Perera, Harsha N
2015-01-01
Notwithstanding the wide use of the Trait Emotional Intelligence Questionnaire-Short Form (TEIQue-SF) as a brief assessment of trait emotional intelligence (TEI), the psychometric properties of this measure have not been systematically examined. This article reports on research conducted to evaluate the latent structure underlying TEIQue-SF item data and test the gender invariance of scores as critical initial steps in determining the psychometric robustness of the inventory. In doing so, the article demonstrates an application of exploratory structural equation modeling as an alternative to the more restrictive independent clusters model of confirmatory factor analysis for examining factorially complex personality data. On the basis of 476 responses to the TEIQue-SF, evidence was obtained for the multidimensionality of the inventory reflected in a retained correlated traits solution. Tests of gender invariance revealed equivalence of item factor loadings, intercepts, uniquenesses, correlated uniquenesses, and the factor variance-covariance matrix, but not latent means. Men were found to be moderately higher on self-control and sociability than women, whereas women scored marginally higher on emotionality than men. No significant gender differences were found on mean levels of well-being. The benefits of the multidimensionality of the TEIQue-SF, limitations of the study, and directions for future research are discussed. PMID:25774661
A Model and Questionnaire of Language Identity in Iran: A Structural Equation Modelling Approach
ERIC Educational Resources Information Center
Khatib, Mohammad; Rezaei, Saeed
2013-01-01
This study consisted of three main phases including the development of a hypothesised model of language identity in Iran, developing and validating a questionnaire based on this model and finally testing the model based on the questionnaire data. In the first phase of this research, a hypothesised model of language identity in Iran was developed…
Structural equations and causation
N. Hall
2007-01-01
Structural equations have become increasingly popular in recent years as tools for understanding causation. But standard structural\\u000a equations approaches to causation face deep problems. The most philosophically interesting of these consists in their failure\\u000a to incorporate a distinction between default states of an object or system, and deviations therefrom. Exploring this problem,\\u000a and how to fix it, helps to illuminate
The Bilevel Structure of the Outcome Questionnaire-45
ERIC Educational Resources Information Center
Bludworth, Jamie L.; Tracey, Terence J. G.; Glidden-Tracey, Cynthia
2010-01-01
The structure of the Outcome Questionnaire-45 (Lambert et al., 2001) was examined in a sample of 1,100 university counseling center clients using confirmatory factor analysis. Specifically, the relative fit of 1-factor, 3-factor orthogonal, 3-factor oblique, 4-factor hierarchical, and 4-factor bilevel models were examined. Although the 3-factor…
Generalized Multilevel Structural Equation Modeling
ERIC Educational Resources Information Center
Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew
2004-01-01
A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…
Structural Equation Modeling for Travel Behavior Research
Golob, Thomas F.
2001-01-01
2 Structural Equation Modeling for Travel Behavior Researchstructural equation modeling in travel behavior research areStructural equation modeling is becoming widely used in travel behavior research,
A structural equation model of residents’ attitudes for tourism development
Dong-Wan Ko; William P. Stewart
2002-01-01
This study tests the structural equation model between residents’ perceived tourism impacts and attitudes toward host community. The model consisted of five latent constructs and nine path hypotheses and is based upon 732 mailback questionnaires returned by residents of Cheju Island, Korea, a major domestic tourism destination. It was found that residents’ ‘community satisfaction’ was closely related to ‘perceived positive’
ERIC Educational Resources Information Center
Cui, Lixia; Lin, Wenwen; Oei, Tian P. S.
2011-01-01
This study investigated cross-cultural differences in the factor structure and psychometric properties of the Young Schema Questionnaire (short form; YSQ-SF). The participants were 712 Chinese undergraduate students. The total sample was randomly divided into two sub-samples. Exploratory Factor Analysis (EFA) was conducted on questionnaire results…
Structural Analysis of the Resident Assistant Cultural Diversity Questionnaire
ERIC Educational Resources Information Center
Johnson, Vanessa D.; Kang, Young-Shin; Thompson, George F.
2011-01-01
This study investigated the five-factor structure of the Resident Assistant Cultural Diversity (RACD) instrument, which assesses resident assistant (RA) confidence in addressing issues of cultural diversity in college and university residence halls. The instrument has five components that explore RA confidence: (1) belief in the need for cultural…
Structural Equation Modeling For Travel Behavior Research
Golob, Thomas F.
2011-01-01
structural equation modeling in travel behavior research areStructural equation modeling is becoming widely used in travel behavior research,Structural equation models, travel behavior, travel demand modeling, Statistical methods, discrete choice models, dynamic models, attitudinal data SEM for travel behavior Research
Structural Equation Modeling For Travel Behavior Research
Golob, Thomas F.
2001-01-01
structural equation modeling in travel behavior research areStructural equation modeling is becoming widely used in travel behavior research,Structural equation models, travel behavior, travel demand modeling, Statistical methods, discrete choice models, dynamic models, attitudinal data SEM for travel behavior Research
Factors contributing to posttraumatic growth: a proposed structural equation model.
Cadell, Susan; Regehr, Cheryl; Hemsworth, David
2003-07-01
With the current shift to include positive outcomes of trauma, this research was designed to explore factors that allow growth to occur. Structural equation modeling was used to test a model for understanding posttraumatic growth. A sample (N = 174) of bereaved HIV/AIDS caregivers completed questionnaires. Spirituality, social support, and stressors were found to have a positive relationship with growth. Facilitation of posttraumatic growth is crucial to all helping professions. PMID:12921208
Use of a safety climate questionnaire in UK health care: factor structure, reliability and usability
Hutchinson, A; Cooper, K L; Dean, J E; McIntosh, A; Patterson, M; Stride, C B; Laurence, B E; Smith, C M
2006-01-01
Aim To explore the factor structure, reliability, and potential usefulness of a patient safety climate questionnaire in UK health care. Setting Four acute hospital trusts and nine primary care trusts in England. Methods The questionnaire used was the 27 item Teamwork and Safety Climate Survey. Thirty three healthcare staff commented on the wording and relevance. The questionnaire was then sent to 3650 staff within the 13 NHS trusts, seeking to achieve at least 600 responses as the basis for the factor analysis. 1307 questionnaires were returned (36% response). Factor analyses and reliability analyses were carried out on 897 responses from staff involved in direct patient care, to explore how consistently the questions measured the underlying constructs of safety climate and teamwork. Results Some questionnaire items related to multiple factors or did not relate strongly to any factor. Five items were discarded. Two teamwork factors were derived from the remaining 11 teamwork items and three safety climate factors were derived from the remaining 11 safety items. Internal consistency reliabilities were satisfactory to good (Cronbach's alpha ?0.69 for all five factors). Conclusions This is one of the few studies to undertake a detailed evaluation of a patient safety climate questionnaire in UK health care and possibly the first to do so in primary as well as secondary care. The results indicate that a 22 item version of this safety climate questionnaire is useable as a research instrument in both settings, but also demonstrates a more general need for thorough validation of safety climate questionnaires before widespread usage. PMID:17074872
ERIC Educational Resources Information Center
Alkherainej, Khaled
2012-01-01
The factor structure and agreement among commonly used questionnaires for identifying children at risk for developmental disability and autism spectrum disorders between the ages of 36 and 66 months were studied. The Age and Stages Questionnaires (ASQ), the Ages and Stages Questionnaire: Social Emotional (ASQ: SE), and the Social Communication…
ERIC Educational Resources Information Center
Rodebaugh, Thomas L.; Holaway, Robert M.; Heimberg, Richard G.
2008-01-01
Despite favorable psychometric properties, the Generalized Anxiety Disorder Questionnaire for the "Diagnostic and Statistical Manual of Mental Disorders" (4th ed.) (GAD-Q-IV) does not have a known factor structure, which calls into question use of its original weighted scoring system (usually referred to as the dimensional score). Analyses…
Temperament factor structure in fragile X syndrome: the children's behavior questionnaire.
Roberts, Jane E; Tonnsen, Bridgette L; Robinson, Marissa; McQuillin, Samuel D; Hatton, Deborah D
2014-02-01
Early patterns of temperament lay the foundation for a variety of developmental constructs such as self-regulation, psychopathology, and resilience. Children with fragile X syndrome (FXS) display unique patterns of temperament compared to age-matched clinical and non-clinical samples, and early patterns of temperament have been associated with later anxiety in this population. Despite these unique patterns in FXS and recent reports of atypical factor structure of temperament questionnaires in Williams Syndrome (Leyfer, John, Woodruff-Borden, & Mervis, 2012), no studies have examined the latent factor structure of temperament scales in FXS to ensure measurement validity in this sample. The present study used confirmatory factor analysis to examine the factor structure of a well-validated parent-reported temperament questionnaire, the Children's Behavior Questionnaire (Rothbart, Ahadi, Hershey, & Fisher, 2001), in a sample of 90 males with FXS ages 3-9 years. Our data produced a similar, but not identical, three-factor model that retained the original CBQ factors of negative affectivity, effortful control, and extraversion/surgency. In particular, our FXS sample demonstrated stronger factor loadings for fear and shyness than previously reported loadings in non-clinical samples, consistent with reports of poor social approach and elevated anxiety in this population. Although the original factor structure of the Children's Behavior Questionnaire is largely retained in children with FXS, differences in factor loading magnitudes may reflect phenotypic characteristics of the syndrome. These findings may inform future developmental and translational research efforts. PMID:24380785
Structural Equation Modeling of Multivariate Time Series
Stephen H. C. du Toit; Michael W. Browne
2007-01-01
The covariance structure of a vector autoregressive process with moving average residuals (VARMA) is derived. It differs from other available expressions for the covariance function of a stationary VARMA process and is compatible with current structural equation methodology. Structural equation modeling programs, such as LISREL, may therefore be employed to fit the model.Particular attention is given to assumptions concerning the
On a Equation in Finite Algebraically Structures
ERIC Educational Resources Information Center
Valcan, Dumitru
2013-01-01
Solving equations in finite algebraically structures (semigroups with identity, groups, rings or fields) many times is not easy. Even the professionals can have trouble in such cases. Therefore, in this paper we proposed to solve in the various finite groups or fields, a binomial equation of the form (1). We specify that this equation has been…
Assessment of structured physical examination skills training using a retro-pre-questionnaire
2013-01-01
Purpose: The effectiveness of physical examination skills (PES) training is very rarely assessed using the “post-then-pre” approach. In this study, a retro-pre-questionnaire was used to study the effect of structured physical examination skills training (SPEST) imparted to second-year undergraduate medical students. Methods: KIST Medical College (KISTMC) affiliated to Tribhuvan University Nepal admitted its first batch of MBBS students in November 2008. The university curriculum recommends the involvement of Medicine and Surgery Departments in PES training, but the methods for teaching and assessment are not well defined. KISTMC has made training more structured and involved the Medicine, Surgery, Gynaecology and Obstetrics, Orthopaedics, ENT, Ophthalmology, Paediatrics, and Family Medicine Departments. SPEST includes the teaching/learning of basic PES for 210 minutes once a week for 28 weeks. Self-assessment is done by using a retro-pre-questionnaire at the end of the last session of training, and these data are analysed using SPSS. Results: Out of 100 students, 98 participated in the objective structured clinical examination (OSCE); 82 completed the retro-pre-questionnaire. Forty-six skills representing various systems were selected for inclusion in the retro-pre-questionnaire from among the many skills taught in different departments. The average perceived skills score (maximum score, 46×4=184) before training was 15.9 and increased to 116.5 after training. The increase was statistically significant upon the application of a paired t-test. Conclusion: The students perceived that their level of skills improved after the training. The retro-pre- instrument seems to be useful for assessing the learners’ self-reported changes in PES after training if a large number of skills need to be assessed. However, it should be noted that although a retro-pre-questionnaire may reveal valuable information, it is not a substitute for an objective measure or gold standard. PMID:24498473
The Specific Analysis of Structural Equation Models
ERIC Educational Resources Information Center
McDonald, Roderick P.
2004-01-01
Conventional structural equation modeling fits a covariance structure implied by the equations of the model. This treatment of the model often gives misleading results because overall goodness of fit tests do not focus on the specific constraints implied by the model. An alternative treatment arising from Pearl's directed acyclic graph theory…
Structural Equation Modeling with Heavy Tailed Distributions
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Bentler, Peter M.; Chan, Wai
2004-01-01
Data in social and behavioral sciences typically possess heavy tails. Structural equation modeling is commonly used in analyzing interrelations among variables of such data. Classical methods for structural equation modeling fit a proposed model to the sample covariance matrix, which can lead to very inefficient parameter estimates. By fitting a…
Factor Structure of the Iranian Version of 12-Item General Health Questionnaire
Rahmati Najarkolaei, Fatemeh; Raiisi, Fatemeh; Rahnama, Parvin; Gholami Fesharaki, Mohammad; Zamani, Omid; Jafari, Mohammad Reza; Montazeri, Ali
2014-01-01
Background: The 12-Item General Health (GHQ-12) questionnaire is one of the most commonly used instruments in screening studies on mental health. Objectives: The current study aimed to examine the factor structure of the GHQ-12 questionnaire among the students in Iran. Materials and Methods: It was a cross-sectional study in which 428 university students were recruited and completed the GHQ-12. Reliability of the GHQ-12 was evaluated using the Cronbach's alpha and the split-half method by applying the Spearman-Brown coefficient. Factor structure of the questionnaire was extracted by exploratory factor analysis (EFA). Confirmatory factor analysis (CFA) was conducted to assess how well the EFA extracted model fitted the observed data. Results: The mean age of the participants was 22.83 years (SD = 3.09). Most of them were female (56.1%) and 81% were unemployed. The Cronbach’s alpha coefficient for the Iranian version of GHQ-12 was 0.85. Using the split-half method, the alpha for the social dysfunction was found to be 0.77; it was 0.76 for the psychological distress. The principal component analysis revealed a two-factor structure for the questionnaire including social dysfunction and psychological distress that explained 48% of the observed variances. The confirmatory factor analysis was showed fit for the data. Conclusions: The current study findings confirm that the Iranian version of GHQ-12 has a good factor structure and is a reliable and valid instrument to measure psychological distress and social dysfunction. PMID:25593708
School Motivation Questionnaire for the Portuguese population: structure and psychometric studies.
Cordeiro, Pedro Miguel Gomes; Figueira, Ana Paula Couceiro; da Silva, José Tomás; Matos, Lennia
2012-11-01
It is presented the structure and psychometric studies of the "School Motivation Questionnaire". The SMQ is a self-report questionnaire with 101 items, organized in sixteen scales that measure the students' goal orientations, the perceived classroom goal structures, the perceived teacher's autonomy support and the use of learning strategies. Twelve scales are adapted from the "Learning Climate Questionnaire", "Perceptions of Instrumentality" and "Cuestionário a Estudiantes". Four scales and five additional items are created new. The psychometric studies rely on a convenience sample consisting of 9th and 12th grade students (N = 485) of Portuguese schools. The factorial and construct validity, verified through several exploratory factorial analyses to the data, presents a final solution of six factors, labelled Strategies (F1), Teacher Extrinsic Goals (F2), Student Extrinsic Goals, Externally Regulated (F3) Teacher Intrinsic Goals (F4), Student Extrinsic Goals, Internally Regulated (F5), and Student Intrinsic Goals (F6). The six-factor solution explains a significant variance of the scale results (53.95%). Good coefficients of internal consistency are obtained for all factors, never below (.858; F6). In sum there is strong evidence to support the multi-dimensionality of SMQ, upholding that the data obtained is exploratory and applies for future validation studies. PMID:23156946
The factor structure of the Strengths and Difficulties Questionnaire (SDQ) in Greek adolescents
Giannakopoulos, George; Tzavara, Chara; Dimitrakaki, Christine; Kolaitis, Gerasimos; Rotsika, Vasiliki; Tountas, Yannis
2009-01-01
Background The Strengths and Difficulties Questionnaire (SDQ) is a practical, economic and user-friendly screening instrument of emotional and behavioural problems in children and adolescents. This study was aimed primarily at evaluating the factor structure of the Greek version of the SDQ. Methods A representative nationwide sample of 1,194 adolescents (11 to 17 years old) completed the questionnaire. Confirmatory factor analysis (CFA) was conducted to assess the factor structure of the SDQ. Results CFA supported the original five-factor structure. The modification of the model provided some improvements. Internal consistency was acceptable for total difficulties, emotional symptoms and prosocial behaviour scale, moderate for hyperactivity/inattention scale and inadequate for peer and conduct problems scale. Older adolescents (aged 15 to 17 years) reported more hyperactivity/inattention and conduct problems than younger ones (aged 11 to 14 years) and girls reported more emotional symptoms and less prosocial behaviour problems than boys. Adolescents of low socioeconomic status (SES) reported more difficulties than those of medium and high SES. Conclusion The Greek SDQ could be potentially considered as a community-wide screening instrument for adolescents' emotional and behavioural problems. PMID:19709422
FROM FROBENIUS STRUCTURES TO DIFFERENTIAL EQUATIONS
Matzat, B.H.
FROM FROBENIUS STRUCTURES TO DIFFERENTIAL EQUATIONS B. H. Matzat February 8, 2008 #12; #12; 0 in arithmetic geometry. In this note we show that over suitable rings, Frobenius endomorphisms de#12;ne di#11;erential structures and vice versa. This includes, for example, di#11;erential rings in positive
Estimation for Polynomial Structural Equation Models
Melanie M. Wall; Yasuo Amemiya
2000-01-01
Structural equation analysis is one of the most widely used statistical methods in social and behavioral science research and has become a popular tool in marketing. Subject matter needs for considering nonlinear structural models have been well documented. But current fitting procedures are available only for a limited class of models. In this article a systematic statistical approach is developed
Judy L. Silberg; Marilyn T. Erickson; Joanne M. Meyer; Lindon J. Eaves; Michael L. Rutter; John K. Hewitt
1994-01-01
The application of structural equation modeling to twin data is used to assess the impact of genetic and environmental factors on children’s behavioral and emotional functioning. The models are applied to the maternal ratings of behavior of a subsample of 515 monozygotic and 749 dizygotic juvenile twin pairs, ages 8 through 16, obtained through mailed questionnaires as part of the
Exploring the factor structure of the Food Cravings Questionnaire-Trait in Cuban adults
Rodríguez-Martín, Boris C.; Molerio-Pérez, Osana
2014-01-01
Food cravings refer to an intense desire to eat specific foods. The Food Cravings Questionnaire-Trait (FCQ-T) is the most commonly used instrument to assess food cravings as a multidimensional construct. Its 39 items have an underlying nine-factor structure for both the original English and Spanish version; but subsequent studies yielded fewer factors. As a result, a 15-item version of the FCQ-T with one-factor structure has been proposed (FCQ-T-reduced; see this Research Topic). The current study aimed to explore the factor structure of the Spanish version for both the FCQ-T and FCQ-T-reduced in a sample of 1241 Cuban adults. Results showed a four-factor structure for the FCQ-T, which explained 55% of the variance. Factors were highly correlated. Using the items of the FCQ-T-reduced only showed a one-factor structure, which explained 52% of the variance. Both versions of the FCQ-T were positively correlated with body mass index (BMI), scores on the Food Thoughts Suppression Inventory and weight cycling. In addition, women had higher scores than men and restrained eaters had higher scores than unrestrained eaters. To summarize, results showed that (1) the FCQ-T factor structure was significantly reduced in Cuban adults and (2) the FCQ-T-reduced may represent a good alternative to efficiently assess food craving on a trait level. PMID:24672503
Barron, David; Swami, Viren; Towell, Tony; Hutchinson, Gerard; Morgan, Kevin D
2015-01-01
Much debate in schizotypal research has centred on the factor structure of the Schizotypal Personality Questionnaire (SPQ), with research variously showing higher-order dimensionality consisting of two to seven dimensions. In addition, cross-cultural support for the stability of those factors remains limited. Here, we examined the factor structure of the SPQ among British and Trinidadian adults. Participants from a White British subsample (n = 351) resident in the UK and from an African Caribbean subsample (n = 284) resident in Trinidad completed the SPQ. The higher-order factor structure of the SPQ was analysed through confirmatory factor analysis, followed by multiple-group analysis for the model of best fit. Between-group differences for sex and ethnicity were investigated using multivariate analysis of variance in relation to the higher-order domains. The model of best-fit was the four-factor structure, which demonstrated measurement invariance across groups. Additionally, these data had an adequate fit for two alternative models: (a) 3-factor and (b) modified 4-factor model. The British subsample had significantly higher scores across all domains than the Trinidadian group, and men scored significantly higher on the disorganised domain than women. The four-factor structure received confirmatory support and, importantly, support for use with populations varying in ethnicity and culture. PMID:25699263
2013-01-01
Background The Otitis Media-6 questionnaire (OM-6) is the most frequently used instrument to measure health related quality of life in children with otitis media. The main objectives of this study are 1) to translate and cross-culturally adapt the OM-6 into Danish, and 2) to assess important psychometric properties including structural validity and interpretability of the OM-6 in a Danish population of children suffering from otitis media. Methods The OM-6 was translated and cross-culturally adapted according to international guidelines. A longitudinal validation study enrolled 491 children and their families, and the measurement properties of the OM-6 were evaluated using the Cosmin taxonomy. The properties assessed were construct and structural validity (confirmatory factor analysis) including internal consistency, reproducibility (test-retest reliability and smallest detectable change), responsiveness and interpretability. Results A total of 435 children were eligible to participate in the study. Analyses of structural validity and internal consistency indicated that parent appraisal of hearing and speech problems may be problematic. Both scales showed similarly good test-retest reliability and construct validity, were able to discriminate between diagnostic subgroups and responsive to change. Cut-off values of 16.7 and 30.0 were found to represent minimal important change for the patients. Conclusions The Danish version of the OM-6 is a reliable, valid, responsive and interpretable questionnaire to measure quality of life in children with otitis media. This study sheds light on possible weaknesses of the instrument that needs to be acknowledged in the utilization of the instrument. However, despite these issues our results support the continuing use of OM-6 as a 1-factor functional health scale with a separate global health rating. Furthermore, indications of values representing minimal important change as perceived by the respondent are presented. PMID:24257471
Kamaruzzaman, Syahrul Nizam; Egbu, C O; Zawawi, Emma Marinie Ahmad; Karim, Saipol Bari Abd; Woon, Chen Jia
2015-05-01
It is accepted that occupants who are more satisfied with their workplace's building internal environment are more productive. The main objective of the study was to measure the occupants' level of satisfaction and the perceived importance of the design or refurbishment on office conditions. The study also attempted to determine the factors affecting the occupants' satisfaction with their building or office conditions. Post-occupancy evaluations were conducted using a structured questionnaire developed by the Built Environment Research Group at the University of Manchester, UK. Our questionnaires incorporate 22 factors relating to the internal environment and rate these in terms of "user satisfaction" and "degree of importance." The questions were modified to reflect the specific setting of the study and take into consideration the local conditions and climate in Malaysia. The overall mean satisfaction of the occupants toward their office environment was 5.35. The results were measured by a single item of overall liking of office conditions in general. Occupants were more satisfied with their state of health in the workplace, but they were extremely dissatisfied with the distance away from a window. The factor analysis divided the variables into three groups, namely intrusion, air quality, and office appearance. Structural equation modeling (SEM) was then used to determine which factor had the most significant influence on occupants' satisfaction: appearance. The findings from the study suggest that continuous improvement in aspects of the building's appearance needs to be supported with effective and comprehensive maintenance to sustain the occupants' satisfaction. PMID:25864077
Composite Reliability in Structural Equations Modeling.
ERIC Educational Resources Information Center
Bacon, Donald R.; And Others
1995-01-01
The potential for bias in reliability estimation and for errors in item selection when alpha or unit-weighted omega coefficients are used is explored under simulated conditions. Results suggest that composite reliability may be an assessment tool but should not be an item selection tool in structural equations. (SLD)
Structural Equation Modeling in Rehabilitation Counseling Research
ERIC Educational Resources Information Center
Chan, Fong; Lee, Gloria K.; Lee, Eun-Jeong; Kubota, Coleen; Allen, Chase A.
2007-01-01
Structural equation modeling (SEM) has become increasingly popular in counseling, psychology, and rehabilitation research. The purpose of this article is to provide an overview of the basic concepts and applications of SEM in rehabilitation counseling research using the AMOS statistical software program.
Errors of Inference in Structural Equation Modeling
ERIC Educational Resources Information Center
McCoach, D. Betsy; Black, Anne C.; O'Connell, Ann A.
2007-01-01
Although structural equation modeling (SEM) is one of the most comprehensive and flexible approaches to data analysis currently available, it is nonetheless prone to researcher misuse and misconceptions. This article offers a brief overview of the unique capabilities of SEM and discusses common sources of user error in drawing conclusions from…
Quantifying Parsimony in Structural Equation Modeling
Kristopher J. Preacher
2006-01-01
Fitting propensity (FP) is defined as a model's average ability to fit diverse data pat- terns, all else being equal. The relevance of FP to model selection is examined in the context of structural equation modeling (SEM). In SEM it is well known that the number of free model parameters influences FP, but other facets of FP are routinely excluded
Structural equation modeling: Back to basics
Ralph O. Mueller
1997-01-01
Major technological advances incorporated into structural equation modeling (SEM) computer programs now make it possible for practitioners who are basically unfamiliar with the purposes and limitations of SEM to use this tool within their research contexts. The current move by program developers to market more user friendly software packages is a welcomed trend in the social and behavioral science research
Challenges in Nonlinear Structural Equation Modeling
Polina Dimitruk; Karin Schermelleh-Engel; Augustin Kelava; Helfried Moosbrugger
2007-01-01
Challenges in evaluating nonlinear effects in multiple regression analyses include reliability, validity, multicollinearity, and dichotomization of continuous variables. While reliability and validity issues are solved by employing nonlinear structural equation modeling, multicollinearity remains a problem which may even be aggravated when using latent variable approaches. Further challenges of nonlinear latent analyses comprise the distribution of latent product terms, a problem
Structural equation modeling for travel behavior research
Thomas F. Golob
2003-01-01
Structural equation modeling (SEM) is an extremely flexible linear-in-parameters multivariate statistical modeling technique. It has been used in modeling travel behavior and values since about 1980, and its use is rapidly accelerating, partially due to the availability of improved software. The number of published studies, now known to be more than 50, has approximately doubled in the past three years.
Structural Equation Modeling of Traveler Information Needs
Yikui Mo; Yongning Niu; Yanbin Fu
2008-01-01
One of the key aspects in the design of Advanced Traveler Information Systems (ATIS) is to make certain that the system can provide the type of information travelers want. In order to analyze the impact of individual characteristics on traveler's information needs and reveal travelers' preferences in different situation, this paper present a structural equation model of traveler information needs,
A TRANSPORT EQUATION FOR CONFINED STRUCTURES DERIVED FROM THE BOLTZMANN EQUATION
Ringhofer, Christian
A TRANSPORT EQUATION FOR CONFINED STRUCTURES DERIVED FROM THE BOLTZMANN EQUATION CLEMENS HEITZINGER for transport in 3d confined structures is derived from the Boltzmann transport equation for charged particles. Transport takes places in confined structures and the scaling in the derivation of the diffusion equation
ERIC Educational Resources Information Center
Sleddens, Ester F. C.; Kremers, Stef P. J.; Candel, Math J. J. M.; De Vries, Nanne N. K.; Thijs, Carel
2011-01-01
In this article, we examined the factorial validity of the Dutch translation of the Children's Behavior Questionnaire (CBQ) and the Very Short Form scores. In addition, we conducted cross-cultural comparisons of temperament structure. In total, 353 parents of 6- to 8-year-olds completed the instrument. The original higher order factor structure of…
Bayesian Model Comparison of Structural Equation Models
Sik-Yum Lee; Xin-Yuan Song
\\u000a Structural equation modeling is a multivariate method for establishing meaningful models to investigate the relationships\\u000a of some latent (causal) and manifest (control) variables with other variables. In the past quarter of a century, it has drawn\\u000a a great deal of attention in psychometrics and sociometrics, both in terms of theoretical developments and practical applications\\u000a (see Bentler and Wu, 2002; Bollen,
Structure formation by the Hartree equation
NASA Astrophysics Data System (ADS)
Lehner, Thierry; Nottale, Laurent; di Menza, Laurent; da Rocha, Daniel; Ceccolini, David
2004-12-01
The Scale Relativity theory predicts that the formation of structures in gravitational interaction can be described by an Hartree equation or equivalently by a set of coupled Schrodinger and Poisson equations. This system is similar to the one used in quantum gravity (with matter only being quantized not the field), but with the substitution of the ratio of the Planck constant to the mass (hbar/m) by a parameter depending of the system under study. By a change of coordinates we get the hydrodynamical equations of Euler and continuity which make appear a term of potential energy (which is understood as a quantum pressure in the case of Bose-Einstein condensation) which would play here the role of a "dark potential". As applications we show the formation of structures in a medium with a homogeneous density and the formation of a disk from dust around a central star. The linear (equilibrium) solutions will be recalled in both cases and they compare favorably with the observations, but we describe also the phase of non linear dynamical evolution which is thought to converge asymptotically in time towards the equilibrium linear solutions (under current study). In particular the Hartree equation has no singularity of blow-up kind in finite time since the dark potential, which is the manifestation of the fractality of space, prevents from gravitational collapse. We make use of variable in time, with 2D and 3D variations in space numerical codes to solve this problem, by setting as initial conditions either the asymptotic states or localized structures of the soliton type.
ERIC Educational Resources Information Center
He, Jian-Ping; Burstein, Marcy; Schmitz, Anja; Merikangas, Kathleen R.
2013-01-01
The Strengths and Difficulties Questionnaire (SDQ) is one of the most commonly used instruments for screening psychopathology in children and adolescents. This study evaluated the hypothesized five-factor structure of the SDQ and examined its convergent validity against comprehensive clinical diagnostic assessments. Data were derived from the…
ERIC Educational Resources Information Center
Kingery, Julie Newman; Kepley, Hayden O.; Ginsburg, Golda S.; Walkup, John T.; Silva, Susan G.; Hoyle, Rick H.; Reinecke, Mark A.; March, John S.
2009-01-01
The factor structure and psychometric properties of the Children's Negative Cognitive Error Questionnaire (CNCEQ) were examined with 427 adolescents ages 12 to 18 (193 boys) with current major depressive disorder. Results of confirmatory factor analysis supported a four-factor model comprised of three content area factors (i.e., social, academic,…
ERIC Educational Resources Information Center
Bjornsdottir, Gyda; Halldorsson, Jonas G.; Steinberg, Stacy; Hansdottir, Ingunn; Kristjansson, Kristleifur; Stefansson, Hreinn; Stefansson, Kari
2014-01-01
This article describes psychometric testing of an Icelandic adaptation of the "Adult Reading History Questionnaire" (ARHQ), designed to detect a history of reading difficulties indicative of dyslexia. Tested in a large and diverse sample of 2,187 adults, the Icelandic adaptation demonstrated internal consistency reliability…
ERIC Educational Resources Information Center
Rudasill, Kathleen Moritz; Foust, Regan Clark; Callahan, Carolyn M.
2007-01-01
Gifted students report that they are often perceived differently than nonidentified students (Cross, Coleman, & Stewart, 1993); thus, they employ social coping strategies to manipulate the visibility of their giftedness. The Social Coping Questionnaire (SCQ; Swiatek, 1995) was designed to assess these strategies. This study's purpose was to…
A Framework for Structural Equation Models in General Pedigrees
Nathan J. Morris; Robert C. Elston; Catherine M. Stein
2010-01-01
Background\\/Aims: Structural Equation Modeling (SEM) is an analysis approach that accounts for both the causal relationships between variables and the errors associated with the measurement of these variables. In this paper, a framework for implementing structural equation models (SEMs) in family data is proposed. Methods: This framework includes both a latent measurement model and a structural model with covariates. It
Structural equations modeling: Fit Indices, sample size, and advanced topics
Dawn Iacobucci
2010-01-01
This article is the second of two parts intended to serve as a primer for structural equations models for the behavioral researcher. The first article introduced the basics: the measurement model, the structural model, and the combined, full structural equations model. In this second article, advanced issues are addressed, including fit indices and sample size, moderators, longitudinal data, mediation, and
Use of structural equation modeling in counseling psychology research
Ruth E. Fassinger
1987-01-01
Structural equation modeling (multivariate analysis with latent variables, also called causal modeling or covariance structure analysis) is a valuable methodological tool for use in counseling psychology research. Essentially the broad framework that subsumes many well-known proce- dures (e.g., multiple linear regression, factor analysis, path analysis), structural equation modeling allows for analysis of causal patterns among unobserved variables represented by multiple
ON THE CONTROLLABILITY OF A WAVE EQUATION WITH STRUCTURAL DAMPING
Rosier, Lionel - Institut de MathÃ©matiques Ã?lie Cartan, UniversitÃ© Henri PoincarÃ©
. Spectrum with structural damping. heat equation, and the second one is constituted of negative real numbersON THE CONTROLLABILITY OF A WAVE EQUATION WITH STRUCTURAL DAMPING Lionel Rosier Pierre Rouchon with structural damping ytt - yxx - ytxx = 0, y(0, t) = 0, y(1, t) = h(t) where is a strictly positive parameter
Structural equation modeling in environmental risk assessment.
Buncher, C R; Succop, P A; Dietrich, K N
1991-01-01
Environmental epidemiology requires effective models that take individual observations of environmental factors and connect them into meaningful patterns. Single-factor relationships have given way to multivariable analyses; simple additive models have been augmented by multiplicative (logistic) models. Each of these steps has produced greater enlightenment and understanding. Models that allow for factors causing outputs that can affect later outputs with putative causation working at several different time points (e.g., linkage) are not commonly used in the environmental literature. Structural equation models are a class of covariance structure models that have been used extensively in economics/business and social science but are still little used in the realm of biostatistics. Path analysis in genetic studies is one simplified form of this class of models. We have been using these models in a study of the health and development of infants who have been exposed to lead in utero and in the postnatal home environment. These models require as input the directionality of the relationship and then produce fitted models for multiple inputs causing each factor and the opportunity to have outputs serve as input variables into the next phase of the simultaneously fitted model. Some examples of these models from our research are presented to increase familiarity with this class of models. Use of these models can provide insight into the effect of changing an environmental factor when assessing risk. The usual cautions concerning believing a model, believing causation has been proven, and the assumptions that are required for each model are operative. PMID:2050063
Monge-Rojas, Rafael; Smith-Castro, Vanesa; Colon-Ramos, Uriyoán; Garita-Arce, Carlos; Sánchez-López, Marta; Chinnock, Anne
2010-10-01
This study designed and validated a questionnaire aimed at examining parental feeding styles to encourage healthy eating habits among Costa Rican adolescents. Adolescents (n=133; mean age 15.4 years), and their parents, participated in the study. The parents completed a parental feeding style questionnaire, and the adolescents completed 3-day food records. Confirmatory factor analyses suggest four distinct parental feeding styles, (a) verbal encouragement of healthy eating behaviors; (b) use of verbal sanctions to indirectly control the intake of healthy food; (c) direct control of access to and intake of food; and (d) use of food to regulate emotions and behavior. There were no correlations between dietary intake and the verbal encouragement of healthy eating behaviors, but there were significant negative correlations between (1) "the use of verbal sanctions to indirectly control the intake of healthy food", and the consumption of fruit and vegetable, of calcium, iron, vitamin B6 and folic acid intake, and (2) between the "direct control of access to and intake of food" and fast food consumption and total carbohydrates intake. The use of food to regulate emotions and behavior was positively correlated with high energy-dense food consumption. Stratification of the data shows significant differences by gender in the correlations between parental feeding style and dietary intake. Understanding parental feeding styles in a Latin American context is a first step in helping researchers develops culturally-appropriate parenting intervention/prevention strategies to encourage healthy eating behaviors during adolescence. PMID:20600415
ERIC Educational Resources Information Center
Piedmont, Ralph L.; Sherman, Martin F.; Sherman, Nancy C.; Williams, Joseph E. G.
2003-01-01
This study examined the psychometrics of the Structured Clinical Interview for DSM-IV Personality Disorders Personality Questionnaire (SCID-IIP) self-report personality questionnaire. The responses to the instrument were found reliable and evidenced good self-other convergence. Correlations with external criteria showed the SCID-IIP to contain…
Dilatonic Equation of Hydrostatic Equilibrium and Neutron Star Structure
S. H. Hendi; G. H. Bordbar; B. Eslam Panah; M. Najafi
2015-06-30
In this paper, we present a new hydrostatic equilibrium equation related to dilaton gravity. We consider a spherical symmetric metric to obtain the hydrostatic equilibrium equation of stars in $4$-dimensions, and generalize TOV equation to the case of regarding a dilaton field. Then, we calculate the structure properties of neutron star using our obtained hydrostatic equilibrium equation employing the modern equations of state of neutron star matter derived from microscopic calculations. We show that the maximum mass of neutron star depends on the parameters of dilaton field and cosmological constant. In other words, by setting the parameters of new hydrostatic equilibrium equation, we calculate the maximum mass of neutron star.
Modeling Attitude toward Statistics by a Structural Equation
ERIC Educational Resources Information Center
Escalera-Chávez, Milka Elena; García-Santillán, Arturo; Venegas-Martínez, Francisco
2014-01-01
In this study, we examined whether the constructs of usefulness, motivation, likeness, confidence, and anxiety influence the student's attitude towards statistics. Two hundred ninety eight students enrolled in the private university were surveyed by using the questionnaire proposed by Auzmendi (1992). Data analysis was done by structural…
Fitting Multivariate Normal Finite Mixtures Subject to Structural Equation Modeling.
ERIC Educational Resources Information Center
Dolan, Conor V.; van der Maas, Han L. J.
1998-01-01
Discusses fitting multivariate normal mixture distributions to structural equation modeling. The model used is a LISREL submodel that includes confirmatory factor and structural equation models. Two approaches to maximum likelihood estimation are used. A simulation study compares confidence intervals based on the observed information and…
Two Rules of Identification for Structural Equation Models
ERIC Educational Resources Information Center
Bollen, Kenneth A.; Davis, Walter R.
2009-01-01
Identification of structural equation models remains a challenge to many researchers. Although empirical tests of identification are readily available in structural equation modeling software, these examine local identification and rely on sample estimates of parameters. Rules of identification are available, but do not include all models…
Evaluating Interventions with Multimethod Data: A Structural Equation Modeling Approach
Claudia Crayen; Christian Geiser; Herbert Scheithauer; Michael Eid
2011-01-01
In many intervention and evaluation studies, outcome variables are assessed using a multimethod approach comparing multiple groups over time. In this article, we show how evaluation data obtained from a complex multitrait–multimethod–multioccasion–multigroup design can be analyzed with structural equation models. In particular, we show how the structural equation modeling approach can be used to (a) handle ordinal items as indicators,
A Bayesian analysis on time series structural equation models
Yi-Fu Wang; Tsai-Hung Fan
2011-01-01
Structural equation models (SEM) have been extensively used in behavioral, social, and psychological research to model relations between the latent variables and the observations. Most software packages for the fitting of SEM rely on frequentist methods. Traditional models and software are not appropriate for analysis of the dependent observations such as time-series data. In this study, a structural equation model
Fitting ARMA Time Series by Structural Equation Models.
ERIC Educational Resources Information Center
van Buuren, Stef
1997-01-01
This paper outlines how the stationary ARMA (p,q) model (G. Box and G. Jenkins, 1976) can be specified as a structural equation model. Maximum likelihood estimates for the parameters in the ARMA model can be obtained by software for fitting structural equation models. The method is applied to three problem types. (SLD)
Sensitivity of rocky planet structures to the equation of state
Swift, D C
2009-06-10
Structures were calculated for Mercury, Venus, Earth, the Moon, and Mars, using a core-mantle model and adjusting the core radius to reproduce the observed mass and diameter of each body. Structures were calculated using Fe and basalt equations of state of different degrees of sophistication for the core and mantle. The choice of equation of state had a significant effect on the inferred structure. For each structure, the moment of inertia ratio was calculated and compared with observed values. Linear Grueneisen equations of state fitted to limited portions of shock data reproduced the observed moments of inertia significantly better than did more detailed equations of state incorporating phase transitions, presumably reflecting the actual compositions of the bodies. The linear Grueneisen equations of state and corresponding structures seem however to be a reasonable starting point for comparative simulations of large-scale astrophysical impacts.
Validating a tourism development theory with structural equation modeling
Yooshik Yoon; Dogan Gursoy; Joseph S. Chen
2001-01-01
This study attempts to examine the structural effects of four tourism-impact factors on total impact and on local residents’ support for tourism development. To achieve the above goal, five research hypotheses are proposed. Three hundred and four questionnaires from a mail survey of randomly selected residents from the Norfolk\\/Virginia Beach\\/Newport News area were analyzed. A confirmatory factor analysis and structural
Bjornsdottir, Gyda; Halldorsson, Jonas G; Steinberg, Stacy; Hansdottir, Ingunn; Kristjansson, Kristleifur; Stefansson, Hreinn; Stefansson, Kari
2014-01-01
This article describes psychometric testing of an Icelandic adaptation of the Adult Reading History Questionnaire (ARHQ), designed to detect a history of reading difficulties indicative of dyslexia. Tested in a large and diverse sample of 2,187 adults, the Icelandic adaptation demonstrated internal consistency reliability (Cronbach's alpha = .92) and test-retest reliability (r = .93). Validity was established by comparing scores of adults who as children received ICD-10 diagnoses of specific reading disorder (F81.0; n = 419) to those of adults defined as nondyslexics (n = 679). ROC curve analysis resulted in an area under the curve of .92 (95% CI = .90, .93, p < .001) and a cutoff score of .43 with sensitivity of 84.5% and specificity of 83.7%. An exploratory factor analysis (n = 2,187) suggested three subscales, Dyslexia Symptoms, Current Reading, and Memory, the mean scores of which differed significantly among diagnosed dyslexics, relatives of dyslexics, and population controls. Our results support the applicability of the ARHQ in Icelandic as a self-report screening tool for adult dyslexia in Iceland. PMID:23456983
Meng, Lina; Liu, Yanhui; Liu, Hongwei; Hu, Yu; Yang, Jipeng; Liu, Jingying
2015-06-01
The aim of the study was to explore the relationship among perceived structural empowerment, psychological empowerment, burnout and intent to stay by nurses in mainland China.With the shortage of nurses in many countries, including China, intent to stay is a dominant factor to influence the quality of care. Also, burnout is identified to negatively affect the quality of care. Empowered clinical nurse practical environment is related to intent to stay and burnout. In the current literature, there is a lack of data based on empowering environment discussing the relationship between burnout and intent to stay. The study used an anonymous questionnaire, filled voluntarily by 219 nurses from different sections in a city in mainland China, 2012.Structural equation modelling (SEM) was used to test the proposed hypotheses. Based on the SEM model, structural empowerment and psychological empowerment had significant positive effects on intent to stay of nurses and negative effects on burnout. Burnout had a significant negative effect on intent to stay. The final modified models yielded ?(2) ?=?58.580, P?>?0.05, ?(2) /df?=?1.046, root mean square error of approximation?=?0.015, Tucker-Lewis Index?=?0.996, comparative fit index?=?0.998,which indicated good fit indices. Creating a positive empowering workplace can encourage nurses to stay long and prevent burnout. Therefore, higher level of empowering environment is required. PMID:25521424
Alternative bi-Hamiltonian structures for WDVV equations of associativity
J. Kalayci; Y. Nutku
1998-10-12
The WDVV equations of associativity in 2-d topological field theory are completely integrable third order Monge-Amp\\`ere equations which admit bi-Hamiltonian structure. The time variable plays a distinguished role in the discussion of Hamiltonian structure whereas in the theory of WDVV equations none of the independent variables merits such a distinction. WDVV equations admit very different alternative Hamiltonian structures under different possible choices of the time variable but all these various Hamiltonian formulations can be brought together in the framework of the covariant theory of symplectic structure. They can be identified as different components of the covariant Witten-Zuckerman symplectic 2-form current density where a variational formulation of the WDVV equation that leads to the Hamiltonian operator through the Dirac bracket is available.
Darcy, Alison M; Hardy, Kristina K; Crosby, Ross D; Lock, James; Peebles, Rebecka
2013-06-01
The study explored the psychometric properties of the Eating Disorder Examination Questionnaire (EDE-Q) among 1637 university students. Participants were divided into male (n=432) and female (n=544) competitive athletes, and male (n=229) and female (n=429) comparison groups comprised of individuals who had not engaged in competitive sports for at least one year. All groups were subjected to confirmatory factor analysis (CFA) to test the fit of the published factor structure in this population, and then exploratory FA (EFA). A three-factor solution was the best fit for three out of four groups, with a two-factor solution providing best fit for the male comparison group. The first factor for all groups resembled a combined Shape and Weight Concern subscale. The factor structure among male and female competitive athletes was remarkably similar; however, non-competitive athletic/low activity males appear qualitatively different from other groups. PMID:23453695
Sleddens, Ester F C; Kremers, Stef P J; Candel, Math J J M; De Vries, Nanne N K; Thijs, Carel
2011-06-01
In this article, we examined the factorial validity of the Dutch translation of the Children's Behavior Questionnaire (CBQ) and the Very Short Form scores. In addition, we conducted cross-cultural comparisons of temperament structure. In total, 353 parents of 6- to 8-year-olds completed the instrument. The original higher order factor structure of the different CBQ forms was generally replicated and represented the three broad dimensions of temperament: Surgency/Extraversion, Negative Affectivity, and Effortful Control. For the Standard Form, results demonstrated a relatively high degree of factor similarity of the Dutch sample with other cultures (e.g., China and Japan). The findings provide evidence for applicability of the CBQ in Western Europe as a promising instrument to comprehensively assess reactive and self-regulative temperamental dimensions in young children. PMID:21381838
The Cleveland Adolescent Sleepiness Questionnaire
Spilsbury, James C.; Drotar, Dennis; Rosen, Carol L.; Redline, Susan
2007-01-01
Study Objectives: Developed the Cleveland Adolescent Sleepiness Questionnaire (CASQ), a brief, self-completed instrument to measure excessive daytime sleepiness in adolescents. Design: Cross-sectional analysis. Participants: A subsample of 411 adolescents 11–17 years of age recruited from area schools, churches, and “control” participants in a sleep disordered breathing cohort study; a second subsample of 62 adolescents with diagnosed sleep disordered breathing also participating in the sleep disordered breathing study. Measurements: Participants completed the CASQ along with two other available measures of daytime sleepiness and other sleep parameters (sleep duration on school nights, sleep duration on non-school nights, and sleep debt, defined as non-school night sleep duration minus school-night sleep duration). Demographic information was obtained from a caregiver-completed questionnaire. The CASQ was developed using exploratory factor analysis, followed by confirmatory factor analysis using structural equation modeling techniques. Results: Goodness-of-fit measures for the final 16-item scale structure ranged from good to excellent. The CASQ's internal consistency was good (? = 0.89). Correlations between the CASQ, two other measures of daytime sleepiness, and sleep parameters gave preliminary evidence of the CASQ's construct validity. Conclusion: The CASQ shows promise as a valid measure of daytime sleepiness in adolescents. Citation: Spilsbury JC; Drotar D; Rosen CL et al. The cleveland adolescent sleepiness questionnaire: a new measure to assess excessive daytime sleepiness in adolescents. PMID:17993042
Integrable structures for a generalized Monge-Ampère equation
NASA Astrophysics Data System (ADS)
Verbovetsky, A. M.; Vitolo, R.; Kersten, P.; Krasil'shchik, I. S.
2012-05-01
We consider a third-order generalized Monge-Ampère equation uyyy - u{xxy/ 2 } + uxxxuxyy = 0, which is closely related to the associativity equation in two-dimensional topological field theory. We describe all integrable structures related to it: Hamiltonian, symplectic, and also recursion operators. We construct infinite hierarchies of symmetries and conservation laws.
The relativistic equations of stellar structure and evolution
K. S. Thorne
1977-01-01
The general-relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. Also, a general-relativistic version of the mixing-length formalism for convection is presented.
USING STRUCTURAL EQUATION MODELING TO INVESTIGATE RELATIONSHIPS AMONG ECOLOGICAL VARIABLES
This paper gives an introductory account of Structural Equation Modeling (SEM) and demonstrates its application using LISREL< with a model utilizing environmental data. Using nine EMAP data variables, we analyzed their correlation matrix with an SEM model. The model characterized...
A general non-linear multilevel structural equation mixture model.
Kelava, Augustin; Brandt, Holger
2014-01-01
In the past 2 decades latent variable modeling has become a standard tool in the social sciences. In the same time period, traditional linear structural equation models have been extended to include non-linear interaction and quadratic effects (e.g., Klein and Moosbrugger, 2000), and multilevel modeling (Rabe-Hesketh et al., 2004). We present a general non-linear multilevel structural equation mixture model (GNM-SEMM) that combines recent semiparametric non-linear structural equation models (Kelava and Nagengast, 2012; Kelava et al., 2014) with multilevel structural equation mixture models (Muthén and Asparouhov, 2009) for clustered and non-normally distributed data. The proposed approach allows for semiparametric relationships at the within and at the between levels. We present examples from the educational science to illustrate different submodels from the general framework. PMID:25101022
Hamiltonian structure of the complex Monge-Ampère equation
Y. Nutku; M. B. Sheftel
2008-02-24
We discover Hamiltonian structure of the complex Monge-Amp`ere equation when written in a first order two-component form. We present Lagrangian and Hamiltonian functions, a symplectic form and the Hamiltonian operator that determines the Poisson bracket.
Hill, Ryan M; Rey, Yasmin; Marin, Carla E; Sharp, Carla; Green, Kelly L; Pettit, Jeremy W
2015-06-01
Five versions of the Interpersonal Needs Questionnaire (INQ), a self-report measure of perceived burdensomeness and thwarted belongingness, have been used in recent studies (including 10-, 12-, 15-, 18-, and 25-items). Findings regarding the associations between perceived burdensomeness, thwarted belongingness, and suicidal ideation using different versions have been mixed, potentially due to differences in measurement scales. This study evaluated factor structure, internal consistency, and concurrent predictive validity of these five versions in three samples. Samples 1 and 2 were comprised of 449 and 218 undergraduates, respectively; Sample 3 included 114 adolescent psychiatric inpatients. All versions demonstrated acceptable internal consistency. The 10-item version and 15-item version demonstrated the best, most consistent model fit in confirmatory factor analyses. Both perceived burdensomeness and thwarted belongingness consistently predicted concurrent suicidal ideation on the 10-item INQ only. Future research should consider using the 15-item or 10-item versions. PMID:25308815
Chioqueta, Andrea P; Stiles, Tore C
2006-08-01
The factor structure of the Norwegian version of the Dysfunctional Attitude Scale and the Automatic Thoughts Questionnaire was investigated with a sample of 344 male military recruits. Principal factor analyses with promax rotation indicated four factors for the former, labeled Performance Evaluation, Need for Approval, Autonomous Attitude, and Perfectionism which accounted for 15.5%, 3.6%, 2.6%, and 2.5% of the total variance, respectively. Two factors comprised the latter. Factor 1 was labeled Negative Self-concept and Personal Maladjustment and accounted for 40% of the total variance, and Factor 2 was labeled Desire for Change and Negative Expectations and accounted for 6.3% of the total variance. The findings may be useful in identifying the specific dysfunctional beliefs and negative automatic thoughts exhibited by military recruits. Such information can also contribute to the development of more effective treatment interventions. PMID:17037474
Kingery, Julie Newman; Kepley, Hayden O; Ginsburg, Golda S; Walkup, John T; Silva, Susan G; Hoyle, Rick H; Reinecke, Mark A; March, John S
2009-11-01
The factor structure and psychometric properties of the Children's Negative Cognitive Error Questionnaire (CNCEQ) were examined with 427 adolescents ages 12 to 18 (193 boys) with current major depressive disorder. Results of confirmatory factor analysis supported a four-factor model comprised of three content area factors (i.e., social, academic, athletic) and a general factor. Internal consistencies ranged between .84 and .94 for the total and three content area scores. Girls scored significantly higher than boys on all factors, but no age differences on the factors were found. Convergent and discriminant validity of the CNCEQ were supported. Results did not support the original subscales organized by type of cognitive distortion (e.g., catastrophizing, overgeneralizing). Findings indicated that the CNCEQ would be a useful clinical tool for assessing cognitive symptoms within relevant domains of functioning (e.g., social, academic) of depressed youth. PMID:20183661
From Questionnaire to Conversation: A Structural Intervention to Improve HIV Test Counseling
Sheon, Nicolas; Lee, Seung-Hee; Facente, Shelley
2010-01-01
Objectives We describe the effects of structural intervention to enhance the quality of HIV test counseling interaction with men who have sex with men (MSM) in San Francisco. Methods Audio recordings of 28 rapid HIV test sessions by seven counselors were collected in two phases: before and after implementation of a waiting room intervention prior to the session. The sessions were analyzed using sequence maps to visualize and compare the sequence and distribution of four activities: counseling, information delivery, data collection, and sample collection. Results Prior to the intervention, counselors and clients often oriented to data collection about the client’s past risk as if it were a survey. In sessions recorded after the intervention, questions about past risk were dispersed throughout the session and embedded within an elaborated discussion of the client’s particular life circumstances. Conclusion Direct observation with the aid of sequence maps illuminates the ways that counselors and clients collaboratively orient to various tasks. Practice Implications We demonstrated the feasibility of a structural intervention that improved the quality of both counseling and the accuracy of client risk data without requiring additional session time or counselor training. PMID:20888723
Ingles, Cándido J; Torregrosa, María S; Hidalgo, María D; Nuñez, Jose C; Castejón, Juan L; García-Fernández, Jose M; Valles, Antonio
2012-03-01
The aim of this study was to analyze the reliability and validity evidence of scores on the Spanish version of Self-Description Questionnaire II (SDQ-II). The instrument was administered in a sample of 2022 Spanish students (51.1% boys) from grades 7 to 10. Confirmatory factor analysis (CFA) was used to examine validity evidence based on internal structure drawn from the scores on the SDQ-II. CFA replicated the correlated II first-order factor structure. Furthermore, hierarchical confirmatory factor analysis (HCFA) was used to examine the hierarchical ordering of self-concept, as measured by scores on the Spanish version of the SDQ-II. Although a series of HCFA models were tested to assess academic and non-academic components organization, support for those hierarchical models was weaker than for the correlated 11 first-order factor structure. Results also indicated that scores on the Spanish version of the SDQ-II had internal consistency and test-retest reliability estimates within an acceptable range. PMID:22379728
On Nonequivalence of Several Procedures of Structural Equation Modeling
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Chan, Wai
2005-01-01
The normal theory based maximum likelihood procedure is widely used in structural equation modeling. Three alternatives are: the normal theory based generalized least squares, the normal theory based iteratively reweighted least squares, and the asymptotically distribution-free procedure. When data are normally distributed and the model structure…
Bayesian Semiparametric Structural Equation Models with Latent Variables
ERIC Educational Resources Information Center
Yang, Mingan; Dunson, David B.
2010-01-01
Structural equation models (SEMs) with latent variables are widely useful for sparse covariance structure modeling and for inferring relationships among latent variables. Bayesian SEMs are appealing in allowing for the incorporation of prior information and in providing exact posterior distributions of unknowns, including the latent variables. In…
Structural Equation Modelling: A Primer for Music Education Researchers
ERIC Educational Resources Information Center
Teo, Timothy
2010-01-01
Structural equation modelling (SEM) is a method for analysis of multivariate data from both non-experimental and experimental research. The method combines a structural model linking latent variables and a measurement model linking observed variables with latent variables. Its use in social science and educational research has grown since the…
Structural Equation Modeling in Clinical Assessment Research With Children
Richard J. Morris; John R. Bergan; John V. Fulginiti
1991-01-01
The use of structural equation modeling has gained increased interest in recent years in the social and behavioral sciences. This article reviews the basic tenets of structural modeling in relation to issues in research and practice involving clinical assessment and compares this approach with more traditional psychometric approaches to the validation of assessment instruments with children. Arguments for and against
Structural Equation Modeling of School Violence Data: Methodological Considerations
ERIC Educational Resources Information Center
Mayer, Matthew J.
2004-01-01
Methodological challenges associated with structural equation modeling (SEM) and structured means modeling (SMM) in research on school violence and related topics in the social and behavioral sciences are examined. Problems associated with multiyear implementations of large-scale surveys are discussed. Complex sample designs, part of any…
Sensitivity Equations for a Size-Structured Population Model
-structured population models. The growth and mortality rates of the shrimp population are affected by severalSensitivity Equations for a Size-Structured Population Model H. T. Banks, Stacey L. Ernstberger and Shuhua Hu Center for Research in Scientific Computation North Carolina State University Raleigh, NC 27695
FROM FROBENIUS STRUCTURES TO DIFFERENTIAL EQUATIONS
Matzat, B.H.
differential structures and vice versa. This includes, for example, differential rings in positive characteristic and complete non-archimedean differential rings in characteristic zero. Further, in the global with the PV-rings of the reduced (iterative) differential modules in positive characteristic (Thm. 5
On integrable structures for a generalized Monge-Ampere equation
Paul Kersten; Iosif Krasil'shchik; Alexander Verbovetsky; Raffaele Vitolo
2011-01-01
We consider a 3rd-order generalized Monge-Ampere equation u_yyy - u_xxy^2 + u_xxx u_xyy = 0 (which is closely related to the associativity equation in the 2-d topological field theory) and describe all integrable structures related to it (i.e., Hamiltonian, symplectic, and recursion operators). Infinite hierarchies of symmetries and conservation laws are constructed as well.
On integrable structures for a generalized Monge-Ampere equation
Paul Kersten; Iosif Krasil'shchik; Alexander Verbovetsky; Raffaele Vitolo
2011-06-03
We consider a 3rd-order generalized Monge-Ampere equation u_yyy - u_xxy^2 + u_xxx u_xyy = 0 (which is closely related to the associativity equation in the 2-d topological field theory) and describe all integrable structures related to it (i.e., Hamiltonian, symplectic, and recursion operators). Infinite hierarchies of symmetries and conservation laws are constructed as well.
Changing Community Structure and Income Distribution: A Structural Equation Model.
ERIC Educational Resources Information Center
Wheelock, Gerald C.
A preliminary model of community economic development processes, consisting of a system of simultaneous equations, is used to describe how these processes influence changes in median family income and income inequality. The analysis was performed on 61 racially mixed counties in Alabama, using 1960-70 census data. Social and demographic variables…
Costello, Tracy J.; Mazas, Carlos; Cofta-Woerpel, Ludmila; Mejia, Luz Maria; Wetter, David W.
2009-01-01
Introduction: Much of the existing research on smoking outcome expectancies has been guided by the Smoking Consequences Questionnaire (SCQ ). Although the original version of the SCQ has been modified over time for use in different populations, none of the existing versions have been evaluated for use among Spanish-speaking Latino smokers in the United States. Methods: The present study evaluated the factor structure and predictive validity of the 3 previously validated versions of the SCQ—the original, the SCQ-Adult, and the SCQ-Spanish, which was developed with Spanish-speaking smokers in Spain—among Spanish-speaking Latino smokers in Texas. Results: The SCQ-Spanish represented the least complex solution. Each of the SCQ-Spanish scales had good internal consistency, and the predictive validity of the SCQ-Spanish was partially supported. Nearly all the SCQ-Spanish scales predicted withdrawal severity even after controlling for demographics and dependence. Boredom Reduction predicted smoking relapse across the 5- and 12-week follow-up assessments in a multivariate model that also controlled for demographics and dependence. Discussion: Our results support use of the SCQ-Spanish with Spanish-speaking Latino smokers in the United States. PMID:19696309
Peirce, Jessica M.; Burke, Christopher K.; Stoller, Kenneth B.; Neufeld, Karin J.; Brooner, Robert K.
2011-01-01
Posttraumatic stress disorder (PTSD) diagnosis requires first identifying a traumatic event, but very few studies have evaluated methods of potential traumatic event assessment and their impact on PTSD diagnosis. We compared a behaviorally-specific comprehensive multiple-item traumatic event measure to a single-item measure to determine their impact on traumatic event identification and subsequent PTSD diagnosis. In a within-subject, counterbalanced design, the Traumatic Life Events Questionnaire (TLEQ; Kubany et al., 2000) was compared to the single-question traumatic event assessment in the Structured Clinical Interview for DSM-IV (SCID; First, Spitzer, Gibbon, & Williams, 1998) in 129 participants in opioid dependence treatment. The TLEQ produced a 9-fold higher rate of traumatic events reported by the participants as compared to the SCID. As a result, PTSD diagnoses in the sample increased to 33% after the TLEQ measure from 24% after the SCID. The increase in potential traumatic event identification and PTSD diagnosis was greater in women than men. This study provides strong support for the use of comprehensive traumatic event assessments to measure traumatic events and PTSD diagnoses, particularly in women. PMID:19485675
ERIC Educational Resources Information Center
Crede, Marcus; Niehorster, Sarah
2012-01-01
This paper presents a meta-analytic review (k = 237, N = 44,668) of the adjustment to college literature. The review, based on studies using the Student Adaptation to College Questionnaire, is organized around three primary themes: (1) the structure of students' adjustment to college, (2) the relationship of adjustment to college constructs with…
Gaussian Process Structural Equation Models with Latent Variables
Silva, Ricardo
2010-01-01
In a variety of disciplines such as social sciences, psychology, medicine and economics, the recorded data are considered to be noisy measurements of latent variables connected by some causal structure. This corresponds to a family of graphical models known as the structural equation model with latent variables. While linear non-Gaussian variants have been well-studied, inference in nonparametric structural equation models is still underdeveloped. We introduce a sparse Gaussian process parameterization that defines a non-linear structure connecting latent variables, unlike common formulations of Gaussian process latent variable models. An efficient Markov chain Monte Carlo procedure is described. We evaluate the stability of the sampling procedure and the predictive ability of the model compared against the current practice.
Killing-Yano equations and G-structures
G. Papadopoulos
2008-04-28
We solve the Killing-Yano equation on manifolds with a $G$-structure for $G=SO(n), U(n), SU(n), Sp(n)\\cdot Sp(1), Sp(n), G_2$ and $Spin(7)$. Solutions include nearly-K\\"ahler, weak holonomy $G_2$, balanced SU(n) and holonomy $G$ manifolds. As an application, we find that particle probes on $AdS_4\\times X$ compactifications of type IIA and 11-dimensional supergravity admit a ${\\cal W}$-type of symmetry generated by the fundamental forms. We also explore the ${\\cal W}$-symmetries of string and particle actions in heterotic and common sector supersymmetric backgrounds. In the heterotic case, the generators of the ${\\cal W}$-symmetries completely characterize the solutions of the gravitino Killing spinor equation, and the structure constants of the ${\\cal W}$-symmetry algebra depend on the solution of the dilatino Killing spinor equation.
Consistent Partial Least Squares for nonlinear structural equation models.
Dijkstra, Theo K; Schermelleh-Engel, Karin
2014-10-01
Partial Least Squares as applied to models with latent variables, measured indirectly by indicators, is well-known to be inconsistent. The linear compounds of indicators that PLS substitutes for the latent variables do not obey the equations that the latter satisfy. We propose simple, non-iterative corrections leading to consistent and asymptotically normal (CAN)-estimators for the loadings and for the correlations between the latent variables. Moreover, we show how to obtain CAN-estimators for the parameters of structural recursive systems of equations, containing linear and interaction terms, without the need to specify a particular joint distribution. If quadratic and higher order terms are included, the approach will produce CAN-estimators as well when predictor variables and error terms are jointly normal. We compare the adjusted PLS, denoted by PLSc, with Latent Moderated Structural Equations (LMS), using Monte Carlo studies and an empirical application. PMID:24306555
A structural equations analysis of commuters' activity and travel patterns
Arun R. Kuppam; Ram M. Pendyala
2001-01-01
An exploratory analysis of commuters' activity and travel patterns was carried out using activity-based travel survey data\\u000a collected in the Washington, DC metropolitan area to investigate and estimate relationships among socio-demographics, activity\\u000a participation, and travel behavior. Structural equations modeling methodology was adopted to determine the structural relationships\\u000a among commuters' demographics, activity patterns, trip generation, and trip chaining information. Three types
Raffaela Blöink; Peter Brieger; Hagop S. Akiskal; Andreas Marneros
2005-01-01
Background: The purpose of the study was to evaluate the psychometric properties of the German version of the TEMPS-A questionnaire. Besides the reliability of the temperament scales, validity was the focus of interest. Therefore, the relationship between the TEMPS-A and the well-established personality questionnaire NEO-FFI, whose factors show theoretical overlap with temperaments, was investigated. Method: A total of 227 students
Robust Structural Equation Modeling with Missing Data and Auxiliary Variables
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Zhang, Zhiyong
2012-01-01
The paper develops a two-stage robust procedure for structural equation modeling (SEM) and an R package "rsem" to facilitate the use of the procedure by applied researchers. In the first stage, M-estimates of the saturated mean vector and covariance matrix of all variables are obtained. Those corresponding to the substantive variables are then…
A Structural Equation Model for Predicting Business Student Performance
ERIC Educational Resources Information Center
Pomykalski, James J.; Dion, Paul; Brock, James L.
2008-01-01
In this study, the authors developed a structural equation model that accounted for 79% of the variability of a student's final grade point average by using a sample size of 147 students. The model is based on student grades in 4 foundational business courses: introduction to business, macroeconomics, statistics, and using databases. Educators and…
Equivalent Structural Equation Models: A Challenge and Responsibility
ERIC Educational Resources Information Center
Raykov, Tenko; Marcoulides, George A.
2007-01-01
Relevant aspects of the example provided by Raykov and Marcoulides (2001) are emphasized, specifically the distinctiveness of infinitely many members of its sequence of equivalent structural equation models. This emphasis appears to be needed in light of recent statements by Markus (2002), whose intended counterexamples do not present a…
Gaussian Process Structural Equation Models with Latent Variables Ricardo Silva
Ghahramani, Zoubin
been well- studied, inference in nonparametric structural equation models is still underdeveloped. We efficiency. We compare the stabil- ity of the sampling procedure and the predictive ability of the model; density estimation; missing data imputa- tion; and causal inference (Pearl, 2000; Spirtes et al., 2000
Habitat fragmentation and reproductive success: a structural equation modelling approach
Helle, Samuli
patches is altered, leading to reduced mean patch size, increased isolation of habitat patchesHabitat fragmentation and reproductive success: a structural equation modelling approach Eric Le on the effects of habitat fragmentation, whereby habitat is lost and the spatial configuration of remaining
Implementing Restricted Maximum Likelihood Estimation in Structural Equation Models
ERIC Educational Resources Information Center
Cheung, Mike W.-L.
2013-01-01
Structural equation modeling (SEM) is now a generic modeling framework for many multivariate techniques applied in the social and behavioral sciences. Many statistical models can be considered either as special cases of SEM or as part of the latent variable modeling framework. One popular extension is the use of SEM to conduct linear mixed-effects…
Introduction to Structural Equation Modeling: Issues and Practical Considerations
ERIC Educational Resources Information Center
Lei, Pui-Wa; Wu, Qiong
2007-01-01
Structural equation modeling (SEM) is a versatile statistical modeling tool. Its estimation techniques, modeling capacities, and breadth of applications are expanding rapidly. This module introduces some common terminologies. General steps of SEM are discussed along with important considerations in each step. Simple examples are provided to…
The Use of Structural Equation Modeling in Counseling Psychology Research
ERIC Educational Resources Information Center
Martens, Matthew P.
2005-01-01
Structural equation modeling (SEM) has become increasingly popular for analyzing data in the social sciences, although several broad reviews of psychology journals suggest that many SEM researchers engage in questionable practices when using the technique. The purpose of this study is to review and critique the use of SEM in counseling psychology…
People Are Variables Too: Multilevel Structural Equations Modeling
ERIC Educational Resources Information Center
Mehta, Paras D.; Neale, Michael C.
2005-01-01
The article uses confirmatory factor analysis (CFA) as a template to explain didactically multilevel structural equation models (ML-SEM) and to demonstrate the equivalence of general mixed-effects models and ML-SEM. An intuitively appealing graphical representation of complex ML-SEMs is introduced that succinctly describes the underlying model and…
A Note on Structural Equation Modeling Estimates of Reliability
ERIC Educational Resources Information Center
Yang, Yanyun; Green, Samuel B.
2010-01-01
Reliability can be estimated using structural equation modeling (SEM). Two potential problems with this approach are that estimates may be unstable with small sample sizes and biased with misspecified models. A Monte Carlo study was conducted to investigate the quality of SEM estimates of reliability by themselves and relative to coefficient…
Hopes and Cautions in Implementing Bayesian Structural Equation Modeling
ERIC Educational Resources Information Center
MacCallum, Robert C.; Edwards, Michael C.; Cai, Li
2012-01-01
Muthen and Asparouhov (2012) have proposed and demonstrated an approach to model specification and estimation in structural equation modeling (SEM) using Bayesian methods. Their contribution builds on previous work in this area by (a) focusing on the translation of conventional SEM models into a Bayesian framework wherein parameters fixed at zero…
Structural Equations and Causal Explanations: Some Challenges for Causal SEM
ERIC Educational Resources Information Center
Markus, Keith A.
2010-01-01
One common application of structural equation modeling (SEM) involves expressing and empirically investigating causal explanations. Nonetheless, several aspects of causal explanation that have an impact on behavioral science methodology remain poorly understood. It remains unclear whether applications of SEM should attempt to provide complete…
Bayesian Data-Model Fit Assessment for Structural Equation Modeling
ERIC Educational Resources Information Center
Levy, Roy
2011-01-01
Bayesian approaches to modeling are receiving an increasing amount of attention in the areas of model construction and estimation in factor analysis, structural equation modeling (SEM), and related latent variable models. However, model diagnostics and model criticism remain relatively understudied aspects of Bayesian SEM. This article describes…
Sensitivity Analysis in Structural Equation Models: Cases and Their Influence
ERIC Educational Resources Information Center
Pek, Jolynn; MacCallum, Robert C.
2011-01-01
The detection of outliers and influential observations is routine practice in linear regression. Despite ongoing extensions and development of case diagnostics in structural equation models (SEM), their application has received limited attention and understanding in practice. The use of case diagnostics informs analysts of the uncertainty of model…
Mental Capacity and Role Taking: A Structural Equations Approach.
ERIC Educational Resources Information Center
Lapsley, Daniel K.; Quintana, Stephen M.
1989-01-01
Used a data analytic strategy that was novel to the M-space literature to examine the mental capacity prerequisites of social-cognitive development of 99 students in grades one, three, and five. Used a structural equations analysis to determine whether M-power was a significant predictor of role-taking development. (RH)
Sensitivity Analysis in Structural Equation Models: Cases and Their Influence
Jolynn Pek; Robert C. MacCallum
2011-01-01
The detection of outliers and influential observations is routine practice in linear regression. Despite ongoing extensions and development of case diagnostics in structural equation models (SEM), their application has received limited attention and understanding in practice. The use of case diagnostics informs analysts of the uncertainty of model estimates under different subsets of the data and highlights unusual and important
Structural Equation Modeling: Reviewing the Basics and Moving Forward
Jodie B. Ullman
2006-01-01
This tutorial begins with an overview of structural equation modeling (SEM) that includes the purpose and goals of the statistical analysis as well as terminology unique to this technique. I will focus on confirmatory factor analysis (CFA), a special type of SEM. After a general intro- duction, CFA is differentiated from exploratory factor analysis (EFA), and the advantages of CFA
Multiple Imputation Strategies for Multiple Group Structural Equation Models
Craig K. Enders; Amanda C. Gottschall
2011-01-01
Although structural equation modeling software packages use maximum likelihood estimation by default, there are situations where one might prefer to use multiple imputation to handle missing data rather than maximum likelihood estimation (e.g., when incorporating auxiliary variables). The selection of variables is one of the nuances associated with implementing multiple imputation, because the imputer must take special care to preserve
Activity-Travel Behavior Analysis Based on Structural Equation Model
Wu Wenjing; Juan Zhicai
2009-01-01
Traveler' process of decision-making is very complicated, which influenced by many factors. Based on the analysis of activity based travel demand theory, the path diagram is given, which describes the decision processes of travelers. Analysis the influence factors from the aspects of socio-demographics, activities participation and travel behaviors, the endogenous and exogenous variables of model are defined and structural equation
Equations for Mix Design of Structural Lightweight Concrete
M. Abdullahi; B. S. Mohammed
Equations for mix design of structural lightweight concrete are presented. Conventionally, mix design of concrete is conducted using the tabular data and charts in standards. This requires extra efforts of understanding the data in the code and interpolations are often required when intermediate values are needed. The process is also liable to human error as data may be erroneously taken
Modeling the informal economy in Mexico. a structural equation approach
Guido Cazzavillan
2010-01-01
This paper uses annual data for the period 1970-2006 in order to estimate and investigate the evolution of the Mexican informal economy. In order to do so, we model the informal economy as a latent variable and try to explain it through relationships between possible cause and indicator variables using structural equation modeling (SEM). The model uses tax burden, salary
Modeling the Informal Economy in Mexico. A Structural Equation Approach
Brambila Macias; Jose Ca
2008-01-01
This paper uses annual data for the period 1970-2006 in order to estimate and investigate the evolution of the Mexican informal economy. In order to do so, we model the informal economy as a latent variable and try to explain it through relationships between possible cause and indicator variables using structural equation modeling (SEM). Our results indicate that the Mexican
Modelling the Informal Economy in Mexico. A Structural Equation Approach
José Brambila Macias; Guido Cazzavillan
2008-01-01
This paper uses annual data for the period 1970-2006 in order to estimate and investigate the evolution of the Mexican informal economy. In order to do so, we model the informal economy as a latent variable and try to explain it through relationships between possible cause and indicator variables using structural equation modeling (SEM). The model uses tax burden, salary
Modeling the informal economy in Mexico. a structural equation approach
Guido Cazzavillan
2010-01-01
:This paper uses annual data for the period 1970-2006 in order to estimate and investigate the evolution of the Mexican informal economy. In order to do so, we model the informal economy as a latent variable and try to explain it through relationships between possible cause and indicator variables using structural equation modeling (SEM). The model uses tax burden, salary
Evaluating Interventions with Multimethod Data: A Structural Equation Modeling Approach
ERIC Educational Resources Information Center
Crayen, Claudia; Geiser, Christian; Scheithauer, Herbert; Eid, Michael
2011-01-01
In many intervention and evaluation studies, outcome variables are assessed using a multimethod approach comparing multiple groups over time. In this article, we show how evaluation data obtained from a complex multitrait-multimethod-multioccasion-multigroup design can be analyzed with structural equation models. In particular, we show how the…
Asymptotic Biases in Exploratory Factor Analysis and Structural Equation Modeling
ERIC Educational Resources Information Center
Ogasawara, Haruhiko
2004-01-01
Formulas for the asymptotic biases of the parameter estimates in structural equation models are provided in the case of the Wishart maximum likelihood estimation for normally and nonnormally distributed variables. When multivariate normality is satisfied, considerable simplification is obtained for the models of unstandardized variables. Formulas…
Structural equations for Killing tensors of arbitrary rank* Thomas Wolf
Wolf, Thomas
Structural equations for Killing tensors of arbitrary rankABFB. The FA are the components of a Killing tensor Ki1...irof arbitrary rank r * *and its symmetrized numerically the number of non-trivial Killing tensors using n* *umerical values for the Riemann tensor
Multi-Hamiltonian structure of Plebanski's second heavenly equation
F. Neyzi; Y. Nutku; M. B. Sheftel
2005-07-14
We show that Plebanski's second heavenly equation, when written as a first-order nonlinear evolutionary system, admits multi-Hamiltonian structure. Therefore by Magri's theorem it is a completely integrable system. Thus it is an example of a completely integrable system in four dimensions.
Multi-Hamiltonian structure of Plebanski's second heavenly equation
F. Neyzi; Y. Nutku; M. B. Sheftel
2005-01-01
We show that Plebanski's second heavenly equation, when written as a first-order nonlinear evolutionary system, admits multi-Hamiltonian structure. Therefore by Magri's theorem it is a completely integrable system. Thus it is an example of a completely integrable system in four dimensions.
Multiple Imputation Strategies for Multiple Group Structural Equation Models
ERIC Educational Resources Information Center
Enders, Craig K.; Gottschall, Amanda C.
2011-01-01
Although structural equation modeling software packages use maximum likelihood estimation by default, there are situations where one might prefer to use multiple imputation to handle missing data rather than maximum likelihood estimation (e.g., when incorporating auxiliary variables). The selection of variables is one of the nuances associated…
Signal processing in the cochlea: The structure equations
2011-01-01
Background Physical and physiological invariance laws, in particular time invariance and local symmetry, are at the outset of an abstract model. Harmonic analysis and Lie theory are the mathematical prerequisites for its deduction. Results The main result is a linear system of partial differential equations (referred to as the structure equations) that describe the result of signal processing in the cochlea. It is formulated for phase and for the logarithm of the amplitude. The changes of these quantities are the essential physiological observables in the description of signal processing in the auditory pathway. Conclusions The structure equations display in a quantitative way the subtle balance for processing information on the basis of phase versus amplitude. From a mathematical point of view, the linear system of equations is classified as an inhomogeneous - equation. In suitable variables the solutions can be represented as the superposition of a particular solution (determined by the system) and a holomorphic function (determined by the incoming signal). In this way, a global picture of signal processing in the cochlea emerges. PMID:22656650
Peculiar symmetry structure of some known discrete nonautonomous equations
NASA Astrophysics Data System (ADS)
Garifullin, R. N.; Habibullin, I. T.; Yamilov, R. I.
2015-06-01
We study the generalized symmetry structure of three known discrete nonautonomous equations. One of them is the semidiscrete dressing chain of Shabat. Two others are completely discrete equations defined on the square lattice. The first one is a discrete analogue of the dressing chain introduced by Levi and Yamilov. The second one is a nonautonomous generalization of the potential discrete KdV equation or, in other words, the H1 equation of the well-known Adler?Bobenko?Suris list. We demonstrate that these equations have generalized symmetries in both directions if and only if their coefficients, depending on the discrete variables, are periodic. The order of the simplest generalized symmetry in at least one direction depends on the period and may be arbitrarily high. We substantiate this picture by some theorems in the case of small periods. In case of an arbitrarily large period, we show that it is possible to construct two hierarchies of generalized symmetries and conservation laws. The same picture should take place in case of any nonautonomous equation of the Adler?Bobenko?Suris list.
A simplified structure for the second order cosmological perturbation equations
NASA Astrophysics Data System (ADS)
Uggla, Claes; Wainwright, John
2013-03-01
Increasingly accurate observations of the cosmic microwave background and the large scale distribution of galaxies necessitate the study of nonlinear perturbations of Friedmann-Lemaitre cosmologies, whose equations are notoriously complicated. In this paper we present a new derivation of the governing equations for second order perturbations within the framework of the metric-based approach that is minimal, as regards amount of calculation and length of expressions, and flexible, as regards choice of gauge and stress-energy tensor. Because of their generality and the simplicity of their structure our equations provide a convenient starting point for determining the behaviour of nonlinear perturbations of FL cosmologies with any given stress-energy content, using either the Poisson gauge or the uniform curvature gauge.
Multidisciplinary optimization of controlled space structures with global sensitivity equations
NASA Technical Reports Server (NTRS)
Padula, Sharon L.; James, Benjamin B.; Graves, Philip C.; Woodard, Stanley E.
1991-01-01
A new method for the preliminary design of controlled space structures is presented. The method coordinates standard finite element structural analysis, multivariable controls, and nonlinear programming codes and allows simultaneous optimization of the structures and control systems of a spacecraft. Global sensitivity equations are a key feature of this method. The preliminary design of a generic geostationary platform is used to demonstrate the multidisciplinary optimization method. Fifteen design variables are used to optimize truss member sizes and feedback gain values. The goal is to reduce the total mass of the structure and the vibration control system while satisfying constraints on vibration decay rate. Incorporating the nonnegligible mass of actuators causes an essential coupling between structural design variables and control design variables. The solution of the demonstration problem is an important step toward a comprehensive preliminary design capability for structures and control systems. Use of global sensitivity equations helps solve optimization problems that have a large number of design variables and a high degree of coupling between disciplines.
Covariant symplectic structure of the complex Monge-Ampère equation
Y. Nutku
2000-04-24
The complex Monge-Amp\\`ere equation admits covariant bi-symplectic structure for complex dimension 3, or higher. The first symplectic 2-form is obtained from a new variational formulation of complex Monge- Amp\\`ere equation in the framework of the covariant Witten-Zuckerman approach to symplectic structure. We base our considerations on a reformulation of the Witten-Zuckerman theory in terms of holomorphic differential forms. The first closed and conserved Witten-Zuckerman symplectic 2-form for the complex Monge-Amp\\`ere equation is obtained in arbitrary dimension and for all cases elliptic, hyperbolic and homogeneous. The connection of the complex Monge-Amp\\`ere equation with Ricci-flat K\\"ahler geometry suggests the use of the Hilbert action. However, we point out that Hilbert's Lagrangian is a divergence for K\\"ahler metrics. Nevertheless, using the surface terms in the Hilbert Lagrangian we obtain the second Witten-Zuckerman symplectic 2-form for complex dimension>2.
2014-01-01
Background Early feeding practices lay the foundation for children’s eating habits and weight gain. Questionnaires are available to assess parental feeding but overlapping and inconsistent items, subscales and terminology limit conceptual clarity and between study comparisons. Our aim was to consolidate a range of existing items into a parsimonious and conceptually robust questionnaire for assessing feeding practices with very young children (<3 years). Methods Data were from 462 mothers and children (age 21–27 months) from the NOURISH trial. Items from five questionnaires and two study-specific items were submitted to a priori item selection, allocation and verification, before theoretically-derived factors were tested using Confirmatory Factor Analysis. Construct validity of the new factors was examined by correlating these with child eating behaviours and weight. Results Following expert review 10 factors were specified. Of these, 9 factors (40 items) showed acceptable model fit and internal reliability (Cronbach’s ?: 0.61-0.89). Four factors reflected non-responsive feeding practices: ‘Distrust in Appetite’, ‘Reward for Behaviour’, ‘Reward for Eating’, and ‘Persuasive Feeding’. Five factors reflected structure of the meal environment and limits: ‘Structured Meal Setting’, ‘Structured Meal Timing’, ‘Family Meal Setting’, ‘Overt Restriction’ and ‘Covert Restriction’. Feeding practices generally showed the expected pattern of associations with child eating behaviours but none with weight. Conclusion The Feeding Practices and Structure Questionnaire (FPSQ) provides a new reliable and valid measure of parental feeding practices, specifically maternal responsiveness to children’s hunger/satiety signals facilitated by routine and structure in feeding. Further validation in more diverse samples is required. PMID:24898364
ERIC Educational Resources Information Center
Ausderau, Karla; Sideris, John; Furlong, Melissa; Little, Lauren M.; Bulluck, John; Baranek, Grace T.
2014-01-01
This national online survey study characterized sensory features in 1,307 children with autism spectrum disorder (ASD) ages 2-12 years using the Sensory Experiences Questionnaire Version 3.0 (SEQ-3.0). Using the SEQ-3.0, a confirmatory factor analytic model with four substantive factors of hypothesized sensory response patterns (i.e.,…
ERIC Educational Resources Information Center
Ottmar, Erin R.; Konold, Timothy R.; Berry, Robert Q.; Grissmer, David W.; Cameron, Claire E.
2014-01-01
Psychometric properties of 24 items from the fifth grade Early Childhood Longitudinal Study-Kindergarten Cohort Mathematics Teacher Questionnaire were investigated in a sample of 5,181 participants. These items asked teachers to report how often they had their classroom students engage in different mathematics content, skills and instructional…
ERIC Educational Resources Information Center
Forde, David R.; Baron, Stephen W.; Scher, Christine D.; Stein, Murray B.
2012-01-01
This study examines the psychometric properties of the Childhood Trauma Questionnaire short form (CTQ-SF) with street youth who have run away or been expelled from their homes (N = 397). Internal reliability coefficients for the five clinical scales ranged from 0.65 to 0.95. Confirmatory Factor Analysis (CFA) was used to test the five-factor…
A guide to multiple-sample structural equation modeling
Richard G. Lomax
1983-01-01
The application of structural equation modeling to the investigation of social phenomena has increased in recent years. Whereas\\u000a description and application of the LISREL methodology to the single-sample situation abound, such is not the case for the\\u000a multiple-sample situation (i.e., simultaneous analysis of independent samples). The multiple-sample case has many possible\\u000a applications in psychology (e.g., the analysis of experimental, nonezperimental,
Extended Navier–Stokes equations, ultrasonic absorption and shock structure
NASA Astrophysics Data System (ADS)
Emanuel, G.
2015-01-01
The Navier-Stokes (N-S) equations for a steady or unsteady, compressible, continuum flow are modified. The extension is based on a Stokesian fluid with a single nonlinear term in an isotropic stress, rate-of-deformation relation. This is the simplest possible nonlinear extension that also satisfies the second law of thermodynamics. The transport coefficient of this term is referred to as the third viscosity coefficient. In the extended version, the momentum and energy equations each contain a nonlinear term that is proportional to this new coefficient. These terms are significant only when the velocity gradient is extremely large. They are inconsequential, e.g., in a laminar boundary layer. Nevertheless, there are flows where the extended version of the N-S equations is relevant. The first of these is an ultrasonic, unsteady, one-dimensional flow, which is used for evaluating the bulk viscosity. In this case, the linearized N-S equations become singular as the ultrasonic frequency increases toward infinity. When the frequency is sufficiently large, nonlinear terms in the extended N-S equations need to be retained. The terms that are proportional to the third viscosity coefficient increase in importance, relative to linear terms, as the fourth power of the frequency. A second example is shock wave structure. A model is established and numerically solved for the normalized density derivative. Results are compared with corresponding measurements for argon when the upstream Mach number is 1.058 and 1.23. Good agreement between the extended N-S predictions and measurements is obtained for both Mach numbers with a single, but extremely small, value for the third viscosity coefficient. An important difference between conventional and extended N-S shock structure solutions is that the extended-model solution depends on the upstream pressure, whereas the conventional solution does not.
Olivier Luminet; Cecile Leroy; Emmanuel Roy
2007-01-01
In this research, we investigated the psychometrical properties of the Trait Emotional Intelligence Questionnaire (TEIQue, Petrides & Furnham, 2003) in a French-speaking population. In summary, we found that (a) TEIQue scores were globally normally distributed and reliable; (b) the United Kingdom four-factor structure (well-being, self-control, emotionality, sociability) replicated in our data; (c) TEIQue scores were dependent on gender but relatively
Structure and Calibration of Constitutive Equations for Granular Soils
NASA Astrophysics Data System (ADS)
Sawicki, Andrzej; S?awi?ska, Justyna; Mierczy?ski, Jacek
2015-02-01
The form of incremental constitutive equations for granular soils is discussed for the triaxial configuration. The classical elasto-plastic approach and the semi-empirical model are discussed on the basis of constitutive relations determined directly from experimental data. First, the general structure of elasto-plastic constitutive equations is presented. Then, the structure of semiempirical constitutive equations is described, and a method of calibrating the model is presented. This calibration method is based on a single experiment, performed in the triaxial apparatus, which also involves a partial verification of the model, on an atypical stress path. The model is shown to give reasonable predictions. An important feature of the semi-empirical incremental model is the definition of loading and unloading, which is different from that assumed in elasto-plasticity. This definition distinguishes between spherical and deviatoric loading/unloading. The definition of deviatoric loading/unloading has been subject to some criticism. It was therefore discussed and clarified in this paper on the basis of the experiment presented.
NASA Astrophysics Data System (ADS)
Papanikolaou, Dimitrios; Papanikolaou, Ioannis; Diakakis, Michalis; Deligiannakis, Georgios
2013-04-01
In the face of a growing number of natural disasters and the increasing costs associated with them, Europe and Greece in particular, have devoted significant efforts and resources in natural hazards mitigation during the last decades. Despite the significant legislative efforts (e.g. 1998/22/EC, 2001/792/EC, 2007/60/EC Directives, 3013/2002 Act) and even though a number of steps has been taken towards improving civil protection, recent catastrophic events have illustrated the weaknesses of current approaches. In particular, in Greece, events such as the 1999 Athens earthquake, the 2007 and 2009 wildfires have shown the inadequacy of prevention and mitigation practices. Given the enhanced civil protection responsibilities, given by the Greek national law (Acts 3013/2002, 3852/2010) to local authorities in Greece, this work analyses and evaluates the existing structure and current management framework under which local authorities function and examines their risk mitigation practices. We conducted the largest questionnaire survey regarding Civil Protections issues, among the municipalities of Greece. To this aim, this work used a innovative online tool to assess current framework. Therefore, a network connecting civil protection departments of municipalities was developed, based on an Internet platform that acted also as a communication tool. Overall, we had feedback either online or offline from 125 municipalities across the country (representing more than one/third of the total municipalities of Greece). Through this network, municipal civil protection officials completed surveys designed to obtain and quantify information on several aspects of civil protection practices and infrastructure. In particular, the examined factors included: (i) personnel and equipment, (ii) inter-agency cooperation, (iii) training, (iv) compliance with existing regulations and (v) persistent problems encountered by civil protection departments, that prevent the effectiveness of current practices. Responses showed that civil protection personnel lack adequate training and expertise, many are overstretched with several duties, while several prevention actions are carried out by seasonal or voluntary staff. Approximately half of the heads of civil protection offices do not hold a university degree, only 27% have a relevant scientific background (geoscientists or engineers) and more than half of them are elected members and not permanent staff, implying that no continuity is secured. Inter-agency cooperation is shown to be poor and organizational learning from international practices not adequate. Half of the municipalities report that the authorization processes are too slow so that prevention actions particularly regarding forest fires are severely delayed. Existing regulations are not followed by a significant portion of municipalities since 19% have not established a civil protection office and 23% have not compiled an action plan yet. Existing action plans lack important information, present no spatial data and are predominantly catalogues and tables of information regarding authorised personnel and equipment. Overall, underfunding, poor coordination of the different actors involved, lack of training and understaffing, lack of proper equipment and several other issues are held responsible by officials for preventing effectiveness of current practices. Finally, the EU emergency number 112 is widely unknown (87%). This work was held under the LIFE+ project "Local Authorities Alliance for Forest Fire Prevention - LIFE08/ENV/GR/000553" which is implemented with the contribution of the LIFE financial instrument of the European Community.
Structure of the field equations in N = 1 chiral supergravity
M. Tsuda; T. Shirafuji
1996-10-16
We study the structure of linearized field equations in $N = 1$ chiral supergravity (SUGRA) with a complex tetrad, as a preliminary to introducing additional auxiliary fields in order that the supersymmetry (SUSY) algebra close off shell. We follow the first-order formulation we have recently constructed using the method of the usual $N = 1$ SUGRA. In particular, we see how the real and imaginary parts of the complex tetrad are coupled to matter fields in the weak field approximation. Starting from the linearized (free) theory of $N = 1$ chiral SUGRA, we then construct a Lagrangian which is invariant under local SUSY transformations to zeroth order of the gravitational constant, and compare the results with the linearized field equations.
ERIC Educational Resources Information Center
Okech, David
2012-01-01
Objectives: Using baseline and second wave data, the study evaluated the measurement and structural properties of parenting stress, personal mastery, and economic strain with N = 381 lower income parents who decided to join and those who did not join in a child development savings account program. Methods: Structural equation modeling mean and…
Valla, J P; Bergeron, L; Bérubé, H; Gaudet, N; St-Georges, M
1994-08-01
This paper presents a structured pictorial instrument, the Dominic questionnaire, to assess mental disorders in 6- to 11-year-old children. Ninety-nine drawings represent situations corresponding to DSM-III-R based ADHD, CD, ODD, MDD, SAD, OAD, and SPh. However, cognitive limitation of 6- to 11-year-old children do not allow for time-related measurement. The instrument takes 15-20 min to administer. Reliability and validity of the Dominic questionnaire were studied in Parent DISC-2 positive and negative outpatient and general population samples and against clinical judgement. The pictorial approach provides acceptable test-retest reliability and the instrument makes standardized assessment possible for children as young as 6 years of age. PMID:7963075
Anisotropic stellar structure equations for magnetized strange stars
NASA Astrophysics Data System (ADS)
Manreza Paret, Daryel; Horvath, Jorge Ernesto; Pérez Martínez, Aurora
2015-07-01
The fact that a fermion system in an external magnetic field breaks the spherical symmetry suggests that its intrinsic geometry is axisymmetric rather than spherical. In this work we analyze the impact of anisotropic pressures, due to the presence of a magnetic field, in the structure equations of a magnetized quark star. We assume a cylindrical metric and an anisotropic energy momentum tensor for the source. We found that there is a maximum magnetic field that a strange star can sustain, closely related to the violation of the virial relations.
Samuel, Steven; Akhtar, Salman
2009-03-01
This paper describes the author's effort to develop a self-rating scale to measure the consolidation of identity in a given individual. It describes the construction of the 35-item Identity Consolidation Inventory (ICI) and, as an appendix to the paper, includes the final version of this questionnaire. The scale's reliability and validity are demonstrated via its administration to 238 normal controls, 80 individuals with Borderline Personality Disorder and 13 subjects with Dissociative Identity Disorder ("multiple personality"). The clinical and research usefulness of ICI lies in the realm of discerning the syndrome of identity diffusion that underlies all severe personality disorders. PMID:19295621
Michigan Questionnaire Documentation System (MQDS)
Cheung, Gina-Qian
2013-04-03
Michigan Questionnaire Documentation System (MQDS) Gina Cheung University of Michigan, Survey Research Center North American DDI Conference April 2-3, 2013 Agenda MQDS Background MQDS current design Demo Survey Lifecycle http... questionnaire roster structure Blaise alien router (external program) Paradata Not a tool for Survey life circle documentation yet…. Where we are going… and DDI for… Mixed Mode Project Management CATI CAPI WEB MAIL Decentralized CATI Mixed Mode Survey...
NASA Astrophysics Data System (ADS)
Jamaluddin, Z.; Razali, A. M.; Mustafa, Z.
2015-02-01
The purpose of this paper is to examine the relationship between the quality management practices (QMPs) and organisational performance for the manufacturing industry in Malaysia. In this study, a QMPs and organisational performance framework is developed according to a comprehensive literature review which cover aspects of hard and soft quality factors in manufacturing process environment. A total of 11 hypotheses have been put forward to test the relationship amongst the six constructs, which are management commitment, training, process management, quality tools, continuous improvement and organisational performance. The model is analysed using Structural Equation Modeling (SEM) with AMOS software version 18.0 using Maximum Likelihood (ML) estimation. A total of 480 questionnaires were distributed, and 210 questionnaires were valid for analysis. The results of the modeling analysis using ML estimation indicate that the fits statistics of QMPs and organisational performance model for manufacturing industry is admissible. From the results, it found that the management commitment have significant impact on the training and process management. Similarly, the training had significant effect to the quality tools, process management and continuous improvement. Furthermore, the quality tools have significant influence on the process management and continuous improvement. Likewise, the process management also has a significant impact to the continuous improvement. In addition the continuous improvement has significant influence the organisational performance. However, the results of the study also found that there is no significant relationship between management commitment and quality tools, and between the management commitment and continuous improvement. The results of the study can be used by managers to prioritize the implementation of QMPs. For instances, those practices that are found to have positive impact on organisational performance can be recommended to managers so that they can allocate resources to improve these practices to get better performance.
Review of Ballistic Limit Equations for Composite Structure Walls of Satellites
Frank K. Schaefer; E. Schneider; M. Lambert
2004-01-01
In this paper a review of existing ballistic limit equations for CFRP (Carbon Fibre Reinforced Plastics) structure walls of satellites is given, and two new ballistic limit equations are presented. The predictive capabilities of the equations are compared to a set of experimental hypervelocity impact test data of CFRP plates and CFRP honeycomb sandwich panels (satellite structure wall) from ENVISAT,
A Liouville theorem for vector valued semilinear heat equations with no gradient structure and
Paris-Sud XI, UniversitÃ© de
A Liouville theorem for vector valued semilinear heat equations with no gradient structure valued semilinear heat equation with no gradient structure. Classical tools such as the maximum principle05, 35K55, 74H35. Keywords: Blow-up, Liouville theorem, uniform estimates, heat equation, vector
Kamel Jedidi; Harsharanjeet S. Jagpal; Wayne S. DeSarbo
1997-01-01
Two endemic problems face researchers in the social sciences (e.g., Marketing, Economics, Psychology, and Finance): unobserved heterogeneity and measurement error in data. Structural equation modeling is a powerful tool for dealing with these difficulties using a simultaneous equation framework with unobserved constructs and manifest indicators which are error-prone. When estimating structural equation models, however, researchers frequently treat the data as
The algebraic structure behind the derivative nonlinear Schroedinger equation
G. S. Franca; J. F. Gomes; A. H. Zimerman
2013-08-01
The Kaup-Newell (KN) hierarchy contains the derivative nonlinear Schr\\" odinger equation (DNLSE) amongst others interesting and important nonlinear integrable equations. In this paper, a general higher grading affine algebraic construction of integrable hierarchies is proposed and the KN hierarchy is established in terms of a $\\hat{s\\ell}_2$ Kac-Moody algebra and principal gradation. In this form, our spectral problem is linear in the spectral parameter. The positive and negative flows are derived, showing that some interesting physical models arise from the same algebraic structure. For instance, the DNLSE is obtained as the second positive, while the Mikhailov model as the first negative flows, respectively. The equivalence between the latter and the massive Thirring model is explicitly demonstrated also. The algebraic dressing method is employed to construct soliton solutions in a systematic manner for all members of the hierarchy. Finally, the equivalence of the spectral problem introduced in this paper with the usual one, which is quadratic in the spectral parameter, is achieved by setting a particular automorphism of the affine algebra, which maps the homogeneous into principal gradation.
Structural equation models of VMT growth in US urbanised areas.
Ewing, Reid; Hamidi, Shima; Gallivan, Frank; Nelson, Arthur C.; Grace, James B.
2014-01-01
Vehicle miles travelled (VMT) is a primary performance indicator for land use and transportation, bringing with it both positive and negative externalities. This study updates and refines previous work on VMT in urbanised areas, using recent data, additional metrics and structural equation modelling (SEM). In a cross-sectional model for 2010, population, income and freeway capacity are positively related to VMT, while gasoline prices, development density and transit service levels are negatively related. Findings of the cross-sectional model are generally confirmed in a more tightly controlled longitudinal study of changes in VMT between 2000 and 2010, the first model of its kind. The cross-sectional and longitudinal models together, plus the transportation literature generally, give us a basis for generalising across studies to arrive at elasticity values of VMT with respect to different urban variables.
Structural equation modeling: building and evaluating causal models: Chapter 8
Grace, James B.; Scheiner, Samuel M.; Schoolmaster, Donald R., Jr.
2015-01-01
Scientists frequently wish to study hypotheses about causal relationships, rather than just statistical associations. This chapter addresses the question of how scientists might approach this ambitious task. Here we describe structural equation modeling (SEM), a general modeling framework for the study of causal hypotheses. Our goals are to (a) concisely describe the methodology, (b) illustrate its utility for investigating ecological systems, and (c) provide guidance for its application. Throughout our presentation, we rely on a study of the effects of human activities on wetland ecosystems to make our description of methodology more tangible. We begin by presenting the fundamental principles of SEM, including both its distinguishing characteristics and the requirements for modeling hypotheses about causal networks. We then illustrate SEM procedures and offer guidelines for conducting SEM analyses. Our focus in this presentation is on basic modeling objectives and core techniques. Pointers to additional modeling options are also given.
Marketing: The Applicant Questionnaire
ERIC Educational Resources Information Center
Huddleston, Thomas, Jr.
1976-01-01
The construction of a market research questionnaire is recommended as one way a college can identify its applicant pool market. Included are an outline of information the applicant pool questionnaire might seek and basic criteria of question writing. (JT)
Equation of State of Structured Matter at Finite Temperature
NASA Astrophysics Data System (ADS)
Maruyama, T.; Yasutake, N.; Tatsumi, T.
We investigate the properties of nuclear matter at the first-order phase transitions such as liquid-gas phase transition and hadron-quark phase transition. As a general feature of the first-order phase transitions of matter consisting of many species of charged particles, there appears a mixed phases with geometrical structures called ``pasta'' due to the balance of the Coulomb repulsion and the surface tension between two phases [G.~D.~Ravenhall, C.~J.~Pethick and J.~R.~Wilson, Phys. Rev. Lett. 50 (1983), 2066. M.~Hashimoto, H.~Seki and M.~Yamada, Prog. Theor. Phys. 71 (1984), 320.] The equation of state (EOS) of mixed phase is different from the one obtained by a bulk application of the Gibbs conditions or by the Maxwell construction due to the effects of the non-uniform structure. We show that the charge screening and strong surface tension make the EOS close to that of the Maxwell construction. The thermal effects are elucidated as well as the above finite-size effects.
Executive functions, impulsivity, and inhibitory control in adolescents: A structural equation model
Fino, Emanuele; Melogno, Sergio; Iliceto, Paolo; D’Aliesio, Sara; Pinto, Maria Antonietta; Candilera, Gabriella; Sabatello, Ugo
2014-01-01
Background. Adolescence represents a critical period for brain development, addressed by neurodevelopmental models to frontal, subcortical-limbic, and striatal activation, a pattern associated with rise of impulsivity and deficits in inhibitory control. The present study aimed at studying the association between self-report measures of impulsivity and inhibitory control with executive function in adolescents, employing structural equation modeling. Method. Tests were administered to 434 high school students. Acting without thinking was measured through the Barratt Impulsiveness Scale and the Dickman Impulsivity Inventory, reward sensitivity through the Behavioral Activation System, and sensation seeking through the Zuckerman–Kuhlman–Aluja Personali- ty Questionnaire. Inhibitory control was assessed through the Behavioral Inhibition System. The performance at the Wisconsin Card Sorting Task indicated executive function. Three models were specified using Sample Covariance Matrix, and the estimated parameters using Maximum Likelihood. Results. In the final model, impulsivity and inhibitory control predicted executive function, but sensation seeking did not. The fit of the model to data was excellent. Conclusions. The hypothesis that inhibitory control and impulsivity are predictors of executive function was supported. Our results appear informative of the validity of self-report measures to examine the relation between impulsivity traits rather than others to regulatory function of cognition and behavior. PMID:25157298
Vilhena, Estela; Pais-Ribeiro, José; Silva, Isabel; Cardoso, Helena; Mendonça, Denisa
2014-01-01
Living with obesity is an experience that may affect multiple aspects of an individual's life. Obesity is considered a relevant public health problem in modern societies. To determine the comparative efficacy of different treatments and to assess their impact on patients' everyday life, it is important to identify factors that are relevant to the quality of life of obese patients. The present study aims to evaluate, in Portuguese obese patients, the simultaneous impact of several psychosocial factors on quality of life. This study also explores the mediating role of stigma in the relationship between positive/negative affect and quality of life. A sample of 215 obese patients selected from the main hospitals in Portugal completed self-report questionnaires to assess sociodemographic, clinical, psychosocial, and quality of life variables. Data were analysed using structural equation modeling. The model fitted the data reasonably well, CFI = 0.9, RMSEA = 0.06. More enthusiastic and more active patients had a better quality of life. Those who reflect lower perception of stigma had a better physical and mental health. Partial mediation effects of stigma between positive affect and mental health and between negative affect and physical health were found. The stigma is pervasive and causes consequences for psychological and physical health. PMID:24693421
NASA Astrophysics Data System (ADS)
Ab Hamid, Mohd Rashid; Mustafa, Zainol; Mohd Suradi, Nur Riza; Idris, Fazli; Abdullah, Mokhtar
2013-04-01
Culture and employee-focused criteria are important factors for the success of any organization. These factors have to be aligned with the productivity initiatives in the organization in order to gear ahead for excellence. Therefore, this article investigated the impact of culture and employee-focused criteria on productivity in Higher Education Institutions (HEIs) in Malaysia using intangible indicators through core values. The hypothesized relationship was tested using Structural Equation Modeling (SEM) with the PLS estimation technique. 429 questionnaires were returned from the target population. The results of the modelling revealed that the PLS estimation confirmed all the hypotheses tested as in the hypothesized model. The results generally support significant relationships between culture values, employee-focused values and productivity-focused values. The study also confirmed the mediating role of employee-focused values for the relationship between culture values and productivity-focused values. In conclusion, the empirically validated results supported the adequacy of the hypothezised model of the impact of culture and employee-focused criteria on productivity in HEI through value-based indicators.
Carretero Domínguez, Noelia; Gil-Monte, Pedro Rafael; Luciano Devis, Juan Vicente
2011-11-01
Most studies focusing on the antecedents and consequences of workplace bullying have used a cross-sectional design, which impedes determining the causality of the relationships. In the present work, we analyzed, by means of structural equation models, the relationship between workplace bullying and some variables that are considered antecedents (interpersonal conflicts, role ambiguity, role conflict, and workplace social support) or consequences (health complaints and inclination to absenteeism from work) of this phenomenon. Multicenter study with two phases. The sample consisted of 696 employees from 66 centers. Workplace bullying was assessed by means of the "Mobbing-UNIPSICO" questionnaire, and the other variables with frequency scales. The cross-sectional models indicated a significant association between role conflict, workplace social support, and workplace bullying in both study periods. Concerning the longitudinal relationships, only workplace social support was a significant predictor of workplace bullying, which, in turn, was a cross-sectional and longitudinal predictor of workers' health complaints. Our results show the mediating effect of workplace bullying between certain work conditions and health complaints, and it is recommendable to replicate these findings in a multi-occupational sample. PMID:22047848
Graphical Methods for Identi cation in Structural Equation Models
California at Los Angeles, University of
.2 Graph Background . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.3 Wright's Method of Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.3 A causal diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.4 Wright's equations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.1 Wright's equations
Dawn Iacobucci
2009-01-01
This article is intended to serve as a primer for structural equations models for the behavioral researcher. The technique is not mysterious—it is a natural extension of factor analysis and regression. The measurement part of a structural equations model is essentially a confirmatory factor analysis, and the structural part of the model is like a regression but vastly more flexible
Xin-Yuan Song; Sik-Yum Lee
2008-01-01
Structural equation models are widely appreciated in behavioral, social, and psychological research to model relations between latent constructs and manifest variables, and to control for measurement errors. Most applications of structural equation models are based on fully observed data that are independently distributed. However, hierarchical data with a correlated structure are common in behavioral research, and very often, missing data
Applications of Multilevel Structural Equation Modeling to Cross-Cultural Research
Mike W.-L. Cheung; Kevin Au
2005-01-01
Multilevel structural equation modeling (MSEM) has been proposed as an extension to structural equation modeling for analyzing data with nested structure. We have be- gun to see a few applications in cross-cultural research in which MSEM fits well as the statistical model. However, given that cross-cultural studies can only afford col- lecting data from a relatively small number of countries,
Estimation of structural equation models with exact and stochastic prior information
Sik-Yum Lee
1988-01-01
Recently, structural equation models are widely used in assessing data in economical and behavioral researches. To give more freedom in defining the structures of the model and obtain more precise and meaningful interpretations to the data, prior informations about the unknown parameters are usually incorporated in the analysis. In this article, basic estimation theory of structural equation models with both
Measuring Metacognition in Cancer: Validation of the Metacognitions Questionnaire 30 (MCQ-30)
Cook, Sharon A.; Salmon, Peter; Dunn, Graham; Fisher, Peter
2014-01-01
Objective The Metacognitions Questionnaire 30 assesses metacognitive beliefs and processes which are central to the metacognitive model of emotional disorder. As recent studies have begun to explore the utility of this model for understanding emotional distress after cancer diagnosis, it is important also to assess the validity of the Metacognitions Questionnaire 30 for use in cancer populations. Methods 229 patients with primary breast or prostate cancer completed the Metacognitions Questionnaire 30 and the Hospital Anxiety and Depression Scale pre-treatment and again 12 months later. The structure and validity of the Metacognitions Questionnaire 30 were assessed using factor analyses and structural equation modelling. Results Confirmatory and exploratory factor analyses provided evidence supporting the validity of the previously published 5-factor structure of the Metacognitions Questionnaire 30. Specifically, both pre-treatment and 12 months later, this solution provided the best fit to the data and all items loaded on their expected factors. Structural equation modelling indicated that two dimensions of metacognition (positive and negative beliefs about worry) were significantly associated with anxiety and depression as predicted, providing further evidence of validity. Conclusions These findings provide initial evidence that the Metacognitions Questionnaire 30 is a valid measure for use in cancer populations. PMID:25215527
ERIC Educational Resources Information Center
Smith, Dennis W.; Lee, Jay T.; Colwell, Brian; Stevens-Manser, Stacey
2008-01-01
In response to the problem of adolescent smoking and limited appropriate cessation resources, this study examined the pattern and structure of the American Lung Association, Why Do You Smoke? (WDS) to determine its appropriateness for use in youth smoking cessation programs. The WDS is used to help smokers identify primary motivations for using…
Structural Equation Modeling for Analyzing Erythrocyte Fatty Acids in Framingham
Pottala, James V.; Djira, Gemechis D.; Espeland, Mark A.; Larson, Martin G.; Harris, William S.
2014-01-01
Research has shown that several types of erythrocyte fatty acids (i.e., omega-3, omega-6, and trans) are associated with risk for cardiovascular diseases. However, there are complex metabolic and dietary relations among fatty acids, which induce correlations that are typically ignored when using them as risk predictors. A latent variable approach could summarize these complex relations into a few latent variable scores for use in statistical models. Twenty-two red blood cell (RBC) fatty acids were measured in Framingham (N = 3196). The correlation matrix of the fatty acids was modeled using structural equation modeling; the model was tested for goodness-of-fit and gender invariance. Thirteen fatty acids were summarized by three latent variables, and gender invariance was rejected so separate models were developed for men and women. A score was developed for the polyunsaturated fatty acid (PUFA) latent variable, which explained about 30% of the variance in the data. The PUFA score included loadings in opposing directions among three omega-3 and three omega-6 fatty acids, and incorporated the biosynthetic and dietary relations among them. Whether the PUFA factor score can improve the performance of risk prediction in cardiovascular diseases remains to be tested. PMID:24959197
Energy conservation equations and interaction contributions at a structural interface between two
Cerveny, Vlastislav
Energy conservation equations and interaction contributions at a structural interface between twoÂmails: johana@seis.karlov.mff.cuni.cz, vcerveny@seis.karlov.mff.cuni.cz Summary Energy conservation equations is to investigate numeriÂ cally the energy conservation equations and the interaction contributions. An attempt
Hard ellipses: Equation of state, structure, and self-diffusion.
Xu, Wen-Sheng; Li, Yan-Wei; Sun, Zhao-Yan; An, Li-Jia
2013-07-14
Despite their fundamental and practical interest, the physical properties of hard ellipses remain largely unknown. In this paper, we present an event-driven molecular dynamics study for hard ellipses and assess the effects of aspect ratio and area fraction on their physical properties. For state points in the plane of aspect ratio (1 ? k ? 9) and area fraction (0.01 ? ? ? 0.8), we identify three different phases, including isotropic, plastic, and nematic states. We analyze in detail the thermodynamic, structural, and self-diffusive properties in the formed various phases of hard ellipses. The equation of state (EOS) is shown for a wide range of aspect ratios and is compared with the scaled particle theory (SPT) for the isotropic states. We find that SPT provides a good description of the EOS for the isotropic phase of hard ellipses. At large fixed ?, the reduced pressure p increases with k in both the isotropic and the plastic phases and, interestingly, its dependence on k is rather weak in the nematic phase. We rationalize the thermodynamics of hard ellipses in terms of particle motions. The static structures of hard ellipses are then investigated both positionally and orientationally in the different phases. The plastic crystal is shown to form for aspect ratios up to k = 1.4, while appearance of the stable nematic phase starts approximately at k = 3. We quantitatively determine the locations of the isotropic-plastic (I-P) transition and the isotropic-nematic (I-N) transition by analyzing the bond-orientation correlations and the angular correlations, respectively. As expected, the I-P transition point is found to increase with k, while a larger k leads to a smaller area fraction where the I-N transition takes place. Moreover, our simulations strongly support that the two-dimensional nematic phase in hard ellipses has only quasi-long-range orientational order. The self-diffusion of hard ellipses is further explored and connections are revealed between the structure and the self-diffusion. We discuss the relevance of our results to the glass transition in hard ellipses. Finally, the results of the isodiffusivity lines are evaluated for hard ellipses and we discuss the effect of spatial dimension on the diffusive dynamics of hard ellipsoidal particles. PMID:23862947
ERIC Educational Resources Information Center
Maslowsky, Julie; Jager, Justin; Hemken, Douglas
2015-01-01
Latent variables are common in psychological research. Research questions involving the interaction of two variables are likewise quite common. Methods for estimating and interpreting interactions between latent variables within a structural equation modeling framework have recently become available. The latent moderated structural equations (LMS)…
An EM Algorithm for Fitting Two-Level Structural Equation Models
ERIC Educational Resources Information Center
Liang, Jiajuan; Bentler, Peter M.
2004-01-01
Maximum likelihood is an important approach to analysis of two-level structural equation models. Different algorithms for this purpose have been available in the literature. In this paper, we present a new formulation of two-level structural equation models and develop an EM algorithm for fitting this formulation. This new formulation covers a…
Maximum Likelihood Analysis of Nonlinear Structural Equation Models with Dichotomous Variables
ERIC Educational Resources Information Center
Song, Xin-Yuan; Lee, Sik-Yum
2005-01-01
In this article, a maximum likelihood approach is developed to analyze structural equation models with dichotomous variables that are common in behavioral, psychological and social research. To assess nonlinear causal effects among the latent variables, the structural equation in the model is defined by a nonlinear function. The basic idea of the…
General structure of the gravitational equations of motion in conformal Weyl gravity
NASA Technical Reports Server (NTRS)
Kazanas, Demosthenes; Mannheim, Philip D.
1991-01-01
A general method for determining the structure of the gravitational equations of motion is presented in the fourth-order theory of gravity based on local conformal Weyl invariance of the gravitational action. The explicit structure for these equations is given for a time-dependent, spherically symmetric geometry.
Modeling Correlation of Family Holiday Activities Based on Structural Equation Model
Xin ZHAO; Hongzhi GUAN; Liyuan GONG
2011-01-01
Previous researches in activities-decision have more in-depth study in context of individuals, while less work has been done within household activity decisions. The structural equation model is applied to analyze the relationship of three household activity categories on holiday using data from 2009 Jinan travel survey. Six attributes were first chosen as exogenous variables for the structural equation model. Meanwhile,
Reinoud D. Stoel; Francisca Galindo Garre; Conor Dolan; Godfried van den Wittenboer
2006-01-01
The authors show how the use of inequality constraints on parameters in structural equation models may affect the distribution of the likelihood ratio test. Inequality constraints are implicitly used in the testing of commonly applied structural equation models, such as the common factor model, the autoregressive model, and the latent growth curve model, although this is not commonly acknowledged. Such
Michel Chavance; Sylvie Escolano; Monique Romon; Arnaud Basdevant; Blandine de Lauzon-Guillain; Marie Aline Charles
2010-01-01
BACKGROUND: The use of structural equation modeling and latent variables remains uncommon in epidemiology despite its potential usefulness. The latter was illustrated by studying cross-sectional and longitudinal relationships between eating behavior and adiposity, using four different indicators of fat mass. METHODS: Using data from a longitudinal community-based study, we fitted structural equation models including two latent variables (respectively baseline adiposity
Applications of structural equation modeling in marketing and consumer research: A review
Hans Baumgartner; Christian Homburg
1996-01-01
This paper reviews prior applications of structural equation modeling in four major marketing journals (the Journal of Marketing, Journal of Marketing Research, International Journal of Research in Marketing, and the Journal of Consumer Research) between 1977 and 1994. After documenting and characterizing the number of applications over time, we discuss important methodological issues related to structural equation modeling and assess
Habitat fragmentation and reproductive success: a structural equation modelling approach.
Le Tortorec, Eric; Helle, Samuli; Käyhkö, Niina; Suorsa, Petri; Huhta, Esa; Hakkarainen, Harri
2013-09-01
1. There is great interest on the effects of habitat fragmentation, whereby habitat is lost and the spatial configuration of remaining habitat patches is altered, on individual breeding performance. However, we still lack consensus of how this important process affects reproductive success, and whether its effects are mainly due to reduced fecundity or nestling survival. 2. The main reason for this may be the way that habitat fragmentation has been previously modelled. Studies have treated habitat loss and altered spatial configuration as two independent processes instead of as one hierarchical and interdependent process, and therefore have not been able to consider the relative direct and indirect effects of habitat loss and altered spatial configuration. 3. We investigated how habitat (i.e. old forest) fragmentation, caused by intense forest harvesting at the territory and landscape scales, is associated with the number of fledged offspring of an area-sensitive passerine, the Eurasian treecreeper (Certhia familiaris). We used structural equation modelling (SEM) to examine the complex hierarchical associations between habitat loss and altered spatial configuration on the number of fledged offspring, by controlling for individual condition and weather conditions during incubation. 4. Against generally held expectations, treecreeper reproductive success did not show a significant association with habitat fragmentation measured at the territory scale. Instead, our analyses suggested that an increasing amount of habitat at the landscape scale caused a significant increase in nest predation rates, leading to reduced reproductive success. This effect operated directly on nest predation rates, instead of acting indirectly through altered spatial configuration. 5. Because habitat amount and configuration are inherently strongly collinear, particularly when multiple scales are considered, our study demonstrates the usefulness of a SEM approach for hierarchical partitioning of habitat amount vs. habitat configuration in landscape ecology that may have bearing on biological conclusions. PMID:23550698
Fixed- and random-effects meta-analytic structural equation modeling: examples and analyses in R.
Cheung, Mike W-L
2014-03-01
Meta-analytic structural equation modeling (MASEM) combines the ideas of meta-analysis and structural equation modeling for the purpose of synthesizing correlation or covariance matrices and fitting structural equation models on the pooled correlation or covariance matrix. Cheung and Chan (Psychological Methods 10:40-64, 2005b, Structural Equation Modeling 16:28-53, 2009) proposed a two-stage structural equation modeling (TSSEM) approach to conducting MASEM that was based on a fixed-effects model by assuming that all studies have the same population correlation or covariance matrices. The main objective of this article is to extend the TSSEM approach to a random-effects model by the inclusion of study-specific random effects. Another objective is to demonstrate the procedures with two examples using the metaSEM package implemented in the R statistical environment. Issues related to and future directions for MASEM are discussed. PMID:23807765
Park, Byung-Chan; Kim, Eun-A; Kim, Soo Geun
2010-01-01
Objectives This study was conducted to develop a model describing the interaction between lifestyle, job, and postural factors and parts of the upper extremities in shipyard workers. Methods A questionnaire survey was given to 2,140 workers at a shipyard in Ulsan City. The questionnaire consisted of questions regarding the subjects' general characteristics, lifestyle, tenure, physical burden, job control, posture and musculoskeletal symptoms. The overall relationship between variables was analyzed by a structural equation model (SEM). Results The positive rate of upper extremity musculoskeletal symptoms increased in employees who worked longer hours, had severe physical burden, and did not have any control over their job. Work with a more frequent unstable posture and for longer hours was also associated with an increased positive rate of musculoskeletal symptoms. Multiple logistic regression analysis showed that unstable posture and physical burden were closely related to the positive rate of musculoskeletal symptoms after controlling for age, smoking, drinking, exercise, tenure, and job control. In SEM analysis, work-related musculoskeletal disease was influenced directly and indirectly by physical and job stress factors, lifestyle, age, and tenure (p < 0.05). The strongest correlations were found between physical factors and work-related musculoskeletal disease. Conclusion The model in this study provides a better approximation of the complexity of the actual relationship between risk factors and work-related musculoskeletal disorders. Among the variables evaluated in this study, physical factors (work posture) had the strongest association with musculoskeletal disorders. PMID:22953172
Massively parallel structured direct solver for equations describing ...
2011-10-17
tial equations in TI media; we then take the 'incomplete acoustic' limit along ... Time-domain strategies rely on the construction of coupled pairs of partial differential ...... number of processors, which is consistent with the analysis we carried out.
W. W Lin; S. F Xu
2006-01-01
Abstract. In this paper, we introduce the doubling transformation, a structure-preserving transformation for symplectic pencils, and present its basic properties. Based on these properties, a unified convergence theory for the structure-preserving doubling algorithms for a class of Riccati-type matrix equations is established, using only elementary matrix theory. Key words. matrix equation, structure-preserving doubling algorithm, convergence rate AMS subject classifications. 15A24,
ERIC Educational Resources Information Center
Mitchell, Jimmy L.; McCormick, Ernest J.
The development and analysis of the Professional and Managerial Position Questionnaire (PMPQ) is reported. PMPQ is intended to serve as a job analysis instrument for higher level occupations than those assessed by the Position Analysis Questionnaire (PAQ). Four approaches to job analysis are described with different emphases on the requirements of…
Solving Differential Equations in Developmental Models of Multicellular Structures Expressed
Prusinkiewicz, Przemyslaw
Anabaena. Reference P. Federl and P. Prusinkiewicz: Solving differential equations in developmental models with a developmental model of the multicellular bacterium Anabaena. 1 Introduction Recent advances in genetics have solution by revisiting the diffusion-based developmental model of the blue-green alga Anabaena catenula [1
Incompatibility of the Shuttleworth equation with Hermann’s mathematical structure of thermodynamics
NASA Astrophysics Data System (ADS)
Bottomley, D. J.; Makkonen, Lasse; Kolari, Kari
2009-01-01
We show that three independent derivations of the Shuttleworth equation, arguably the second most important equation in surface physics, are inconsistent with Hermann's mathematical structure of thermodynamics [R. Hermann, Geometry, Physics and Systems, Marcel Dekker Inc., New York, USA, 1973 (Chapter 6)]. The possible implications of this result are discussed.
Hyperbolic heat conduction equation for materials with a nonhomogeneous inner structure
W. Kaminski
1990-01-01
The physical meaning of the constant Ï in Cattaneo and Vernotte's equation for materials with a nonhomogeneous inner structure has been considered. An experimental determination of the constant Ï has been proposed and some values for selected products have been given. The range of differences in the description of heat transfer by parabolic and hyperbolic heat conduction equations has been
Uwe Peter Kanning
2006-01-01
In the current article, the development and validation of a German-language version of the Interpersonal Competence Questionnaire (ICQ; Buhrmester, Furman, Wittenberg, & Reis, 1988) are described. The five-factor structure of the ICQ is confirmed by structure equation analysis and reliability is well documented (Cronbach's ? = .72–.84). The validation is carried out using the NEO-FFI (Costa & McCrae, 1992) as
ERIC Educational Resources Information Center
Raines-Eudy, Ruth
2000-01-01
Demonstrates empirically a structural equation modeling technique for group comparison of reliability and validity. Data, which are from a study of 495 mothers' attitudes toward pregnancy, have a one-factor measurement model and three sets of subpopulation comparisons. (SLD)
ERIC Educational Resources Information Center
Zhang, Duan; Willson, Victor L.
2006-01-01
Both structural equation models and hierarchical linear models (HLMs) have been commonly used in multilevel analysis. This study utilized simulated data to investigate the power difference among 3 multilevel models: HLM, deviation structural equation models, and a hybrid approach of HLM and structural equation models. Two factors were examined:…
A Robust Bayesian Approach for Structural Equation Models with Missing Data
Sik-Yum Lee; Ye-Mao Xia
2008-01-01
In this paper, normal\\/independent distributions, including but not limited to the multivariate t distribution, the multivariate contaminated distribution, and the multivariate slash distribution, are used to develop a\\u000a robust Bayesian approach for analyzing structural equation models with complete or missing data. In the context of a nonlinear\\u000a structural equation model with fixed covariates, robust Bayesian methods are developed for estimation
On the structure of nonlinear constitutive equations for fiber reinforced composites
NASA Technical Reports Server (NTRS)
Jansson, Stefan
1992-01-01
The structure of constitutive equations for nonlinear multiaxial behavior of transversely isotropic fiber reinforced metal matrix composites subject to proportional loading was investigated. Results from an experimental program were combined with numerical simulations of the composite behavior for complex stress to reveal the full structure of the equations. It was found that the nonlinear response can be described by a quadratic flow-potential, based on the polynomial stress invariants, together with a hardening rule that is dominated by two different hardening mechanisms.
Sébastien Bertrand; Alfred M. Grundland; Alexander J. Hariton
2015-04-21
The paper presents the bosonic and fermionic supersymmetric extensions of the structural equations describing conformally parametrized surfaces immersed in a Grasmann superspace, based on the authors' earlier results. A detailed analysis of the symmetry properties of both the classical and supersymmetric versions of the Gauss-Weingarten equations is performed. A supersymmetric generalization of the conjecture establishing the necessary conditions for a system to be integrable in the sense of soliton theory is formulated and illustrated by the examples of supersymmetric versions of the sine-Gordon equation and the Gauss-Codazzi equations.
McGuire, Brian E.; Morrison, Todd G.; Barker, Lynne A.; Morton, Nicholas; McBrinn, Judith; Caldwell, Sheena; Wilson, Colin F.; McCann, John; Carton, Simone; Delargy, Mark; Walsh, Jane
2014-01-01
Aims: This study sought to address two questions: (1) what is the inter-rater reliability of the Dysexecutive Questionnaire (DEX) when completed by patients, their significant others, and clinicians; and (2) does the factor structure of the DEX vary for these three groups? Methods: We obtained DEX ratings for 113 patients with an acquired brain injury from two brain injury services in the UK and two services in Ireland. We gathered data from two groups of raters—“significant others” (DEX-SO) such as partners and close family members and “clinicians” (DEX-C), who were psychologists or rehabilitation physicians working closely with the patient and who were able to provide an opinion about the patient’s level of everyday executive functioning. Intra-class correlation coefficients and their 95% confidence intervals were calculated between each of the three groups (self, significant other, clinician). Principal axis factor (PAF) analyses were also conducted for each of the three groups. Results: The factor analysis revealed a consistent one-factor model for each of the three groups of raters. However, the inter-rater reliability analyses showed a low level of agreement between the self-ratings and the ratings of the two groups of independent raters. We also found low agreement between the significant others and the clinicians. Conclusion: Although there was a consistent finding of a single factor solution for each of the three groups, the low level of agreement between significant others and clinicians raises a question about the reliability of the DEX. PMID:25346668
$R$-matrices and Hamiltonian Structures for Certain Lax Equations
Chao-Zhong Wu
2013-05-06
In this paper a list of $R$-matrices on a certain coupled Lie algebra is obtained. With one of these $R$-matrices, we construct infinitely many bi-Hamiltonian structures for each of the two-component BKP and the Toda lattice hierarchies. We also show that, when such two hierarchies are reduced to their subhierarchies, these bi-Hamiltonian structures are reduced correspondingly.
ERIC Educational Resources Information Center
Goldstein, Harvey; Bonnet, Gerard; Rocher, Thierry
2007-01-01
The Programme for International Student Assessment comparative study of reading performance among 15-year-olds is reanalyzed using statistical procedures that allow the full complexity of the data structures to be explored. The article extends existing multilevel factor analysis and structural equation models and shows how this can extract richer…
Using Mx to Analyze Cross-Level Effects in Two-Level Structural Equation Models
ERIC Educational Resources Information Center
Bai, Yun; Poon, Wai-Yin
2009-01-01
Two-level data sets are frequently encountered in social and behavioral science research. They arise when observations are drawn from a known hierarchical structure, such as when individuals are randomly drawn from groups that are randomly drawn from a target population. Although 2-level data analysis in the context of structural equation modeling…
ERIC Educational Resources Information Center
Kim, Young-Mi; Neff, James Alan
2010-01-01
A model incorporating the direct and indirect effects of parental monitoring on adolescent alcohol use was evaluated by applying structural equation modeling (SEM) techniques to data on 4,765 tenth-graders in the 2001 Monitoring the Future Study. Analyses indicated good fit of hypothesized measurement and structural models. Analyses supported both…
NASA Technical Reports Server (NTRS)
Taylor, Lawrence W., Jr.; Rajiyah, H.
1991-01-01
Partial differential equations for modeling the structural dynamics and control systems of flexible spacecraft are applied here in order to facilitate systems analysis and optimization of these spacecraft. Example applications are given, including the structural dynamics of SCOLE, the Solar Array Flight Experiment, the Mini-MAST truss, and the LACE satellite. The development of related software is briefly addressed.
David Kaplan
1988-01-01
The purpose of this paper is to assess the impact of misspecification on the estimation, testing, and improvement of structural equation models. A population study is con- ducted whereby a prototypical latent variable model is misspecified in various ways. Measurement model and structural model misspecifications are considered separately and together. The maximum likelihood estimator (ML) is compared to a limited
Using Mx to Analyze Cross-Level Effects in Two-Level Structural Equation Models
Yun Bai; Wai-Yin Poon
2009-01-01
Two-level data sets are frequently encountered in social and behavioral science research. They arise when observations are drawn from a known hierarchical structure, such as when individuals are randomly drawn from groups that are randomly drawn from a target population. Although 2-level data analysis in the context of structural equation modeling can be conducted by easily accessible software such as
Solution of linear systems of equations with a structural analysis code on the NAS CRAY2
E. L. Poole; A. L. Overman
1988-01-01
Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted
Maximum Likelihood Analysis of a Two-Level Nonlinear Structural Equation Model with Fixed Covariates
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan
2005-01-01
In this article, a maximum likelihood (ML) approach for analyzing a rather general two-level structural equation model is developed for hierarchically structured data that are very common in educational and/or behavioral research. The proposed two-level model can accommodate nonlinear causal relations among latent variables as well as effects…
High-accuracy deterministic solution of the Boltzmann equation for the shock wave structure
NASA Astrophysics Data System (ADS)
Malkov, E. A.; Bondar, Ye. A.; Kokhanchik, A. A.; Poleshkin, S. O.; Ivanov, M. S.
2015-07-01
A new deterministic method of solving the Boltzmann equation has been proposed. The method has been employed in numerical studies of the plane shock wave structure in a hard sphere gas. Results for Mach numbers and have been compared with predictions of the direct simulation Monte Carlo (DSMC) method, which has been used to obtain the reference solution. Particular attention in estimating the solution accuracy has been paid to a fine structural effect: the presence of a total temperature peak exceeding the temperature value further downstream. The results of solving the Boltzmann equation for the shock wave structure are in excellent agreement with the DSMC predictions.
Salama-Younes, Mareï; Montazeri, Ali; Ismaïl, Amany; Roncin, Charles
2009-01-01
Background The objectives of this study were to test the factor structure and internal consistency of the 12-item General Health Questionnaire (GHQ-12) and the Subjective Vitality Scale (VS) in elderly French people, and to test the relationship between these two questionnaires. Methods Using a standard 'forward-backward' translation procedure, the English language versions of the two instruments (i.e. the 12-item General Health Questionnaire and the Subjective Vitality Scale) were translated into French. A sample of adults aged 58–72 years then completed both questionnaires. Internal consistency was assessed by Cronbach's alpha coefficient. The factor structures of the two instruments were extracted by confirmatory factor analysis (CFA). Finally, the relationship between the two instruments was assessed by correlation analysis. Results In all, 217 elderly adults participated in the study. The mean age of the respondents was 61.7 (SD = 6.2) years. The mean GHQ-12 score was 17.4 (SD = 8.0), and analysis showed satisfactory internal consistency (Cronbach's alpha coefficient = 0.78). The mean VS score was 22.4 (SD = 7.4) and its internal consistency was found to be good (Cronbach's alpha coefficient = 0.83). While CFA showed that the VS was uni-dimensional, analysis for the GHQ-12 demonstrated a good fit not only to the two-factor model (positive vs. negative items) but also to a three-factor model. As expected, there was a strong and significant negative correlation between the GHQ-12 and the VS (r = -0.71, P < 0.001). Conclusion The results showed that the French versions of the 12-item General Health Questionnaire (GHQ-12) and the Subjective Vitality Scale (VS) are reliable measures of psychological distress and vitality. They also confirm a significant negative correlation between these two instruments, lending support to their convergent validity in an elderly French population. The findings indicate that both measures have good structural characteristics. PMID:19265516
The Preschool Behavior Questionnaire
Lenore B. Behar
1977-01-01
In summary, the Preschool Behavior Questionnaire was developed as a screening instrument for use by preschool teachers, providing norms for children, ages 3–6. During the 34-month period since its publication in late 1974, the scale has been used to a considerable extent in the screening of young children. Those who have used the scale evaluate it highly. However, the variations
Identification Number:.... Questionnaire Four
Boschetti, Fabio
the complete complex system?'' This is the last questionnaire for the experiment. It asks about your general thoughts and your learning from this experiment. Could you give some information that could explain how you particularly easy? If so what were they and why? Were there any specific aspects that were particularly
Questionnaire typography and production.
Gray, M
1975-06-01
This article describes the typographic principles and practice which provide the basis of good design and print, the relevant printing processes which can be used, and the graphic designer's function in questionnaire production. As they impose constraints on design decisions to be discussed later in the text, the various methods of printing and production are discussed first. PMID:15677172
NATIONAL INSTITUTES OF HEALTH Diet History Questionnaire Today's date: MONTH DAY YEAR |___|___| 0 0 1 1 2 2 3 3 4 5 6 7 8 01 Jan 02 Feb 03 Mar 04 Apr 05 May 06 Jun 07 Jul 08 Aug 09 Sep 10 Oct 11 Nov 12
Philosophy of Glasser Questionnaire.
ERIC Educational Resources Information Center
Masters, James R.; Laverty, Grace E.
As part of the instrumentation to assess the effectiveness of the Schools Without Failure (SWF) program in 10 elementary schools in the New Castle, Pa. School District, the Philosophy of Glasser Questionnaire was developed. This 15-item scale measuring attitudes toward the philosophy of William Glasser had a coefficient alpha reliability of .77…
OpenMx: An Open Source Extended Structural Equation Modeling Framework
Steven Boker; Michael Neale; Hermine Maes; Michael Wilde; Michael Spiegel; Timothy Brick; Jeffrey Spies; Ryne Estabrook; Sarah Kenny; Timothy Bates; Paras Mehta; John Fox
2011-01-01
OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx runs within the R statistical programming environment on Windows, Mac OS–X, and Linux computers. The rationale for developing OpenMx is discussed\\u000a along with the philosophy behind the user interface. The OpenMx data structures are introduced—these novel structures define\\u000a the user interface framework and provide new opportunities for model
Multiband k·p Riccati equation for electronic structure and transport in type-II heterostructures
A. E. Botha
2007-01-01
An alternative method is proposed and implemented to calculate electronic structure and quantum transport properties of type-II heterojunctions. By deriving a multiband k·p Riccati equation for the envelope function matrix, it is shown how to obtain the reflection matrix through a simple numerical integration of the Riccati equation. Numerical instability, which is usually associated with type-II systems due to the
NASA Technical Reports Server (NTRS)
Guruswamy, Guru P.; Byun, Chansup; VanDalsem, William (Technical Monitor)
1994-01-01
Aeroelasticity which involves strong coupling of fluids, structures and controls is an important element in designing an aircraft. Computational aeroelasticity using low fidelity methods such as the linear aerodynamic flow equations coupled with the modal structural equations are well advanced. Though these low fidelity approaches are computationally less intensive, they are not adequate for the analysis of modern aircraft such as High Speed Civil Transport (HSCT) and Advanced Subsonic Transport (AST) which can experience complex flow/structure interactions. HSCT can experience vortex induced aeroelastic oscillations whereas AST can experience transonic buffet associated structural oscillations. Both aircraft may experience a dip in the flutter speed at the transonic regime. For accurate aeroelastic computations at these complex fluid/structure interaction situations, high fidelity equations such as the Navier-Stokes for fluids and the finite-elements for structures are needed. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional supercomputers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overcome the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENASERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.
N. H. Tenneij; Chris K. W. Schotte; Damiaan A. J. P. Denys; Megen van H. J. G. M; Herman G. M. Westenberg
2003-01-01
In patients with obsessive-compulsive disorder, personality disorders are not many times assessed according to DSM-IV criteria. The purpose of the present study is to examine the prevalence of personality disorders diagnosed according to the DSM-IV in a severely disordered OCD popula- tion (n = 65) with three different methods of assessing personality disor- ders (structured interview, questionnaire, and clinical diagnoses).
Jacinta M. Douglas; Christine A. Bracy; Pamela C. Snow
2007-01-01
Background: Self and close other reports of communication ability can provide a time?efficient means of evaluating conversational discourse after traumatic brain injury (TBI). The La Trobe Communication Questionnaire (LCQ) measures perceived communication ability from various sources including self?perceptions and perceptions of others. Content and test–retest reliability and discriminant validity of the LCQ have been demonstrated previously with adults following TBI.Aims:
An analysis of the vertical structure equation for arbitrary thermal profiles
NASA Technical Reports Server (NTRS)
Cohn, Stephen E.; Dee, Dick P.
1987-01-01
The vertical structure equation is a singular Sturm-Liouville problem whose eigenfunctions describe the vertical dependence of the normal modes of the primitive equations linearized about a given thermal profile. The eigenvalues give the equivalent depths of the modes. The spectrum of the vertical structure equation and the appropriateness of various upper boundary conditions, both for arbitrary thermal profiles were studied. The results depend critically upon whether or not the thermal profile is such that the basic state atmosphere is bounded. In the case of a bounded atmosphere it is shown that the spectrum is always totally discrete, regardless of details of the thermal profile. For the barotropic equivalent depth, which corresponds to the lowest eigen value, upper and lower bounds which depend only on the surface temperature and the atmosphere height were obtained. All eigenfunctions are bounded, but always have unbounded first derivatives. It was proved that the commonly invoked upper boundary condition that vertical velocity must vanish as pressure tends to zero, as well as a number of alternative conditions, is well posed. It was concluded that the vertical structure equation always has a totally discrete spectrum under the assumptions implicit in the primitive equations.
Greenshields, Christopher J
2007-01-01
Howard Brenner has recently proposed modifications to the Navier-Stokes equations that relate to a diffusion of fluid volume that would be significant for flows with high density gradients. In a previous paper (Greenshields & Reese, 2007), we found these modifications gave good predictions of the viscous structure of shock waves in argon in the range Mach 1.0-12.0 (while conventional Navier-Stokes equations are known to fail above about Mach 2). However, some areas of concern with this model were a somewhat arbitrary choice of modelling coefficient, and potentially unphysical and unstable solutions. In this paper, we therefore present slightly different modifications to include molecule mass diffusion fully in the Navier-Stokes equations. These modifications are shown to be stable and produce physical solutions to the shock problem of a quality broadly similar to those from the family of extended hydrodynamic models that includes the Burnett equations. The modifications primarily add a diffusion term to t...
Bayesian Analysis of Nonlinear Structural Equation Models with Nonignorable Missing Data
Sik-Yum Lee; NIAN-SHENG TANG
2006-01-01
A Bayesian approach is developed for analyzing nonlinear structural equation models with nonignorable missing data. The nonignorable\\u000a missingness mechanism is specified by a logistic regression model. A hybrid algorithm that combines the Gibbs sampler and\\u000a the Metropolis–Hastings algorithm is used to produce the joint Bayesian estimates of structural parameters, latent variables,\\u000a parameters in the nonignorable missing model, as well as
Using Presence Questionnaires in Reality Using Presence Questionnaires in Reality
Slater, Mel
compared to immersive virtual. #12;Using Presence Questionnaires in Reality 2 1. Introduction The concept1 Using Presence Questionnaires in Reality Using Presence Questionnaires in Reality Martin Usoh different presence question- naires can distinguish between real and virtual experiences. One group of 10
ERIC Educational Resources Information Center
Kim, Minkee; Song, Jinwoong
2010-01-01
Many models in science education have tried to clarify the causal relationships of affective variables on student performance, by presenting theoretical models, exploratory SEM (structural equation models), and confirmatory SEM. Based on the literature, the recent AS-TI-CU model scrutinised the most robust stimuli of conceptual understanding (CU):…
Rumination and Distraction Among Chronic Depressives in Treatment: A Structural Equation Analysis
Bruce A. Arnow; Diane Spangler; Daniel N. Klein; David D. Burns
2004-01-01
Response Styles Theory hypothesizes that rumination about one's symptoms amplifies and prolongs depressed mood, whereas distraction has the opposite effect. Response styles are also hypothesized to be trait-like dispositions. The generalizability of Response Styles Theory, as well as the linkages that may account for correlations between rumination, distraction, and depression, were explored with structural equation modeling in a sample of
ERIC Educational Resources Information Center
Bechger, Timo M.; Maris, Gunter
2004-01-01
This paper is about the structural equation modelling of quantitative measures that are obtained from a multiple facet design. A facet is simply a set consisting of a finite number of elements. It is assumed that measures are obtained by combining each element of each facet. Methods and traits are two such facets, and a multitrait-multimethod…
The Effect of Varying Degrees of Nonnormality in Structural Equation Modeling
ERIC Educational Resources Information Center
Lei, Ming; Lomax, Richard G.
2005-01-01
This simulation study investigated the robustness of structural equation modeling to different degrees of nonnormality under 2 estimation methods, generalized least squares and maximum likelihood, and 4 sample sizes, 100, 250, 500, and 1,000. Each of the slight and severe nonnormality degrees was comprised of pure skewness, pure kurtosis, and both…
Strategic Competence as a Fourth-Order Factor Model: A Structural Equation Modeling Approach
ERIC Educational Resources Information Center
Phakiti, Aek
2008-01-01
This article reports on an empirical study that tests a fourth-order factor model of strategic competence through the use of structural equation modeling (SEM). The study examines the hierarchical relationship of strategic competence to (a) strategic knowledge of cognitive and metacognitive strategy use in general (i.e., trait) and (b) strategic…
ERIC Educational Resources Information Center
Caro, Daniel H.; Sandoval-Hernández, Andrés; Lüdtke, Oliver
2014-01-01
The article employs exploratory structural equation modeling (ESEM) to evaluate constructs of economic, cultural, and social capital in international large-scale assessment (LSA) data from the Progress in International Reading Literacy Study (PIRLS) 2006 and the Programme for International Student Assessment (PISA) 2009. ESEM integrates the…
Giannakis, Georgios
1 Inference of gene regulatory networks with sparse structural equation models exploiting genetic Integrating genetic perturbations with gene expression data not only improves accuracy of regulatory net- work topology inference, but also enables learning of causal regulatory relations between genes. Although
Properties of the BFKL equation and structure function predictions for HERA
A. J. Askew; J. Kwiecinski; A. D. Martin; P. J. Sutton
1993-10-11
The general properties of the Lipatov or BFKL equation are reviewed. Modifications to the infrared region are proposed. Numerical predictions for the deep-inelastic electron-proton structure functions at small $x$ are presented and confronted with recent HERA measurements.
A Structural Equation Modelling of the Academic Self-Concept Scale
ERIC Educational Resources Information Center
Matovu, Musa
2014-01-01
The study aimed at validating the academic self-concept scale by Liu and Wang (2005) in measuring academic self-concept among university students. Structural equation modelling was used to validate the scale which was composed of two subscales; academic confidence and academic effort. The study was conducted on university students; males and…
Tropical storm motion and structure in a fine mesh primitive equation model
M. B. Mathur
1992-01-01
Summary Convective to planetary scale processes govern the motion and structure of tropical storms. A model with a high resolution and a large domain is required for accurate prediction of a storm's track and intensity. A series of integrations are performed using a primitive equation model and an initial state that defines a tropical storm that later developed into a
Differential equations to calculate the ionicity factor of hexagonal structure semiconductors
NASA Astrophysics Data System (ADS)
Arif, Ghassan E.; Al-Douri, Y.; Abdullah, Farah Aini; Khenata, R.
2013-01-01
New mathematical models based on analytical expression and differential equations are established. The work aims to model ionicity factor based on energy gap of hexagonal structure semiconductors using density functional theory (DFT) of full-potential linear augmented plane wave (FP-LAPW) within Engel Vosko-General Gradient Approximation (EV-GGA). Our calculated values are in agreement with experimental and theoretical results.
ERIC Educational Resources Information Center
Macho, Siegfried; Ledermann, Thomas
2011-01-01
The phantom model approach for estimating, testing, and comparing specific effects within structural equation models (SEMs) is presented. The rationale underlying this novel method consists in representing the specific effect to be assessed as a total effect within a separate latent variable model, the phantom model that is added to the main…
Structural Equation Modeling in Language Testing and Learning Research: A Review
ERIC Educational Resources Information Center
In'nami, Yo; Koizumi, Rie
2011-01-01
Despite the recent increase of structural equation modeling (SEM) in language testing and learning research and Kunnan's (1998) call for the proper use of SEM to produce useful findings, there seem to be no reviews about how SEM is applied in these areas or about the extent to which the current application accords with appropriate practices. To…
ERIC Educational Resources Information Center
Cheung, Mike W. L.; Chan, Wai
2009-01-01
Structural equation modeling (SEM) is widely used as a statistical framework to test complex models in behavioral and social sciences. When the number of publications increases, there is a need to systematically synthesize them. Methodology of synthesizing findings in the context of SEM is known as meta-analytic SEM (MASEM). Although correlation…
Equivalence and Differences between Structural Equation Modeling and State-Space Modeling Techniques
ERIC Educational Resources Information Center
Chow, Sy-Miin; Ho, Moon-ho R.; Hamaker, Ellen L.; Dolan, Conor V.
2010-01-01
State-space modeling techniques have been compared to structural equation modeling (SEM) techniques in various contexts but their unique strengths have often been overshadowed by their similarities to SEM. In this article, we provide a comprehensive discussion of these 2 approaches' similarities and differences through analytic comparisons and…
An Application of Structural Equation Modeling for Developing Good Teaching Characteristics Ontology
ERIC Educational Resources Information Center
Phiakoksong, Somjin; Niwattanakul, Suphakit; Angskun, Thara
2013-01-01
Ontology is a knowledge representation technique which aims to make knowledge explicit by defining the core concepts and their relationships. The Structural Equation Modeling (SEM) is a statistical technique which aims to explore the core factors from empirical data and estimates the relationship between these factors. This article presents an…
Fixed-Effects Meta-Analyses as Multiple-Group Structural Equation Models
ERIC Educational Resources Information Center
Cheung, Mike W. -L.
2010-01-01
Meta-analysis is the statistical analysis of a collection of analysis results from individual studies, conducted for the purpose of integrating the findings. Structural equation modeling (SEM), on the other hand, is a multivariate technique for testing hypothetical models with latent and observed variables. This article shows that fixed-effects…
Prescriptive Statements and Educational Practice: What Can Structural Equation Modeling (SEM) Offer?
ERIC Educational Resources Information Center
Martin, Andrew J.
2011-01-01
Longitudinal structural equation modeling (SEM) can be a basis for making prescriptive statements on educational practice and offers yields over "traditional" statistical techniques under the general linear model. The extent to which prescriptive statements can be made will rely on the appropriate accommodation of key elements of research design,…
ERIC Educational Resources Information Center
Green, Samuel B.; Yang, Yanyun
2009-01-01
A method is presented for estimating reliability using structural equation modeling (SEM) that allows for nonlinearity between factors and item scores. Assuming the focus is on consistency of summed item scores, this method for estimating reliability is preferred to those based on linear SEM models and to the most commonly reported estimate of…
Hypothesis Testing and Model Comparison in Two-Level Structural Equation Models.
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan
2001-01-01
Demonstrates the use of the well-known Bayes factor in the Bayesian literature for hypothesis testing and model comparison in general two-level structural equation models. Shows that the proposed method is flexible and can be applied to situations with a wide variety of nonnested models. (SLD)
ERIC Educational Resources Information Center
Karadag, Engin; Kilicoglu, Gökhan; Yilmaz, Derya
2014-01-01
The purpose of this study is to explain constructed theoretical models that organizational cynicism perceptions of primary school teachers affect school culture and academic achievement, by using structural equation modeling. With the assumption that there is a cause-effect relationship between three main variables, the study was constructed with…
Equivalence and Differences Between Structural Equation Modeling and State-Space Modeling Techniques
Sy-Miin Chow; Moon-ho R. Ho; Ellen L. Hamaker; Conor V. Dolan
2010-01-01
State-space modeling techniques have been compared to structural equation modeling (SEM) techniques in various contexts but their unique strengths have often been overshadowed by their similarities to SEM. In this article, we provide a comprehensive discussion of these 2 approaches' similarities and differences through analytic comparisons and numerical simulations, with a focus on their use in representing intraindividual dynamics and
A structural equation model of the effect of poverty and unemployment on alcohol abuse
Shaila Khan; Robert P Murray; Gordon E Barnes
2002-01-01
The short- and long-term effects of poverty and unemployment on alcohol abuse are investigated using structural equation modelling (SEM) to better understand the observed conflicting relationships among them. We studied 795 community residents who provided complete data in both 1989 and 1991 in the Winnipeg Health and Drinking Survey (WHDS), with equal representation of males and females. Results indicate that
Does Method of Handling Missing Data Affect Results of a Structural Equation Model?
ERIC Educational Resources Information Center
Witta, E. Lea
The influence of method of handling missing data on estimates produced by a structural equation model of the effects of part-time work on high-school student achievement was investigated. Missing data methods studied were listwise deletion, pairwise deletion, the expectation maximization (EM) algorithm, regression, and response pattern. The 26…
Maximum Likelihood Estimation of Nonlinear Structural Equation Models with Ignorable Missing Data
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan; Lee, John C. K.
2003-01-01
The existing maximum likelihood theory and its computer software in structural equation modeling are established on the basis of linear relationships among latent variables with fully observed data. However, in social and behavioral sciences, nonlinear relationships among the latent variables are important for establishing more meaningful models…
The Issue of Isopower in Power Analysis for Tests of Structural Equation Models
ERIC Educational Resources Information Center
MacCallum, Robert; Lee, Taehun; Browne, Michael W.
2010-01-01
Two general frameworks have been proposed for evaluating statistical power of tests of model fit in structural equation modeling (SEM). Under the Satorra-Saris (1985) approach, to evaluate the power of the test of fit of Model A, a Model B, within which A is nested, is specified as the alternative hypothesis and considered as the true model. We…
Self-Conscious Emotions in Response to Perceived Failure: A Structural Equation Model
ERIC Educational Resources Information Center
Bidjerano, Temi
2010-01-01
This study explored the occurrence of self-conscious emotions in response to perceived academic failure among 4th-grade students from the United States and Bulgaria, and the author investigated potential contributors to such negative emotional experiences. Results from structural equation modeling indicated that regardless of country, negative…
A Demonstration of a Systematic Item-Reduction Approach Using Structural Equation Modeling
ERIC Educational Resources Information Center
Larwin, Karen; Harvey, Milton
2012-01-01
Establishing model parsimony is an important component of structural equation modeling (SEM). Unfortunately, little attention has been given to developing systematic procedures to accomplish this goal. To this end, the current study introduces an innovative application of the jackknife approach first presented in Rensvold and Cheung (1999). Unlike…
Analysis of Individuals' Activity-Travel Behavior Based on a Structural Equation Model
Fan Rui; Wang Wei; Yang Min
2010-01-01
Using the activity-travel survey data of Shangyu, a typical medium sized city of China, this paper describes the development, estimation and interpretation of a model relating to socio-demographics, activity participation and travel behavior, A complex set of interrelationships among the variables of interest is estimated simultaneously using the structural equation modeling methodology, with activity participation and travel behavior endogenous to
Structural equation modeling and the latent linearity hypothesis in social and behavioral research
Tenko Raykov; Spiridon Penev
1997-01-01
The issue of sensitivity of the structural equation modeling (SEM) methodology to violations of the underlying hypothesis of linear latent relationships is the focus of this paper. The identity of overall goodness-of-fit indices of an initially considered linear latent pattern model and of an equivalent model not making this assumption exemplifies the lack of routinely available global means within the
Mike W. L. Cheung
2007-01-01
Mediators are variables that explain the association between an independent variable and a dependent variable. Structural equation modeling (SEM) is widely used to test models with mediating effects. This article illustrates how to construct confidence intervals (CIs) of the mediating effects for a variety of models in SEM. Specifically, mediating models with 1 mediator, 2 intermediate mediators, 2 specific mediators,
Transit market research using structural equation modeling and attitudinal market segmentation
Yoram Shiftan; Maren L. Outwater; Yushuang Zhou
2008-01-01
This paper presents a comprehensive approach for identifying potential transit markets and for developing strategies to increase public transport ridership. The approach uses structural equation modeling (SEM) to identify simultaneously travelers’ attitudes, travel behavior, and the causal relationships between a traveler's socioeconomic profile and his\\/her attitude toward travel. Travel attitudes are also used to identify distinct market segments and to
Andreas G. Klein; Bengt O. Muthén
2007-01-01
In this article, a nonlinear structural equation model is introduced and a quasi-maximum likelihood method for simultaneous estimation and testing of multiple nonlinear effects is developed. The focus of the new methodology lies on efficiency, robustness, and computational practicability. Monte-Carlo studies indicate that the method is highly efficient and that the likelihood ratio test of nonlinear effects is robust and
Jacqueline Mayfield; Milton Mayfield
2008-01-01
Purpose – This paper aims to examine the creative environment's effect on a worker's intent to turnover. It was designed to investigate the creative environment's role on garden variety creativity (non-elite) workers' organizational outcomes. Design\\/methodology\\/approach – A survey was used to collect data from a heterogeneous sample of garden variety creativity workers. This data was analyzed using a structural equation
Standards-Based Evaluation and Teacher Career Satisfaction: A Structural Equation Modeling Analysis
Sharon Conley; Donna E. Muncey; Sukkyung You
2005-01-01
Structural equation modeling was used to assess the plausibility of a conceptual model specifying hypothesized linkages among perceptions of characteristics of standards-based evaluation, work environment mediators, and career satisfaction and other outcomes. Four comprehensive high schools located in two neighboring counties in southern California provided the data for this study. The schools’ districts had recently developed and implemented evaluation systems
Structural Equation Models for Evaluating Dynamic Concepts Within Longitudinal Twin Analyses
John J. McArdle; Fumiaki Hamagami
2003-01-01
A great deal of prior research using structural equation models has focused on longitudinal analyses and biometric analyses. Some of this research has even considered the simultaneous analysis of both kinds of analytic problems. The key benefits of these kinds of analyses come from the estimation of novel parameters, such as the heritability of changes. This paper discusses some recent
A Structural Equation Modeling Evaluation of the General Model of Instructional Communication
James A. Katt; James C. McCroskey; Stephen A. Sivo; Virginia P. Richmond; Kristin M. Valencic
2009-01-01
The General Model of Instructional Communication introduced by McCroskey, Valencic, and Richmond (2004) is supported in its original conception by canonical data. This study, however, uses structural equation modeling (SEM) to provide a more detailed analysis. Although the model as originally hypothesized fits the data poorly, analysis of the SEM results suggests adjustments to the original model that substantially improve
Bias and Efficiency in Structural Equation Modeling: Maximum Likelihood Versus Robust Methods
Xiaoling Zhong; Ke-Hai Yuan
2011-01-01
In the structural equation modeling literature, the normal-distribution-based maximum likelihood (ML) method is most widely used, partly because the resulting estimator is claimed to be asymptotically unbiased and most efficient. However, this may not hold when data deviate from normal distribution. Outlying cases or nonnormally distributed data, in practice, can make the ML estimator (MLE) biased and inefficient. In addition
Mike W.L. Cheung; Wai Chan
2009-01-01
Structural equation modeling (SEM) is widely used as a statistical framework to test complex models in behavioral and social sciences. When the number of publications increases, there is a need to systematically synthesize them. Methodology of synthesizing findings in the context of SEM is known as meta-analytic SEM (MASEM). Although correlation matrices are usually preferred in MASEM, there are cases
A structural equation model of activity participation and travel behavior using longitudinal data
Jin-Hyuk Chung; Taewan Kim; Hojong Baik; Yun-Sook Choi
2009-01-01
This paper presents a dynamic structural equation model (SEM) that explicitly addresses complicated causal relationships among socio-demographics, activity participation, and travel behavior. The model assumes that activity participation and travel patterns in the current year are affected by those in previous years. Using the longitudinal dataset collected from Puget sound transportation panel ‘wave 3’ and ‘wave 4,’ these assumptions are
James T. Austin; Robert F. Calderón
1996-01-01
Theoretical and technical research in structural equation modeling (SEM) focuses on the procedures per se rather than on substantive applications of the procedures. An earlier bibliography annotated nearly 300 technical publications about latent variable models. Since that bibliography was published in 1991, there has been a distinct surge in theoretical?technical publications, organized around model evaluation, multifaceted extensions to levels, groups,
Juline Elaine Mills
2002-01-01
The objective of this research was to develop a survey instrument and structural equation model of customer satisfaction (e-satisfaction) with travel Websites. The study proposed that customer satisfaction with a travel Website is determined by the customer's experience at the travel Website. Customer experience at the travel Website is in turn a function of three higher-order constructs, travel Website interface,
Hector Andres Gonzalez
2000-01-01
The purpose of the study is to explore the relationship of spirituality and marital interpersonal relationships from within a Human Ecology Theory framework. Utilizing Structural Equation Modeling with LISREL version 8, a series of three models were tested. A regressive model tested the correlation between the construct Spirituality, which was defined by three spirituality instruments, Religious Orientation Scale, Quest Scale
Katja Kröller; Petra Warschburger
2009-01-01
BACKGROUND: Research concerning child's food intake have considered various influencing factors, for example parental feeding strategies, demographic and weight factors. At this time, however, there are few findings that explore these factors simultaneously. Accordingly, the aim of this study was to test a structural equation model regarding the associations between maternal feeding strategies and child's food intake. METHODS: 556 mothers
ERIC Educational Resources Information Center
In'nami, Yo; Koizumi, Rie
2010-01-01
Because structural equation models are widely used in testing and assessment, investigation into the accuracy of such models may help raise awareness of the value of reanalysis or replication. We focused on second language testing and learning studies and examined: (a) To what extent is information necessary for replication provided by authors?…
ERIC Educational Resources Information Center
Chen, Wei; Wang, Long; Zhang, Xing-Li; Shi, Jian-Nong
2012-01-01
The objective of this study was to investigate the impact of trauma exposure on the posttraumatic stress symptomatology (PTSS) of children who resided near the epicenter of the 2008 Wenchuan earthquake. The mechanisms of this impact were explored via structural equation models with self-esteem and coping strategies included as mediators. The…
A unified equation of state of dense matter and neutron star structure
F. Douchin; P. Haensel
2001-01-01
An equation of state (EOS) of neutron star matter, describing both the neutron star crust and the liquid core, is calculated. It is based on the effective nuclear interaction SLy of the Skyrme type, which is particularly suitable for the application to the calculation of the properties of very neutron rich matter (Chabanat et al. 1997, 1998). The structure of
Bayesian Structural Equation Modeling: A More Flexible Representation of Substantive Theory
ERIC Educational Resources Information Center
Muthen, Bengt; Asparouhov, Tihomir
2012-01-01
This article proposes a new approach to factor analysis and structural equation modeling using Bayesian analysis. The new approach replaces parameter specifications of exact zeros with approximate zeros based on informative, small-variance priors. It is argued that this produces an analysis that better reflects substantive theories. The proposed…
The Trauma Outcome Process Assessment Model: A Structural Equation Model Examination of Adjustment
ERIC Educational Resources Information Center
Borja, Susan E.; Callahan, Jennifer L.
2009-01-01
This investigation sought to operationalize a comprehensive theoretical model, the Trauma Outcome Process Assessment, and test it empirically with structural equation modeling. The Trauma Outcome Process Assessment reflects a robust body of research and incorporates known ecological factors (e.g., family dynamics, social support) to explain…
Painleve singularity structure analysis of three component Gross-Pitaevskii type equations
Kanna, T.; Sakkaravarthi, K. [Department of Physics, Bishop Heber College, Tiruchirapalli 620 017 (India); Kumar, C. Senthil [Department of Physics, VMKV Engineering College, Periaseeragapadi, Salem 636 308 (India); Lakshmanan, M. [Centre for Nonlinear Dynamics, Bharathidasan University, Tiruchirapalli 620 024 (India); Wadati, M. [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)
2009-11-15
In this paper, we have studied the integrability nature of a system of three-coupled Gross-Pitaevskii type nonlinear evolution equations arising in the context of spinor Bose-Einstein condensates by applying the Painleve singularity structure analysis. We show that only for two sets of parametric choices, corresponding to the known integrable cases, the system passes the Painleve test.
Estimation of health effects of prenatal methylmercury exposure using structural equation models
Esben Budtz-Jørgensen; Niels Keiding; Philippe Grandjean; Pal Weihe
2002-01-01
BACKGROUND: Observational studies in epidemiology always involve concerns regarding validity, especially measurement error, confounding, missing data, and other problems that may affect the study outcomes. Widely used standard statistical techniques, such as multiple regression analysis, may to some extent adjust for these shortcomings. However, structural equations may incorporate most of these considerations, thereby providing overall adjusted estimations of associations. This
Blow-up results for vector-valued nonlinear heat equations with no gradient structure
Zaag, Hatem
Blow-up results for vector-valued nonlinear heat equations with no gradient structure Hatem Zaag, nonlinear optics). See for example Levermore and Olivier [15] and the references inside. Blow-up results(t)|H + when t T, we say: u(t) blows-up in finite time T in H. In this paper, we are interested in the finite
Spagnolo, Filippo
278 Structural equation modelling of affects and learning approach in mathematics education Samuel to mathematics achievement. Based on the presage-process-product model of student learning, a hypothesized model and attitudes towards mathematics and mathematics education, influence cognitive activities in the learning
Testing a theory of aircraft noise annoyance: A structural equation analysis
Maarten Kroesen; Eric J. E. Molin; Bert van Wee
2008-01-01
Previous research has stressed the relevance of nonacoustical factors in the perception of aircraft noise. However, it is largely empirically driven and lacks a sound theoretical basis. In this paper, a theoretical model which explains noise annoyance based on the psychological stress theory is empirically tested. The model is estimated by applying structural equation modeling based on data from residents
ERIC Educational Resources Information Center
Zhang, Dongbo
2012-01-01
Using structural equation modeling analysis, this study examined the contribution of vocabulary and grammatical knowledge to second language reading comprehension among 190 advanced Chinese English as a foreign language learners. Vocabulary knowledge was measured in both breadth (Vocabulary Levels Test) and depth (Word Associates Test);…
ERIC Educational Resources Information Center
Elrod, Terry; Haubl, Gerald; Tipps, Steven W.
2012-01-01
Recent research reflects a growing awareness of the value of using structural equation models to analyze repeated measures data. However, such data, particularly in the presence of covariates, often lead to models that either fit the data poorly, are exceedingly general and hard to interpret, or are specified in a manner that is highly data…
An Examination of Statistical Power in Multigroup Dynamic Structural Equation Models
ERIC Educational Resources Information Center
Prindle, John J.; McArdle, John J.
2012-01-01
This study used statistical simulation to calculate differential statistical power in dynamic structural equation models with groups (as in McArdle & Prindle, 2008). Patterns of between-group differences were simulated to provide insight into how model parameters influence power approximations. Chi-square and root mean square error of…
Stuart McDonald
2007-01-01
This paper presents a new approach for numerically simulating the yield curve for the term structure of a zero coupon bond in which the forward rate process is modelled as as tochastic partial differential equations (SPDEs). The numerical technique involves using the method of lines (MOL) to convert the SPDE into a system of SDEs. As stated in chapter four,
ERIC Educational Resources Information Center
Li, Spencer D.
2011-01-01
Mediation analysis in child and adolescent development research is possible using large secondary data sets. This article provides an overview of two statistical methods commonly used to test mediated effects in secondary analysis: multiple regression and structural equation modeling (SEM). Two empirical studies are presented to illustrate the…
Guides & Reports for Questionnaire Design
Applied Research Program (ARP) staff use a variety of methods to develop and test questionnaires, including established Questionnaire Design Principles, empirical methods such as Cognitive Testing and psychometric methods such as Item Response Theory Modeling.
Diet History Questionnaire: International Applications
ARP staff adapted the Diet History Questionnaire (DHQ) for use by Canadian populations in collaboration with the Alberta Cancer Board. This questionnaire takes into account the different food fortification polices of the US and Canada.
Elzahaf, Raga A; Tashani, Osama A; Johnson, Mark I
2013-06-01
There are few studies estimating the prevalence of chronic pain in countries from the Middle East. We translated the Structured Telephone Interviews Questionnaire on Chronic Pain from English into Arabic and assessed its reliability and linguistic validity before using it in a telephone survey in Libya to gather preliminary prevalence data for chronic pain. Intraclass correlations for scaled items were high, and there were no differences in answers to nominal items between the first and second completions of the questionnaire. One hundred and 4 individuals participated in a telephone survey. The prevalence of chronic pain was 25.0% (95% CI, 16.7% to 33.3%) and 50.0% (95% CI: 30.8% to 69.2) of the participants with chronic pain scored ? 12 on the Arabic S-LANSS. Mean ± SD duration of pain was 2.8 ± 1.2 years, and pain was more frequent in women (P = 0.02). 53.8% of participants had taken prescription medication for their pain, and 76.9% had used nondrug methods of treatment including traditional Libyan methods such as Kamara, a local herbal concoction. Eighty percent believed that their doctor would rather treat their illness than their pain, and 35% reported that their doctor did not think that their pain was a problem. Some participants complained that the questionnaire was too long with a mean ± SD call duration of 20 ± 5.4 minutes. We conclude that the Arabic Structured Telephone Interviews Questionnaire on Chronic Pain was reliable and linguistically valid and could be used in a large-scale telephone survey on the Libyan population. Our preliminary estimate of prevalence should be considered with caution because of the small sample size. PMID:22978448
Empathy in group psychoanalytic psychotherapy: questionnaire development.
Pavlovi?, Slavica; Vlastelica, Mirela
2008-09-01
The aim of this study is to develop a questionnaire that can observe empathy in group psychoanalytic psychotherapy and examine the structure of its factors. A questionnaire comprised of 160 items in five-point Likert-type scale was developed through analysis of communication and interaction related to empathizing during group sessions. The questionnaire was applied on 256 patients from 40 therapy groups in 9 cities in Croatia. All 20 group analysts are trained in the Institute for Group Analysis in Zagreb. The patients were selected based on group analysis criteria. After item discrimination and principal component analysis limited to five factors were assessed, 80 items were isolated, 20 of which made a control scale for socially desirable responses. Two parallel questionnaire forms were developed: Group-Analysis-Empathy 1 (GA-Em1) and Group-Analysis-Empathy 2 (GA-Em2). A new, reliable and valid questionnaire for empathy observation employable in group psychotherapy was designed. The following factors were isolated by means of factor analysis: 1. Emotional disclosure and sensibility; 2. Containing and metabolizing; 3. Immersion; 4. Resonance and responsiveness; 5. Insight. A new questionnaire on empathy in group-analytical psychotherapy can measure the capacity for emotional communication among group members and between the group and the group analyst - conductor. PMID:18982775
General features and master equations for structurization in complex dusty plasmas
Tsytovich, V. N., E-mail: tsytov@lpi.ru [Russian Academy of Science, General Physics Institute (Russian Federation); Morfill, G. E., E-mail: gem@mpe.mpg.de [Max Planck Institute for Extraterrestrial Physics (Germany)
2012-02-15
Dust structurization is considered to be typical for complex plasmas. Homogeneous dusty plasmas are shown to be universally unstable. The dusty plasma structurization instability is similar to the gravitational instability and can results in creation of different compact dust structures. A general approach for investigation of the nonlinear stage of structurization in dusty plasmas is proposed and master equations for the description of self-organized structures are formulated in the general form that can be used for any nonlinear model of dust screening. New effects due to the scattering of ions on the nonlinearly screened grains are calculated: nonlinear ion dust drag force and nonlinear ion diffusion. The physics of confinement of dust and plasma components in the equilibria of compact dust structures is presented and is supported by numerical calculations of master equations. The necessary conditions for the existence of equilibrium structures are found for an arbitrary nonlinearity in dust screening. Features of compact dust structures observed in recent experiments agree with the numerically calculated ones. Some proposals for future experiments in spherical chamber are given.
NASA Astrophysics Data System (ADS)
Pankavich, S.; Shreif, Z.; Miao, Y.; Ortoleva, P.
2009-05-01
The kinetics of the self-assembly of nanocomponents into a virus, nanocapsule, or other composite structure is analyzed via a multiscale approach. The objective is to achieve predictability and to preserve key atomic-scale features that underlie the formation and stability of the composite structures. We start with an all-atom description, the Liouville equation, and the order parameters characterizing nanoscale features of the system. An equation of Smoluchowski type for the stochastic dynamics of the order parameters is derived from the Liouville equation via a multiscale perturbation technique. The self-assembly of composite structures from nanocomponents with internal atomic structure is analyzed and growth rates are derived. Applications include the assembly of a viral capsid from capsomers, a ribosome from its major subunits, and composite materials from fibers and nanoparticles. Our approach overcomes errors in other coarse-graining methods, which neglect the influence of the nanoscale configuration on the atomistic fluctuations. We account for the effect of order parameters on the statistics of the atomistic fluctuations, which contribute to the entropic and average forces driving order parameter evolution. This approach enables an efficient algorithm for computer simulation of self-assembly, whereas other methods severely limit the timestep due to the separation of diffusional and complexing characteristic times. Given that our approach does not require recalibration with each new application, it provides a way to estimate assembly rates and thereby facilitate the discovery of self-assembly pathways and kinetic dead-end structures.
NASA Astrophysics Data System (ADS)
Myeong, Jeon-Ok; Crawley, Frank E.
The theory of reasoned action (Ajzen & Fishbein, 1980; Fishbein & Ajzen, 1975) was used to predict and understand Korean high school students' track choice for college entrance. First-year high school students (N = 665) from four representative regions of Korea participated in the study. The survey instruments were questionnaires developed according to the guidelines of the TRA. The target behavior of interest in this study was Korean students' choice of the science track when they completed the track application forms during the first year of high school. Predictors included TRA model and external variables. Multiple regression and the structural equation modeling with LISREL (Jöreskog & Sörbom, 1986) were used to analyze the data. The TRA was found to be applicable for understanding and predicting track choice, with minor modifications. Subjective norm was found to exert a direct influence on personal beliefs and the target behavior.
Non-Uniform Structure of Matter and the Equation of State
Toshiki Maruyama; Satoshi Chiba; Toshitaka Tatsumi
2007-11-22
We investigate the non-uniform structures and the equation of state (EOS) of nuclear matter in the context of the first-order phase transitions (FOPT) such as liquid-gas phase transition, kaon condensation, and hadron-quark phase transition. During FOPT the mixed phases appear, where matter exhibits non-uniform structures called ``Pasta'' structures due to the balance of the Coulomb repulsion and the surface tension between two phases. We treat these effects self-consistently, properly taking into account of the Poisson equation and the Gibbs conditions. Consequently, they make the EOS of the mixed phase closer to that of Maxwell construction due to the Debye screening. This is a general feature of the mixed phase consisting of many species of charged particles.
Wu, Jiun-Yu
2011-10-21
Conventional statistical methods assuming data sampled under simple random sampling are inadequate for use on complex survey data with a multilevel structure and non-independent observations. In structural equation modeling ...
Quantization of wave equations and hermitian structures in partial differential varieties
Paneitz, S. M.; Segal, I. E.
1980-01-01
Sufficiently close to 0, the solution variety of a nonlinear relativistic wave equation—e.g., of the form ?? + m2? + g?p = 0—admits a canonical Lorentz-invariant hermitian structure, uniquely determined by the consideration that the action of the differential scattering transformation in each tangent space be unitary. Similar results apply to linear time-dependent equations or to equations in a curved asymptotically flat space-time. A close relation of the Riemannian structure to the determination of vacuum expectation values is developed and illustrated by an explicit determination of a perturbative 2-point function for the case of interaction arising from curvature. The theory underlying these developments is in part a generalization of that of M. G. Krein and collaborators concerning stability of differential equations in Hilbert space and in part a precise relation between the unitarization of given symplectic linear actions and their full probabilistic quantization. The unique causal structure in the infinite symplectic group is instrumental in these developments. PMID:16592923
Solution of quadratic matrix equations for free vibration analysis of structures.
NASA Technical Reports Server (NTRS)
Gupta, K. K.
1973-01-01
An efficient digital computer procedure and the related numerical algorithm are presented herein for the solution of quadratic matrix equations associated with free vibration analysis of structures. Such a procedure enables accurate and economical analysis of natural frequencies and associated modes of discretized structures. The numerically stable algorithm is based on the Sturm sequence method, which fully exploits the banded form of associated stiffness and mass matrices. The related computer program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be substantially more accurate and economical than other existing procedures of such analysis. Numerical examples are presented for two structures - a cantilever beam and a semicircular arch.
Asymptotics, structure, and integration of sound-proof atmospheric flow equations
Rupert Klein
2009-01-01
Relative to the full compressible flow equations, sound-proof models filter acoustic waves while maintaining advection and\\u000a internal waves. Two well-known sound-proof models, an anelastic model by Bannon and Durran’s pseudo-incompressible model,\\u000a are shown here to be structurally very close to the full compressible flow equations. Essentially, the anelastic model is\\u000a obtained by suppressing ?\\u000a t\\u000a \\u000a ? in the mass continuity
Robert W Haley; Gordon D Luk; Frederick Petty
2001-01-01
To attempt to replicate the syndrome-like structure identified by exploratory factor analysis of symptom reports from 249 Gulf War veterans of a Naval reserve battalion (the developmental sample), we administered Haley's original symptom questionnaire to 335 Gulf War veterans who served primarily in active-duty US Army units living in North Texas (the validation sample). On the basis of recently validated
Denise Catalano; Fong Chan; Lisa Wilson; Chung-Yi Chiu; Veronica R. Muller
2011-01-01
Objective: To translate the theoretical constructs from a model of resilience into a structural equation model and evaluate relationships among the model's theoretical constructs associated with resilience and the occurrence of depressive symptoms. Design: Quantitative descriptive research design using structural equation modeling (SEM). Participants: Two-hundred and fifty-five individuals with SCI recruited from the Canadian Paraplegic Association (CPA). Outcome Measures: Outcome
Construct Validity of the Social Coping Questionnaire
ERIC Educational Resources Information Center
Swiatek, Mary Ann; Cross, Tracy L.
2007-01-01
The Social coping Questionnaire (SCQ) measures strategies used by gifted adolescents to minimize the negative effect they believe their high ability has on their social interactions. Previous studies have supported the factor structure, internal consistency, and test-retest reliability of the SCQ. The current study provides construct validity…
Global Bifurcation Structure and Parameter Dependence of the Hodgkin-Huxley Equations
NASA Astrophysics Data System (ADS)
Pan, Zhenxing; Doi, Shinji
The Hodgkin-Huxley (HH) equations of a squid giant axon are the most important mathematical model in electrophysiology and biology, and are also important in the development of various biologically inspired intelligent devices such as artificial neuron device and neural networks. The HH equations, however, include various constants or parameters whose values were determined based on physiological experiments, and thus the values possess inherent ambiguities. Also, the ‘constants’ are not really constant but change temporally. Thus, in this paper, we study the effects of the change of the constants or parameters on the dynamics of the HH equations and consider the parameter dependence and sensitivity of the equations; we study the bifurcation structure of the HH equations by changing their various parameters. In particular, we take the voltage-dependency of the dynamics of so-called gating variables as typical bifurcation parameters and show that the HH dynamics is very sensitive to the steady-state functions but not sensitive to the time ‘constants’ of gating variables.
Patelarou, Athina E; Dafermos, Vasilis; Brokalaki, Hero; Melas, Christos D; Koukia, Evmorfia
2015-06-01
The present study reports on the translation, cultural adaptation and validation of the Evidence-Based Practice Readiness Survey into the Greek language. Back-translation strategy for cross-cultural research was used to translate the questionnaire into Greek. The psychometric measurements that were performed included: reliability coefficients and explanatory factor analysis using a Varimax Rotation and Principal Components Method. In a further step, confirmatory analysis of the principal components was conducted. The internal consistency of the Greek Evidence-Based Practice Readiness Survey version, as assessed by the Cronbach's alpha coefficient, showed satisfactory results. The value for alpha was found equal to 0.85. The explanatory and confirmatory factor analysis demonstrated a four-factor structure of the tool. PMID:26057651
Iliceto, Paolo; Pompili, Maurizio; Lester, David; Gonda, Xenia; Niolu, Cinzia; Girardi, Nicoletta; Rihmer, Zoltán; Candilera, Gabriella; Girardi, Paolo
2011-01-01
The purpose of this study was to test the validity of affective temperaments for predicting psychiatric morbidity and suicide risk, using a two-factor model to explain the relationships between temperament, anxiety, depression, and hopelessness. We investigated 210 high school students, 103 males and 107 females, 18-19 years old, who were administered self-report questionnaires to assess temperament (TEMPS-A), depression (BDI-II), anxiety (STAI) and hopelessness (BHS). The final structural model had a good fit with the data, with two factors significantly correlated, the first labeled unstable cyclothymic temperament including Dysthymic/Cyclothymic/Anxious temperament, Irritable temperament and Depression, and the second labeled Demoralization including Anxiety (State/Trait) and Hopelessness. Depression, anxiety and hopelessness are in a complex relationship partly mediated by temperament. PMID:21789278
Iliceto, Paolo; Pompili, Maurizio; Lester, David; Gonda, Xenia; Niolu, Cinzia; Girardi, Nicoletta; Rihmer, Zoltán; Candilera, Gabriella; Girardi, Paolo
2011-01-01
The purpose of this study was to test the validity of affective temperaments for predicting psychiatric morbidity and suicide risk, using a two-factor model to explain the relationships between temperament, anxiety, depression, and hopelessness. We investigated 210 high school students, 103 males and 107 females, 18-19 years old, who were administered self-report questionnaires to assess temperament (TEMPS-A), depression (BDI-II), anxiety (STAI) and hopelessness (BHS). The final structural model had a good fit with the data, with two factors significantly correlated, the first labeled unstable cyclothymic temperament including Dysthymic/Cyclothymic/Anxious temperament, Irritable temperament and Depression, and the second labeled Demoralization including Anxiety (State/Trait) and Hopelessness. Depression, anxiety and hopelessness are in a complex relationship partly mediated by temperament. PMID:21789278
Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation
NASA Technical Reports Server (NTRS)
Deng, Z. T.; Oviedo-Rojas, Ruben; Chow, Alan; Litchford, Ron J.; Cook, Stephen (Technical Monitor)
2002-01-01
This paper reports the recent research results of shockwave structure predictions using a new developed code. The modified Rankine-Hugoniot relations across a standing normal shock wave are discussed and adopted to obtain jump conditions. Coupling a electrostatic body force to the Burnett equations, the weakly ionized flow field across the shock wave was solved. Results indicated that the Modified Rankine-Hugoniot equations for shock wave are valid for a wide range of ionization fraction. However, this model breaks down with small free stream Mach number and with large ionization fraction. The jump conditions also depend on the value of free stream pressure, temperature and density. The computed shock wave structure with ionization provides results, which indicated that shock wave strength may be reduced by existence of weakly ionized gas.
An, Hongli; Fan, Engui; Zhu, Haixing
2015-01-01
The 2+1-dimensional compressible Euler equations are investigated here. A power-type elliptic vortex ansatz is introduced and thereby reduction obtains to an eight-dimensional nonlinear dynamical system. The latter is shown to have an underlying integral Ermakov-Ray-Reid structure of Hamiltonian type. It is of interest to notice that such an integrable Ermakov structure exists not only in the density representations but also in the velocity components. A class of typical elliptical vortex solutions termed pulsrodons corresponding to warm-core eddy theory is isolated and its behavior is simulated. In addition, a Lax pair formulation is constructed and the connection with stationary nonlinear cubic Schrödinger equations is established. PMID:25679730
Quantum structure emerging from the transformation design of the Dirac equation
Lin, De-Hone, E-mail: dhlin@mail.nsysu.edu.tw
2014-06-15
It is shown that a quantum structure can be created by a set of chosen constraint conditions that emerge from the transformation design of the Dirac equation in general relativity. As an explanation, the constraints that cause novel bound states with the quantization rule of a 2D Coulomb system are presented. The discussion in this paper provides a systematic way to look for constraints that generate a required quantization rule. -- Highlights: •We perform the transformation design of space and time for spin-1/2 matter waves. •A quantum rule could naturally emerge as constraints imposed on the Dirac equation itself. •New fermion states share the quantum spectrum of a 2D Coulomb system. •Transformation design uncovers a new exact solvable model. •A quantum spectrum can be created by a geometric structure.
Numerical solution of quadratic matrix equations for free vibration analysis of structures
NASA Technical Reports Server (NTRS)
Gupta, K. K.
1975-01-01
This paper is concerned with the efficient and accurate solution of the eigenvalue problem represented by quadratic matrix equations. Such matrix forms are obtained in connection with the free vibration analysis of structures, discretized by finite 'dynamic' elements, resulting in frequency-dependent stiffness and inertia matrices. The paper presents a new numerical solution procedure of the quadratic matrix equations, based on a combined Sturm sequence and inverse iteration technique enabling economical and accurate determination of a few required eigenvalues and associated vectors. An alternative procedure based on a simultaneous iteration procedure is also described when only the first few modes are the usual requirement. The employment of finite dynamic elements in conjunction with the presently developed eigenvalue routines results in a most significant economy in the dynamic analysis of structures.
S. Ryan; F. Schaefer; R. Destefanis; M. Lambert
2008-01-01
During a recent experimental test campaign performed in the framework of ESA Contract 16721, the ballistic performance of multiple satellite-representative Carbon Fibre Reinforced Plastic (CFRP)\\/Aluminium honeycomb sandwich panel structural configurations (GOCE, Radarsat-2, Herschel\\/Planck, BeppoSax) was investigated using the two-stage light-gas guns at EMI. The experimental results were used to develop and validate a new empirical Ballistic Limit Equation (BLE), which
The Trauma Outcome Process Assessment Model: A Structural Equation Model Examination of Adjustment
Susan E. Borja; Jennifer L. Callahan
2009-01-01
This investigation sought to operationalize a comprehensive theoretical model, the Trauma Outcome Process Assessment, and test it empirically with structural equation modeling. The Trauma Outcome Process Assessment reflects a robust body of research and incorporates known ecological factors (e.g., family dynamics, social support) to explain internalizing distress (e.g., anxiety, depression), externalizing distress (e.g., aggression), and recovery outcomes following traumatic events.
Implicit SUPG solution of Euler equations using edge-based data structures
Lucia Catabriga; Alvaro L. G. A. Coutinho
2002-01-01
In this work we present an implicit, edge-based implementation of the semi-discrete SUPG formulation with shock-capturing for the Euler equations in conservative variables. By disassembling the resulting finite element matrices into their edge contributions, sparse matrix coefficients, residuals and matrix-vector products needed in Krylov-update techniques are computed based on edge data structures. The resulting solution method requires less memory and
Spinor structural equations for Killing tensors in Einstein spaces of general relativity.
NASA Astrophysics Data System (ADS)
Kudrya, Yu. M.
Structural equations and their first series of integrability conditions are obtained for Killing tensors of rank two associated with quadratic first integrals of motion of test bodies in Einstin space-times by the use of spinor formalism of general relativity. The complete sets of integrability conditions are derived in symmetric spaces of Petrov type N and D. The numbers of quadratic integrals are calculated.
Joyce L. Y. Kwan; Wai Chan
We propose a two-stage method for comparing standardized coefficients in structural equation modeling (SEM). At stage 1, we\\u000a transform the original model of interest into the standardized model by model reparameterization, so that the model parameters\\u000a appearing in the standardized model are equivalent to the standardized parameters of the original model. At stage 2, we impose\\u000a appropriate linear equality constraints
Xin Tong; Zhiyong Zhang; Ke-Hai Yuan
2011-01-01
Traditional structural equation modeling (SEM) techniques have trouble dealing with incomplete and\\/or nonnormal data that are often encountered in practice. Yuan and Zhang (2011a) developed a two-stage procedure for SEM to handle nonnormal missing data and proposed four test statistics for overall model evaluation. Although these statistics have been shown to work well with complete data, their performance for incomplete
Michael N. Bagley; Patricia L. Mokhtarian
2002-01-01
. Using a system of structural equations, this paper empirically examines the relationship of residential neighborhood type\\u000a to travel behavior, incorporating attitudinal, lifestyle, and demographic variables. Data on these variables were collected\\u000a from residents of five neighborhoods in the San Francisco Bay Area in 1993 (final N=515), including “traditional” and “suburban” as well as mixtures of those two extremes. A
Fixed-Effects Meta-Analyses as Multiple-Group Structural Equation Models
Mike W.-L. Cheung
2010-01-01
Meta-analysis is the statistical analysis of a collection of analysis results from individual studies, conducted for the purpose of integrating the findings. Structural equation modeling (SEM), on the other hand, is a multivariate technique for testing hypothetical models with latent and observed variables. This article shows that fixed-effects meta-analyses with the following characteristics can be modeled in the SEM framework:
Structural equation modeling in practice: A review and recommended two-step approach
James C. Anderson; David W. Gerbing
1988-01-01
In this article, we provide guidance for substantive researchers on the use of structural equation modeling in practice for theory testing and development. We present a comprehensive, two-step modeling approach that employs a series of nested models and sequential chi-square difference tests. We discuss the comparative advantages of this approach over a one-step approach. Considerations in specification, assessment of fit,
On Discerning Dynamical Structure from the Once-Integrated Momentum Equation
J. Klewicki; P. Fife
A critical initial step in multiscale\\/singular perturbation-type studies of the mean flow structure of steady wall-bounded tur- bulent flows involves determining the appropriately reduced, asymptotically approximate, forms of the mean momentum equationsuchthattheyaccuratelyreflectthedynamicsover spe- cific subdomains of the flow. Traditionally, such analyses be- gin with the once-integrated mean momentum equation, rather thanits unintegratedform. Simple examples(turbulent Couette, laminar Poiseuille) of flows with
A Structural Equation Analysis of Family Accommodation in Pediatric Obsessive-Compulsive Disorder
Nicole Elise Caporino; Jessica Morgan; Jason Beckstead; Vicky Phares; Tanya K. Murphy; Eric A. Storch
2011-01-01
Family accommodation of symptoms is counter to the primary goals of cognitive-behavioral therapy for pediatric obsessive-compulsive\\u000a disorder (OCD) and can pose an obstacle to positive treatment outcomes. Although increased attention has been given to family\\u000a accommodation in pediatric OCD, relatively little is known about associated child and parent characteristics, and their mediating\\/moderating\\u000a effects. This study examined a structural equation model
A preference free partial differential equation for the term structure of interest rates
Carl Chiarella; Nadima El-Hassan
1996-01-01
The objectives of this paper are two-fold: the first is the reconciliation of the differences between the Vasicek and the\\u000a Heath-Jarrow-Morton approaches to the modelling of term structure of interest rates. We demonstrate that under certain (not\\u000a empirically unreasonable) assumptions prices of interest-rate sensitive claims within the Heath-Jarrow-Morton framework can\\u000a be expressed as a partial differential equation which both is
Cosmological Structure Formation under MOND: a new numerical solver for Poisson's equation
Claudio Llinares; Alexander Knebe; HongSheng Zhao
2008-09-17
We present a novel solver for an analogue to Poisson's equation in the framework of modified Newtonian dynamics (MOND). This equation is highly non-linear and hence standard codes based upon tree structures and/or FFT's in general are not applicable; one needs to defer to multi-grid relaxation techniques. After a detailed description of the necessary modifications to the cosmological N-body code AMIGA (formerly known as MLAPM) we utilize the new code to revisit the issue of cosmic structure formation under MOND. We find that the proper (numerical) integration of a MONDian Poisson's equation has some noticable effects on the final results when compared against simulations of the same kind but based upon rather ad-hoc assumptions about the properties of the MONDian force field. Namely, we find that the large-scale structure evolution is faster in our revised MOND model leading to an even stronger clustering of galaxies, especially when compared to the standard LCDM paradigm.
Chu, Hsin; Liao, Yuan-Mei; Chen, Chiung-Hua; Ou, Keng-Liang; Chang, Lu-I; Chou, Kuei-Ru
2013-01-01
Background Global efforts in response to the increased prevalence of the human immunodeficiency virus (HIV) are mainly aimed at reducing high risk sexual behaviors among young people. However, knowledge regarding intentions of young people to engage in protective sexual behaviors is still lacking in many countries around the world, especially in Sub-Saharan Africa where prevalence of human immunodeficiency virus is the highest. The objective of this study was to test the theory of planned behavior (TPB) for predicting factors associated with protective sexual behaviors, including sexual abstinence and condom use, among in-school youths aged between 15 and 19 years in Swaziland. Methods This cross-sectional survey was conducted using a anonymous questionnaire. A two-stage stratified and cluster random sampling method was used. Approximately one hundred pupils from each of four schools agreed to participate in the study, providing a total sample size of 403 pupils of which 369 were ultimately included for data analysis. The response rate was 98%. Structural equation modeling was used to analyse hypothesized paths. Results The TPB model used in this study was effective in predicting protective sexual behavior among Swazi in-school youths, as shown by model fit indices. All hypothesized constructs significantly predicted intentions for abstinence and condom use, except perceived abstinence controls. Subjective norms were the strongest predictors of intention for premarital sexual abstinence; however, perceived controls for condom use were the strongest predictors of intention for condom use. Conclusions Our findings support application of the model in predicting determinants of condom use and abstinence intentions among Swazi in-school youths. PMID:23861756
Detilleux, J; Theron, L; Beduin, J-M; Hanzen, C
2012-12-01
In dairy cattle, many farming practices have been associated with occurrence of mastitis but it is often difficult to disentangle the causal threads. Structural equation models may reduce the complexity of such situations. Here, we applied the method to examine the links between mastitis (subclinical and clinical) and risk factors such as herd demographics, housing conditions, feeding procedures, milking practices, and strategies of mastitis prevention and treatment in 345 dairy herds from the Walloon region of Belgium. During the period January 2006 to October 2007, up to 110 different herd management variables were recorded by two surveyors using a questionnaire for the farm managers and during a farm visit. Monthly somatic cell counts of all lactating cows were collected by the local dairy herd improvement association. Structural equation models were created to obtain a latent measure of mastitis and to reduce the complexity of the relationships between farming practices, between indicators of herd mastitis and between both. Robust maximum likelihood estimates were obtained for the effects of the herd management variables on the latent measure of herd mastitis. Variables associated directly (p<0.05) with the latent measure of herd mastitis were the addition of urea in the rations; the practices of machine stripping, of pre-and post-milking teat disinfection; the presence of cows with hyperkeratotic teats, of cubicles for housing and of dirty liners before milking; the treatment of subclinical cases of mastitis; and the age of the herd (latent variable for average age and parity of cows, and percentage of heifers in the herd). Treatment of subclinical mastitis was also an intermediate in the association between herd mastitis and post-milking teat disinfection. The study illustrates how structural equation model provides information regarding the linear relationships between risk factors and a latent measure of mastitis, distinguishes between direct relationships and relationships mediated through intermediate risk factors, allows the construction of latent variables and tests the directional hypotheses proposed in the model. PMID:22770804
Rusli, Bin Nordin; Edimansyah, Bin Abdin; Naing, Lin
2008-01-01
Background The relationships between working conditions [job demand, job control and social support]; stress, anxiety, and depression; and perceived quality of life factors [physical health, psychological wellbeing, social relationships and environmental conditions] were assessed using a sample of 698 male automotive assembly workers in Malaysia. Methods The validated Malay version of the Job Content Questionnaire (JCQ), Depression Anxiety Stress Scales (DASS) and the World Health Organization Quality of Life-Brief (WHOQOL-BREF) were used. A structural equation modelling (SEM) analysis was applied to test the structural relationships of the model using AMOS version 6.0, with the maximum likelihood ratio as the method of estimation. Results The results of the SEM supported the hypothesized structural model (?2 = 22.801, df = 19, p = 0.246). The final model shows that social support (JCQ) was directly related to all 4 factors of the WHOQOL-BREF and inversely related to depression and stress (DASS). Job demand (JCQ) was directly related to stress (DASS) and inversely related to the environmental conditions (WHOQOL-BREF). Job control (JCQ) was directly related to social relationships (WHOQOL-BREF). Stress (DASS) was directly related to anxiety and depression (DASS) and inversely related to physical health, environment conditions and social relationships (WHOQOL-BREF). Anxiety (DASS) was directly related to depression (DASS) and inversely related to physical health (WHOQOL-BREF). Depression (DASS) was inversely related to the psychological wellbeing (WHOQOL-BREF). Finally, stress, anxiety and depression (DASS) mediate the relationships between job demand and social support (JCQ) to the 4 factors of WHOQOL-BREF. Conclusion These findings suggest that higher social support increases the self-reported quality of life of these workers. Higher job control increases the social relationships, whilst higher job demand increases the self-perceived stress and decreases the self-perceived quality of life related to environmental factors. The mediating role of depression, anxiety and stress on the relationship between working conditions and perceived quality of life in automotive workers should be taken into account in managing stress amongst these workers. PMID:18254966
The Attitudes to Ageing Questionnaire: Mokken Scaling Analysis
Shenkin, Susan D.; Watson, Roger; Laidlaw, Ken; Starr, John M.; Deary, Ian J.
2014-01-01
Background Hierarchical scales are useful in understanding the structure of underlying latent traits in many questionnaires. The Attitudes to Ageing Questionnaire (AAQ) explored the attitudes to ageing of older people themselves, and originally described three distinct subscales: (1) Psychosocial Loss (2) Physical Change and (3) Psychological Growth. This study aimed to use Mokken analysis, a method of Item Response Theory, to test for hierarchies within the AAQ and to explore how these relate to underlying latent traits. Methods Participants in a longitudinal cohort study, the Lothian Birth Cohort 1936, completed a cross-sectional postal survey. Data from 802 participants were analysed using Mokken Scaling analysis. These results were compared with factor analysis using exploratory structural equation modelling. Results Participants were 51.6% male, mean age 74.0 years (SD 0.28). Three scales were identified from 18 of the 24 items: two weak Mokken scales and one moderate Mokken scale. (1) ‘Vitality’ contained a combination of items from all three previously determined factors of the AAQ, with a hierarchy from physical to psychosocial; (2) ‘Legacy’ contained items exclusively from the Psychological Growth scale, with a hierarchy from individual contributions to passing things on; (3) ‘Exclusion’ contained items from the Psychosocial Loss scale, with a hierarchy from general to specific instances. All of the scales were reliable and statistically significant with ‘Legacy’ showing invariant item ordering. The scales correlate as expected with personality, anxiety and depression. Exploratory SEM mostly confirmed the original factor structure. Conclusions The concurrent use of factor analysis and Mokken scaling provides additional information about the AAQ. The previously-described factor structure is mostly confirmed. Mokken scaling identifies a new factor relating to vitality, and a hierarchy of responses within three separate scales, referring to vitality, legacy and exclusion. This shows what older people themselves consider important regarding their own ageing. PMID:24892302
JOB EVALUATION QUESTIONNAIRE ANSWER SHEET
Amin, S. Massoud
JOB EVALUATION QUESTIONNAIRE ANSWER SHEET DO NOT WRITE IN THIS SPACE N.C. Date Received Reclass New Starting Date in Class Yes No NA (NA if Temporary Job) Notice # Effective Date If Reclassified IS TO BE USED WITH THE JOB EVALUATION QUESTIONNAIRE (BA 802) ONLY FOR POSITIONS COVERED BY CIVIL SERVICE
Geometric Properties of the Maxwell Set and a Vortex Filament Structure for Burgers Equation
NASA Astrophysics Data System (ADS)
Neate, A. D.; Truman, A.
2007-04-01
The inviscid limit of the stochastic Burgers equation is discussed in terms of the level surfaces of the minimising Hamilton Jacobi function, the classical mechanical caustic and the Maxwell set and their algebraic pre-images under the classical mechanical flow map. We examine the geometry of the Maxwell set in terms of the behaviour of the pre-Maxwell set, the pre-caustic and the pre-level surfaces. In particular, contrary to the ideas of Helmholtz and Lord Kelvin, we prove that even if initially the fluid flow is irrotational, in the inviscid limit, associated with the advent of the Maxwell set a non-zero vorticity vector forms in the fluid with vortex lines on the Maxwell set. This suggests that in quite general circumstances for small viscosity there is a vortex filament structure near the Maxwell set for both deterministic and stochastic Burgers equations.
Structure and decay constant of the {rho} meson within the Bethe-Salpeter equation
Wang, Z. G. [Department of Physics, North China Electric Power University, Baoding 071003 (China); Wan, S. L. [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)
2007-08-15
In this article, we study the structure of the {rho} meson in the framework of the coupled rainbow Schwinger-Dyson equation and ladder Bethe-Salpeter equation with a confining effective potential. The u and d quark propagators get significantly modified, the mass poles are absent in the timelike region, which implements confinement naturally. The Bethe-Salpeter amplitudes of the {rho} meson center around zero momentum and extend to the energy scale about q{sup 2}=1 GeV{sup 2}, which happens to be the energy scale of chiral symmetry breaking, strong interactions in the infrared region result in bound state. The numerical results of the mass and decay constant of the {rho} meson are in agreement with the experimental data.
NASA Astrophysics Data System (ADS)
Andreasen, J.; Kolesik, M.
2012-09-01
Unidirectional pulse propagation equations [UPPE, Phys. Rev. E10.1103/PhysRevE.70.036604 70, 036604 (2004)] have provided a theoretical underpinning for computer-aided investigations into dynamics of high-power ultrashort laser pulses and have been successfully utilized for almost a decade. Unfortunately, they are restricted to applications in bulk media or, with additional approximations, to simple waveguide geometries in which only a few guided modes can approximate the propagating waveform. The purpose of this work is to generalize the directional pulse propagation equations to structures characterized by strong refractive index differences and material interfaces. We also outline a numerical solution framework that draws on the combination of the bulk-media UPPE method with single-frequency beam-propagation techniques.
Myron W. Evans
2004-01-01
The first and second Maurer-Cartan structure relations are combined with the Evans field equation [1] for differential forms to build a grand unified field theory based on differential geometry. The tetrad or vielbein plays a central role in this theory, and all four fields currently thought to exist in nature can be described by the same equations, the tangent space
Sideridis, Georgios; Simos, Panagiotis; Papanicolaou, Andrew; Fletcher, Jack
2014-01-01
The present study assessed the impact of sample size on the power and fit of structural equation modeling applied to functional brain connectivity hypotheses. The data consisted of time-constrained minimum norm estimates of regional brain activity during performance of a reading task obtained with magnetoencephalography. Power analysis was first conducted for an autoregressive model with 5 latent variables (brain regions), each defined by 3 indicators (successive activity time bins). A series of simulations were then run by generating data from an existing pool of 51 typical readers (aged 7.5-12.5 years). Sample sizes ranged between 20 and 1,000 participants and for each sample size 1,000 replications were run. Results were evaluated using chi-square Type I errors, model convergence, mean RMSEA (root mean square error of approximation) values, confidence intervals of the RMSEA, structural path stability, and D-Fit index values. Results suggested that 70 to 80 participants were adequate to model relationships reflecting close to not so close fit as per MacCallum et al.'s recommendations. Sample sizes of 50 participants were associated with satisfactory fit. It is concluded that structural equation modeling is a viable methodology to model complex regional interdependencies in brain activation in pediatric populations. PMID:25435589
Kirby, James B; Bollen, Kenneth A
2009-07-01
Structural Equation Modeling with latent variables (SEM) is a powerful tool for social and behavioral scientists, combining many of the strengths of psychometrics and econometrics into a single framework. The most common estimator for SEM is the full-information maximum likelihood estimator (ML), but there is continuing interest in limited information estimators because of their distributional robustness and their greater resistance to structural specification errors. However, the literature discussing model fit for limited information estimators for latent variable models is sparse compared to that for full information estimators. We address this shortcoming by providing several specification tests based on the 2SLS estimator for latent variable structural equation models developed by Bollen (1996). We explain how these tests can be used to not only identify a misspecified model, but to help diagnose the source of misspecification within a model. We present and discuss results from a Monte Carlo experiment designed to evaluate the finite sample properties of these tests. Our findings suggest that the 2SLS tests successfully identify most misspecified models, even those with modest misspecification, and that they provide researchers with information that can help diagnose the source of misspecification. PMID:20419054
Pressure-induced structural phase transition and equation of state of LiTaO3.
Xiang, Shikai; Liu, Lei; Zhao, Jianzhou; Zhou, Xianming; Jing, Qiuming; Zhang, Yi; Liu, Shenggang; Wang, Zhigang; Bi, Yan; Xu, Ji'an; Geng, Huayun; Dai, Chengda; Cai, Lingcang; Wu, Qiang; Liu, Jing; Wang, Chenju; Zhang, Xiulu
2013-05-29
Using in situ high-pressure x-ray diffraction and ab initio techniques, a high-pressure structure of LiTaO3 has been determined to be an orthorhombic phase with the space group Pnma. At ambient temperature, the transition pressure from the R3c phase (the ordinary phase at ambient pressure and temperature) to the Pnma phase is about 33.0 GPa and the phase transition is reversible. This phase transition can be reproduced qualitatively by ab initio calculations, but with a lower transition pressure of 19.9 GPa. The equation of state of LiTaO3 is also reported. PMID:23649105
NASA Astrophysics Data System (ADS)
Tsytovich, V. N.
2009-05-01
Basic equations for dust structures are formulated that account for the balance of the forces, plasma fluxes, and grain charges with allowance for nonlinearity in the screening of individual grains and possible violation of quasineutrality due to the interaction of collective fields with plasma fluxes. A theory of non-linear drag forces exerted by plasma fluxes on dust grains is developed for moderate drift flux velocities, higher than the mean ion thermal velocity but much lower than the acoustic speed. It is shown that equilibrium dust structures have finite sizes and negative charges and that they can exist only in a certain range of intensities of external fluxes on their surfaces. When there is no additional volume ionization, the size of the structures is determined by the intensity of the external flux. A study is made of a weakly ionized dusty plasma in which the interaction of its components with neutral gas atoms plays a major role. The ion, electron, and dust density distributions, as well as the distributions of the dust grain charges and plasma fluxes, are calculated self-consistently as functions of the distance from the center of a structure.
Killing-Yano equations with torsion, worldline actions and G-structures
G. Papadopoulos
2011-11-29
We determine the geometry of the target spaces of supersymmetric non-relativistic particles with torsion and magnetic couplings, and with symmetries generated by the fundamental forms of G-structures for $G= U(n), SU(n), Sp(n), Sp(n)\\cdot Sp(1), G_2$ and $Spin(7)$. We find that the Killing-Yano equation, which arises as a condition for the invariance of the worldline action, does not always determine the torsion coupling uniquely in terms of the metric and fundamental forms. We show that there are several connections with skew-symmetric torsion for $G=U(n), SU(n)$ and $G_2$ that solve the invariance conditions. We describe all these compatible connections for each of the $G$-structures and explain the geometric nature of the couplings.
Kim, Min-Geun; Jang, Hong-Lae [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)] [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, Seonho, E-mail: secho@snu.ac.kr [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)] [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)
2013-05-01
An efficient adjoint design sensitivity analysis method is developed for reduced atomic systems. A reduced atomic system and the adjoint system are constructed in a locally confined region, utilizing generalized Langevin equation (GLE) for periodic lattice structures. Due to the translational symmetry of lattice structures, the size of time history kernel function that accounts for the boundary effects of the reduced atomic systems could be reduced to a single atom’s degrees of freedom. For the problems of highly nonlinear design variables, the finite difference method is impractical for its inefficiency and inaccuracy. However, the adjoint method is very efficient regardless of the number of design variables since one additional time integration is required for the adjoint GLE. Through numerical examples, the derived adjoint sensitivity turns out to be accurate and efficient through the comparison with finite difference sensitivity.
Bayesian analysis of the structural equation models with application to a longitudinal myopia trial.
Wang, Yi-Fu; Fan, Tsai-Hung
2012-01-30
Myopia is becoming a significant public health problem, affecting more and more people. Studies indicate that there are two main factors, hereditary and environmental, suspected to have strong impact on myopia. Motivated by the increase in the number of people affected by this problem, this paper focuses primarily on the utilization of mathematical methods to gain further insight into their relationship with myopia. Accordingly, utilizing multidimensional longitudinal myopia data with correlation between both eyes, we develop a Bayesian structural equation model including random effects. With the aid of the MCMC method, it is capable of expressing the correlation between repeated measurements as well as the two-eye correlation and can be used to explore the relational structure among the variables in the model. We consider four observed factors, including intraocular pressure, anterior chamber depth, lens thickness, and axial length. The results indicate that the genetic effect has much greater influence on myopia than the environmental effects. PMID:21976389
Guidelines for a graph-theoretic implementation of structural equation modeling
Grace, James B.; Schoolmaster, Donald R., Jr.; Guntenspergen, Glenn R.; Little, Amanda M.; Mitchell, Brian R.; Miller, Kathryn M.; Schweiger, E. William
2012-01-01
Structural equation modeling (SEM) is increasingly being chosen by researchers as a framework for gaining scientific insights from the quantitative analyses of data. New ideas and methods emerging from the study of causality, influences from the field of graphical modeling, and advances in statistics are expanding the rigor, capability, and even purpose of SEM. Guidelines for implementing the expanded capabilities of SEM are currently lacking. In this paper we describe new developments in SEM that we believe constitute a third-generation of the methodology. Most characteristic of this new approach is the generalization of the structural equation model as a causal graph. In this generalization, analyses are based on graph theoretic principles rather than analyses of matrices. Also, new devices such as metamodels and causal diagrams, as well as an increased emphasis on queries and probabilistic reasoning, are now included. Estimation under a graph theory framework permits the use of Bayesian or likelihood methods. The guidelines presented start from a declaration of the goals of the analysis. We then discuss how theory frames the modeling process, requirements for causal interpretation, model specification choices, selection of estimation method, model evaluation options, and use of queries, both to summarize retrospective results and for prospective analyses. The illustrative example presented involves monitoring data from wetlands on Mount Desert Island, home of Acadia National Park. Our presentation walks through the decision process involved in developing and evaluating models, as well as drawing inferences from the resulting prediction equations. In addition to evaluating hypotheses about the connections between human activities and biotic responses, we illustrate how the structural equation (SE) model can be queried to understand how interventions might take advantage of an environmental threshold to limit Typha invasions. The guidelines presented provide for an updated definition of the SEM process that subsumes the historical matrix approach under a graph-theory implementation. The implementation is also designed to permit complex specifications and to be compatible with various estimation methods. Finally, they are meant to foster the use of probabilistic reasoning in both retrospective and prospective considerations of the quantitative implications of the results.
Physical Activity Questionnaire Search Results
The Brunel Lifestyle Physical Activity Questionnaire a4 If you add together each session of pre-planned physical activity that you engage in during a normal week, how much time would you estimate that you spend in total?
The inheritance of migraine with aura estimated by means of structural equation modelling
Ulrich, V.; Gervil, M.; Kyvik, K.; Olesen, J.; Russell, M.
1999-01-01
Studies of migraine with aura (MA) have shown familial aggregation of the disorder, which cannot be explained by simple mendelian inheritance. The interest in a genetic basis for the disorder has increased after identification of three genetic loci for familial hemiplegic migraine (FHM), which is a rare subtype of MA with autosomal dominant inheritance. Both genetic and environmental factors seem to be important in the expression of MA. To elucidate the molecular pathogenesis of MA, knowledge of the relative role of genetic and environmental factors is essential. Twin studies are a classic way to analyse this. We applied structural equation modelling on MA with twin data obtained from a population based twin register in order to evaluate the effects of genes and environment. The correlation in liability of MA was 0.68 in monozygotic (MZ) and 0.22 in dizygotic (DZ) twin pairs, indicating a high degree of genetic determination in the total variance of liability. The best fitting model combined additive genetic effects and environmental effects that were not shared by the twins. The estimate of heritability was 0.65 and similar in males and females.???Keywords: migraine with aura; inheritance; twins; structural equation modelling PMID:10204850
Grace, J.B.; Bollen, K.A.
2008-01-01
Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling heterogeneous concepts of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially-reduced-form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influence of suites of variables are often of interest. ?? Springer Science+Business Media, LLC 2007.
Mohamed Habashy Hussein
2010-01-01
The Peer Interaction in Primary School Questionnaire (PIPSQ) was developed to assess individuals’ levels of bullying and victimization.\\u000a This study used the approach of latent means analysis (LMA) within the framework of structural equation modeling (SEM) to\\u000a explore the factor structure and gender differences associated with the PIPSQ in a sample of Egyptian (N = 361), Saudi Arabian (N = 350) and USA (270)
Kramer, Lena; Hirsch, Oliver; Becker, Annette; Donner-Banzhoff, Norbert
2014-01-01
Introduction: The implementation of complex medical interventions in daily practice is often fraught with difficulties. According to the iterative phase model proposed by the British Medical Research Council (MRC), the development, implementation and evaluation of complex interventions should be theory-driven. A conceptual model that seems to be a promising framework is the Theory of planned behaviour (TPB). In our study we aimed to develop and validate a generic and multifaceted questionnaire based on the TPB to detect physicians’ willingness to implement complex medical interventions and the factors influencing this willingness. Methods: The questionnaire was developed according to the literature and was informed by previous qualitative research of our department. It was validated on the example of an electronic library of decision aids, arriba-lib. The sample consisted of 181 General Practitioners (GPs) who received a training regarding arriba-lib and subsequently filled in the questionnaire, assessing the TPB variables attitude, subjective norm, perceived behaviour control and intention. Follow-up assessments were conducted after two (assessing retest reliability) and eight weeks (assessing target behaviour). We performed a confirmatory factor analysis investigating the factorial structure of our questionnaire according to the TPB. Beside the calculation of the questionnaire’s psychometric properties we conducted a structural equation model and an ordinal regression to predict actual behaviour regarding the installation and application of arriba-lib. Results: The postulated three factorial model (attitude, subjective norm, perceived behaviour control) of our questionnaire based on the TPB was rejected. A two factorial model with a combined factor subjective norm/perceived behaviour control was accepted. The explained variance in the ordinal regression was low (Nagelkerke’s R2=.12). Neither attitude nor intention were able to predict the use or non-use of arriba-lib (attitude: p=.68, intention: p=.44). For the combined factor subjective norm/perceived behaviour control a significant, but small effect (p=.03) was shown. Conclusions: The TPB is not an adequate theoretical framework to guide the development of a generic questionnaire in the context of the implementation of complex interventions. To enable the successful implementation of complex medical interventions evaluators have to go through the whole development and evaluation process according to the MRC-model, without short cuts. Further, it has to be discussed if a generic instrument can be valid and useful. Regarding the TPB a publication bias regarding the theory’s applicability might have to be considered. PMID:24696674
ERIC Educational Resources Information Center
Caldas, Stephen J.; Cornigans, Linda
2015-01-01
This study used structural equation modeling to conduct a first and second order confirmatory factor analysis (CFA) of a scale developed by McDonald and Moberg (2002) to measure three dimensions of social capital among a diverse group of middle- and upper-middle-class elementary school parents in suburban New York. A structural path model was…
Joao de Abreu e Silva; Konstadinos G Goulias
2009-01-01
This paper addresses the relationship between travel behavior and land use patterns through the use of a structural equations modeling framework and a more comprehensive modeling than in the past. The proposed model structure is by design heavily influenced by a model developed for Lisbon, Portugal, to allow comparisons. In a related paper about that model, the existence of significant
David Kaplan
1989-01-01
This article considers the sampling variability and z-values of parameter estimates from misspecified structural equation models. A Monte Carlo study is employed wherein a prototype structural model is analyzed under one incorrect restriction and two incorrect restrictions. True values of the misspecified parameters are varied to reflect increasing distances from the null hypothesis. Sample size differences are also considered. Comparisons
João de Abreu e Silva; Catherine Morency; Konstadinos G. Goulias
2012-01-01
This paper addresses the relations between travel behavior and land use patterns using a Structural Equations Modeling (SEM) framework. The proposed model structure draws on two earlier models developed for Lisbon and Seattle which show significant effects of land use patterns on travel behavior. The travel behavior variables included here are multifaceted including commuting distance, car ownership, the amount of
ERIC Educational Resources Information Center
Betoret, Fernando Domenech
2009-01-01
This study examines the relationship between school resources, teacher self-efficacy, potential multi-level stressors and teacher burnout using structural equation modelling. The causal structure for primary and secondary school teachers was also examined. The sample was composed of 724 primary and secondary Spanish school teachers. The changes…
Boettger, J.C.; Wills, J.M.
1992-03-01
High precision electronic band structure calculations for BeO have revealed a large volume discontinuity structural phase transition on the 0 K isotherm at about 1 Mbar. Although, this transition has not been observed experimentally, the accuracy of the calculations is such that the existence of this transition is unambiguous. A transition of this magnitude is likely to have a substantial impact on hydrodynamic simulations involving BeO. Here we report the creation of a new SESAME equations of state for BeO which incorporates the effect of the theoretically determined phase transition. This new EOS will be added to the SESAME library as material number 7612.
Singularity Structures in Coulomb-Type Potentials in Two-Body Dirac Equations of Constraint Dynamics
Crater, H. W. [University of Tennessee Space Institute; Yoon, Jin-Hee [Inha University, Korea; Wong, Cheuk-Yin [ORNL
2009-01-01
Two-body Dirac equations (TBDE) of Dirac's relativistic constraint dynamics have been successfully applied to obtain a covariant nonperturbative description of QED and QCD bound states. Coulomb-type potentials in these applications lead naively in other approaches to singular relativistic corrections at short distances that require the introduction of either perturbative treatments or smoothing parameters. We examine the corresponding singular structures in the effective potentials of the relativistic Schroedinger equation obtained from the Pauli reduction of the TBDE. We find that the relativistic Schroedinger equation leads in fact to well-behaved wave function solutions when the full potential and couplings of the system are taken into account. The most unusual case is the coupled triplet system with S=1 and L={l_brace}(J-1),(J+1){r_brace}. Without the inclusion of the tensor coupling, the effective S-state potential would become attractively singular. We show how including the tensor coupling is essential in order that the wave functions be well-behaved at short distances. For example, the S-state wave function becomes simply proportional to the D-state wave function and dips sharply to zero at the origin, unlike the usual S-state wave functions. Furthermore, this behavior is similar in both QED and QCD, independent of the asymptotic freedom behavior of the assumed QCD vector potential. Light- and heavy-quark meson states can be described well by using a simplified linear-plus-Coulomb-type QCD potential apportioned appropriately between world scalar and vector potentials. We use this potential to exhibit explicitly the origin of the large pi-rho splitting and effective chiral symmetry breaking. The TBDE formalism developed here may be used to study quarkonia in quark-gluon plasma environments.
Kang, H.S.; Ree, F.H.
1997-12-01
Recently, we developed the perturbative hypernetted-chain (PHNC) integral equation which can predict reliable thermodynamic and structural data for a system of particles interacting with either short range or long range (Coulomb) potential. The present work extends this earlier work to mixtures. This is done by employing a reference potential which is designed to satisfy a thermodynamic consistency on the isothermal compressibility as described in the next section. We test the present theory in Sec. III by applying it to plasma mixtures interacing with either an unscreened or a screened Coulomb potential. We made comparisons of results from the present theory with those from the best available theory, i.e., Rosenfeld`s density functional theory (DFT). The DFT was shown to give internal energy with three to five fignre accuracy compared to a wide range of Monte Carlo data. Meanwhile, small deviations of excess internal energy from the so-called ``liner mixing rule`` (LMR) are better predicted by a less sophiscated theory like the hypernetted- chain (HNC) equation. This rule relates thermodynamics of an unscreened mixture to those for individual components in a strongly coupled regime where the potential energy of a constituent particle is much larger than its kinetic energy. We also apply the present theory to a H{sub 2} + H mixture interacting with Morse potentials. For this sytem, comparison of thermodynamic properties and radial distribution functions from the present theory will be made with those from another successful theory of dense fluid, i.e., the HMSA equation of Zerah and Hansen.
Solving the 3D Acoustic Wave-equation on Generalized Structured Meshes: A FDTD Approach
NASA Astrophysics Data System (ADS)
Shragge, J. C.
2014-12-01
The key computational kernel of most advanced 3D seismic imaging and inversion algorithms involves calculating solutions of the 3D acoustic wave equation, most commonly with a finite-difference time-domain (FDTD) methodology. While well suited for regularly sampled rectilinear computational domains, FDTD methods seemingly have limited applicability in scenarios involving irregular 3D domain boundary surfaces and mesh interiors that are best described by non-Cartesian geometry (e.g., surface topography). Using coordinate mapping relationships and differential geometry, a FDTD approach can be developed for generating solutions to the 3D acoustic wave equation that is applicable to generalized 3D coordinate systems and (quadrilateral-faced hexahedral) structured meshes. The developed numerical implementation is similar to established Cartesian approaches, save for a necessary introduction of weighted first- and mixed second-order partial-derivative operators that account for spatially varying geometry. The approach is validated on three different types of computational meshes: (1) an ``internal boundary'' mesh conforming to a dipping water bottom; (2) analytical ``semi-orthogonal cylindrical" coordinates; and (3) analytic semi-orthogonal and numerically specified ``topographic" coordinate meshes. Impulse response tests and numerical analysis demonstrate the viability of the approach for kernel computations for 3D seismic imaging and inversion experiments for non-Cartesian geometry scenarios.
ERIC Educational Resources Information Center
Ellison, William D.; Levy, Kenneth N.
2012-01-01
Using exploratory structural equation modeling and multiple regression, we examined the factor structure and criterion relations of the primary scales of the Inventory of Personality Organization (IPO; Kernberg & Clarkin, 1995) in a nonclinical sample. Participants (N = 1,260) completed the IPO and measures of self-concept clarity, defenses,…
A two-level structural equation model approach for analyzing multivariate longitudinal responses
Song, Xin-Yuan; Lee, Sik-Yum; Hser, Yih-Ing
2010-01-01
SUMMARY The analysis of longitudinal data to study changes in variables measured repeatedly over time has received considerable attention in many fields. This paper proposes a two-level structural equation model for analyzing multivariate longitudinal responses that are mixed continuous and ordered categorical variables. The first-level model is defined for measures taken at each time point nested within individuals for investigating their characteristics that are changed with time. The second level is defined for individuals to assess their characteristics that are invariant with time. The proposed model accommodates fixed covariates, nonlinear terms of the latent variables, and missing data. A maximum likelihood (ML) approach is developed for the estimation of parameters and model comparison. Results of a simulation study indicate that the performance of the ML estimation is satisfactory. The proposed methodology is applied to a longitudinal study concerning cocaine use. PMID:18416447
2012-01-01
Background Structural equation modeling developed as a statistical melding of path analysis and factor analysis that obscured a fundamental tension between a factor preference for multiple indicators and path modeling’s openness to fewer indicators. Discussion Multiple indicators hamper theory by unnecessarily restricting the number of modeled latents. Using the few best indicators – possibly even the single best indicator of each latent – encourages development of theoretically sophisticated models. Additional latent variables permit stronger statistical control of potential confounders, and encourage detailed investigation of mediating causal mechanisms. Summary We recommend the use of the few best indicators. One or two indicators are often sufficient, but three indicators may occasionally be helpful. More than three indicators are rarely warranted because additional redundant indicators provide less research benefit than single indicators of additional latent variables. Scales created from multiple indicators can introduce additional problems, and are prone to being less desirable than either single or multiple indicators. PMID:23088287
Analyzing average and conditional effects with multigroup multilevel structural equation models
Mayer, Axel; Nagengast, Benjamin; Fletcher, John; Steyer, Rolf
2014-01-01
Conventionally, multilevel analysis of covariance (ML-ANCOVA) has been the recommended approach for analyzing treatment effects in quasi-experimental multilevel designs with treatment application at the cluster-level. In this paper, we introduce the generalized ML-ANCOVA with linear effect functions that identifies average and conditional treatment effects in the presence of treatment-covariate interactions. We show how the generalized ML-ANCOVA model can be estimated with multigroup multilevel structural equation models that offer considerable advantages compared to traditional ML-ANCOVA. The proposed model takes into account measurement error in the covariates, sampling error in contextual covariates, treatment-covariate interactions, and stochastic predictors. We illustrate the implementation of ML-ANCOVA with an example from educational effectiveness research where we estimate average and conditional effects of early transition to secondary schooling on reading comprehension. PMID:24795668
A Comparison of Methods for Estimating Quadratic Effects in Nonlinear Structural Equation Models
Harring, Jeffrey R.; Weiss, Brandi A.; Hsu, Jui-Chen
2012-01-01
Two Monte Carlo simulations were performed to compare methods for estimating and testing hypotheses of quadratic effects in latent variable regression models. The methods considered in the current study were (a) a 2-stage moderated regression approach using latent variable scores, (b) an unconstrained product indicator approach, (c) a latent moderated structural equation method, (d) a fully Bayesian approach, and (e) marginal maximum likelihood estimation. Of the 5 estimation methods, it was found that overall the methods based on maximum likelihood estimation and the Bayesian approach performed best in terms of bias, root-mean-square error, standard error ratios, power, and Type I error control, although key differences were observed. Similarities as well as disparities among methods are highlight and general recommendations articulated. As a point of comparison, all 5 approaches were fit to a reparameterized version of the latent quadratic model to educational reading data. PMID:22429193
Marino, Teresa L; Negy, Charles; Hammons, Mary E; McKinney, Cliff; Asberg, Kia
2007-11-01
Despite a general consensus in the United States that overtly racist acts are unacceptable, many ambiguous situations in everyday life raise questions of whether racism has influenced a person's behavior in an interracial encounter. The authors of the present study sought to (a) examine simultaneously an array of variables thought to be related to perceived racism and (b) investigate how the contribution of these variables may differ with respect to the asymmetry hypothesis, which suggests that acts of discrimination from a dominant person toward a subordinate person will be viewed as more biased than if the situation were reversed. The authors used a dual structural equation modeling approach. Results indicated that ethnic identity significantly predicted perceived racism. In addition, the extent to which cognitive interpretation style significantly predicted perceived racism depended on the ethnicity of participants involved in the interaction. PMID:18044276
A Structural Equation Model of HIV-Related Stigma, Depressive Symptoms, and Medication Adherence
Rao, Deepa; Feldman, Betsy J.; Fredericksen, Rob J.; Crane, Paul K.; Simoni, Jane M.; Kitahata, Mari M.; Crane, Heidi M.
2011-01-01
HIV-related stigma has a damaging effect on health outcomes among people living with HIV (PLWH), as studies have associated it with poor HIV medication adherence and depressive symptoms. We investigated whether depressive symptoms mediate the relationship between stigma and medication adherence. In a cross-sectional study, 720 PLWH completed instruments measuring HIV-related stigma, depressive symptoms, and HIV medication adherence. We used structural equation modeling (SEM) to investigate associations among these constructs. In independent models, we found that poorer adherence was associated with higher levels of stigma and depressive symptoms. In the simultaneous model that included both stigma and depressive symptoms, depression had a direct effect on adherence, but the effect of stigma on adherence was not statistically significant. This pattern suggested that depressive symptoms at least partially mediated the association between HIV-related stigma and HIV medication adherence. These findings suggest that interconnections between several factors have important consequences for adherence. PMID:21380495
IT vendor selection model by using structural equation model & analytical hierarchy process
NASA Astrophysics Data System (ADS)
Maitra, Sarit; Dominic, P. D. D.
2012-11-01
Selecting and evaluating the right vendors is imperative for an organization's global marketplace competitiveness. Improper selection and evaluation of potential vendors can dwarf an organization's supply chain performance. Numerous studies have demonstrated that firms consider multiple criteria when selecting key vendors. This research intends to develop a new hybrid model for vendor selection process with better decision making. The new proposed model provides a suitable tool for assisting decision makers and managers to make the right decisions and select the most suitable vendor. This paper proposes a Hybrid model based on Structural Equation Model (SEM) and Analytical Hierarchy Process (AHP) for long-term strategic vendor selection problems. The five steps framework of the model has been designed after the thorough literature study. The proposed hybrid model will be applied using a real life case study to assess its effectiveness. In addition, What-if analysis technique will be used for model validation purpose.
From patterns to causal understanding: Structural equation modeling (SEM) in soil ecology
Eisenhauer, Nico; Powell, Jeff R; Grace, James B.; Bowker, Matthew A.
2015-01-01
In this perspectives paper we highlight a heretofore underused statistical method in soil ecological research, structural equation modeling (SEM). SEM is commonly used in the general ecological literature to develop causal understanding from observational data, but has been more slowly adopted by soil ecologists. We provide some basic information on the many advantages and possibilities associated with using SEM and provide some examples of how SEM can be used by soil ecologists to shift focus from describing patterns to developing causal understanding and inspiring new types of experimental tests. SEM is a promising tool to aid the growth of soil ecology as a discipline, particularly by supporting research that is increasingly hypothesis-driven and interdisciplinary, thus shining light into the black box of interactions belowground.
Ji-Hai Xu; Yong Ren; C. S. Ting
1995-01-01
The properties of a d2x-y2-wave superconductor in an external magnetic field are investigated on the basis of Gorkov's theory of weakly coupled superconductors. The Ginzburg-Landau (GL) equations, which govern the spatial variations of the order parameter and the supercurrent, are microscopically derived. The single vortex structure and surface problems in such a superconductor are studied using these equations. It is
Pennig, Sibylle; Schady, Arthur
2014-01-01
In some regions the exposure to railway noise is extremely concentrated, which may lead to high residential annoyance. Nonacoustical factors contribute to these reactions, but there is limited evidence on the interrelations between the nonacoustical factors that influence railway noise annoyance. The aims of the present study were (1) to examine exposure-response relationships between long-term railway noise exposure and annoyance in a region severely affected by railway noise and (2) to determine a priori proposed interrelations between nonacoustical factors by structural equation analysis. Residents (n = 320) living close to railway tracks in the Middle Rhine Valley completed a socio-acoustic survey. Individual noise exposure levels were calculated by an acoustical simulation model for this area. The derived exposure-response relationships indicated considerably higher annoyance at the same noise exposure level than would have been predicted by the European Union standard curve, particularly for the night-time period. In the structural equation analysis, 72% of the variance in noise annoyance was explained by the noise exposure (L(den)) and nonacoustical variables. The model provides insights into several causal mechanisms underlying the formation of railway noise annoyance considering indirect and reciprocal effects. The concern about harmful effects of railway noise and railway traffic, the perceived control and coping capacity, and the individual noise sensitivity were the most important factors that influence noise annoyance. All effects of the nonacoustical factors on annoyance were mediated by the perceived control and coping capacity and additionally proposed indirect effects of the theoretical model were supported by the data. PMID:25387535
High-pressure structural behavior and equation of state of NaZnF{sub 3}
Yakovlev, Sergey, E-mail: s.yakovlev@tnw.utwente.n [Bragg Institute, Australian Nuclear Science and Technology Organisation, 1 PBM, Menai, NSW 2234 (Australia); Avdeev, Maxim [Bragg Institute, Australian Nuclear Science and Technology Organisation, 1 PBM, Menai, NSW 2234 (Australia); Mezouar, Mohamed [ID-27, European Synchrotron Radiation Facility (ESRF), 6 rue Jules Horowitz, PB220, 38043 Grenoble CEDEX (France)
2009-06-15
We report the results of density functional theory ab-initio calculations and monochromatic synchrotron X-ray diffraction study carried out for orthorhombic NaZnF{sub 3} in the pressure range 0-40 GPa. Perovskite-to-postperovskite phase transition was anticipated by first-principles computations and then observed in high-pressure diamond anvil cell synchrotron diffraction experiment between 14 and 22 GPa. Above 25 GPa postperovskite structure (CaIrO{sub 3} type, space group Cmcm) coexists with another phase, yet unidentified. On decompression, pure postperovskite-type structure was found to be stable down to 4 GPa; below this pressure sample contained both perovskite and postperovskite modifications. Fit of experimental P-V data to the third-order Birch-Murnaghan equation of state gave bulk moduli, K{sub P,0} 64.98+-2.67 and 69.88+-3.69 GPa for perovskite and postperovskite modifications, respectively. Both phases demonstrated strong anisotropy of compressibility. For postperovskite NaZnF{sub 3}, the highest compression was observed along the direction perpendicular to the planes of ZnF{sub 6} octahedra arrangement. - Graphical Abstract: Fit of P-V data obtained from high-pressure X-ray diffraction study of perovskite and postperovskite NaZnF{sub 3} to the third-order Birch-Murnaghan equation of state (solid line). Open and closed symbols represent experimental data corresponding to compression and decompression, respectively. Bulk moduli, K{sub 0,P}, of perovskite and postperovskite phases are 64.98+-2.67 and 69.88+-3.69 GPa.
Giuseppe Saccomandi; Raffaele Vitolo
2014-08-26
Using the theory of $1+1$ hyperbolic systems we put in perspective the mathematical and geometrical structure of the celebrated circularly polarized waves solutions for isotropic hyperelastic materials determined by Carroll in Acta Mechanica 3 (1967) 167--181. We show that a natural generalization of this class of solutions yields an infinite family of \\emph{linear} solutions for the equations of isotropic elastodynamics. Moreover, we determine a huge class of hyperbolic partial differential equations having the same property of the shear wave system. Restricting the attention to the usual first order asymptotic approximation of the equations determining transverse waves we provide the complete integration of this system using generalized symmetries.
TIME MANAGEMENT Time Management Questionnaire
TIME MANAGEMENT WORKSHOP #12;2 Time Management Questionnaire Self Assessment: Answer "Yes" or "No you tend to complete your assignments on time? 3. ____ Have you estimated how long it takes to read schedule time to study for exams? 8. ____ Do you have a job that requires more than 20 hours a week? 9
Instructional Television Questionnaire -- Teacher Form.
ERIC Educational Resources Information Center
Payne, David A.; And Others
The instructional television questionnaire for teachers consists primarily of statements to be answered with a rating scale. The first seventeen statements ask for evaluative judgments about various aspects of instructional television. The remainder of the statements require judgments of frequency. Questions to ascertain personal data and use of…
Physical Activity Questionnaire Search Results
The Physical Activity Questionnaire for Elderly Japanese (PAQ-EJ) 1 Over 7 typical days, how often did you take a walk or ride a bicycle on errands such as going to or from a store or taking children to school?
A Split Questionnaire Survey Design
Trivellore E. Raghunathan; James E. Grizzle
1995-01-01
This article develops a survey design where the questionnaire is split into components and individuals are administered the varying subsets of the components. A multiple imputation method for analyzing data from this design is developed, in which the imputations are created by random draws from the posterior predictive distribution of the missing parts, given the observed parts by using Gibbs
Exit Interview Questionnaire Employee's Name
Oyet, Alwell
Exit Interview Questionnaire Employee's Name: Department/Unit: Position Title: Date Hired Good Poor Very Poor Comments: #12;Job satisfaction Very High High Average Low Very Low Comments: Overall satisfaction with Memorial as an employer Very High High Average Low Very Low Comments: Overall
Physical Activity Questionnaire Search Results
Global Physical Activity Questionnaire (GPAQ) 13 Do you do any moderate-intensity sports, fitness or recreational (leisure) activities that causes a small increase in breathing or heart rate such as brisk walking, cycling, swimming, volleyball) for at least 10 minutes continuously?
College Student Services Accreditation Questionnaire.
ERIC Educational Resources Information Center
Cassel, Russell N.
1979-01-01
This questionnaire is intended for use as one aspect in accrediting the "Student Personnel Services" which an institution of higher learning provides for students. Areas in question include personal development, health fostering, vocational preparation, effective personalized learning, economic viability, transpersonal offerings, and satisfactory…
Swedler, David I; Verma, Santosh K; Huang, Yueng-Hsiang; Lombardi, David A; Chang, Wen-Ruey; Brennan, Melayne; Courtney, Theodore K
2015-01-01
Objective Safety climate has previously been associated with increasing safe workplace behaviours and decreasing occupational injuries. This study seeks to understand the structural relationship between employees’ perceptions of safety climate, performing a safety behaviour (ie, wearing slip-resistant shoes) and risk of slipping in the setting of limited-service restaurants. Methods At baseline, we surveyed 349 employees at 30 restaurants for their perceptions of their safety training and management commitment to safety as well as demographic data. Safety performance was identified as wearing slip-resistant shoes, as measured by direct observation by the study team. We then prospectively collected participants’ hours worked and number of slips weekly for the next 12?weeks. Using a confirmatory factor analysis, we modelled safety climate as a higher order factor composed of previously identified training and management commitment factors. Results The 349 study participants experienced 1075 slips during the 12-week follow-up. Confirmatory factor analysis supported modelling safety climate as a higher order factor composed of safety training and management commitment. In a structural equation model, safety climate indirectly affected prospective risk of slipping through safety performance, but no direct relationship between safety climate and slips was evident. Conclusions Results suggest that safety climate can reduce workplace slips through performance of a safety behaviour as well as suggesting a potential causal mechanism through which safety climate can reduce workplace injuries. Safety climate can be modelled as a higher order factor composed of safety training and management commitment. PMID:25710968
Wills, John M [Los Alamos National Laboratory; Mattsson, Ann E [Sandia National Laboratories
2012-06-06
Brooks, Johansson, and Skriver, using the LMTO-ASA method and considerable insight, were able to explain many of the ground state properties of the actinides. In the many years since this work was done, electronic structure calculations of increasing sophistication have been applied to actinide elements and compounds, attempting to quantify the applicability of DFT to actinides and actinide compounds and to try to incorporate other methodologies (i.e. DMFT) into DFT calculations. Through these calculations, the limits of both available density functionals and ad hoc methodologies are starting to become clear. However, it has also become clear that approximations used to incorporate relativity are not adequate to provide rigorous tests of the underlying equations of DFT, not to mention ad hoc additions. In this talk, we describe the result of full-potential LMTO calculations for the elemental actinides, comparing results obtained with a full Dirac basis with those obtained from scalar-relativistic bases, with and without variational spin-orbit. This comparison shows that the scalar relativistic treatment of actinides does not have sufficient accuracy to provide a rigorous test of theory and that variational spin-orbit introduces uncontrolled errors in the results of electronic structure calculations on actinide elements.
Jacques Pouchot; Jean-Paul Larbre; Irène Lemelle; Danièle Sommelet; Eric Grouteau; Louis David; Agnès Duquesne; Chantal Job Deslandre; Isabelle Kone Paut; Pascal Pillet; Laurence Goumy; Catherine Barbier; Marie-Hélène Guyot; Françoise Mazingue; Sylvie Gandon Laloum; Michel Fischbach; Pierre Quartier; Claude Guyot; Sylvie Jean; Edouard Legall; Emmanuel Plouvier; Michel Bost; Lionel de Lumley; Christian Brégeon; Francis Guillemin; Joël Coste; Anne-Marie Prieur
2002-01-01
Objectives. Develop and validate a French version of the Childhood Health Assessment Questionnaire (CHAQ), a disability measure for children suffering from Juvenile Idiopathic Juvenile Arthritis (JIA) adapted from the Health Assessment Questionnaire (HAQ). Children and methods. Following the structured development of a cross-cultural French version of the CHAQ, the questionnaire has been validated in a cross sectional multicentric study in
Algebraic structure of $tt^*$ equations for Calabi-Yau sigma models
Murad Alim
2014-12-10
The $tt^*$ equations define a flat connection on the moduli spaces of $2d, \\mathcal{N}=2$ quantum field theories. For conformal theories with $c=3d$, which can be realized as nonlinear sigma models into Calabi-Yau d-folds, this flat connection is equivalent to special geometry for threefolds and to its analogs in other dimensions. We show that the non-holomorphic content of the $tt^*$ equations in the cases $d=1,2,3$ is captured in terms of finitely many generators of special functions, which close under derivatives. The generators are understood as coordinates on a larger moduli space. This space parameterizes a freedom in choosing representatives of the chiral ring while preserving a constant topological metric. Geometrically, the freedom corresponds to a choice of forms on the target space respecting the Hodge filtration and having a constant pairing. Linear combinations of vector fields on that space are identified with generators of a Lie algebra. This Lie algebra replaces the non-holomorphic derivatives of $tt^*$ and provides these with a finer and algebraic meaning. For sigma models into lattice polarized $K3$ manifolds, the differential ring of special functions on the moduli space is constructed, extending known structures for $d=1$ and 3. The generators of the differential rings of special functions are given by quasi-modular forms for $d=1$ and their generalizations in $d=2,3$. Some explicit examples are worked out including the case of the mirror of the quartic in $CP^3$, where due to further algebraic constraints, the differential ring coincides with quasi modular forms.
NASA Astrophysics Data System (ADS)
Natarajan, Logesh Kumar
This dissertation presents a structure-borne noise analysis technology that is focused on providing a cost-effective noise reduction strategy. Structure-borne sound is generated or transmitted through structural vibration; however, only a small portion of the vibration can effectively produce sound and radiate it to the far-field. Therefore, cost-effective noise reduction is reliant on identifying and suppressing the critical vibration components that are directly responsible for an undesired sound. However, current technologies cannot successfully identify these critical vibration components from the point of view of direct contribution to sound radiation and hence cannot guarantee the best cost-effective noise reduction. The technology developed here provides a strategy towards identifying the critical vibration components and methodically suppressing them to achieve a cost-effective noise reduction. The core of this technology is Helmholtz equation least squares (HELS) based nearfield acoustic holography method. In this study, the HELS formulations derived in spherical co-ordinates using spherical wave expansion functions utilize the input data of acoustic pressures measured in the nearfield of a vibrating object to reconstruct the vibro-acoustic responses on the source surface and acoustic quantities in the far field. Using these formulations, three steps were taken to achieve the goal. First, hybrid regularization techniques were developed to improve the reconstruction accuracy of normal surface velocity of the original HELS method. Second, correlations between the surface vibro-acoustic responses and acoustic radiation were factorized using singular value decomposition to obtain orthogonal basis known here as the forced vibro-acoustic components (F-VACs). The F-VACs enables one to identify the critical vibration components for sound radiation in a similar manner that modal decomposition identifies the critical natural modes in a structural vibration. Finally, the dominant F-VAC responsible for acoustic radiation are decomposed into the natural modes of a vibrating structure, and the critical vibration modes responsible for the dominant F-VAC are identified. Experimental validation for this technology was conducted using a baffled square plate and a scaled model vehicle cabin subject to a point force excitation inside a fully anechoic chamber.
Development of the Parental Psychological Flexibility Questionnaire.
Burke, Kylie; Moore, Susan
2015-08-01
This paper describes development and validation of the Parental Psychological Flexibility (PPF) Questionnaire, a parent-report measure designed to assess psychological flexibility among parents of pre-adolescents and adolescents (aged 10-18 years). Psychological flexibility within parenting refers to parents' accepting negative thoughts, emotions and urges about one's child and still acting in ways that are consistent with effective parenting. Exploratory factor analysis (n = 178 parents) of a 43-item draft measure, resulted in a 30-item, 3-factor structure. Three subscales were created, consistent with the psychological flexibility literature: acceptance, cognitive defusion and committed action. A second sample of parents (n = 192) was then used to confirm the factor structure and reliability and validity of the PPF. Results supported the 3-factor structure, reduced the number of items to 19 and demonstrated that the PPF subscales have adequate reliability and validity and are thus suitable for researching psychological flexibility among parents of pre-adolescents and adolescents. PMID:25236325
Global structure in spatiotemporal chaos of the Matthews-Cox equations.
Sakaguchi, Hidetsugu; Tanaka, Dan
2007-08-01
We find that an amplitude death state and a spatiotemporally chaotic state coexist spontaneously in the Matthews-Cox equations and this coexistence is robust. Although the entire system is far from equilibrium, the domain wall between the two states is stabilized by a negative-feedback effect due to a conservation law. This is analogous to the phase separation in conserved systems that exhibit spinodal decompositions. We observe similar phenomena also in the Nikolaevskii equation, from which the Matthews-Cox equations were derived. A Galilean invariance of the former equation corresponds to the conservation law of the latter equations. PMID:17930094
ERIC Educational Resources Information Center
de Guzman, Allan B.; Jimenez, Benito Christian B.; Jocson, Kathlyn P.; Junio, Aileen R.; Junio, Drazen E.; Jurado, Jasper Benjamin N.; Justiniano, Angela Bianca F.
2013-01-01
Anchored on the key constucts of Ajzen's Theory of Planned Behavior (1985), this paper seeks to test a model that explores the influence of knowledge, attitude, and caring behavior on nursing students' behavioral intention toward geriatric care. A five-part survey-questionnaire was administered to 839 third and fourth year nursing students from a…
NASA Technical Reports Server (NTRS)
Byun, Chansup; Guruswamy, Guru P.
1993-01-01
This paper presents a procedure for computing the aeroelasticity of wing-body configurations on multiple-instruction, multiple-data (MIMD) parallel computers. In this procedure, fluids are modeled using Euler equations discretized by a finite difference method, and structures are modeled using finite element equations. The procedure is designed in such a way that each discipline can be developed and maintained independently by using a domain decomposition approach. A parallel integration scheme is used to compute aeroelastic responses by solving the coupled fluid and structural equations concurrently while keeping modularity of each discipline. The present procedure is validated by computing the aeroelastic response of a wing and comparing with experiment. Aeroelastic computations are illustrated for a High Speed Civil Transport type wing-body configuration.
Sabry M. Abd-El-Fattah
2006-01-01
A structural equation modelling analysis was used to investigate the notion that the effects of parents’ education and family\\u000a structure on students’ academic achievement and school disengagement would be mediated through students’ perception of parental\\u000a involvement. The Perception of Parental Involvement Scale was administered to a sample of 275 first-year students (147 males\\u000a and 128 females) enrolled in two high
Kruglikov, B S [M.V. Lomonosov Moscow State University, Moscow (Russian Federation)
1998-12-31
Three related classification problems on four-manifolds are discussed. First, regular distributions are considered and described locally. After that a classification of almost complex structures of general position in terms of distributions is proposed. Finally, non-degenerate generalized Monge-Ampere equations are classified in terms of {l_brace}e{r_brace}-structures. Symplectic Lie algebras are also considered in an appendix.
ERIC Educational Resources Information Center
In'nami, Yo; Koizumi, Rie
2013-01-01
The importance of sample size, although widely discussed in the literature on structural equation modeling (SEM), has not been widely recognized among applied SEM researchers. To narrow this gap, we focus on second language testing and learning studies and examine the following: (a) Is the sample size sufficient in terms of precision and power of…
ERIC Educational Resources Information Center
Museus, Samuel D.; Vue, Rican
2013-01-01
The purpose of this study is to examine socioeconomic differences in the interpersonal factors that influence college access among Asian Americans and Pacific Islanders (AAPIs). Data on 1,460 AAPIs from the Education Longitudinal Study (ELS: 02/06) were analyzed using structural equation modeling techniques. Findings suggest that parental…
ERIC Educational Resources Information Center
Ferrer, Emilio; Hamagami, Fumiaki; McArdle, John J.
2004-01-01
This article offers different examples of how to fit latent growth curve (LGC) models to longitudinal data using a variety of different software programs (i.e., LISREL, Mx, Mplus, AMOS, SAS). The article shows how the same model can be fitted using both structural equation modeling and multilevel software, with nearly identical results, even in…
ERIC Educational Resources Information Center
Jen, Tsung-Hau; Lee, Che-Di; Chien, Chin-Lung; Hsu, Ying-Shao; Chen, Kuan-Ming
2013-01-01
Based on the Trends in International Mathematics and Science Study 2007 study and a follow-up national survey, data for 3,901 Taiwanese grade 8 students were analyzed using structural equation modeling to confirm a social-relation-based affection-driven model (SRAM). SRAM hypothesized relationships among students' perceived social relationships in…
ERIC Educational Resources Information Center
Byrne, Barbara M.
2001-01-01
Uses a confirmatory factor analytic (CFA) model as a paradigmatic basis for the comparison of three widely used structural equation modeling computer programs: (1) AMOS 4.0; (2) EQS 6; and (3) LISREL 8. Comparisons focus on aspects of programs that bear on the specification and testing of CFA models and the treatment of incomplete, nonnormally…
ERIC Educational Resources Information Center
Stephens, Ana C.; Knuth, Eric J.; Blanton, Maria L.; Isler, Isil; Gardiner, Angela Murphy; Marum, Tim
2013-01-01
This paper reports results from a written assessment given to 290 third-, fourth-, and fifth-grade students prior to any instructional intervention. We share and discuss students' responses to items addressing their understanding of equation structure and the meaning of the equal sign. We found that many students held an operational conception of…
ERIC Educational Resources Information Center
Lai, Keke; Kelley, Ken
2011-01-01
In addition to evaluating a structural equation model (SEM) as a whole, often the model parameters are of interest and confidence intervals for those parameters are formed. Given a model with a good overall fit, it is entirely possible for the targeted effects of interest to have very wide confidence intervals, thus giving little information about…
ERIC Educational Resources Information Center
Hoyle, Rick H.
1998-01-01
In response to H. W. Marsh and K.-T. Hau's (1996) article on the potential for inferential errors when parsimony is rewarded in the evaluation of overall fit of structural equation models, a design-sensitive adjustment to the standard parsimony ratio is proposed. This ratio renders a more reasonable upper bound than does the standard parsimony…
Lin-An Chen; Stephen Portnoy
1996-01-01
We propose a two-stage trimmed least squares estimator for the parameters of structural equation model and provide the corresponding asymptotic distribution theory. The estimator is based on two-stage regression quan-tiles, which generalize the standard linear model regression quantiles introduced by Koenker and Bassett (1978) . The asymptotic theory is developed by means of \\
ERIC Educational Resources Information Center
Enders, Craig K.
2008-01-01
Recent missing data studies have argued in favor of an "inclusive analytic strategy" that incorporates auxiliary variables into the estimation routine, and Graham (2003) outlined methods for incorporating auxiliary variables into structural equation analyses. In practice, the auxiliary variables often have missing values, so it is reasonable to…
ERIC Educational Resources Information Center
Yang, Chongming; Nay, Sandra; Hoyle, Rick H.
2010-01-01
Lengthy scales or testlets pose certain challenges for structural equation modeling (SEM) if all the items are included as indicators of a latent construct. Three general approaches to modeling lengthy scales in SEM (parceling, latent scoring, and shortening) have been reviewed and evaluated. A hypothetical population model is simulated containing…
ERIC Educational Resources Information Center
Cheung, Mike W.-L.
2008-01-01
Meta-analysis and structural equation modeling (SEM) are two important statistical methods in the behavioral, social, and medical sciences. They are generally treated as two unrelated topics in the literature. The present article proposes a model to integrate fixed-, random-, and mixed-effects meta-analyses into the SEM framework. By applying an…
ERIC Educational Resources Information Center
Santos-George, Arlene A.
2012-01-01
This dissertation empirically tested Tinto's student integration theory through structural equation modeling using a national sample of 2,847 first-time entering community college students. Tinto theorized that the more academically and socially integrated a student is to the college environment, the more likely the student will persist…
ERIC Educational Resources Information Center
Rosário, Pedro; Núñez, José Carlos; Vallejo, Guilermo; Paiva, Olímpia; Valle, António; Fuentes, Sonia; Pinto, Ricardo
2014-01-01
In the framework of teacher's approaches to teaching, this study investigates the relationship between student-related variables (i.e., study time, class absence, domain knowledge, and homework completion), students' approaches to learning, and teachers' approaches to teaching using structural equation modeling (SEM) with two…
ERIC Educational Resources Information Center
Willoughby, Michael; Vandergrift, Nathan; Blair, Clancy; Granger, Douglas A.
2007-01-01
This study introduces a novel application of structural equation modeling (SEM) for the analysis of cortisol data that are collected using a pre-post-post design. By way of an extended example, an SEM model is developed that permits an examination of both the overall level of cortisol, as well as changes in cortisol (reactivity and regulation), as…
NASA Astrophysics Data System (ADS)
Aburjania, G. D.; Kharshiladze, O. A.; Chargazia, Kh. Z.
2013-09-01
A corresponding model system of nonlinear dynamic equations for the lower ionosphere has been constructed in order to study the generation and further nonlinear dynamics of internal gravity wave (IGW) structures in a dissipative ionosphere in the presence of a nonuniform zonal wind (shear flow). The criterion for the development of the IGW shear instability in the ionosphere has been obtained.
Tomas Chamorro-Premuzic; Montserrat Gomà-i-Freixanet; Adrian Furnham; Anna Muro
2009-01-01
This study replicates and extends a recent study on personality, intelligence and uses of music [Chamorro-Premuzic, T., & Furnham, A. (2007). Personality and music: Can traits explain how people use music in everyday life? British Journal of Psychology, 98, 175–185] using Spanish participants and structural equation modeling. Data from 245 university students showed that, in line with our hypotheses, individuals
ERIC Educational Resources Information Center
Mazaheri, Mehrdad; Theuns, Peter
2009-01-01
The current study evaluates three hypothesized models on subjective well-being, comprising life domain ratings (LDR), overall satisfaction with life (OSWL), and overall dissatisfaction with life (ODWL), using structural equation modeling (SEM). A sample of 1,310 volunteering students, randomly assigned to six conditions, rated their overall life…
ERIC Educational Resources Information Center
Xie, Qin; Andrews, Stephen
2013-01-01
This study introduces Expectancy-value motivation theory to explain the paths of influences from perceptions of test design and uses to test preparation as a special case of washback on learning. Based on this theory, two conceptual models were proposed and tested via Structural Equation Modeling. Data collection involved over 870 test takers of…
ERIC Educational Resources Information Center
Lee, Sik-Yum; Xia, Ye-Mao
2006-01-01
By means of more than a dozen user friendly packages, structural equation models (SEMs) are widely used in behavioral, education, social, and psychological research. As the underlying theory and methods in these packages are vulnerable to outliers and distributions with longer-than-normal tails, a fundamental problem in the field is the…
ERIC Educational Resources Information Center
Ogasawara, Haruhiko
2007-01-01
Higher-order approximations to the distributions of fit indexes for structural equation models under fixed alternative hypotheses are obtained in nonnormal samples as well as normal ones. The fit indexes include the normal-theory likelihood ratio chi-square statistic for a posited model, the corresponding statistic for the baseline model of…
Irene R. R. Lu; Ernest Kwan; D. Roland Thomas; Marzena Cedzynski
2011-01-01
The application of structural equation models (SEMs) is common in marketing and the behavioral sciences. Accordingly, the exploration of more effective methods to estimate SEMs is also a popular area of research. Croon (2002) and Skrondal and Laake (2001) have each proposed a new method for estimating SEMs, but since these proposals nearly a decade ago, these methods have been
Heather Ward; Valerie Tarasuk; Rena Mendelson; Gail McKeown-Eyssen
2007-01-01
TITLE: An exploration of socioeconomic variation in lifestyle factors and adiposity in the Ontario Food Survey through structural equation models. BACKGROUND: Socioeconomic indicators have been inversely associated with overweight and obesity, with stronger associations observed among women. The objective of the present secondary analysis was to examine the relationships among socioeconomic measures and adiposity for men and women participating in
Michael Willoughby; Nathan Vandergrift; Clancy Blair; Douglas A. Granger
2007-01-01
This study introduces a novel application of structural equation modeling (SEM) for the analysis of cortisol data that are collected using a pre-post-post design. By way of an extended example, an SEM model is developed that permits an examination of both the overall level of cortisol, as well as changes in cortisol (reactivity and regula- tion), as predictors of cognitive
Pediatric Health-Related Quality of Life: A Structural Equation Modeling Approach
Villalonga-Olives, Ester; Kawachi, Ichiro; Almansa, Josué; Witte, Claudia; Lange, Benjamin; Kiese-Himmel, Christiane; von Steinbüchel, Nicole
2014-01-01
Objectives One of the most referenced theoretical frameworks to measure Health Related Quality of Life (HRQoL) is the Wilson and Cleary framework. With some adaptions this framework has been validated in the adult population, but has not been tested in pediatric populations. Our goal was to empirically investigate it in children. Methods The contributory factors to Health Related Quality of Life that we included were symptom status (presence of chronic disease or hospitalizations), functional status (developmental status), developmental aspects of the individual (social-emotional) behavior, and characteristics of the social environment (socioeconomic status and area of education). Structural equation modeling was used to assess the measurement structure of the model in 214 German children (3–5 years old) participating in a follow-up study that investigates pediatric health outcomes. Results Model fit was ?2?=?5.5; df?=?6; p?=?0.48; SRMR ?=?0.01. The variance explained of Health Related Quality of Life was 15%. Health Related Quality of Life was affected by the area education (i.e. where kindergartens were located) and development status. Developmental status was affected by the area of education, socioeconomic status and individual behavior. Symptoms did not affect the model. Conclusions The goodness of fit and the overall variance explained were good. However, the results between children' and adults' tests differed and denote a conceptual gap between adult and children measures. Indeed, there is a lot of variety in pediatric Health Related Quality of Life measures, which represents a lack of a common definition of pediatric Health Related Quality of Life. We recommend that researchers invest time in the development of pediatric Health Related Quality of Life theory and theory based evaluations. PMID:25415751
La Peyre, M.K.; Mendelssohn, I.A.; Reams, M.A.; Templet, P.H.; Grace, J.B.
2001-01-01
Integrated management and policy models suggest that solutions to environmental issues may be linked to the socioeconomic and political Characteristics of a nation. In this study, we empirically explore these suggestions by applying them to the wetland management activities of nations. Structural equation modeling was used to evaluate a model of national wetland management effort and one of national wetland protection. Using five predictor variables of social capital, economic capital, environmental and political characteristics, and land-use pressure, the multivariate models were able to explain 60% of the variation in nations' wetland protection efforts based on data from 90 nations, as defined by level of participation, in the international wetland convention. Social capital had the largest direct effect on wetland protection efforts, suggesting that increased social development may eventually lead to better wetland protection. In contrast, increasing economic development had a negative linear relationship with wetland protection efforts, suggesting the need for explicit wetland protection programs as nations continue to focus on economic development. Government, environmental characteristics, and land-use pressure also had a positive direct effect on wetland protection, and mediated the effect of social capital on wetland protection. Explicit wetland protection policies, combined with a focus on social development, would lead to better wetland protection at the national level.
Determinants of Phubbing, Which is the Sum of Many Virtual Addictions: A Structural Equation Model
Karada?, Engi?n; Tosunta?, ?ule Betül; Erzen, Evren; Duru, Pinar; Bostan, Nalan; ?ahi?n, Berrak Mizrak; Çulha, ?LKAY; Babada?, Burcu
2015-01-01
Background and Aims Phubbing can be described as an individual looking at his or her mobile phone during a conversation with other individuals, dealing with the mobile phone and escaping from interpersonal communication. In this research, determinants of phubbing behavior were investigated; in addition, the effects of gender, smart phone ownership and social media membership were tested as moderators. Methods To examine the cause–effect relations among the variables of the theoretical model, the research employs a correlational design. Participants were 409 university students who were selected via random sampling. Phubbing was obtained via the scales featuring mobile phone addiction, SMS addiction, internet addiction, social media addiction and game addiction. The obtained data were analyzed using a correlation analysis, multiple linear regression analysis and structural equation model. Results The results showed that the most important determinants of phubbing behavior are mobile phone, SMS, social media and internet addictions. Discussion Although the findings show that the highest correlation value explaining phubbing is a mobile phone addiction, the other correlation values reflect a dependency on the phone. Conclusions There is an increasing tendency towards mobile phone use, and this tendency prepares the basis of phubbing. PMID:26014669
O'Brien, Kelly K; Davis, Aileen M; Gardner, Sandra; Bayoumi, Ahmed M; Rueda, Sergio; Hart, Trevor A; Cooper, Curtis; Solomon, Patricia; Rourke, Sean B; Hanna, Steven
2014-02-01
As individuals age with HIV it is increasingly important to consider the health-related consequences of HIV and multiple morbidities, known as disability. We assessed relationships between four dimensions of disability among adults living with HIV. We conducted a structural equation modeling analysis using data from 913 participants in the Ontario HIV Treatment Network Cohort Study to determine relationships between four latent variables of disability in the Episodic Disability Framework: physical symptoms and impairments, mental health symptoms and impairments, difficulties with day-to-day activities, and challenges to social inclusion. Results indicated that physical symptoms and impairments, mental health symptoms and impairments and difficulties with day-to-day activities directly or indirectly predicted challenges to social inclusion for adults living with HIV. Challenges to social inclusion were directly predicted by mental health symptoms and indirectly by physical health symptoms via (mediated by) having difficulties carrying out day-to-day activities and mental health symptoms and impairments. These findings provide a basis for conceptualizing disability experienced by people living with HIV. PMID:23132208
De Stavola, Bianca L.; Daniel, Rhian M.; Ploubidis, George B.; Micali, Nadia
2015-01-01
The study of mediation has a long tradition in the social sciences and a relatively more recent one in epidemiology. The first school is linked to path analysis and structural equation models (SEMs), while the second is related mostly to methods developed within the potential outcomes approach to causal inference. By giving model-free definitions of direct and indirect effects and clear assumptions for their identification, the latter school has formalized notions intuitively developed in the former and has greatly increased the flexibility of the models involved. However, through its predominant focus on nonparametric identification, the causal inference approach to effect decomposition via natural effects is limited to settings that exclude intermediate confounders. Such confounders are naturally dealt with (albeit with the caveats of informality and modeling inflexibility) in the SEM framework. Therefore, it seems pertinent to revisit SEMs with intermediate confounders, armed with the formal definitions and (parametric) identification assumptions from causal inference. Here we investigate: 1) how identification assumptions affect the specification of SEMs, 2) whether the more restrictive SEM assumptions can be relaxed, and 3) whether existing sensitivity analyses can be extended to this setting. Data from the Avon Longitudinal Study of Parents and Children (1990–2005) are used for illustration. PMID:25504026
Robustness of fit indices to outliers and leverage observations in structural equation modeling.
Yuan, Ke-Hai; Zhong, Xiaoling
2013-06-01
Normal-distribution-based maximum likelihood (NML) is the most widely used method in structural equation modeling (SEM), although practical data tend to be nonnormally distributed. The effect of nonnormally distributed data or data contamination on the normal-distribution-based likelihood ratio (LR) statistic is well understood due to many analytical and empirical studies. In SEM, fit indices are used as widely as the LR statistic. In addition to NML, robust procedures have been developed for more efficient and less biased parameter estimates with practical data. This article studies the effect of outliers and leverage observations on fit indices following NML and two robust methods. Analysis and empirical results indicate that good leverage observations following NML and one of the robust methods lead most fit indices to give more support to the substantive model. While outliers tend to make a good model superficially bad according to many fit indices following NML, they have little effect on those following the two robust procedures. Implications of the results to data analysis are discussed, and recommendations are provided regarding the use of estimation methods and interpretation of fit indices. PMID:23527606
Lee, Sik-Yum; Song, Xin-Yuan
2004-05-01
Missing data are very common in behavioural and psychological research. In this paper, we develop a Bayesian approach in the context of a general nonlinear structural equation model with missing continuous and ordinal categorical data. In the development, the missing data are treated as latent quantities, and provision for the incompleteness of the data is made by a hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm. We show by means of a simulation study that the Bayesian estimates are accurate. A Bayesian model comparison procedure based on the Bayes factor and path sampling is proposed. The required observations from the posterior distribution for computing the Bayes factor are simulated by the hybrid algorithm in Bayesian estimation. Our simulation results indicate that the correct model is selected more frequently when the incomplete records are used in the analysis than when they are ignored. The methodology is further illustrated with a real data set from a study concerned with an AIDS preventative intervention for Filipina sex workers. PMID:15171804
Testing a theory of aircraft noise annoyance: a structural equation analysis.
Kroesen, Maarten; Molin, Eric J E; van Wee, Bert
2008-06-01
Previous research has stressed the relevance of nonacoustical factors in the perception of aircraft noise. However, it is largely empirically driven and lacks a sound theoretical basis. In this paper, a theoretical model which explains noise annoyance based on the psychological stress theory is empirically tested. The model is estimated by applying structural equation modeling based on data from residents living in the vicinity of Amsterdam Airport Schiphol in The Netherlands. The model provides a good model fit and indicates that concern about the negative health effects of noise and pollution, perceived disturbance, and perceived control and coping capacity are the most important variables that explain noise annoyance. Furthermore, the model provides evidence for the existence of two reciprocal relationships between (1) perceived disturbance and noise annoyance and (2) perceived control and coping capacity and noise annoyance. Lastly, the model yielded two unexpected results. Firstly, the variables noise sensitivity and fear related to the noise source were unable to explain additional variance in the endogenous variables of the model and were therefore excluded from the model. And secondly, the size of the total effect of noise exposure on noise annoyance was relatively small. The paper concludes with some recommended directions for further research. PMID:18537376
A structural equation analysis of family accommodation in pediatric obsessive-compulsive disorder.
Caporino, Nicole E; Morgan, Jessica; Beckstead, Jason; Phares, Vicky; Murphy, Tanya K; Storch, Eric A
2012-01-01
Family accommodation of symptoms is counter to the primary goals of cognitive-behavioral therapy for pediatric obsessive-compulsive disorder (OCD) and can pose an obstacle to positive treatment outcomes. Although increased attention has been given to family accommodation in pediatric OCD, relatively little is known about associated child and parent characteristics, and their mediating/moderating effects. This study examined a structural equation model of parent and child variables related to parent reports of family accommodation. Sixty-one children with OCD (ages 6-17 years, 39% female) and their parents were recruited from a university-based clinic. They were administered clinician- and parent-rated measures of child OCD symptom severity, OCD-specific impairment, internalizing problems, and externalizing problems as well as parent anxiety, depression, empathy, consideration of future consequences, and accommodation. Results generally supported the hypothesized model. Family accommodation mediated the relationship between OCD symptom severity and parent-rated functional impairment; child internalizing problems mediated the relationship between parent anxiety and family accommodation; and parent empathy and consideration of future consequences interacted to predict family accommodation. Child externalizing problems were significantly associated with family accommodation but neither of these two variables was associated with parent depression. Findings suggest that reductions in family accommodation might be maximized by routinely screening for comorbid psychopathology in children with OCD and their parents, and using prescriptive or modular approaches to intervention. Directions for future research are discussed. PMID:21842196
A Psychometric Investigation of the Suicide Opinion Questionnaire
ERIC Educational Resources Information Center
Anderson, Amy L.; Lester, David; Rogers, James R.
2008-01-01
The factor structure of the Suicide Opinion Questionnaire (SOQ) was investigated in 2 studies. In the first study, the SOQ was administered to 568 participants to investigate the relative strength of 3 competing latent structure models previously identified in the literature. Confirmatory factor analyses provided no support for any of the prior…
ERIC Educational Resources Information Center
Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z.; Chamorro-Premuzic, Tomas
2013-01-01
This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM)…
NASA Technical Reports Server (NTRS)
Lakin, W. D.
1981-01-01
The use of integrating matrices in solving differential equations associated with rotating beam configurations is examined. In vibration problems, by expressing the equations of motion of the beam in matrix notation, utilizing the integrating matrix as an operator, and applying the boundary conditions, the spatial dependence is removed from the governing partial differential equations and the resulting ordinary differential equations can be cast into standard eigenvalue form. Integrating matrices are derived based on two dimensional rectangular grids with arbitrary grid spacings allowed in one direction. The derivation of higher dimensional integrating matrices is the initial step in the generalization of the integrating matrix methodology to vibration and stability problems involving plates and shells.
Symmetry analysis and algebraic structures of the Hu-Paz-Zhang Master Equation
Richard M. Morris; Peter G. L. Leach
2015-07-08
We apply the Lie Theory of continuous groups to investigate the symmetries of the Hu-Paz-Zhang Master Equation which arises in the modelling of the interaction of a harmonic oscillator with a linear passive heat bath of oscillators. We examine the case in which the parameters of the equation are constant.
Satoshi Fujii; Ryuichi Kitamura
2000-01-01
A structural equations model system which represents the effects of transportation control measures on commuters’ daily activity patterns after work hours is presented. A commuter’s daily activity after work till going to sleep is defined in terms of variables that indicate time use and travel. These variables are the endogenous variables of the structural equations model system. The parameters of
A structural equation model analysis of postfire plant diversity in California shrublands.
Grace, James B; Keeley, Jon E
2006-04-01
This study investigates patterns of plant diversity following wildfires in fire-prone shrublands of California, seeks to understand those patterns in terms of both local and landscape factors, and considers the implications for fire management. Ninety study sites were established following extensive wildfires in 1993, and 1000-m(2) plots were used to sample a variety of parameters. Data on community responses were collected for five years following fire. Structural equation modeling (SEM) was used to relate plant species richness to plant abundance, fire severity, abiotic conditions, within-plot heterogeneity, stand age, and position in the landscape. Temporal dynamics of average richness response was also modeled. Richness was highest in the first year following fire, indicating postfire enhancement of diversity. A general decline in richness over time was detected, with year-to-year variation attributable to annual variations in precipitation. Peak richness in the landscape was found where (1) plant abundance was moderately high, (2) within-plot heterogeneity was high, (3) soils were moderately low in nitrogen, high in sand content, and with high rock cover, (4) fire severity was low, and (5) stands were young prior to fire. Many of these characteristics were correlated with position in the landscape and associated conditions. We infer from the SEM results that postfire richness in this system is strongly influenced by local conditions and that these conditions are, in turn, predictably related to landscape-level conditions. For example, we observed that older stands of shrubs were characterized by more severe fires, which were associated with a low recovery of plant cover and low richness. These results may have implications for the use of prescribed fire in this system if these findings extrapolate to prescribed burns as we would expect. PMID:16711040
A Structural Equation Model Analysis of Relationships among ENSO, Seasonal Descriptors and Wildfires
Slocum, Matthew G.; Orzell, Steve L.
2013-01-01
Seasonality drives ecological processes through networks of forcings, and the resultant complexity requires creative approaches for modeling to be successful. Recently ecologists and climatologists have developed sophisticated methods for fully describing seasons. However, to date the relationships among the variables produced by these methods have not been analyzed as networks, but rather with simple univariate statistics. In this manuscript we used structural equation modeling (SEM) to analyze a proposed causal network describing seasonality of rainfall for a site in south-central Florida. We also described how this network was influenced by the El Niño-Southern Oscillation (ENSO), and how the network in turn affected the site’s wildfire regime. Our models indicated that wet and dry seasons starting later in the year (or ending earlier) were shorter and had less rainfall. El Niño conditions increased dry season rainfall, and via this effect decreased the consistency of that season’s drying trend. El Niño conditions also negatively influenced how consistent the moistening trend was during the wet season, but in this case the effect was direct and did not route through rainfall. In modeling wildfires, our models showed that area burned was indirectly influenced by ENSO via its effect on dry season rainfall. Area burned was also indirectly reduced when the wet season had consistent rainfall, as such wet seasons allowed fewer wildfires in subsequent fire seasons. Overall area burned at the study site was estimated with high accuracy (R2 score = 0.63). In summary, we found that by using SEMs, we were able to clearly describe causal patterns involving seasonal climate, ENSO and wildfire. We propose that similar approaches could be effectively applied to other sites where seasonality exerts strong and complex forcings on ecological processes. PMID:24086670
Dang, Bich N.; Westbrook, Robert A.; Black, William C.; Rodriguez-Barradas, Maria C.; Giordano, Thomas P.
2013-01-01
Introduction Analogous to the business model of customer satisfaction and retention, patient satisfaction could serve as an innovative, patient-centered focus for increasing retention in HIV care and adherence to HAART, and ultimately HIV suppression. Objective To test, through structural equation modeling (SEM), a model of HIV suppression in which patient satisfaction influences HIV suppression indirectly through retention in HIV care and adherence to HAART. Methods We conducted a cross-sectional study of adults receiving HIV care at two clinics in Texas. Patient satisfaction was based on two validated items, one adapted from the Consumer Assessment of Healthcare Providers and Systems survey (“Would you recommend this clinic to other patients with HIV?) and one adapted from the Delighted-Terrible Scale, (“Overall, how do you feel about the care you got at this clinic in the last 12 months?”). A validated, single-item question measured adherence to HAART over the past 4 weeks. Retention in HIV care was based on visit constancy in the year prior to the survey. HIV suppression was defined as plasma HIV RNA <48 copies/mL at the time of the survey. We used SEM to test hypothesized relationships. Results The analyses included 489 patients (94% of eligible patients). The patient satisfaction score had a mean of 8.5 (median 9.2) on a 0- to 10- point scale. A total of 46% reported “excellent” adherence, 76% had adequate retention, and 70% had HIV suppression. In SEM analyses, patient satisfaction with care influences retention in HIV care and adherence to HAART, which in turn serve as key determinants of HIV suppression (all p<.0001). Conclusions Patient satisfaction may have direct effects on retention in HIV care and adherence to HAART. Interventions to improve the care experience, without necessarily targeting objective clinical performance measures, could serve as an innovative method for optimizing HIV outcomes. PMID:23382948
Huang, Cheng; Guo, Chaoran; Yu, Shaohua; Feng, Yan; Song, Julia; Eriksen, Michael; Redmon, Pam; Koplan, Jeffrey
2013-01-01
Objective To investigate smoking prevalence and cessation services provided by male physicians in hospitals in three Chinese cities. Methods Data were collected from a survey of male physicians employed at 33 hospitals in Changsha, Qingdao and Wuxi City (n=720). Exploratory factor analysis was performed to identify latent variables, and confirmatory structural equation modelling analysis was performed to test the relationships between predictor variables and smoking in male physicians, and their provision of cessation services. Results Of the sampled male physicians, 25.7% were current smokers, and 54.0% provided cessation services by counselling (18.8%), distributing self-help materials (17.1%), and providing traditional remedies or medication (18.2%). Factors that predicted smoking included peer smoking (OR 1.14 95% CI 1.03 to 1.26) and uncommon knowledge (OR 0.94 95% CI 0.89 to 0.99), a variable measuring awareness of the association of smoking with stroke, heart attack, premature ageing and impotence in male adults as well as the role of passive smoking in heart attack. Factors that predicted whether physicians provided smoking cessation services included peer smoking (OR 0.82 95% CI 0.76 to 0.89), physicians’ own smoking (OR 0.87 95% CI 0.81 to 0.93), training in cessation (OR 1.36 95% CI 1.27 to 1.45) and access to smoking cessation resources (OR 1.69 95% CI 1.58 to 1.82). Conclusions The smoke-free policy is not strictly implemented at healthcare facilities, and smoking remains a public health problem among male physicians. A holistic approach, including a stricter implementation of the smoke-free policy, comprehensive education on the hazards of smoking, training in standard smoking-cessation techniques and provision of cessation resources, is needed to curb the smoking epidemic among male physicians and to promote smoking cessation services in China. PMID:23821489
Family burden in inherited ichthyosis: creation of a specific questionnaire
2013-01-01
Background The concept of individual burden, associated with disease, has been introduced recently to determine the “disability” caused by the pathology in the broadest sense of the word (psychological, social, economic, physical). Inherited ichthyosis belong to a large heterogeneous group of Mendelian Disorders of Cornification. Skin symptoms have a major impact on patients’ Quality of Life but little is known about the burden of the disease on the families of patients. Objectives To develop and validate a specific burden questionnaire for the families of patients affected by ichthyosis. Methods Two steps were required. First, the creation of the questionnaire which followed a strict methodological process involving a multidisciplinary team and families. Secondarily, the validation of the questionnaire, including the assessment of its reliability, external validity, reproducibility and sensitivity, was carried out on a population of patients affected by autosomal recessive congenital ichthyosis. A population of parents of patients affected by ichthyosis was enrolled to answer the new questionnaire in association with the Short Form Q12 questionnaire (SF-12) and a clinical severity score was filled for each patient. Results Ninety four families were interviewed to construct the verbatim in order to create the questionnaire and a cognitive debriefing was realized. The concept of burden could be structured around five components: “economic”, “daily life”, “familial and personal relationship”, “work”, and “psychological impact”. As a result, “Family Burden Ichthyosis” (FBI) reproducible questionnaire of 25 items was created. Forty two questionnaires were analyzable for psychometric validation. Reliability (Cronbach’s alpha coefficient?=?0.89), reflected the good homogeneity of the questionnaire. The correlation between mental dimensions of the SF-12 and the FBI questionnaire was statistically significant which confirmed the external validity. The mean FBI score was 71.7?±?18.8 and a significant difference in the FBI score was shown between two groups of severity underlining a good sensitivity of the questionnaire. Conclusions The internal and external validity of the “FBI” questionnaire was confirmed and it is correlated to the severity of ichtyosis. Ichthyoses, and other chronic pathologies, are difficult to assess by clinical or Quality of Life aspects alone as their impact can be multidimensional. “FBI” takes them all into consideration in order to explain every angle of the handicap generated. PMID:23414570
Development of the Pharmacy Safety Climate Questionnaire: a principal components analysis
D M Ashcroft; D Parker
2009-01-01
Objective:To develop, and examine the component structure and internal consistency, of a questionnaire designed to assess safety climate in the community pharmacy setting.Methods:998 pharmacists working in community pharmacies in England completed the questionnaire. Item selection was determined by principal components analysis (PCA) which also defined the underlying structure of the questionnaire. Scales were constructed from the items that loaded on
Surveys and questionnaires in nursing research.
Timmins, Fiona
2015-06-17
Surveys and questionnaires are often used in nursing research to elicit the views of large groups of people to develop the nursing knowledge base. This article provides an overview of survey and questionnaire use in nursing research, clarifies the place of the questionnaire as a data collection tool in quantitative research design and provides information and advice about best practice in the development of quantitative surveys and questionnaires. PMID:26080989
Confirmatory factor analysis of the equity preference questionnaire
Brian K. Miller
2009-01-01
Purpose – The purpose of this paper is to provide an analysis of the factor structure of the equity preference questionnaire (EPQ). Design\\/methodology\\/approach – Individual level data are collected from two samples (n1=382, n2=455) and subjected to confirmatory factor analysis of an a priori two-factor structure for equity sensitivity. Sample two is randomly split and one half subjected to structural
Giuseppe Buffoni; Sara Pasquali
2010-01-01
Individual-based models describe the growth dynamics of a population by performing numerical simulations of the life histories\\u000a of its individuals. The life of an individual is determined by the basic processes of development, reproduction and mortality.\\u000a In this paper the model equations for the development process are stochastic difference equations with discrete time and describe\\u000a the time evolution of the
Donggen Wang; Fion Yuk Ting Law
2007-01-01
The objective of this paper is to contribute an empirical study to the literature on transportation impacts of Information\\u000a and Communications Technologies (ICT). The structural equation model (SEM) is employed to analyze the impacts of ICT usage\\u000a on time use and travel behavior. The sample is derived from the travel characteristic survey conducted in Hong Kong in 2002.\\u000a The usage
O. Lyubimova; X. Liu; Sergey Gusarov; A. E. Kobryn; Andriy Kovalenko
2011-01-01
Solvation structure and gelation ability of novel oligomeric electrolyte poly(pyridinium-1,4-diyliminocarbonyl-1,4-phenylenemethylene chloride) (1·Cl) as well as its derivatives 1·X obtained by counterion substitution: X? = BF4?, PF6?, TFSA?, I?, SCN?, DCA?, ClO4?, SO3CF3? have been studied by quantum chemistry methods and integral equation theory of molecular liquids. The interaction energy, ?Etot, between the counterions and polymer chains has been estimated in
Carolyn E. Ievers-Landis; Rachel Neff Greenley; Chris Burant; Elaine Borawski
2006-01-01
\\u000aPurpose: To examine the roles of cognitive social maturity and life change events in a structural equation model (SEM) to explain adolescents' use of marijuana, tobacco, and alcohol. Methods: Data were derived from 1322 9th and 10th graders in a HIV prevention study. Students completed a survey of their cognitive social maturity, recent life events and substance use habits. A
Mike W.-L. Cheung
2008-01-01
Meta-analysis and structural equation modeling (SEM) are two important statistical methods in the behavioral, social, and medical sciences. They are generally treated as two unrelated topics in the literature. The present article proposes a model to integrate fixed-, random-, and mixed-effects meta-analyses into the SEM framework. By applying an appropriate transformation on the data, studies in a meta-analysis can be
Ehri Ryu
A simulation study investigated the effects of skewness and kurtosis on level-specific maximum likelihood (ML) test statistics\\u000a based on normal theory in multilevel structural equation models. The levels of skewness and kurtosis at each level were manipulated\\u000a in multilevel data, and the effects of skewness and kurtosis on level-specific ML test statistics were examined. When the\\u000a assumption of multivariate normality
Sik-Yum Lee; Ye-Mao Xia
2006-01-01
By means of more than a dozen user friendly packages, structural equation models (SEMs) are widely used in behavioral, education,\\u000a social, and psychological research. As the underlying theory and methods in these packages are vulnerable to outliers and\\u000a distributions with longer-than-normal tails, a fundamental problem in the field is the development of robust methods to reduce\\u000a the influence of outliers
Briki, Walid; Chaouachi, Anis; Patrick, Thomas; Chamari, Karim
2015-01-01
Aim The present study attempted to test McCullough and Willoughby’s hypothesis that self-control mediates the relationships between religiosity and psychosocial outcomes. Specifically, this study examined whether trait self-control (TSC) mediates the relationship of identified-introjected religiosity with positive and negative health-related-feelings (HRF) in healthy Muslims. Methods Two hundred eleven French-speaking participants (116 females, 95 males; Mage = 28.15, SDage = 6.90) answered questionnaires. One hundred ninety participants were retained for the analyses because they reported to be healthy (105 females, 85 males; Mage = 27.72, SDage = 6.80). To examine the relationships between religiosity, TSC and HRF, two competing mediation models were tested using structural equation model analysis: While a starting model used TSC as mediator of the religiosity-HRF relationship, an alternative model used religiosity as mediator of the TSC-HRF relationship. Results The findings revealed that TSC mediated the relationship between identified religiosity and positive HRF, and that identified religiosity mediated the relationship between TSC and positive and negative HRF, thereby validating both models. Moreover, the comparison of both models showed that the starting model explained 13.211% of the variance (goodness of fit = 1.000), whereas the alternative model explained 6.877% of the variance (goodness of fit = 0.987). Conclusion These results show that the starting model is the most effective model to account for the relationships between religiosity, TSC, and HRF. Therefore, this study provides initial insights into how religiosity influences psychological health through TSC. Important practical implications for the religious education are suggested. PMID:25962179
Yuki, Kenya; Asaoka, Ryo; Tsubota, Kazuo
2015-01-01
Purpose To investigate the relationship between visual function and the risks of falling and injurious falls in subjects with primary open angle glaucoma (POAG) Methods Questionnaires were conducted in 365 POAG patients to assess history of falls and falls with injury and general patient health. Structural equation modeling (SEM) was used to investigate the relationship between visual function, as measured by a patient’s binocular integrated visual field and visual acuity (VA), general health and the risks of falling and injurious falls. Results Among the 365 subjects, 55 subjects experienced falls in the past year. A significant difference was observed in worse-eye VA between the faller and non-faller groups (p = 0.03). SEM of fallers obtained a Root Mean Square Error of Approximation (RMSEA) of 0.035 and a Comparative Fit Index (CFI) of 0.99. The 95% confidence intervals (CI) of regression coefficients from this model suggested better VA and worse VA were significant risk factors for falling. Among the 55 fallers, 22 subjects experienced an associated injury. There was a significant difference in gender between the non-injurious and injurious faller groups (p = 0.002). SEM of injurious fallers obtained a RMSEA of 0.074 and a CFI of 0.97. In this SEM model, the 95% CI of regression coefficients suggested gender and average total deviation values in the lower peripheral visual field were significant risk factors for an injurious fall. Conclusions This study suggests that worse-eye and better-eye VAs are associated with falls. Furthermore, patients with inferior visual field loss and females were found to be at greater risk of injurious falls. PMID:26053502
The ARSQ: the athletes' received support questionnaire.
Freeman, Paul; Coffee, Pete; Moll, Tjerk; Rees, Tim; Sammy, Nadine
2014-04-01
To address calls for context-specific measurement of social support, this article reports the development of the Athletes' Received Support Questionnaire (ARSQ) and demonstrates initial evidence for its validity. Across four studies there was support for a four-dimensional structure reflecting emotional, esteem, informational, and tangible received support. There was also support for unidimensional and higher-order models. Further, Study 3 provided some support for convergent validity, with significant correlations between the corresponding dimensions of the ARSQ and the Inventory of Socially Supportive Behaviors. Study 4 provided evidence for the nomological validity of the ARSQ. Emotional and esteem support significantly predicted self-confidence and positive affect, and tangible support significantly moderated the relationship between stress and negative affect. Collectively, these results provide initial evidence for the validity of the ARSQ, and offer researchers flexibility to adopt either a multidimensional or aggregated approach to measuring received support. PMID:24686955
Swope, Sarah M; Parker, Ingrid M
2012-12-01
Herbivores, seed predators, and pollinators can exert strong impacts on their host plants. They can also affect the strength of each other's impact by modifying traits in their shared host, producing super- or sub-additive outcomes. This phenomenon is especially relevant to biological control of invasive plants because most invaders are attacked by multiple agents. Unfortunately, complex interactions among agents are rarely studied. We used structural equation modeling (SEM) to quantify the effect of two biocontrol agents and generalist pollinators on the invasive weed Centaurea solstitialis, and to identify and quantify the direct and indirect interaction pathways among them. The weevil Eustenopus villosus is both a bud herbivore and a predispersal seed predator; the fly Chaetorellia succinea is also a predispersal seed predator; Apis mellifera is the primary pollinator. We conducted this work at three sites spanning the longitudinal range of C. solstitialis in California (USA) from the coast to the Sierra Nevada Mountains. SEM revealed that bud herbivory had the largest total effect on the weed's fecundity. The direct effect of bud herbivory on final seed set was 2-4 times larger in magnitude than the direct effect of seed predation by both agents combined. SEM also revealed important indirect interactions; by reducing the number of inflorescences plants produced, bud herbivory indirectly reduced the plant's attractiveness to ovipositing seed predators. This indirect, positive pathway reduced bud herbivory's direct negative effect by 11-25%. In the same way, bud herbivory also reduced pollinator visitation, although the magnitude of this pathway was relatively small. E. villosus oviposition deterred C. succinea oviposition, which is unfortunate because C. succinea is the more voracious of the seed predators. Finally, C. succinea oviposition indirectly deterred pollinator visitation, thereby enhancing its net effect on the plant. This study demonstrates the powerful insights that can be gained from the SEM approach in understanding the multiple direct and indirect interactions among agents and pollinators and their effects on an invasive weed. Such an approach may improve our ability to manage weeds with biocontrol agents by identifying pathways that could be exploited by future agents and minimizing the possibility of interference with established agents. PMID:23387114
NASA Technical Reports Server (NTRS)
Byun, Chansup; Guruswamy, Guru P.; Kutler, Paul (Technical Monitor)
1994-01-01
In recent years significant advances have been made for parallel computers in both hardware and software. Now parallel computers have become viable tools in computational mechanics. Many application codes developed on conventional computers have been modified to benefit from parallel computers. Significant speedups in some areas have been achieved by parallel computations. For single-discipline use of both fluid dynamics and structural dynamics, computations have been made on wing-body configurations using parallel computers. However, only a limited amount of work has been completed in combining these two disciplines for multidisciplinary applications. The prime reason is the increased level of complication associated with a multidisciplinary approach. In this work, procedures to compute aeroelasticity on parallel computers using direct coupling of fluid and structural equations will be investigated for wing-body configurations. The parallel computer selected for computations is an Intel iPSC/860 computer which is a distributed-memory, multiple-instruction, multiple data (MIMD) computer with 128 processors. In this study, the computational efficiency issues of parallel integration of both fluid and structural equations will be investigated in detail. The fluid and structural domains will be modeled using finite-difference and finite-element approaches, respectively. Results from the parallel computer will be compared with those from the conventional computers using a single processor. This study will provide an efficient computational tool for the aeroelastic analysis of wing-body structures on MIMD type parallel computers.
High-Accuracy Finite Difference Equations for Simulation of Photonic Structures
Hadley, G.R.
1999-04-23
Progress towards the development of such algorithms as been reported for waveguide analysis'-3and vertical-cavity laser simulation. In all these cases, the higher accuracy order was obtained for a single spatial dimension. More recently, this concept was extended to differencing of the Helmholtz Equation on a 2-D grid, with uniform regions treated to 4th order and dielectric interfaces to 3'd order5. No attempt was made to treat corners properly. In this talk I will describe the extension of this concept to allow differencing of the Helmholtz Equation on a 2-D grid to 6* order in uniform regions and 5* order at dielectric interfaces. In addition, the first known derivation of a finite difference equation for a dielectric comer that allows correct satisfaction of all boundary conditions will be presented. This equation is only accurate to first order, but as will be shown, results in simulations that are third-order-accurate. In contrast to a previous approach3 that utilized a generalized Douglas scheme to increase the accuracy order of the difference second derivative, the present method invokes the Helmholtz Equation itself to convert derivatives of high order in a single direction into mixed
Further Evaluation of the Outcome Questionnaire-45.2
ERIC Educational Resources Information Center
Rice, Kenneth G.; Suh, Hanna; Ege, Engin
2014-01-01
Data from clinical and nonclinical samples ("Ns" = 2,096, 618) were used to evaluate and replicate the measurement structure of the Outcome Questionnaire-45.2. Different measurement models and invariance tests were evaluated and the best psychometric support was found for a shortened measure of two factors: overall maladjustment and…
The Development and Evaluation of the Academic Entitlement Questionnaire
ERIC Educational Resources Information Center
Kopp, Jason P.; Zinn, Tracy E.; Finney, Sara J.; Jurich, Daniel P.
2011-01-01
Validity evidence was gathered for the Academic Entitlement Questionnaire (AEQ). After reviewing entitlement literature, items were written to cover the breadth of academic entitlement. Results provide evidence for the substantive, structural, and external aspects of validity of the AEQ. Implications for research and use of the AEQ are discussed.…
The higher grading structure of the WKI hierarchy and the two-component short pulse equation
G. S. Franca; J. F. Gomes; A. H. Zimerman
2012-08-28
A higher grading affine algebraic construction of integrable hierarchies, containing the Wadati-Konno-Ichikawa (WKI) hierarchy as a particular case, is proposed. We show that a two-component generalization of the Sch\\" afer-Wayne short pulse equation arises quite naturally from the first negative flow of the WKI hierarchy. Some novel integrable nonautonomous models are also proposed. The conserved charges, both local and nonlocal, are obtained from the Riccati form of the spectral problem. The loop-soliton solutions of the WKI hierarchy are systematically constructed through gauge followed by reciprocal B\\" acklund transformation, establishing the precise connection between the whole WKI and AKNS hierarchies. The connection between the short pulse equation with the sine-Gordon model is extended to a correspondence between the two-component short pulse equation and the Lund-Regge model.
The equation of state of neutron matter, symmetry energy, and neutron star structure
S. Gandolfi; J. Carlson; S. Reddy; A. W. Steiner; R. B. Wiringa
2013-07-22
We review the calculation of the equation of state of pure neutron matter using quantum Monte Carlo (QMC) methods. QMC algorithms permit the study of many-body nuclear systems using realistic two- and three-body forces in a nonperturbative framework. We present the results for the equation of state of neutron matter, and focus on the role of three-neutron forces at supranuclear density. We discuss the correlation between the symmetry energy, the neutron star radius and the symmetry energy. We also combine QMC and theoretical models of the three-nucleon interactions, and recent neutron star observations to constrain the value of the symmetry energy and its density dependence.
The solution of linear systems of equations with a structural analysis code on the NAS CRAY-2
NASA Technical Reports Server (NTRS)
Poole, Eugene L.; Overman, Andrea L.
1988-01-01
Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted the Computational Structural Mechanics (CSM) Testbed. A description of the techniques used to integrate the two solvers into the Testbed is given. Storage schemes, memory requirements, operation counts, and reformatting procedures are discussed. Finally, results from the new methods are compared with results from the initial Testbed sparse Choleski equation solver for three structural analysis problems. The new direct solvers described achieve the highest computational rates of the methods compared. The new iterative methods are not able to achieve as high computation rates as the vectorized direct solvers but are best for well conditioned problems which require fewer iterations to converge to the solution.
Kramer, A; Assadian, O; Helfrich, J; Krüger, C; Pfenning, I; Ryll, S; Perner, A; Loczenski, B
2013-01-01
From January to May 2012, 1,860 hospitals throughout Germany received a questionnaire encompassing 77 items. Additionally, 300 outpatient care services and 310 nursing homes for elderly in Berlin also received a 10-item questionnaire asking on their implemented infection control practices. All questionnaires were anonymous. A total of 229 completed questionnaires from hospitals, 14 questionnaires from outpatient care services, and 16 questionnaires from nursing homes were eligible for further analysis. The lack of Infection Control physicians was identified as the largest issue. In hospitals sized 400-999 beds a gap of 71%, and in hospitals sized ?1,000 beds a gap of 17% was reported. Depending on the number of hospital beds, 13-29% of hospitals sized ?100 beds reported not havening one infection control nurse. Since based on the number of beds in larger institutions or in facilities caring for high-risk patients several infection control nurses may be required, the deficiency in infection control nurses may even be higher, particularly in secondary and tertiary care facilities. Furthermore, the analysis revealed that the legal requirements for surveillance and reporting of notifiable infectious diseases have not yet been implemented in 11% of the facilities. The implementation of antibiotic strategies did show significant gaps. However, deficiencies in the implemented measures for the prevention of surgical site infections were less frequent. Yet 12% of the participants did not have a dedicated infection control concept for their surgical services. Eight percent of hospitals were not prepared for an outbreak management and 10% did not have established regulations for wearing surgical scrubs. Deficiencies in waste disposal and the control of air-conditioning systems were also noted. Based on the results of this survey, conclusions on the optimal resource allocation for further improvement of patient safety may be drawn. While all participating nursing homes had some sort of infection control consultation, this only applied to 12 out of 16 outpatient nursing services. However, all 16 nursing services worked on the basis of an implemented infection control plan. Though legally binding hygiene recommendations have not yet been implemented for nursing homes, the necessity of infection control to assure patient safety has obviously been recognised throughout these services. PMID:23967397
Lion, SÃ©bastien
moment equations SeÂ´bastien Lion Ã? Institute for Biodiversity and Ecosystem Dynamics, University this problem (Tilman and Kareiva, 1997; Dieckmann et al., 2000; Rousset, 2004; Lion and van Baalen, 2008). Most and Kareiva, 1997; Dieckmann et al., 2000; Rousset, 2004; Lion and van Baalen, 2008). Such deme
New examples of damped wave equations with gradient-like structure
Joly, Romain
study the case where the damping (x) of (1.1) can be slightly negative on some part of . Notice that. Â· Classically, the damping (x) of the wave equation is non-negative. In Section 3, the damping has an indefinite rate of the species compared to the speed of diffusion may be seen as a negative damping. Â· Many papers
Cinabro, David
of questions designed to identify areas of audit risk, the presence of internal controls to mitigateSelf Audit QuestionnaireSelf Audit QuestionnaireSelf Audit QuestionnaireSelf Audit Questionnaire A Self-Audit of your unit is included in the Internal Audit Plan for the current year. A Self-Audit
Development and Preliminary Validation of Chinese Preschoolers’ Eating Behavior Questionnaire
Zhang, Yuhai; Wang, Baoxi; Sun, Lijun; Shang, Lei
2014-01-01
Background The objective of this study was to develop a questionnaire for caregivers to assess the eating behavior of Chinese preschoolers. Methods To assess children’s eating behaviors, 152 items were derived from a broad review of the literature related to epidemiology surveys and the assessment of children’s eating behaviors. All of these items were reviewed by 50 caregivers of preschoolers and 10 experienced pediatricians. Seventy-seven items were selected for use in a primary questionnaire. After conducting an exploratory factor analysis and a variability analysis on the data from 313 preschoolers used to evaluate this primary questionnaire, we deleted 39 of these 77 items. A Chinese Preschoolers’ Eating Behavior Questionnaire (CPEBQ) was finally established from the remaining 38 items. The structure of this questionnaire was explored by factor analysis, and its reliability, validity and discriminative ability were evaluated with data collected from caregivers of 603 preschoolers. Results The CPEBQ consisted of 7 dimensions and 38 items. The 7 dimensions were food fussiness, food responsiveness, eating habit, satiety responsiveness, exogenous eating, emotional eating and initiative eating. The Cronbach’s ? coefficient for the questionnaire was 0.92, and the test-retest reliability was 0.72. There were significant differences between the scores of normal-weight, overweight and obese preschoolers when it was referred to food fussiness, food responsiveness, eating habits, satiety responsiveness and emotional eating (p<0.05). Differences in caregiver’s education levels also had significant effects on scores for food fussiness, eating habits and exogenous eating (p<0.05). Conclusions The CPEBQ satisfies the conditions of reliability and validity, in accordance with psychometric demands. The questionnaire can be employed to evaluate the characteristics of Chinese preschoolers’ eating behaviors; therefore, it can be used in child health care practice and research. PMID:24520359
A family psychosocial risk questionnaire for use in pediatric practice.
Pati, Susmita; Guevara, James; Zhang, Guangxiang; Bhatt, Suraj K; Kavanagh, Jane; Gerdes, Marsha; Localio, Russell; Forrest, Christopher B
2013-12-01
The objective of this study is to develop new methods to better identify psychosocial risk such that children with the greatest risk of poor future outcomes receive more intensive preventive health services. Based on structured literature review and secondary data analysis, a 52-item psychosocial risk questionnaire was administered to 2,083 families of children (<36 months). To quantify the questionnaire's construct validity, developmental concern was assessed with the Ages and Stages Questionnaire version II (ASQ) [n = 1,163]. An iterative model selection process was used to produce the most parsimonious predictive model. Model fit was examined using c-statistics, the Hosmer-Lemeshow test, and a heuristic measure of model overfit based on the fitted log-likelihood values and associated number of degrees of freedom. We found 13 items easily obtained from parental report produced a regression model with a c-statistic of 0.70. Using an integer scoring system derived from the regression model, we calculated stratum specific likelihood ratios to revise a given prior probability of ASQ failure. The posterior probability of ASQ failure was 44.9 % for a child in the highest risk group (score >25) on the questionnaire, more than double our observed average failure rate of 19.5 %, while it was less than 7 % for a child with the lowest possible score on the questionnaire. Thirteen parent-reported items can be compiled into a summary psychosocial risk questionnaire that predicts failure on developmental screening among preschool children. With further validation, this questionnaire could conceivably be used by clinicians to tailor pediatric preventive care to children at varying levels of risk. PMID:23238832
Waldyr A. Rodrigues Jr.; Samuel A. Wainer
2015-06-01
We discuss the physics of interacting tensor fields and particles living in $M=\\mathrm{S0}(1,4)/\\mathrm{S0} (1,3)\\simeq\\mathbb{R}\\times S^{3}$ a submanifold of $\\mathring{M}=(\\mathbb{R}^{5},\\boldsymbol{\\mathring{g}})$, where $\\boldsymbol{\\mathring {g}}$ has signature $(1,4)$. Structure $(M,\\boldsymbol{g})$ where $(\\boldsymbol{g=i}^{\\ast}\\boldsymbol{\\mathring{g}})$ is a Lorentzian manifold. Structure $(M,\\boldsymbol{g,}\\tau_{\\boldsymbol{g}},\\uparrow)$ is primely used to study the energy-momentum conservation law (for a system of physical fields (and particles) living in $M$ and to get the respective equations of motion. We construct two different de Sitter spacetime structures $M^{dSL}=(M,\\boldsymbol{g,D},\\tau_{\\boldsymbol{g}},\\uparrow)$ and $M^{dSTP}=(M,\\boldsymbol{g,\
NASA Astrophysics Data System (ADS)
Wang, Rui; Wang, Shaofeng; Wu, Xiaozhi
2011-04-01
We have employed the improved Peierls-Nabarro (P-N) equation to study the properties of 1/2lang110rang edge dislocation in the {111} plane in face-centered cubic (FCC) metals Al, Cu, Ir, Pd and Pt. The generalized-stacking-fault energy surface entering the equation is calculated by using first-principles density functional theory (DFT). The accuracy of the method has been tested by calculating the values for various stacking fault energies that favorably compare with previous theoretical and experimental results. The core structures, including the core widths of the edge and screw components, and dissociation behavior have been investigated. The dissociated distance between two partials for Al in our calculation agrees well with the values obtained from numerical simulation with DFT and molecular dynamics simulation, as well as experiment. Our calculations show that it is preferred to create partial dislocations in Cu, and easily observed full dislocations in Al, Ir, Pd and especially Pt.
White, R D; Robson, R E
2011-09-01
In this paper, we generalize the semiclassical Boltzmann kinetic equation for dilute gases to consider highly nonequilibrium electrons and positrons in soft condensed matter, accounting rigorously for all types of interactions, including positronium formation, and allowing for both coherent and incoherent scattering processes. The limitations inherent in the seminal paper of Cohen and Lekner [M. H. Cohen and J. Lekner, Phys. Rev. 158, 305 (1967); Y. Sakai, J. Phys. D 40, R441 (2007)] are avoided by solving the kinetic equation using a "multiterm" spherical harmonic representation of the velocity distribution function, as well as formulating a necessarily nonperturbative treatment of nonconservative collisional processes such as positronium formation. Numerical calculations of transport properties are carried out for a Percus-Yevick model of a hard-sphere system, and for positrons in liquid argon. New phenomena are predicted, including structure-induced negative conductivity and anisotropic diffusion. PMID:22060346
Vocadlo, Lidunka
: Equations of state; 8124 Tectonophysics: Earth's interior--composition and state (old 8105). CitationThe equation of state of CsCl-structured FeSi to 40 GPa: Implications for silicon in the Earth and Ian G. Wood Department of Earth Sciences, University College London, London, UK Received 5 September
Ishii, Hitoshi; Shimatsu, Akira; Okimura, Yasuhiko; Tanaka, Toshiaki; Hizuka, Naomi; Kaji, Hidesuke; Hanew, Kunihiko; Oki, Yutaka; Yamashiro, Sayuri; Takano, Koji; Chihara, Kazuo
2012-01-01
Objective To develop and validate the Adult Hypopituitarism Questionnaire (AHQ) as a disease-specific, self-administered questionnaire for evaluation of quality of life (QOL) in adult patients with hypopituitarism. Methods We developed and validated this new questionnaire, using a standardized procedure which included item development, pilot-testing and psychometric validation. Of the patients who participated in psychometric validation, those whose clinical conditions were judged to be stable were asked to answer the survey questionnaire twice, in order to assess test-retest reliability. Results Content validity of the initial questionnaire was evaluated via two pilot tests. After these tests, we made minor revisions and finalized the initial version of the questionnaire. The questionnaire was constructed with two domains, one psycho-social and the other physical. For psychometric assessment, analyses were performed on the responses of 192 adult patients with various types of hypopituitarism. The intraclass correlations of the respective domains were 0.91 and 0.95, and the Cronbach’s alpha coefficients were 0.96 and 0.95, indicating adequate test-retest reliability and internal consistency for each domain. For known-group validity, patients with hypopituitarism due to hypothalamic disorder showed significantly lower scores in 11 out of 13 sub-domains compared to those who had hypopituitarism due to pituitary disorder. Regarding construct validity, the domain structure was found to be almost the same as that initially hypothesized. Exploratory factor analysis (n?=?228) demonstrated that each domain consisted of six and seven sub-domains. Conclusion The AHQ showed good reliability and validity for evaluating QOL in adult patients with hypopituitarism. PMID:22984490
On a Singular Solution in Higgs Field (1)- Basic equation and structure for SM Higgs boson mass
NASA Astrophysics Data System (ADS)
Kitazawa, Kazuyoshi
2011-04-01
A formula for mass of SM Higgs boson (H0) is derived by considering certain asymptotic behavior for singular solution of EOM of Higgs field via Euler-Lagrange equation, in which MH0 is shown as a rest mass of Higgs boson mass of the field, which maintains Lorentz invariance. Where the asymptotic formula extracts a proper information near the singular solution. By modifying the mass formula with H0 production scheme of W/Z-fusion process, the value of MH0 is determined at 120.611 GeV/c2. Then the mass structure of H0 is discussed by top quark decay processes in electroweak and quark sectors with newly enlarged equation of motion (Non-Linear Klein-Gordon), calculating the mass value of top quark as 171.266 GeV/c2. And from the difference between the value by assuming that H0 is a virtual bound state of top quark- pair ((t t)*) itself with the mass formula obtained by requirement of minimal mass production and the theoretical mass value of H0 (120.611 GeV/c2), it is expected that H0 is to be a composite scalar meson after emitting one photon from the (t t)* through radiative decay. Finally, a mass structure of H0 which is composed of all spin 0 mesons' masses, is proposed. Where the truncated-Octahedron mass structure is recursively (doubly) seen.
The Hamiltonian structure of Dirac's equation in tensor form and its Fermi quantization
NASA Technical Reports Server (NTRS)
Reifler, Frank; Morris, Randall
1992-01-01
Currently, there is some interest in studying the tensor forms of the Dirac equation to elucidate the possibility of the constrained tensor fields admitting Fermi quantization. We demonstrate that the bispinor and tensor Hamiltonian systems have equivalent Fermi quantizations. Although the tensor Hamiltonian system is noncanonical, representing the tensor Poisson brackets as commutators for the Heisenberg operators directly leads to Fermi quantization without the use of bispinors.
On the structure of varieties with equationally definable principal congruences IV
W. J. Blok; Don Pigozzi
1994-01-01
The notion of apseudo-interior algebra is introduced; it is a hybrid of a (topological) interior algebra and a residuated partially ordered monoid. The elementary arithmetic of pseudo-interior algebras is developed leading to a simple equational axiomatization. A notion ofopen filter analogous to the open filters of interior algebras is investigated. Pseudo-interior algebras represent, in algebraic form, the logic inherent in
G. Cardone; R. Fares; G. P. Panasenko
2012-01-10
The Stokes equation with the varying viscosity is considered in a thin tube structure, i.e. in a connected union of thin rectangles with heights of order $\\varepsilon<<1 $ and with bases of order 1 with smoothened boundary. An asymptotic expansion of the solution is constructed: it contains some Poiseuille type flows in the channels (rectangles) with some boundary layers correctors in the neighborhoods of the bifurcations of the channels. The estimates for the difference of the exact solution and its asymptotic approximation are proved.
X. Y. Song; S. Y. Lee; R. C. W. Ma; W. Y. So; J. H. Cai; C. Tam; V. Lam; W. Ying; M. C. Y. Ng; J. C. N. Chan
2009-01-01
Aims\\/hypothesis Cardiovascular and renal diseases share common risk factors. We used structural equation modelling (SEM) to evaluate the independent\\u000a and combined effects of phenotypes and genotypes implicated in cardiovascular diseases on renal function in type 2 diabetes.\\u000a \\u000a \\u000a \\u000a Methods 1,188 type 2 diabetic patients were stratified into high-risk and low-risk groups according to bimodal distributions of the\\u000a logarithmically transformed (loge) urinary albumin:creatinine ratio
Analysis of a Two-Level Structural Equation Model with Group-Specific Variables in LISREL
ERIC Educational Resources Information Center
Bai, Yun; Poon, Wai-Yin; Cheung, Gordon Wai Hung
2006-01-01
Two-level data sets are frequently encountered in social and behavioral science research. They arise when observations are drawn from a known hierarchical structure, as when individuals are randomly drawn from groups that are randomly drawn from a target population. When the covariance structures in the group level and the individual level are the…
NASA Astrophysics Data System (ADS)
Rusov, V. D.; Vlasenko, D. S.
2012-05-01
Based on the Chetaev theorem on stable dynamical trajectories in the presence of dissipative forces, we obtain the generalized condition for stability of relativistic classical Hamiltonian systems (with an invariant evolution parameter) in the form of the Stückelberg equation. As is known, this equation is the basis of a competing paradigm known as parametrized relativistic quantum mechanics (pRQM). It is shown that the energy of dissipative forces, which generate the Chetaev generalized condition of stability, coincides exactly with Bohmian relativistic quantum potential. Within the framework of Bohmian RQM supplemented by the generalized Chetaev theorem and on the basis of the principle of least action for dissipative forces, we show that the squared amplitude of a wave function in the Stückelberg equation is equivalent to the probability density function for the number of particle trajectories, relative to which the velocity and the position of the particle are not hidden parameters. The conditions for reasonableness of trajectory interpretation of pRQM are discussed. Based on analysis of a general formalism for vacuum-flavor mixing of neutrino within the context of the standard and pRQM models we show that the corresponding expressions for the probability of transition from one neutrino flavour to another differ appreciably, but they are experimentally testable: the estimations of absolute value for neutrino mass based on modern experimental data for solar and atmospheric neutrinos show that the pRQM results have a preference. It is noted that the selection criterion of mass solutions relies on proximity between the average size of condensed neutrino clouds, which is described by the Muraki formula (29th ICRC, 2005) and depends on the neutrino mass, and the average size of typical observed void structure (dark matter + hydrogen gas), which plays the role of characteristic dimension of large-scale structure of the Universe.
Kimura, Daisuke; Nakatani, Ken; Takeda, Tokunori; Fujita, Takashi; Sunahara, Nobuyuki; Inoue, Katsumi; Notoya, Masako
2015-01-01
The purpose of this study is to identify a potentiality factor that is a preventive factor for decline in cognitive function. Additionally, this study pursues to clarify the causal relationship between the each potential factor and its influence on cognitive function. Subjects were 366 elderly community residents (mean age 73.7 ± 6.4, male 51, female 315) who participated in the Taketoyo Project from 2007 to 2011. Factor analysis was conducted to identify groupings within mental, social, life, physical and cognitive functions. In order to detect clusters of 14 variables, the item scores were subjected to confirmatory factor analysis. We performed Structural Equation Modeling analysis to calculate the standardization coefficient and correlation coefficient for every factor. The cause and effect hypothesis model was used to gather two intervention theory hypotheses for dementia prevention (direct effect, indirect effect) in one system. Finally, we performed another Structural Equation Modeling analysis to calculate the standardization of the cause and effect hypothesis model. Social participation was found to be activated by the improvement of four factors, and in turn, activated “Social participation” acted on cognitive function. PMID:25658829
Hamilton, J.D. (Rohm and Haas Company, Spring House, PA (United States)); O'Flaherty, E.J.; Shukla, R.; Gartside, P.S. (Univ. of Cincinnati, OH (United States)); Ross, R. (Univ. of Cincinnati Medical Center, Cincinnati, OH (United States))
1994-01-01
This study provided an assessment of the effects of lead on early growth in rats based on structural equation modeling and nested analysis of variance (ANOVA). Structural equation modeling showed that lead in drinking water (250, 500, or 1000 ppm) had a direct negative effect on body weight and tail length (i.e., growth) in female rats during the first week of exposure. During the following 2 weeks of exposure, high correlation between growth measurements taken over time resulted in reduced early postnatal growth. By the fourth week of exposure, reduced growth was not evident. Mating began after 8 weeks of exposure, and exposure continued during gestation. Decreased fetal body weight was detected when the effects of litter size, intrauterine position, and sex were controlled in a nested ANOVA. Lead exposure did not appear to affect fetal skeletal development, possibly because lead did not alter maternal serum calcium and phosphorus levels. The effect of lead on individual fetal body weight suggests that additional studies are needed to examine the effect of maternal lead exposure on fetal development and early postnatal growth. 24 refs., 4 figs., 6 tabs.
Duo-quan, Wang; Lin-hua, Tang; Heng-hui, Liu; Zhen-cheng, Gu; Xiang, Zheng
2013-01-01
Objective To identify the major ecological drivers for malaria vector density using the structural equation model (SEM) in the Three Gorges Reservoir. Method An 11-year longitudinal surveillance of malaria vector as well as its related ecological factors was carried out in the Three Gorges Reservoir. The Delphi method was used to identify associated ecological factors. The structural equation model was repeatedly corrected and improved by the corrected index, combined with the actual situation. The final model was defined by relative simplicity, best fitting as well as the practicality. Result The final model indicated that the direct effects of temperature, livestock, humidity, and breeding on the vector were 0.015, ?0.228, 0.450, 0.516 respectively, their total effects on the vector were 0.359, ?0.112, 0.850, and 0.043 through different pathways. Conclusion SEM was effective and convenient in elucidating the mechanism by which malaria vector dynamics operated in this study. It identified that the breeding had the highest direct effect on vector and played a key role for mediating effect of temperature and humidity. PMID:23935887
ERIC Educational Resources Information Center
Honey, Emma; McConachie, Helen; Turner, Michelle; Rodgers, Jacqui
2012-01-01
The repetitive behaviour questionnaire (RBQ) (Turner, 1995) is one of the three most commonly used interview/questionnaire measures of repetitive behaviour (Honey et al., in preparation). Despite this there is a scarcity of information concerning its structure, reliability and validity. The psychometric properties of the RBQ were examined when…
Pete Kines; Jorma Lappalainen; Kim Lyngby Mikkelsen; Espen Olsen; Anders Pousette; Jorunn Tharaldsen; Kristinn Tómasson; Marianne Törner
2011-01-01
Although there is a plethora of questionnaire instruments for measuring safety climate or culture, very few have proven able to present a factor structure that is consistent in different contexts, and many have a vague theoretical grounding. The Nordic Safety Climate Questionnaire (NOSACQ-50) was developed by a team of Nordic occupational safety researchers based on organizational and safety climate theory,
The Prospective and Retrospective Memory Questionnaire (PRMQ): Normative data and latent
Crawford, John R.
The Prospective and Retrospective Memory Questionnaire (PRMQ): Normative data and latent structure The Prospective and Retrospective Memory Questionnaire (PRMQ; Smith, Della Sala, Logie, & Maylor, 2000) was developed to provide a self-report measure of prospective and retrospective memory slips in everyday life
Psychometric properties of the Questionnaire for Secondary Traumatization
Weitkamp, Katharina; Daniels, Judith K.; Klasen, Fionna
2014-01-01
Background During the past several years, there has been a growing interest in the negative effects that providing therapy may have on therapists. Of special interest is a phenomenon called secondary traumatization, which can arise while working with traumatized clients. To develop a simple screening tool for secondary traumatization, a quantitative assessment instrument was constructed using a data-driven approach based on qualitative interviews with affected trauma therapists as well as experienced supervisors in trauma therapy. Objective The aim of the current study was to analyze the psychometric properties of the newly developed Questionnaire for Secondary Traumatization (FST) acute and lifetime version and to determine the most appropriate scoring procedure. Method To this end, three independent samples of psychotherapists (n=371), trauma therapists in training (n=80), and refugee counselors (n=197) filled out an online questionnaire battery. Data structure was analyzed using factor analyses, cluster analyses, and reliability analyses. Results Factor analyses yielded a six-factor structure for both the acute and the lifetime version with only a small number of items loading on differing factors. Cluster analyses suggested a single scale structure of the questionnaire. The FST total score showed good internal consistencies across all three samples, while internal consistency of the six extracted factors was mixed. Conclusion With the FST, a reliable screening instrument for acute and lifetime secondary traumatization is now available which is free of charge and yields a sum score for quick evaluation. The six-factor structure needs to be verified with confirmatory factor analyses. PMID:24427450
Variable-complexity aerodynamic optimization of an HSCT wing using structural wing-weight equations
NASA Technical Reports Server (NTRS)
Hutchison, M. G.; Unger, E. R.; Mason, W. H.; Grossman, B.; Haftka, R. T.
1992-01-01
A new approach for combining conceptual and preliminary design techniques for wing optimization is presented for the high-speed civil transport (HSCT). A wing-shape parametrization procedure is developed which allows the linking of planform and airfoil design variables. Variable-complexity design strategies are used to combine conceptual and preliminary-design approaches, both to preserve interdisciplinary design influences and to reduce computational expense. In the study, conceptual-design-level algebraic equations are used to estimate aircraft weight, supersonic wave drag, friction drag and drag due to lift. The drag due to lift and wave drag are also evaluated using more detailed, preliminary-design-level techniques. The methodology is applied to the minimization of the gross weight of an HSCT that flies at Mach 3.0 with a range of 6500 miles.
Schizotypal personality questionnaire: new sources of validity evidence in college students.
Fonseca-Pedrero, Eduardo; Fumero, Ascensión; Paino, Mercedes; de Miguel, Adelia; Ortuño-Sierra, Javier; Lemos-Giráldez, Serafín; Muñiz, José
2014-09-30
Schizotypal traits represent the behavioral expression of vulnerability to psychosis in general population. Among the most widely used measurement instruments, we could find the Schizotypal Personality Questionnaire (SPQ) (Raine, 1991). However, some aspects of its psychometric quality have yet to be analyzed. The main goal of the present study was to gather new sources of validity evidence of the SPQ scores in non-clinical young adults. The final sample was made up of 1123 college students (M=20.3 years; S.D.=2.6). The study of the internal structure using exploratory factor analysis revealed that SPQ items were grouped in a theoretical structure of seven second-order factors. Confirmatory factor analyses showed that the four-factor model (Paranoid) displayed better goodness-of-fit indices than the other hypothetical dimensional models tested. More complex measurement models, such as those tested using second-order confirmatory factor analyses and Exploratory Structural Equation Modeling, also showed adequate goodness-of-fit indices. The reliability of the SPQ scores ranged from 0.80 to 0.91. A total of 11 items showed differential functioning by gender. Advances in psychosis phenotype measurement open up new horizons to understand the structure and content of schizotypy. PMID:24889846
ERIC Educational Resources Information Center
Stapleton, Laura M.
2008-01-01
This article discusses replication sampling variance estimation techniques that are often applied in analyses using data from complex sampling designs: jackknife repeated replication, balanced repeated replication, and bootstrapping. These techniques are used with traditional analyses such as regression, but are currently not used with structural…
A Comparison of Normal and Elliptical Estimation Methods in Structural Equation Models.
ERIC Educational Resources Information Center
Schumacker, Randall E.; Cheevatanarak, Suchittra
Monte Carlo simulation compared chi-square statistics, parameter estimates, and root mean square error of approximation values using normal and elliptical estimation methods. Three research conditions were imposed on the simulated data: sample size, population contamination percent, and kurtosis. A Bentler-Weeks structural model established the…
Aristophanes Dimakis; Folkert Mueller-Hoissen
2014-09-27
It is shown that higher Bruhat orders admit a decomposition into a higher Tamari order, the corresponding dual Tamari order, and a "mixed order". We describe simplex equations (including the Yang-Baxter equation) as realizations of higher Bruhat orders. Correspondingly, a family of "polygon equations" realizes higher Tamari orders. They generalize the well-known pentagon equation. The structure of simplex and polygon equations is visualized in terms of deformations of maximal chains in posets forming 1-skeletons of polyhedra. The decomposition of higher Bruhat orders induces a reduction of the N-simplex equation to the (N+1)-gon equation, its dual, and a compatibility equation.
Querying databases of trajectories of differential equations: Data structures for trajectories
NASA Technical Reports Server (NTRS)
Grossman, Robert
1989-01-01
One approach to qualitative reasoning about dynamical systems is to extract qualitative information by searching or making queries on databases containing very large numbers of trajectories. The efficiency of such queries depends crucially upon finding an appropriate data structure for trajectories of dynamical systems. Suppose that a large number of parameterized trajectories gamma of a dynamical system evolving in R sup N are stored in a database. Let Eta is contained in set R sup N denote a parameterized path in Euclidean Space, and let the Euclidean Norm denote a norm on the space of paths. A data structure is defined to represent trajectories of dynamical systems, and an algorithm is sketched which answers queries.
Harmonic structure of English Channel/Southern Bight tides from a wave equation simulation
NASA Astrophysics Data System (ADS)
Werner, Francisco E.; Lynch, Daniel R.
The harmonic structure of a long-term time-stepping simulation is obtained by least-squares decomposition. The structure of 11 major constituents used to force the model is displayed, reproducing the major tidal features of this system. The problem of incomplete field data is discussed and analyzed, in terms of these and 40 additional constituents which were generated internally. At least two semi-diurnal constituents (2 MS2 and 2 MN2) which had been previously neglected are shown to be contributors to apparent errors in time-domain comparisons with field data. By excluding these and all other unforced constituents, improved RMS error estimates are obtained in the time domain.
Nooijen, Marcel; Huntington, Lee M. [Department of Chemistry, University of Waterloo, Waterloo, N2L 3G1, Ontario (Canada)] [Department of Chemistry, University of Waterloo, Waterloo, N2L 3G1, Ontario (Canada); Demel, Ond?ej [J. Heyrovský Institute of Physical Chemistry of AS CR v.v.i., Prague (Czech Republic)] [J. Heyrovský Institute of Physical Chemistry of AS CR v.v.i., Prague (Czech Republic); Datta, Dipayan [Institut for Physikalische Chemie, Johannes Gutenberg Universität, Mainz (Germany)] [Institut for Physikalische Chemie, Johannes Gutenberg Universität, Mainz (Germany); Kong, Liguo [Department of Chemistry, Stanford University, Stanford, California 94305 (United States)] [Department of Chemistry, Stanford University, Stanford, California 94305 (United States); Shamasundar, K. R. [Department of Chemistry, Mohali University, IISER Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli PO 140306 (India)] [Department of Chemistry, Mohali University, IISER Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli PO 140306 (India); Lotrich, V. [Quantum Theory Project, University of Florida, Gainesville, Florida 32611-8435 (United States)] [Quantum Theory Project, University of Florida, Gainesville, Florida 32611-8435 (United States); Neese, Frank [Max Planck Institut für Chemische Energiekonversion, Mülheim an der Ruhr (Germany)] [Max Planck Institut für Chemische Energiekonversion, Mülheim an der Ruhr (Germany)
2014-02-28
The novel multireference equation-of-motion coupled-cluster (MREOM-CC) approaches provide versatile and accurate access to a large number of electronic states. The methods proceed by a sequence of many-body similarity transformations and a subsequent diagonalization of the transformed Hamiltonian over a compact subspace. The transformed Hamiltonian is a connected entity and preserves spin- and spatial symmetry properties of the original Hamiltonian, but is no longer Hermitean. The final diagonalization spaces are defined in terms of a complete active space (CAS) and limited excitations (1h, 1p, 2h, …) out of the CAS. The methods are invariant to rotations of orbitals within their respective subspaces (inactive, active, external). Applications to first row transition metal atoms (Cr, Mn, and Fe) are presented yielding results for up to 524 electronic states (for Cr) with an rms error compared to experiment of about 0.05 eV. The accuracy of the MREOM family of methods is closely related to its favorable extensivity properties as illustrated by calculations on the O{sub 2}–O{sub 2} dimer. The computational costs of the transformation steps in MREOM are comparable to those of closed-shell Coupled Cluster Singles and Doubles (CCSD) approach.
Information Assurance, Privacy, and Security in Ubiquitous Questionnaire
Yuichi Goto; Jingde Cheng
2009-01-01
Ubiquitous questionnaire is to provide users with e-questionnaire services anytime and anywhere such that one can use e-questionnaire servers without even thinking about them. An e-questionnaire server for ubiquitous questionnaire should provide guarantees to satisfy any user-specified requirement on information assurance, privacy, and security because some questionnaires may concern organization secrets as well as personal privacy, and some questionnaires such
Development of the Eating Habits Questionnaire
Graham, Erin Collins
2005-02-17
The purpose of the studies presented was to develop and examine the psychometric properties of the Eating Habits Questionnaire (EHQ). The author designed the 21-item self-report inventory to assess cognitions, behaviors, and feelings related...
Web Developer, TBD Job Description Questionnaire (JDQ)
Barrash, Warren
Web Developer, TBD Job Description Questionnaire (JDQ) Professional Staff Instructions What Below to Certify Approval or Disapproval: Approval Disapproval ( ) ( ) TBD, Web Developer Position Title: Web Developer Employee Name: TBD Phone: Supervisor Name & Title: TBD, Production Team
Multimedia Developer, TBD Job Description Questionnaire (JDQ)
Barrash, Warren
Multimedia Developer, TBD Job Description Questionnaire (JDQ) Professional Staff Instructions What Below to Certify Approval or Disapproval: Approval Disapproval ( ) ( ) TBD, Multimedia Developer Position Title: Multimedia Developer Employee Name: TBD Phone: Supervisor Name & Title: TBD, Production
Development of the Sport Orientation Questionnaire.
ERIC Educational Resources Information Center
Gill, Diane L.; Deeter, Thomas E.
1988-01-01
An analysis of the Sport Orientation Questionnaire, a multidimensional, sport-specific measure of individual differences in achievement orientation, indicates that it is a valid and reliable measure of individual sport achievement orientation. (JD)
Warner, James E; Diaz, Manuel I; Aquino, Wilkins; Bonnet, Marc
2014-09-01
This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level. PMID:25339790
NASA Astrophysics Data System (ADS)
Warner, James E.; Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc
2014-09-01
This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level.
Dai, Chao-Qing; Wang, Yan
2014-01-01
The spatiotemporal nonlinear Schrödinger equation with power-law nonlinearity in -symmetric potentials is investigated, and two families of analytical three-dimensional spatiotemporal structure solutions are obtained. The stability of these solutions is tested by the linear stability analysis and the direct numerical simulation. Results indicate that solutions are stable below some thresholds for the imaginary part of -symmetric potentials in the self-focusing medium, while they are always unstable for all parameters in the self-defocusing medium. Moreover, some dynamical properties of these solutions are discussed, such as the phase switch, power and transverse power-flow density. The span of phase switch gradually enlarges with the decrease of the competing parameter k in -symmetric potentials. The power and power-flow density are all positive, which implies that the power flow and exchange from the gain toward the loss domains in the cell. PMID:24983624
Weiler, Monica R; Lavender, Steven A; Crawford, J Mac; Reichelt, Paul A; Conrad, Karen M; Browne, Michael W
2013-01-01
Patient-handling tasks are integral to Emergency Medical Service (EMS) work as are the musculoskeletal injuries associated with these tasks. The aim of this study was to develop and test a structural equation model that describes the interactions between previously identified factors that contribute to the adoption of a specific ergonomics intervention designed for EMS work. EMS responders (n = 187), from six different organisations, participated in a 2-month longitudinal study following the introduction of a foldable patient transfer-board (slide-board) designed to assist with lateral patient transfers. Surveys administered at baseline, after 1 month and after 2 months sampled factors potentially influencing EMS responders' adoption decisions. Perceived ergonomics advantage, which was influenced by access and storage concerns and prior tool experience, contributed most strongly to intention to use at the end of the first month and to the emergence of champions, which contributed to the intention to use at the end of the second month. PMID:24063664
Ryu, Ehri
2011-12-01
A simulation study investigated the effects of skewness and kurtosis on level-specific maximum likelihood (ML) test statistics based on normal theory in multilevel structural equation models. The levels of skewness and kurtosis at each level were manipulated in multilevel data, and the effects of skewness and kurtosis on level-specific ML test statistics were examined. When the assumption of multivariate normality was violated, the level-specific ML test statistics were inflated, resulting in Type I error rates that were higher than the nominal level for the correctly specified model. Q-Q plots of the test statistics against a theoretical chi-square distribution showed that skewness led to a thicker upper tail and kurtosis led to a longer upper tail of the observed distribution of the level-specific ML test statistic for the correctly specified model. PMID:21671139
Dai, Chao-Qing; Wang, Yan
2014-01-01
The spatiotemporal nonlinear Schrödinger equation with power-law nonlinearity in PT-symmetric potentials is investigated, and two families of analytical three-dimensional spatiotemporal structure solutions are obtained. The stability of these solutions is tested by the linear stability analysis and the direct numerical simulation. Results indicate that solutions are stable below some thresholds for the imaginary part of PT-symmetric potentials in the self-focusing medium, while they are always unstable for all parameters in the self-defocusing medium. Moreover, some dynamical properties of these solutions are discussed, such as the phase switch, power and transverse power-flow density. The span of phase switch gradually enlarges with the decrease of the competing parameter k in PT-symmetric potentials. The power and power-flow density are all positive, which implies that the power flow and exchange from the gain toward the loss domains in the PT cell. PMID:24983624
Knouse, Laura E.; Traeger, Lara; O’Cleirigh, Conall; Safren, Steven A.
2013-01-01
Relationships among Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms and adult personality traits have not been examined in larger clinically diagnosed samples. We collected multi-source ADHD symptom and self-report NEO Five-Factor Inventory (Costa & McCrae, 1992a) data from 117 adults with ADHD and tested symptom-trait associations using structural equation modeling. The final model fit the data. Inattention was positively associated with Neuroticism and negatively associated with Conscientiousness. Based on ADHD expression in adulthood, hyperactivity and impulsivity were estimated as separate constructs and showed differential relationships to Extraversion and Agreeableness. A significant positive relationship between Hyperactivity and Conscientiousness arose in the context of other pathways. ADHD symptoms are reliably associated with personality traits, suggesting a complex interplay across development that warrants prospective study into adulthood. PMID:24080671
Pettus-Davis, Carrie; Howard, Matthew O.
2012-01-01
In an effort to self-medicate psychological distress stemming from exposure to traumatic life events, at-risk youth may be likely to seek intoxication via substance use. Concomitantly, self-medication with psychoactive substances is theorized to confer risk of developing future psychiatric and substance use disorders. The present study employed structural equation modeling to examine self-medication among a sample of 723 youth in residential treatment for antisocial behavior via recursive and non-recursive relationships between trauma history, substance misuse, and psychological distress. Results supported study hypotheses that: (a) the effects of trauma history on psychological distress are partially mediated by substance misuse, and (b) exposure to traumatic life events drives a feedback loop between substance misuse and psychological distress. Findings from this large-scale survey of adolescents exhibiting behavioral dysfunction suggest that identification of self-medication processes among traumatized youth may be crucial for developing targeted prevention and treatment initiatives. PMID:22454227
Validation of a maternal questionnaire on correlates of physical activity in preschool children
McMinn, Alison M; van Sluijs, Esther M F; Harvey, Nicholas C; Cooper, Cyrus; Inskip, Hazel M; Godfrey, Keith M; Griffin, Simon J
2009-12-02
Abstract Background Valid measures of physical activity correlates in preschool children are lacking. This study aimed to assess the validity, factor structure and internal consistency of a maternal questionnaire on potential correlates of four...
Fu-gang Hu
2010-01-01
In the first part of this dissertation, the integral equation approaches are developed to analyze the wave propagation in periodic structures. Firstly, an integral equation approach is developed to analyze the two-dimensional (2-D) scattering from multilayered periodic array. The proposed approach is capable of handling scattering from the array filled with different media in different layers.\\u000aCombining the equivalence principle
Wu, Yue; Bamgbade, Babatunde A; Burgess, Ward A; Tapriyal, Deepak; Baled, Hseen O; Enick, Robert M; McHugh, Mark A
2013-07-25
The cis and trans conformation of a branched cyclic hydrocarbon affects the packing and, hence, the density, exhibited by that compound. Reported here are density data for branched cyclohexane (C6) compounds including methylcyclohexane, ethylcyclohexane (ethylcC6), cis-1,2-dimethylcyclohexane (cis-1,2), cis-1,4-dimethylcyclohexane (cis-1,4), and trans-1,4-dimethylcyclohexane (trans-1,4) determined at temperatures up to 525 K and pressures up to 275 MPa. Of the four branched C6 isomers, cis-1,2 exhibits the largest densities and the smallest densities are exhibited by trans-1,4. The densities are modeled with the Peng-Robinson (PR) equation of state (EoS), the high-temperature, high-pressure, volume-translated (HTHP VT) PREoS, and the perturbed chain, statistical associating fluid theory (PC-SAFT) EoS. Model calculations highlight the capability of these equations to account for the different densities observed for the four isomers investigated in this study. The HTHP VT-PREoS provides modest improvements over the PREoS, but neither cubic EoS is capable of accounting for the effect of isomer structural differences on the observed densities. The PC-SAFT EoS, with pure component parameters from the literature or from a group contribution method, provides improved density predictions relative to those obtained with the PREoS or HTHP VT-PREoS. However, the PC-SAFT EoS, with either set of parameters, also cannot fully account for the effect of the C6 isomer structure on the resultant density. PMID:23815675
Guenole, Nigel; Brown, Anna
2014-01-01
We report a Monte Carlo study examining the effects of two strategies for handling measurement non-invariance - modeling and ignoring non-invariant items - on structural regression coefficients between latent variables measured with item response theory models for categorical indicators. These strategies were examined across four levels and three types of non-invariance - non-invariant loadings, non-invariant thresholds, and combined non-invariance on loadings and thresholds - in simple, partial, mediated and moderated regression models where the non-invariant latent variable occupied predictor, mediator, and criterion positions in the structural regression models. When non-invariance is ignored in the latent predictor, the focal group regression parameters are biased in the opposite direction to the difference in loadings and thresholds relative to the referent group (i.e., lower loadings and thresholds for the focal group lead to overestimated regression parameters). With criterion non-invariance, the focal group regression parameters are biased in the same direction as the difference in loadings and thresholds relative to the referent group. While unacceptable levels of parameter bias were confined to the focal group, bias occurred at considerably lower levels of ignored non-invariance than was previously recognized in referent and focal groups. PMID:25278911
Abilio Reig-Ferrer; Antonio Cepeda-Benito
2007-01-01
The factor structure of smoking expectancies was examined in daily smokers and never smokers. Participants completed the Smoking Consequences Questionnaire—Spanish (SCQ—Spanish; [Cepeda-Benito, A., & Reig-Ferrer, A. (2000). Smoking consequences questionnaire—Spanish. Psychology of Addictive Behaviors, 14, 219-230.]). Using confirmatory factor analysis (CFA), the eight-factor structure of the SCQ—Spanish was replicated in smokers only. Except for beliefs about negative-health outcome expectancies, daily
Body image during pregnancy: an evaluation of the suitability of the body attitudes questionnaire
2012-01-01
Background Available data suggest that body dissatisfaction is common during pregnancy and may even be a precursor to post-natal depression. However, in order to accurately identify at-risk women, it is essential to first establish that body image measures function appropriately in pregnant populations. Our study examines the suitability of the Body Attitudes Questionnaire (BAQ) for measuring body dissatisfaction among pregnant women by comparing the psychometric functioning of the BAQ: (1) across key phases of pregnancy, and (2) between pregnant and non-pregnant women. Methods A total of 176 pregnant women from Melbourne, Victoria filled out a questionnaire battery containing demographic questions and the Body Attitudes Questionnaire at 16, 24, and 32 weeks during pregnancy. A comparison group of 148 non-pregnant women also completed the questionnaire battery at Time 1. Evaluations of the psychometric properties of the BAQ consisted of a series of measurement invariance tests conducted within a structural equation modelling framework. Results Although the internal consistency and factorial validity of the subscales of the BAQ were established across time and also in comparisons between pregnant and non-pregnant women, measurement invariance tests showed non-invariant item intercepts across pregnancy and also in comparison with the non-pregnant subgroup. Inspection of modification indices revealed a complex, non-uniform pattern of differences in item intercepts across groups. Conclusions Collectively, our findings suggest that comparisons of body dissatisfaction between pregnant and non-pregnant women (at least based on the BAQ) are likely to be conflated by differential measurement biases that serve to undermine attempts to accurately assess level of body dissatisfaction. Researchers should be cautious in assessments of body dissatisfaction among pregnant women until a suitable measure has been established for use in this population. Given the fact that body dissatisfaction is often associated with maladaptive behaviours, such as unhealthy eating and extreme weight loss behaviours, and with ante-and post-natal depression, that have serious negative implications for women’s health and well-being, and potentially also for the unborn foetus during pregnancy, developing a suitable body image screening tool, specific to the perinatal period is clearly warranted. PMID:22950761
NASA Astrophysics Data System (ADS)
Zhao, Wenwen; Chen, Weifang; Liu, Hualin; Agarwal, Ramesh K.
2014-12-01
This paper describes the computations of hypersonic shock wave structure in a gas in rotational non-equilibrium using a newly developed simplified set of Burnett equations designated as Simplified Conventional Burnett (SCB) equations. Since the original formulation by Burnett, a number of variations to the original Burnett equations have been proposed and the differences among these variants and their merits/shortcomings have been described in the literature. A new variant is created based on the conventional Burnett equations for hypersonic flows by neglecting terms that are inversely proportional to the Mach number. This simplified set of conventional Burnett equations is linearly stable for small disturbances in contrast to the conventional Burnett equations which suffer from Bobylev instability. To simulate the rotational non-equilibrium effect in a diatomic gas, both the Navier-Stokes (NS) and the SCB equations are modified by including a rotational non-equilibrium relaxation model. The flow variables (density, translational and rotational temperature) in a typical 1-D shock at different Mach numbers (1.2, 5, and 10) in Nitrogen are computed using the SCB and NS equations and are compared with the DSMC results. SCB calculations are in close agreement with the DSMC results at high Mach numbers.
Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z; Chamorro-Premuzic, Tomas
2013-02-01
This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM) technique, the authors show that model fits improve markedly over conventional confirmatory factor analyses (CFA) of the same data set, but that (a) factor interpretations do not change under ESEM analyses, (b) ESEM factor scores, just like CFA factors scores, correlate at near unity with sums of observed scores, (c) NEO-PI-R facets under ESEM analyses are invariant across gender, and (d) ESEM highlights the inappropriateness of alpha and beta as a higher order representation of NEO-PI-R facets, whereas a CFA approach might lead researchers to believe in the appropriateness of these higher order factors. These results, coupled with the existing validity evidence for the NEO-PI-R, suggest that the five-factor structure is the most parsimonious structure for summarizing NEO-PI-R responses from high-stakes settings in the United Kingdom. PMID:22837539
NASA Astrophysics Data System (ADS)
Hollingshead, Kyle B.; Truskett, Thomas M.
2015-04-01
We use molecular dynamics simulations to test integral equation theory predictions for the structure of fluids of spherical particles with eight different piecewise-constant pair-interaction forms comprising a hard core and a combination of two shoulders and/or wells. Since model pair potentials like these are of interest for discretized or coarse-grained representations of effective interactions in complex fluids (e.g., for computationally intensive inverse optimization problems), we focus here on assessing how accurately their properties can be predicted by analytical or simple numerical closures including Percus-Yevick, hypernetted-chain, and reference hypernetted-chain closures and first-order mean spherical and modified first-order mean spherical approximations. To make quantitative comparisons between the predicted and simulated radial distribution functions, we introduce a cumulative structural error metric. For equilibrium fluid state points of these models, we find that the reference hypernetted-chain closure is the most accurate of the tested approximations as characterized by this metric or related thermodynamic quantities.
Factor analysis of the Autism Spectrum Screening Questionnaire.
Posserud, Britt; Lundervold, Astri J; Steijnen, Maaike C; Verhoeven, Sophie; Stormark, Kjell Morten; Gillberg, Christopher
2008-01-01
The present study investigated the factor structure of parent and teacher Autism Spectrum Screening Questionnaire (ASSQ) in a population of 7-9 years old children. For validation purposes, factors derived were correlated with results on the Strengths and Difficulties Questionnaire (SDQ). A three-factor solution was identified on both parent and teacher ASSQ. Most of the variance was explained by one factor including measures of social function, validated by a high correlation with the SDQ peer problems scale. The second factor included measures of autism-associated problems. The items allocated to the third factor were more specific for a cognitive style typically found in high-functioning individuals with autism/Asperger syndrome. This factor did not correlate highly with any of the SDQ subscales. The results indicated that the screening efficiency of ASSQ could be increased by closer examination of the individual profile of factor scores. PMID:18178599
Conner, Tom; Prokhorov, Artem; Page, Connie; Fang, Yu; Xiao, Yimin; Post, Lori A
2011-01-01
Elder abuse in long-term care has become a very important public health concern. Recent estimates of elder abuse prevalence are in the range of 2% to 10% (Lachs & Pillemer, 2004), and current changes in population structure indicate a potential for an upward trend in prevalence (Malley-Morrison, Nolido, & Chawla, 2006; Post et al., 2006). More than 20 years ago, Karl Pillemer called for sociological research on patient maltreatment in nursing homes and provided an overview model for the conduct of such research (Pillemer, 1988). The research literature since then has not provided the definitive model to account for patient maltreatment that Pillemer hoped for. Instead, it has produced a laundry list of risk factors that includes the patient's functional disability, cognitive impairment, social isolation, age, race, income, family background, life events, dementia, and depression (Dyer, Pavlik, Murphy, & Hyman, 2000; Lachs & Pillemer, 2004; Lachs,Williams, Obrien, Hurst, & Horwitz, 1997; Pavlik, Hyman, Festa, & Dyer, 2001; Schofield & Mishra, 2003). However, no theory exists to place these factors in a causal structure that relates the factors to each other and to whether abuse occurs. This study is a first step in that direction. Nine hypotheses were generated focusing on the effects of two dimensions of impairment--(a) physical and cognitive and (b) age and behavior problems--on susceptibility to abuse among elderly in long-term care.The relationships between factors and from factors to susceptibility to abuse are specified in a structural equation model where "susceptibility to abuse," "physical impairment," and "cognitive impairment" are latent variables, and behavior problems and age are directly measured. PMID:20448233
ERIC Educational Resources Information Center
Schembre, Susan M.; Riebe, Deborah A.
2011-01-01
Non-exercise equations developed from self-reported physical activity can estimate maximal oxygen uptake (VO[subscript 2]max) as well as sub-maximal exercise testing. The International Physical Activity Questionnaire is the most widely used and validated self-report measure of physical activity. This study aimed to develop and test a VO[subscript…
Development of the young spine questionnaire
2013-01-01
Background Back pain in children is common and early onset of back pain has been shown to increase the risk of back pain significantly in adulthood. Consequently, preventive efforts must be targeted the young population but research relating to spinal problems in this age group is scarce. Focus has primarily been on the working age population, and therefore specific questionnaires to measure spinal pain and its consequences, specifically aimed at children and adolescents are absent. The purpose of this study was to develop a questionnaire for schoolchildren filling this gap. Methods The Young Spine Questionnaire (YSQ) was developed in three phases – a conceptualisation, development and testing phase. The conceptualisation phase followed the Wilson and Cleary model and included questions regarding spinal prevalence estimates, pain frequency and intensity, activity restrictions, care seeking behaviour and influence of parental back trouble. Items from existing questionnaires and the “Revised Faces Pain Scale” (rFPS) were included during the development phase. The testing phase consisted of a mixed quantitative and qualitative iterative method carried out in two pilot tests using 4th grade children and focusing on assessment of spinal area location and item validity. Results The testing phase resulted in omission of the pain drawings and the questions and answer categories were simplified in several questions. Agreement between the questionnaire prevalence estimates and the interviews ranged between 83.7% (cervical pain today) and 97.9% (thoracic pain today). To improve the understanding of the spinal boundaries we added bony landmarks to the spinal drawings after pilot test I. This resulted in an improved sense of spinal boundary location in pilot test II. Correlations between the rFPS and the interview pain score ranged between 0.67 (cervical spine) and 0.79 (lumbar spine). Conclusions The Young Spine Questionnaire contains questions that assess spinal pain and its consequences. The items have been tested for content understanding and agreement between questionnaire scores and interview findings among target respondents. These preliminary results suggest that the YSQ is feasible, has content validity and is a well understood questionnaire to be used in studies of children aged 9 to 11 years. PMID:23758965
Mengoli, Carlo; Andreis, Samantha; Scaggiante, Renzo; Cruciani, Mario; Bosco, Oliviero; Ferretto, Roberto; Leone, D.; Maffongelli, Gaetano; Basso, Monica; Sarmati, Loredana; Andreoni, Massimo; Palù, Giorgio; Giuseppe Parisi, Saverio
2014-01-01
Introduction Aim of the study was to evaluate the relevance of baseline (BL) plasma tropism of HIV on the achievement of a viral suppression within six months of antiviral therapy (ARV) in naïve patients by a structural-equation-modelling. Materials and Methods Two-hundred and twenty-seven patients were enrolled; viral tropism on plasma was determined at baseline (BL) by sequencing and interpretation by genotopheno algorithm. Booster atazanavir or lopinavir , or efavirenz or nevirapine were used, in combination with either abacavir/lamivudine or tenofovir-emtricitabine. Results X4-tropism correlate negatively with CD4 cell count at BL and follow-up (FU), and CD4 correlate negatively with BL-plasma viremia (PLV). BL-PLV correlate positively with FU-PLV. We have developed the hypothesis that the variables BL-CD4 and BL-PLV represent a mediators chain among X4-tropism and outcome of plasma viraemia at six months. This model, after structural-equation-modelling (SEM, Stata13), is shown in Figure 1. The indirect effect of X4-tropism on Fup-PLV is significant (p<0.01) but about 10 fold lower than the direct effect by BL-PLV. X4-tropism also has a direct negative effect on BL-CD4 (p<0.001) and an indirect positive effect on BL-PLV (p<0.001), irrespective of the drug regimen. Path model explaining direct and mediated effects of “tro (tropism),” “gender,” “age,” “cd0 (BL-CD4)” and “lrna0 (BL-PLV)” on the final outcome (“lrna1-Fup-PLV),” where “tro,” “gender,” and “age” are exogenous, cd0 and lrna0 are endogenous (mediators). Numbers on the arrows indicate direct effects. Circles indicate residuals related to endogenous/dependent variables; numbers near to circles are the corresponding variances. Conclusions This model shows the relevance of BL-tropism on the outcome of plasma viraemia in naïve patients after six months of therapy, irrespective of drug regimen used. PMID:25397429