’ Eating Patterns over the Benefit Month: A Time Use Perspective

PubMed Central

2016-01-01

Individuals receiving monthly benefits through the U.S. Supplemental Nutrition Assistance Program (SNAP) often fall short of food at the end of the month and some report feelings of hunger. To investigate this situation, we used time diaries from the 2006–08 American Time Use Survey and Eating & Health Module to identify the timing of days where respondents reported no eating occurrences. Analysis includes descriptive statistics, a logit model, and a simulated benefit month. We found that SNAP participants were increasingly more likely than nonparticipants to report a day with no eating occurrences over the benefit issuance cycle. This supports the view that there is a monthly cycle in food consumption associated with the SNAP monthly benefit issuance policy. PMID:27410962

Three essays on resource economics. Demand systems for energy forecasting: Practical considerations for estimating a generalized logit model, To borrow or not to borrow: A variation on the MacDougal-Kemp theme, and, Valuing reduced risk for households with children or the retired

NASA Astrophysics Data System (ADS)

Weng, Weifeng

This thesis presents papers on three areas of study within resource and environmental economics. "Demand Systems For Energy Forecasting" provides some practical considerations for estimating a Generalized Logit model. The main reason for using this demand system for energy and other factors is that the derived price elasticities are robust when expenditure shares are small. The primary objective of the paper is to determine the best form of the cross-price weights, and a simple inverse function of the expenditure share is selected. A second objective is to demonstrate that the estimated elasticities are sensitive to the units specified for the prices, and to show how price scales can be estimated as part of the model. "To Borrow or Not to Borrow: A Variation on the MacDougal-Kemp Theme" studies the impact of international capital movements on the conditional convergence of economies differing from each other only in initial wealth. We found that in assets, income, consumption and utility, convergence obtains, with and only with, the absence of international capital movement. When a rich country invests in a poor country, the balance of debt increases forever. Asset ownership is increased in all periods for the lender, and asset ownership of the borrower is deceased. Also, capital investment decreases the lender's utility for early periods, but increases it forever after a cross-over point. In contrast, the borrower's utility increases for early periods, but then decreases forever. "Valuing Reduced Risk for Households with Children or the Retired" presents a theoretical model of how families value risk and then exams family automobile purchases to impute the average Value of a Statistical Life (VSL) for each type of family. Data for fatal accidents are used to estimate survival rates for individuals in different types of accidents, and the probabilities of having accidents for different types of vehicle. These models are used to determine standardized risks for vehicles in hedonic models of the purchase price and fuel efficiency. The hedonic models determine the marginal capital and operating costs of reducing the risk of mortality. We find that households with children are valued much more highly than the average VSL of $2 million, and households with seniors are valued less than average.

Analysis of injury severity of drivers involved in single- and two-vehicle crashes on highways in Ontario.

PubMed

Lee, Chris; Li, Xuancheng

2014-10-01

This study analyzes driver's injury severity in single- and two-vehicle crashes and compares the effects of explanatory variables among various types of crashes. The study identified factors affecting injury severity and their effects on severity levels using 5-year crash records for provincial highways in Ontario, Canada. Considering heteroscedasticity in the effects of explanatory variables on injury severity, the heteroscedastic ordered logit (HOL) models were developed for single- and two-vehicle crashes separately. The results of the models show that there exists heteroscedasticity for young drivers (≤30), safety equipment and ejection in the single-vehicle crash model, and female drivers, safety equipment and head-on collision in the two-vehicle crash models. The results also show that young car drivers have opposite effects between single-car and car-car crashes, and sideswipe crashes have opposite effects between car-car and truck-truck crashes. The study demonstrates that separate HOL models for single-vehicle and different types of two-vehicle crashes can identify differential effects of factors on driver's injury severity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficacy of Prophylactic Antibiotics at Peritoneal Catheter Insertion on Early Peritonitis: Data from the Catheter Section of the French Language Peritoneal Dialysis Registry.

PubMed

Lanot, Antoine; Lobbedez, Thierry; Bechade, Clémence; Verger, Christian; Fabre, Emmanuel; Dratwa, Max; Vernier, Isabelle

2016-01-01

International guidelines recommend the use of a prophylactic antibiotic before the peritoneal dialysis (PD) catheter can be inserted. The main objective of this study was to assess whether this practice is associated with a lower risk of early peritonitis and to estimate the magnitude of the centre effect. A retrospective, multi-centric study was conducted, in which data from the French Language Peritoneal Dialysis Registry was analysed. Patients were separated into 2 groups based on whether or not prophylactic antibiotics were used prior to catheter placement. Out of the 2,014 patients who had a PD catheter placed between February 1, 2012 and December 31, 2014, 1,105 were given a prophylactic antibiotic. In a classical logit model, the use of prophylactic antibiotics was found to protect the individual against the risk of early peritonitis (OR 0.67, 95% CI 0.49-0.92). However, this association lost significance in a mixed logistic regression model with centre as a random effect: OR 0.73 (95% CI 0.48-1.09). Covariates associated with the risk of developing early peritonitis were age over 65: OR 0.73 (95% CI 0.39-0.85), body mass index over 35 kg/m2: OR 1.99 (95% CI 1.13-3.47), transfer to PD due to graft failure: OR 2.24 (95% CI 1.22-4.11), assisted PD: OR 1.96 (95% CI 1.31-2.93), and the use of the Moncrief technique: OR 3.07 (95% CI 1.85-5.11). There is a beneficial effect of prophylactic antibiotic used prior to peritoneal catheter placement, on the occurence of early peritonitis. However, the beneficial effect could be masked by a centre effect. © 2016 S. Karger AG, Basel.

Advance Care Planning in an Accountable Care Organization Is Associated with Increased Advanced Directive Documentation and Decreased Costs.

PubMed

Bond, William F; Kim, Minchul; Franciskovich, Chris M; Weinberg, Jason E; Svendsen, Jessica D; Fehr, Linda S; Funk, Amy; Sawicki, Robert; Asche, Carl V

2018-04-01

Advance care planning (ACP) documents patient wishes and increases awareness of palliative care options. To study the association of outpatient ACP with advanced directive documentation, utilization, and costs of care. This was a case-control study of cases with ACP who died matched 1:1 with controls. We used 12 months of data pre-ACP/prematch and predeath. We compared rates of documentation with logit model regression and conducted a difference-in-difference analysis using generalized linear models for utilization and costs. Medicare beneficiaries attributed to a large rural-suburban-small metro multisite accountable care organization from January 2013 to April 2016, with cross reference to ACP facilitator logs to find cases. The presence of advance directive forms was verified by chart review. Cost analysis included all utilization and costs billed to Medicare. We matched 325 cases and 325 controls (51.1% female and 48.9% male, mean age 81). 320/325 (98.5%) ACP versus 243/325 (74.8%) of controls had a Healthcare Power of Attorney (odds ratio [OR] 21.6, 95% CI 8.6-54.1) and 172/325(52.9%) ACP versus 145/325 (44.6%) controls had Practitioner Orders for Life Sustaining Treatment (OR 1.40, 95% CI 1.02-1.90) post-ACP/postmatch. Adjusted results showed ACP cases had fewer inpatient admissions (-0.37 admissions, 95% CI -0.66 to -0.08), and inpatient days (-3.66 days, 95% CI -6.23 to -1.09), with no differences in hospice, hospice days, skilled nursing facility use, home health use, 30-day readmissions, or emergency department visits. Adjusted costs were $9,500 lower in the ACP group (95% CI -$16,207 to -$2,793). ACP increases documentation and was associated with a reduction in overall costs driven primarily by a reduction in inpatient utilization. Our data set was limited by small numbers of minorities and cancer patients.

Developing an instrument to assess the endoscopic severity of ulcerative colitis: the Ulcerative Colitis Endoscopic Index of Severity (UCEIS).

PubMed

Travis, Simon P L; Schnell, Dan; Krzeski, Piotr; Abreu, Maria T; Altman, Douglas G; Colombel, Jean-Frédéric; Feagan, Brian G; Hanauer, Stephen B; Lémann, Marc; Lichtenstein, Gary R; Marteau, Phillippe R; Reinisch, Walter; Sands, Bruce E; Yacyshyn, Bruce R; Bernhardt, Christian A; Mary, Jean-Yves; Sandborn, William J

2012-04-01

Variability in endoscopic assessment necessitates rigorous investigation of descriptors for scoring severity of ulcerative colitis (UC). To evaluate variation in the overall endoscopic assessment of severity, the intra- and interindividual variation of descriptive terms and to create an Ulcerative Colitis Endoscopic Index of Severity which could be validated. A two-phase study used a library of 670 video sigmoidoscopies from patients with Mayo Clinic scores 0-11, supplemented by 10 videos from five people without UC and five hospitalised patients with acute severe UC. In phase 1, each of 10 investigators viewed 16/24 videos to assess agreement on the Baron score with a central reader and agreed definitions of 10 endoscopic descriptors. In phase 2, each of 30 different investigators rated 25/60 different videos for the descriptors and assessed overall severity on a 0-100 visual analogue scale. κ Statistics tested inter- and intraobserver variability for each descriptor. A general linear mixed regression model based on logit link and β distribution of variance was used to predict overall endoscopic severity from descriptors. There was 76% agreement for 'severe', but 27% agreement for 'normal' appearances between phase I investigators and the central reader. In phase 2, weighted κ values ranged from 0.34 to 0.65 and 0.30 to 0.45 within and between observers for the 10 descriptors. The final model incorporated vascular pattern, (normal/patchy/complete obliteration) bleeding (none/mucosal/luminal mild/luminal moderate or severe), erosions and ulcers (none/erosions/superficial/deep), each with precise definitions, which explained 90% of the variance (pR(2), Akaike Information Criterion) in the overall assessment of endoscopic severity, predictions varying from 4 to 93 on a 100-point scale (from normal to worst endoscopic severity). The Ulcerative Colitis Endoscopic Index of Severity accurately predicts overall assessment of endoscopic severity of UC. Validity and responsiveness need further testing before it can be applied as an outcome measure in clinical trials or clinical practice.

Market and organizational factors associated with hospital vertical integration into sub-acute care.

PubMed

Hogan, Tory H; Lemak, Christy Harris; Hearld, Larry R; Sen, Bisakha P; Wheeler, Jack R C; Menachemi, Nir

2018-04-11

Changes in payment models incentivize hospitals to vertically integrate into sub-acute care (SAC) services. Through vertical integration into SAC, hospitals have the potential to reduce the transaction costs associated with moving patients throughout the care continuum and reduce the likelihood that patients will be readmitted. The purpose of this study is to examine the correlates of hospital vertical integration into SAC. Using panel data of U.S. acute care hospitals (2008-2012), we conducted logit regression models to examine environmental and organizational factors associated with hospital vertical integration. Results are reported as average marginal effects. Among 3,775 unique hospitals (16,269 hospital-year observations), 25.7% vertically integrated into skilled nursing facilities during at least 1 year of the study period. One measure of complexity, the availability of skilled nursing facilities in a county (ME = -1.780, p < .001), was negatively associated with hospital vertical integration into SAC. Measures of munificence, percentage of the county population eligible for Medicare (ME = 0.018, p < .001) and rural geographic location (ME = 0.069, p < .001), were positively associated with hospital vertical integration into SAC. Dynamism, when measured as the change county population between 2008 and 2011 (ME = 1.19e-06, p < .001), was positively associated with hospital vertical integration into SAC. Organizational resources, when measured as swing beds (ME = 0.069, p < .001), were positively associated with hospital vertical integration into SAC. Organizational resources, when measured as investor owned (ME = -0.052, p < .1) and system affiliation (ME = -0.041, p < .1), were negatively associated with hospital vertical integration into SAC. Hospital adaption to the changing health care landscape through vertical integration varies across market and organizational conditions. Current Centers for Medicare and Medicaid reimbursement programs do not take these factors into consideration. Vertical integration strategy into SAC may be more appropriate under certain market conditions. Hospital leaders may consider how to best align their organization's SAC strategy with their operating environment.

The compression of deaths above the mode.

PubMed

Thatcher, A Roger; Cheung, Siu Lan K; Horiuchi, Shiro; Robine, Jean-Marie

2010-03-26

Kannisto (2001) has shown that as the frequency distribution of ages at death has shifted to the right, the age distribution of deaths above the modal age has become more compressed. In order to further investigate this old-age mortality compression, we adopt the simple logistic model with two parameters, which is known to fit data on old-age mortality well (Thatcher 1999). Based on the model, we show that three key measures of old-age mortality (the modal age of adult deaths, the life expectancy at the modal age, and the standard deviation of ages at death above the mode) can be estimated fairly accurately from death rates at only two suitably chosen high ages (70 and 90 in this study). The distribution of deaths above the modal age becomes compressed when the logits of death rates fall more at the lower age than at the higher age. Our analysis of mortality time series in six countries, using the logistic model, endorsed Kannisto's conclusion. Some possible reasons for the compression are discussed.

The relation between social cohesion and smoking cessation among Black smokers, and the potential role of psychosocial mediators.

PubMed

Reitzel, Lorraine R; Kendzor, Darla E; Castro, Yessenia; Cao, Yumei; Businelle, Micheal S; Mazas, Carlos A; Cofta-Woerpel, Ludmila; Li, Yisheng; Cinciripini, Paul M; Ahluwalia, Jasjit S; Wetter, David W

2013-04-01

Social cohesion, the self-reported trust and connectedness between neighbors, may affect health behaviors via psychosocial mechanisms. Relations between individual perceptions of social cohesion and smoking cessation were examined among 397 Black treatment-seeking smokers. Continuation ratio logit models examined the relation of social cohesion and biochemically verified continuous smoking abstinence through 6 months post-quit. Indirect effects were examined in single mediator models using a nonparametric bootstrapping procedure. All analyses controlled for sociodemographics, tobacco dependence, and treatment. The total effect of social cohesion on continuous abstinence was non-significant (β = 0.05, p = 0.10). However, social cohesion was associated with social support, positive affect, negative affect, and stress, which, in turn, were each associated with abstinence in adjusted models (ps < 0.05). Results suggest that social cohesion may facilitate smoking cessation among Black smokers through desirable effects on psychosocial mechanisms that can result from living in a community with strong interpersonal connections.

The Relation between Social Cohesion and Smoking Cessation among Black Smokers, and the Potential Role of Psychosocial Mediators

PubMed Central

Reitzel, Lorraine R.; Kendzor, Darla E.; Castro, Yessenia; Cao, Yumei; Businelle, Micheal S.; Mazas, Carlos A.; Cofta-Woerpel, Ludmila; Li, Yisheng; Cinciripini, Paul M.; Ahluwalia, Jasjit S.; Wetter, David W.

2012-01-01

Background Social cohesion, the self-reported trust and connectedness between neighbors, may affect health behaviors via psychosocial mechanisms. Purpose Relations between individual perceptions of social cohesion and smoking cessation were examined among 397 Black treatment-seeking smokers. Methods Continuation ratio logit models examined the relation of social cohesion and biochemically-verified continuous smoking abstinence through 6 months post-quit. Indirect effects were examined in single mediator models using a nonparametric bootstrapping procedure. All analyses controlled for sociodemographics, tobacco dependence, and treatment. Results The total effect of social cohesion on continuous abstinence was non-significant (β=.05, p=.10). However, social cohesion was associated with social support, positive affect negative affect, and stress, which, in turn, were each associated with abstinence in adjusted models (ps<.05). Conclusions Results suggest that social cohesion may facilitate smoking cessation among Black smokers through desirable effects on psychosocial mechanisms that can result from living in a community with strong interpersonal connections. PMID:23135831

An Optimal Hierarchical Decision Model for a Regional Logistics Network with Environmental Impact Consideration

PubMed Central

Zhang, Dezhi; Li, Shuangyan

2014-01-01

This paper proposes a new model of simultaneous optimization of three-level logistics decisions, for logistics authorities, logistics operators, and logistics users, for regional logistics network with environmental impact consideration. The proposed model addresses the interaction among the three logistics players in a complete competitive logistics service market with CO2 emission charges. We also explicitly incorporate the impacts of the scale economics of the logistics park and the logistics users' demand elasticity into the model. The logistics authorities aim to maximize the total social welfare of the system, considering the demand of green logistics development by two different methods: optimal location of logistics nodes and charging a CO2 emission tax. Logistics operators are assumed to compete with logistics service fare and frequency, while logistics users minimize their own perceived logistics disutility given logistics operators' service fare and frequency. A heuristic algorithm based on the multinomial logit model is presented for the three-level decision model, and a numerical example is given to illustrate the above optimal model and its algorithm. The proposed model provides a useful tool for modeling competitive logistics services and evaluating logistics policies at the strategic level. PMID:24977209

Modeling detour behavior of pedestrian dynamics under different conditions

NASA Astrophysics Data System (ADS)

Qu, Yunchao; Xiao, Yao; Wu, Jianjun; Tang, Tao; Gao, Ziyou

2018-02-01

Pedestrian simulation approach has been widely used to reveal the human behavior and evaluate the performance of crowd evacuation. In the existing pedestrian simulation models, the social force model is capable of predicting many collective phenomena. Detour behavior occurs in many cases, and the important behavior is a dominate factor of the crowd evacuation efficiency. However, limited attention has been attracted for analyzing and modeling the characteristics of detour behavior. In this paper, a modified social force model integrated by Voronoi diagram is proposed to calculate the detour direction and preferred velocity. Besides, with the consideration of locations and velocities of neighbor pedestrians, a Logit-based choice model is built to describe the detour direction choice. The proposed model is applied to analyze pedestrian dynamics in a corridor scenario with either unidirectional or bidirectional flow, and a building scenario in real-world. Simulation results show that the modified social force model including detour behavior could reduce the frequency of collision and deadlock, increase the average speed of the crowd, and predict more practical crowd dynamics with detour behavior. This model can also be potentially applied to understand the pedestrian dynamics and design emergent management strategies for crowd evacuations.

An optimal hierarchical decision model for a regional logistics network with environmental impact consideration.

PubMed

Zhang, Dezhi; Li, Shuangyan; Qin, Jin

2014-01-01

This paper proposes a new model of simultaneous optimization of three-level logistics decisions, for logistics authorities, logistics operators, and logistics users, for regional logistics network with environmental impact consideration. The proposed model addresses the interaction among the three logistics players in a complete competitive logistics service market with CO2 emission charges. We also explicitly incorporate the impacts of the scale economics of the logistics park and the logistics users' demand elasticity into the model. The logistics authorities aim to maximize the total social welfare of the system, considering the demand of green logistics development by two different methods: optimal location of logistics nodes and charging a CO2 emission tax. Logistics operators are assumed to compete with logistics service fare and frequency, while logistics users minimize their own perceived logistics disutility given logistics operators' service fare and frequency. A heuristic algorithm based on the multinomial logit model is presented for the three-level decision model, and a numerical example is given to illustrate the above optimal model and its algorithm. The proposed model provides a useful tool for modeling competitive logistics services and evaluating logistics policies at the strategic level.

Saving for Success: Financial Education and Savings Goal Achievement in Individual Development Accounts

ERIC Educational Resources Information Center

Grinstead, Mary L.; Mauldin, Teresa; Sabia, Joseph J.; Koonce, Joan; Palmer, Lance

2011-01-01

Using microdata from the American Dream Demonstration, the current study examines factors associated with savings and savings goal achievement (indicated by a matched withdrawal) among participants of individual development account (IDA) programs. Multinomial logit results show that hours of participation in financial education programs, higher…

Monitoring Antitobacco Sentiment among Community Leaders

ERIC Educational Resources Information Center

Bechtel, Gordon G.; Lyons-Lepke, Elaine M.

2003-01-01

Two public health objectives, one methodological and the other substantive, are realized in the present study. First, average survey ratings are replaced by negated mean cumulative logits (MCLs), which have the advantage of interitem commensuration. Second, these negated MCLs improve the analysis of two Florida tobacco control surveys of community…

A Multimonial Logit Analysis of Teenage Fertility and High School Completion.

ERIC Educational Resources Information Center

Ribar, David C.

1993-01-01

Uses data from the 1979 National Longitudinal Survey of Youth to examine economic, institutional, and sociological antecedents of high school completion and adolescent fertility. Welfare generosity appears to have a significant positive effect on adolescent childbearing. Other important determinants of teenage parenthood and educational attainment…

'If your husband calls, you have to go': understanding sexual agency among young married women in urban South India.

PubMed

Pande, Rohini Prabha; Falle, Tina Y; Rathod, Sujit; Edmeades, Jeffrey; Krishnan, Suneeta

2011-03-01

Early marriage is common in many developing countries, including India. Women who marry early have little power within their marriage, particularly in the sexual domain. Research is limited on women's ability to control their marital sexual experiences. We identified factors affecting sexual communication among married women aged 16-25, in Bangalore, India, and how factors associated with sexual communication differed from those influencing non-sexual agency. We ran ordered logit regression models for one outcome of sexual agency (sexual communication, n = 735) and two outcomes of non-sexual agency (fertility control, n = 735, and financial decision-making, n = 728). Sexual communication was more restricted (83 women (11.3%) with high sexual communication) than financial decision-making (183 women (25.1%) with high financial decision-making agency) and fertility control (238 women (32.4%) with high fertility control). Feeling prepared before the first sexual experience was significantly associated with sexual communication (odds ratio (OR) = 1.8; 95% confidence interval (CI) = 1.13-2.89). Longer marriage duration (OR 2.13; 95% CI = 1.42-3.20) and having worked pre-marriage (OR 1.38; 95% CI = 1.02-1.86) were also significant. Few other measures of women's resources increased their odds of sexual communication. Education, having children, pre-marital vocational training and marital intimacy were significant for non-sexual outcomes but not sexual communication. Policy-makers seeking to enhance young married women's sexual communication need to consider providing sex education to young women before they marry. More broadly, interventions designed to increase women's agency need to be tailored to the type of agency being examined.

Influence of weather, rank, and home advantage on football outcomes in the Gulf region.

PubMed

Brocherie, Franck; Girard, Olivier; Farooq, Abdulaziz; Millet, Grégoire P

2015-02-01

The objective of this study was to investigate the effects of weather, rank, and home advantage on international football match results and scores in the Gulf Cooperation Council (GCC) region. Football matches (n = 2008) in six GCC countries were analyzed. To determine the weather influence on the likelihood of favorable outcome and goal difference, generalized linear model with a logit link function and multiple regression analysis were performed. In the GCC region, home teams tend to have greater likelihood of a favorable outcome (P < 0.001) and higher goal difference (P < 0.001). Temperature difference was identified as a significant explanatory variable when used independently (P < 0.001) or after adjustment for home advantage and team ranking (P < 0.001). The likelihood of favorable outcome for GCC teams increases by 3% for every 1-unit increase in temperature difference. After inclusion of interaction with opposition, this advantage remains significant only when playing against non-GCC opponents. While home advantage increased the odds of favorable outcome (P < 0.001) and goal difference (P < 0.001) after inclusion of interaction term, the likelihood of favorable outcome for a GCC team decreased (P < 0.001) when playing against a stronger opponent. Finally, the temperature and wet bulb globe temperature approximation were found as better indicators of the effect of environmental conditions than absolute and relative humidity or heat index on match outcomes. In GCC region, higher temperature increased the likelihood of a favorable outcome when playing against non-GCC teams. However, international ranking should be considered because an opponent with a higher rank reduced, but did not eliminate, the likelihood of a favorable outcome.

Vision-related Quality of Life in Korean Glaucoma Patients.

PubMed

Sung, Kyung Rim; Chun, Yeoun Sook; Park, Chan Kee; Kim, Hwang Ki; Yoo, Chungkwon; Kim, Yong Yeon; Park, Ki Ho; Kim, Chan Yun; Choi, Kyu-Ryong; Lee, Kyoo Won; Han, Seungbong; Kim, Chang-Sik

2017-02-01

The purpose of the study was to evaluate vision-related quality of life in Korean glaucoma patients and to explore the associated factors. A total of 907 glaucoma patients were recruited from the prospectively designed LIGHT (Life quality of the glaucoma patient who underwent treatment) study organized by the Korean Glaucoma Society. Basic questionnaire that included items related to socioeconomic status, comorbidity, and lifestyle, and the validated Korean version of the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) were collected. The Rasch score, a logit-based interval scale estimate to summarizing the NEI VFQ-25 responses, was calculated. The univariate and multivariable regression models were used to evaluate associations between the Rasch score and variables. The mean patient age was 58.1±14.1 years, visual field mean deviation (VF MD) of the better and worse eyes was -4.92±6.14 and -9.77±8.31 dB, binocular-integrated VF (IVF) MD was -3.55±5.31 dB, respectively. The lower NEI VFQ-25 Rasch score showed a significant association with the presence of other ocular diseases (P=0.020), a high school level of education or less [vs. university (P=0.006), vs. graduate school or higher (P=0.019)], an anxious personality [vs. a moderate personality (P<0.001), vs. a relaxed personality (P<0.001)], the number of glaucoma medications in use (P=0.049), worse eye visual acuity (P<0.001), and IVF MD (P<0.001). Visual function parameters are important for the vision-related quality of life of Korean glaucoma patients, notably for worse eye visual acuity and IVF MD. However, social factors, self-assessed personality, and treatment-related issues are also substantial predictors of overall life quality.

Differentiating between Glioblastoma and Primary CNS Lymphoma Using Combined Whole-tumor Histogram Analysis of the Normalized Cerebral Blood Volume and the Apparent Diffusion Coefficient.

PubMed

Bao, Shixing; Watanabe, Yoshiyuki; Takahashi, Hiroto; Tanaka, Hisashi; Arisawa, Atsuko; Matsuo, Chisato; Wu, Rongli; Fujimoto, Yasunori; Tomiyama, Noriyuki

2018-05-31

This study aimed to determine whether whole-tumor histogram analysis of normalized cerebral blood volume (nCBV) and apparent diffusion coefficient (ADC) for contrast-enhancing lesions can be used to differentiate between glioblastoma (GBM) and primary central nervous system lymphoma (PCNSL). From 20 patients, 9 with PCNSL and 11 with GBM without any hemorrhagic lesions, underwent MRI, including diffusion-weighted imaging and dynamic susceptibility contrast perfusion-weighted imaging before surgery. Histogram analysis of nCBV and ADC from whole-tumor voxels in contrast-enhancing lesions was performed. An unpaired t-test was used to compare the mean values for each type of tumor. A multivariate logistic regression model (LRM) was performed to classify GBM and PCNSL using the best parameters of ADC and nCBV. All nCBV histogram parameters of GBMs were larger than those of PCNSLs, but only average nCBV was statistically significant after Bonferroni correction. Meanwhile, ADC histogram parameters were also larger in GBM compared to those in PCNSL, but these differences were not statistically significant. According to receiver operating characteristic curve analysis, the nCBV average and ADC 25th percentile demonstrated the largest area under the curve with values of 0.869 and 0.838, respectively. The LRM combining these two parameters differentiated between GBM and PCNSL with a higher area under the curve value (Logit (P) = -21.12 + 10.00 × ADC 25th percentile (10 -3 mm 2 /s) + 5.420 × nCBV mean, P < 0.001). Our results suggest that whole-tumor histogram analysis of nCBV and ADC combined can be a valuable objective diagnostic method for differentiating between GBM and PCNSL.