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Sample records for questionnaire structural equation

  1. The Polish version of the Body Image Avoidance Questionnaire: an exploratory structural equation modeling approach.

    PubMed

    Brytek-Matera, Anna; Rogoza, Radosław

    2016-03-01

    The objective of the study was to validate a Polish version of the Body Image Avoidance Questionnaire (BIAQ). The study included 115 participants with no diagnosis (control group) (Mage = 20.53, SD = 1.80) on which we have based factor analyses, 48 participants diagnosed with anorexia nervosa (Mage = 18.69, SD = 3.52) and 39 participants diagnosed with bulimia nervosa (Mage = 22.28, SD = 3.80). In the current study, we have run confirmatory factor analysis; however, the analysis did not fit the data (CFI = 0.81, RMSEA = 0.09). Three-factor solution (number of factors were chosen basing on parallel analysis and MAP) was assessed using exploratory structural equation modeling approach (extraction: Maximum Likelihood; rotation: Geomin) which appeared to fit the data well (CFI = 0.90, RMSEA = 0.07). Validation with the clinical sample was performed using multi-group ESEM. Since the models achieved only configural level of invariance, we have examined the structure of clinical group with next ESEM model (CFI = 0.95, RMSEA = 0.05). To evaluate internal consistency, we have employed Omega (ω) and Cronbach's α with bootstrapped 95 % confidence interval (95 % CI). The first factor (food and weight preoccupation) was 0.79 (95 % CI = 0.74-0.83), for second factor (social activities) was 0.86 (95 % CI = 0.81-0.90), and for third factor (clothing) was 0.84 (95 % CI = 0.79-0.87). Convergent validity was assessed by correlating the Eating Disorder Inventory and the Body Attitude Test scores. The results have shown that the Polish version of the BIAQ fulfilled basic psychometric criteria and may be used for evaluation of body image avoidance behaviors among Polish women. PMID:26183601

  2. The Internal Structure of Responses to the Trait Emotional Intelligence Questionnaire-Short Form: An Exploratory Structural Equation Modeling Approach.

    PubMed

    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

  3. 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…

  4. Testing measurement invariance across Spanish and English versions of the physical self-description questionnaire: an application of exploratory structural equation modeling.

    PubMed

    Toms, Ins; Marsh, Herbert W; Gonzlez-Rom, Vicente; Valls, Vctor; Nagengast, Benjamin

    2014-04-01

    Test of measurement invariance across translated versions of questionnaires is a critical prerequisite to comparing scores on the different versions. In this study, we used exploratory structural equation modeling (ESEM) as an alternative approach to evaluate the measurement invariance of the Spanish version of the Physical Self-Description Questionnaire (PSDQ). The two versions were administered to large samples of Australian and Spanish adolescents. First, we compared the CFA and ESEM approaches and showed that ESEM fitted the data much better and resulted in substantially more differentiated factors. We then tested measurement invariance with a 13-model ESEM taxonomy. Results justified using the Spanish version of the PSDQ to carry out cross-cultural comparisons in sport and exercise psychology research. Overall, the study can stimulate research on physical self-concept across countries and foster better cross-cultural comparisons. PMID:24686954

  5. Psychometric Evaluation of the Overexcitability Questionnaire-Two Applying Bayesian Structural Equation Modeling (BSEM) and Multiple-Group BSEM-Based Alignment with Approximate Measurement Invariance

    PubMed Central

    De Bondt, Niki; Van Petegem, Peter

    2015-01-01

    The Overexcitability Questionnaire-Two (OEQ-II) measures the degree and nature of overexcitability, which assists in determining the developmental potential of an individual according to Dabrowski's Theory of Positive Disintegration. Previous validation studies using frequentist confirmatory factor analysis, which postulates exact parameter constraints, led to model rejection and a long series of model modifications. Bayesian structural equation modeling (BSEM) allows the application of zero-mean, small-variance priors for cross-loadings, residual covariances, and differences in measurement parameters across groups, better reflecting substantive theory and leading to better model fit and less overestimation of factor correlations. Our BSEM analysis with a sample of 516 students in higher education yields positive results regarding the factorial validity of the OEQ-II. Likewise, applying BSEM-based alignment with approximate measurement invariance, the absence of non-invariant factor loadings and intercepts across gender is supportive of the psychometric quality of the OEQ-II. Compared to males, females scored significantly higher on emotional and sensual overexcitability, and significantly lower on psychomotor overexcitability. PMID:26733931

  6. Paper to Electronic Questionnaires: Effects on Structured Questionnaire Forms

    NASA Technical Reports Server (NTRS)

    Trujillo, Anna C.

    2009-01-01

    With the use of computers, paper questionnaires are being replaced by electronic questionnaires. The formats of traditional paper questionnaires have been found to effect a subject's rating. Consequently, the transition from paper to electronic format can subtly change results. The research presented begins to determine how electronic questionnaire formats change subjective ratings. For formats where subjects used a flow chart to arrive at their rating, starting at the worst and middle ratings of the flow charts were the most accurate but subjects took slightly more time to arrive at their answers. Except for the electronic paper format, starting at the worst rating was the most preferred. The paper and electronic paper versions had the worst accuracy. Therefore, for flowchart type of questionnaires, flowcharts should start at the worst rating and work their way up to better ratings.

  7. Developing Structural Equation Models.

    ERIC Educational Resources Information Center

    Schumacker, Randall E.

    1993-01-01

    Structural equation models merge multiple regression, path analysis, and factor analysis techniques into a single data analytic framework. Measurement models are developed to define latent variables, and structural equations are then established among the latent variables. Explains the development of these models. (KS)

  8. Structural Validity of the Multifactor Leadership Questionnaire.

    ERIC Educational Resources Information Center

    Tepper, Bennett J.; Percy, Paul M.

    1994-01-01

    Two studies with 290 college students and 95 business managers investigated the latent structure of items from the Multifactor Leadership Questionnaire (MLQ). Results support models in which transformational and transactional leadership items load on separate factors and suggest that charismatic and inspirational leadership scales converge for…

  9. Structural Equation Model Trees

    ERIC Educational Resources Information Center

    Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

    2013-01-01

    In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree

  10. Structural Equation Model Trees

    ERIC Educational Resources Information Center

    Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

    2013-01-01

    In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…

  11. Structural Equation Model Trees

    PubMed Central

    Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

    2015-01-01

    In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree structures that separate a data set recursively into subsets with significantly different parameter estimates in a SEM. SEM Trees provide means for finding covariates and covariate interactions that predict differences in structural parameters in observed as well as in latent space and facilitate theory-guided exploration of empirical data. We describe the methodology, discuss theoretical and practical implications, and demonstrate applications to a factor model and a linear growth curve model. PMID:22984789

  12. Selective Mutism Questionnaire: Measurement Structure and Validity

    ERIC Educational Resources Information Center

    Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.

    2008-01-01

    The psychometric properties of the Selective Mutism Questionnaire (SMQ) are evaluated using a clinical sample of children with selective mutism (SM). The study shows that SMQ is useful in determining the severity of a child's nonspeaking behaviors, the scope of these behaviors and necessary follow up assessment.

  13. Using a structured questionnaire improves seizure description by medical students

    PubMed Central

    Kapadia, Saher; Shah, Hemang; McNair, Nancy; Pruitt, J. Ned; Murro, Anthony

    2016-01-01

    Objectives The purpose of this study was to evaluate a structured questionnaire for improving a medical students’ ability to identify, describe and interpret a witnessed seizure. Methods Ninety two 3rd year medical students, blinded to seizure diagnosis, viewed videos of a primary generalized seizure and a complex partial seizure.  Students next completed an unstructured questionnaire that asked the students to describe the seizure video recordings. The students then completed a structured questionnaire that asked the student to respond to 17 questions regarding specific features occurring during the seizures.  We determined the number and types of correct responses for each questionnaire. Results Overall, the structured questionnaire was more effective in eliciting an average of 9.25 correct responses compared to the unstructured questionnaire eliciting an average of 5.30 correct responses (p < 0.001). Additionally, 10 of the 17 seizure features were identified more effectively with the structured questionnaire. Potentially confounding factors, prior knowledge of someone with epilepsy or a prior experience of viewing a seizure, did not predict the student’s ability to correctly identify any of the 17 features. Conclusions A structured questionnaire significantly improves a medical student’s ability to provide an accurate clinical description of primary generalized and complex partial witnessed seizures. Our analysis identified the 10 specific features improved by using the structured questionnaire. PMID:26752118

  14. Factor Structure of the Strengths and Difficulties Questionnaire in a Canadian Elementary School Sample

    ERIC Educational Resources Information Center

    Aitken, Madison; Martinussen, Rhonda; Wolfe, Richard G.; Tannock, Rosemary

    2015-01-01

    The Strengths and Difficulties Questionnaire (SDQ) is a 25-item screening measure for emotional and behavioral problems in children and adolescents aged 4 to 16. Structural equation modeling was used to test the five-factor structure of teacher and parent ratings on the British version of the SDQ in a community sample of 501 Canadian children aged…

  15. A Confirmatory Factor Analysis of the Structure of Temperament Questionnaire

    ERIC Educational Resources Information Center

    Bishop, David I.; Hertenstein, Matthew J.

    2004-01-01

    This study examines the factor structure of scores on the English-language version of the Structure of Temperament Questionnaire. Scores from 300 college students were subjected to maximum-likelihood confirmatory factor analyses (CFA). A first-order model consisting of eight correlated factors and a second-order model consisting of two…

  16. A Structural Examination of the Learning Experiences Questionnaire

    ERIC Educational Resources Information Center

    Tokar, David M.; Buchanan, Taneisha S.; Subich, Linda M.; Hall, Rosalie J.; Williams, Christine M.

    2012-01-01

    The underlying factor structure of the Learning Experiences Questionnaire (LEQ; Schaub, 2004) was examined using data from 742 male and female college-age respondents. The LEQ items reflect a variety of learning experiences (generated based on Bandura's (1986, 1997) four sources of self-efficacy perceptions) that might occur in each of Holland's

  17. A Structural Examination of the Learning Experiences Questionnaire

    ERIC Educational Resources Information Center

    Tokar, David M.; Buchanan, Taneisha S.; Subich, Linda M.; Hall, Rosalie J.; Williams, Christine M.

    2012-01-01

    The underlying factor structure of the Learning Experiences Questionnaire (LEQ; Schaub, 2004) was examined using data from 742 male and female college-age respondents. The LEQ items reflect a variety of learning experiences (generated based on Bandura's (1986, 1997) four sources of self-efficacy perceptions) that might occur in each of Holland's…

  18. 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…

  19. Structural and Convergent Validity of the Homework Performance Questionnaire

    ERIC Educational Resources Information Center

    Pendergast, Laura L.; Watkins, Marley W.; Canivez, Gary L.

    2014-01-01

    Homework is a requirement for most school-age children, but research on the benefits and drawbacks of homework is limited by lack of psychometrically sound measurement of homework performance. This study examined the structural and convergent validity of scores from the newly developed Homework Performance Questionnaire -- Teacher Scale (HPQ-T).…

  20. The Structure and Validity of the Multidimensional Social Support Questionnaire

    ERIC Educational Resources Information Center

    Hardesty, Patrick H.; Richardson, George B.

    2012-01-01

    The factor structure and concurrent validity of the Multidimensional Social Support Questionnaire, a brief measure of perceived social support for use with adolescents, was examined. Findings suggest that four dimensions of perceived social support may yield more information than assessments of the unitary construct of support. (Contains 8 tables…

  1. Structural and Convergent Validity of the Homework Performance Questionnaire

    ERIC Educational Resources Information Center

    Pendergast, Laura L.; Watkins, Marley W.; Canivez, Gary L.

    2014-01-01

    Homework is a requirement for most school-age children, but research on the benefits and drawbacks of homework is limited by lack of psychometrically sound measurement of homework performance. This study examined the structural and convergent validity of scores from the newly developed Homework Performance Questionnaire -- Teacher Scale (HPQ-T).

  2. Factor structure, reliability, and validity of the Therapist Response Questionnaire.

    PubMed

    Tanzilli, Annalisa; Colli, Antonello; Del Corno, Franco; Lingiardi, Vittorio

    2016-04-01

    The aim of this study was to examine the stability of the factor structure and psychometric properties of the Therapist Response Questionnaire (Betan, Heim, Zittel Conklin, & Westen, 2005; Zittel Conklin & Westen, 2003), a clinician report instrument able to measure the clinician's emotional reactions to the patient in psychotherapy. A national sample of psychiatrists and clinical psychologists (N = 332) of psychodynamic and cognitive-behavioral orientation completed the Therapist Response Questionnaire, as well as the Shedler-Westen Assessment Procedure-200 (Westen & Shedler, 1999a, 1999b), to assess personality disorders and level of psychological functioning, regarding a patient currently in their care. They also administered the Symptom Checklist-90-Revised (Derogatis, 1994) to the patients. Exploratory and confirmatory factor analyses revealed 9 distinct countertransference factors that were similar to 8 dimensions identified in the original version of the measure: (a) helpless/inadequate, (b) overwhelmed/disorganized, (c) positive/satisfying, (d) hostile/angry, (e) criticized/devalued, (f) parental/protective, (g) special/overinvolved, (h) sexualized, and (i) disengaged. These scales showed excellent internal consistencies and good validity. They were especially able to capture the quality and intensity of emotional states that therapists experience while treating personality-disordered patients, as well as to better differentiate them; additionally, they tapped into the complexity of clinicians' reactions toward patients experiencing severe psychiatric symptomatology. Results seem to confirm that Therapist Response Questionnaire is a valid and reliable instrument that allows to evaluate patterns of countertransference responses in clinically sensitive and psychometrically robust ways, regardless of therapists' orientations. The clinical and research implications of these findings are addressed. (PsycINFO Database Record PMID:26389623

  3. Structural Equation Modeling of Multivariate Time Series

    ERIC Educational Resources Information Center

    du Toit, Stephen H. C.; Browne, Michael W.

    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

  4. 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…

  5. Factors contributing to posttraumatic growth: a proposed structural equation model.

    PubMed

    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

  6. A Computer Program for Solving a Set of Conditional Maximum Likelihood Equations Arising in the Rasch Model for Questionnaires.

    ERIC Educational Resources Information Center

    Andersen, Erling B.

    A computer program for solving the conditional likelihood equations arising in the Rasch model for questionnaires is described. The estimation method and the computational problems involved are described in a previous research report by Andersen, but a summary of those results are given in two sections of this paper. A working example is also…

  7. 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…

  8. 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…

  9. Bifactor structure of the schizotypal personality questionnaire (SPQ).

    PubMed

    Preti, Antonio; Siddi, Sara; Vellante, Marcello; Scanu, Rosanna; Muratore, Tamara; Gabrielli, Mersia; Tronci, Debora; Masala, Carmelo; Petretto, Donatella Rita

    2015-12-30

    The schizotypal personality questionnaire (SPQ) is used to characterize schizotypy, a complex construct helpful for the investigation of schizophrenia-related psychopathology and putative endophenotypes. The SPQ factor structure at item level has been rarely replicated and no study had tested a bifactor model of the SPQ so far. The unidimensional, the correlated, the second-order and the bifactor models of the SPQ were tested to evaluate whether the items converge into a major single factor defining the schizotypy-proneness of the participants, to be used for grouping purpose. Parallel principal component analysis (PCA) and confirmatory factor analysis (CFA) were used to determine the optimal number of factors and components in a cross-sectional, survey design involving 649 college students (males: 47%). The first-order, nine-subscale model was confirmed by CFA in the whole sample. The best evidence from parallel PCA in the training set was in favor of a two-factor model; the bifactor implementation of this model showed good fit in the subsequent CFA. Two main dimensions of positive and negative symptoms underlie schizotypy in non-clinical samples, entailing specific risk of psychosis. On a measurement level, the study provided support for the use of the total scores of the SPQ to characterize schizotypy. PMID:26607431

  10. Bayesian Lasso for Semiparametric Structural Equation Models

    PubMed Central

    Guo, Ruixin; Zhu, Hongtu; Chow, Sy-Miin; Ibrahim, Joseph G.

    2011-01-01

    Summary There has been great interest in developing nonlinear structural equation models and associated statistical inference procedures, including estimation and model selection methods. In this paper a general semiparametric structural equation model (SSEM) is developed in which the structural equation is composed of nonparametric functions of exogenous latent variables and fixed covariates on a set of latent endogenous variables. A basis representation is used to approximate these nonparametric functions in the structural equation and the Bayesian Lasso method coupled with a Markov Chain Monte Carlo (MCMC) algorithm is used for simultaneous estimation and model selection. The proposed method is illustrated using a simulation study and data from the Affective Dynamics and Individual Differences (ADID) study. Results demonstrate that our method can accurately estimate the unknown parameters and correctly identify the true underlying model. PMID:22376150

  11. Differential equations and conformal structures

    NASA Astrophysics Data System (ADS)

    Nurowski, Paweł

    2005-09-01

    We provide five examples of conformal geometries which are naturally associated with ordinary differential equations (ODEs). The first example describes a one-to-one correspondence between the Wuenschmann class of third order ODEs considered modulo contact transformations of variables and (local) three-dimensional conformal Lorentzian geometries. The second example shows that every point equivalent class of third order ODEs satisfying the Wuenschmann and the Cartan conditions define a three-dimensional Lorentzian-Einstein-Weyl geometry. The third example associates to each point equivalence class of third order ODEs a six-dimensional conformal geometry of neutral signature. The fourth example exhibits the one-to-one correspondence between point equivalent classes of second order ODEs and four-dimensional conformal Fefferman-like metrics of neutral signature. The fifth example shows the correspondence between undetermined ODEs of the Monge type and conformal geometries of signature (3, 2). The Cartan normal conformal connection for these geometries is reducible to the Cartan connection with values in the Lie algebra of the noncompact form of the exceptional group G2. All the examples are deeply rooted in Elie Cartan's works on exterior differential systems.

  12. Systems of fuzzy equations in structural mechanics

    NASA Astrophysics Data System (ADS)

    Skalna, Iwona; Rama Rao, M. V.; Pownuk, Andrzej

    2008-08-01

    Systems of linear and nonlinear equations with fuzzy parameters are relevant to many practical problems arising in structure mechanics, electrical engineering, finance, economics and physics. In this paper three methods for solving such equations are discussed: method for outer interval solution of systems of linear equations depending linearly on interval parameters, fuzzy finite element method proposed by Rama Rao and sensitivity analysis method. The performance and advantages of presented methods are described with illustrative examples. Extended version of the present paper can be downloaded from the web page of the UTEP [I. Skalna, M.V. Rama Rao, A. Pownuk, Systems of fuzzy equations in structural mechanics, The University of Texas at El Paso, Department of Mathematical Sciences Research Reports Series, , Texas Research Report No. 2007-01, 2007].

  13. Hierarchical Regression Analysis in Structural Equation Modeling.

    ERIC Educational Resources Information Center

    de Jong, Peter F.

    1999-01-01

    Describes how a hierarchical regression analysis may be conducted in structural equation modeling. The main procedure is to perform a Cholesky or triangular decomposition of the intercorrelations among the latest predictors. Provides an example of a hierarchical regression analysis with latent variables. (SLD)

  14. Structural Equation Modeling with Interchangeable Dyads

    ERIC Educational Resources Information Center

    Olsen, Joseph A.; Kenny, David A.

    2006-01-01

    Structural equation modeling (SEM) can be adapted in a relatively straightforward fashion to analyze data from interchangeable dyads (i.e., dyads in which the 2 members cannot be differentiated). The authors describe a general strategy for SEM model estimation, comparison, and fit assessment that can be used with either dyad-level or pairwise…

  15. A Brief Guide to Structural Equation Modeling

    ERIC Educational Resources Information Center

    Weston, Rebecca; Gore, Paul A., Jr.

    2006-01-01

    To complement recent articles in this journal on structural equation modeling (SEM) practice and principles by Martens and by Quintana and Maxwell, respectively, the authors offer a consumer's guide to SEM. Using an example derived from theory and research on vocational psychology, the authors outline six steps in SEM: model specification,…

  16. Quantifying Parsimony in Structural Equation Modeling

    ERIC Educational Resources Information Center

    Preacher, Kristopher J.

    2006-01-01

    Fitting propensity (FP) is defined as a model's average ability to fit diverse data patterns, 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…

  17. Prolongation structures of nonlinear evolution equations. II

    NASA Technical Reports Server (NTRS)

    Estabrook, F. B.; Wahlquist, H. D.

    1976-01-01

    The prolongation structure of a closed ideal of exterior differential forms is further discussed, and its use illustrated by application to an ideal (in six dimensions) representing the cubically nonlinear Schroedinger equation. The prolongation structure in this case is explicitly given, and recurrence relations derived which support the conjecture that the structure is open - i.e., does not terminate as a set of structure relations of a finite-dimensional Lie group. We introduce the use of multiple pseudopotentials to generate multiple Baecklund transformation, and derive the double Baecklund transformation. This symmetric transformation concisely expresses the (usually conjectured) theorem of permutability, which must consequently apply to all solutions irrespective of asymptotic constraints.

  18. Factor Structure and Psychometric Properties of the Young Schema Questionnaire (Short Form) in Chinese Undergraduate Students

    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…

  19. 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…

  20. Personality Structure as Revealed in Questionnaire Responses at the Preschool Level

    ERIC Educational Resources Information Center

    Cattell, Raymond B.; Dreger, Ralph M.

    1974-01-01

    Personality structure, as measured by the Preschool Personality Questionnaire, was studied in preschool children. Two studies are reported which discuss factor analysis, including the ability factors of the PSPQ. (ST)

  1. Mediation from Multilevel to Structural Equation Modeling

    PubMed Central

    MacKinnon, David P.; Valente, Matthew J.

    2016-01-01

    Background/Aims The purpose of this article is to outline multilevel structural equation modeling (MSEM) for mediation analysis of longitudinal data. The introduction of mediating variables can improve experimental and nonexperimental studies of child growth in several ways as discussed throughout this article. Single-mediator individual-level and multilevel mediation models illustrate several current issues in the estimation of mediation with longitudinal data. The strengths of incorporating structural equation modeling (SEM) with multilevel mediation modeling are described. Summary and Key Messages Longitudinal mediation models are pervasive in many areas of research including child growth. Longitudinal mediation models are ideally modeled as repeated measurements clustered within individuals. Further, the combination of MSEM and SEM provides an ideal approach for several reasons, including the ability to assess effects at different levels of analysis, incorporation of measurement error and possible random effects that vary across individuals. PMID:25413658

  2. Occupants' satisfaction toward building environmental quality: structural equation modeling approach.

    PubMed

    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

  3. A Structural Equation Modelling Approach for Massive Blended Synchronous Teacher Training

    ERIC Educational Resources Information Center

    Kannan, Kalpana; Narayanan, Krishnan

    2015-01-01

    This paper presents a structural equation modelling (SEM) approach for blended synchronous teacher training workshop. It examines the relationship among various factors that influence the Satisfaction (SAT) of participating teachers. Data were collected with the help of a questionnaire from about 500 engineering college teachers. These teachers…

  4. A Structural Equation Modelling Approach for Massive Blended Synchronous Teacher Training

    ERIC Educational Resources Information Center

    Kannan, Kalpana; Narayanan, Krishnan

    2015-01-01

    This paper presents a structural equation modelling (SEM) approach for blended synchronous teacher training workshop. It examines the relationship among various factors that influence the Satisfaction (SAT) of participating teachers. Data were collected with the help of a questionnaire from about 500 engineering college teachers. These teachers

  5. The Trait Emotional Intelligence Questionnaire: Internal Structure, Convergent, Criterion, and Incremental Validity in an Italian Sample

    ERIC Educational Resources Information Center

    Andrei, Federica; Smith, Martin M.; Surcinelli, Paola; Baldaro, Bruno; Saklofske, Donald H.

    2016-01-01

    This study investigated the structure and validity of the Italian translation of the Trait Emotional Intelligence Questionnaire. Data were self-reported from 227 participants. Confirmatory factor analysis supported the four-factor structure of the scale. Hierarchical regressions also demonstrated its incremental validity beyond demographics, the…

  6. Reducing the Length of Questionnaires through Structurally Incomplete Designs: An Illustration

    ERIC Educational Resources Information Center

    Smits, Niels; Vorst, Harrie C. M.

    2007-01-01

    This paper serves as an illustration of the usefulness of structurally incomplete designs as an approach to reduce the length of educational questionnaires. In structurally incomplete test designs, respondents only fill out a subset of the total item set, while all items are still provided to the whole sample. The scores on the unadministered…

  7. The Trait Emotional Intelligence Questionnaire: Internal Structure, Convergent, Criterion, and Incremental Validity in an Italian Sample

    ERIC Educational Resources Information Center

    Andrei, Federica; Smith, Martin M.; Surcinelli, Paola; Baldaro, Bruno; Saklofske, Donald H.

    2016-01-01

    This study investigated the structure and validity of the Italian translation of the Trait Emotional Intelligence Questionnaire. Data were self-reported from 227 participants. Confirmatory factor analysis supported the four-factor structure of the scale. Hierarchical regressions also demonstrated its incremental validity beyond demographics, the

  8. Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models

    ERIC Educational Resources Information Center

    Song, Xin-Yuan; Xia, Ye-Mao; Pan, Jun-Hao; Lee, Sik-Yum

    2011-01-01

    Structural equation models have wide applications. One of the most important issues in analyzing structural equation models is model comparison. This article proposes a Bayesian model comparison statistic, namely the "L[subscript nu]"-measure for both semiparametric and parametric structural equation models. For illustration purposes, we consider…

  9. Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models

    ERIC Educational Resources Information Center

    Song, Xin-Yuan; Xia, Ye-Mao; Pan, Jun-Hao; Lee, Sik-Yum

    2011-01-01

    Structural equation models have wide applications. One of the most important issues in analyzing structural equation models is model comparison. This article proposes a Bayesian model comparison statistic, namely the "L[subscript nu]"-measure for both semiparametric and parametric structural equation models. For illustration purposes, we consider

  10. AN ATMOSPHERIC STRUCTURE EQUATION FOR GRAIN GROWTH

    SciTech Connect

    Ormel, C.W.

    2014-07-01

    We present a method to include the evolution of the grain size and grain opacity κ{sub gr} in the equations describing the structure of protoplanetary atmospheres. The key assumption of this method is that a single grain size dominates the grain size distribution at any height r. In addition to following grain growth, the method accounts for mass deposition by planetesimals and grain porosity. We illustrate this method by computation of a simplified atmosphere structure model. In agreement with previous works, grain coagulation is seen to be very efficient. The opacity drops to values much below the often-used ''interstellar medium opacities'' (∼1 cm{sup 2} g{sup –1}) and the atmosphere structure profiles for temperature and density resemble that of the grain-free case. Deposition of planetesimals in the radiative part of the atmosphere hardly influences this outcome as the added surface is quickly coagulated away. We observe a modest dependence on the internal structure (porosity), but show that filling factors cannot become too large because of compression by gas drag.

  11. Structural equation modeling: strengths, limitations, and misconceptions.

    PubMed

    Tomarken, Andrew J; Waller, Niels G

    2005-01-01

    Because structural equation modeling (SEM) has become a very popular data-analytic technique, it is important for clinical scientists to have a balanced perception of its strengths and limitations. We review several strengths of SEM, with a particular focus on recent innovations (e.g., latent growth modeling, multilevel SEM models, and approaches for dealing with missing data and with violations of normality assumptions) that underscore how SEM has become a broad data-analytic framework with flexible and unique capabilities. We also consider several limitations of SEM and some misconceptions that it tends to elicit. Major themes emphasized are the problem of omitted variables, the importance of lower-order model components, potential limitations of models judged to be well fitting, the inaccuracy of some commonly used rules of thumb, and the importance of study design. Throughout, we offer recommendations for the conduct of SEM analyses and the reporting of results. PMID:17716081

  12. String gravitational equations with Hermitian structure

    NASA Astrophysics Data System (ADS)

    Naderi, F.; Rezaei-Aghdam, A.; Darabi, F.

    2016-02-01

    We consider a string model at one-loop related to a σ-model whose antisymmetric tensor field is constructed as complex structure on the background manifold, especially on a manifold R × N where N is a complex manifold. As an example, we consider a homogeneous anisotropic (1 + 4)-dimensional σ-model where space part of the background is a four-dimensional complex manifold. By solving the related one-loop β-functions, we obtain a static solution so that by reduction of this solution to (1 + 3)-dimension, we obtain a static solution of Einstein equation where the matter sector is effectively interpreted as an inhomogeneous, anisotropic and barotropic matter satisfying all the energy conditions. Finally, the T-dual background of the solution is investigated and it is shown that the duality transformation and reduction processes commute with each other.

  13. The Feeding Practices and Structure Questionnaire (FPSQ-28): A parsimonious version validated for longitudinal use from 2 to 5 years.

    PubMed

    Jansen, Elena; Williams, Kate E; Mallan, Kimberley M; Nicholson, Jan M; Daniels, Lynne A

    2016-05-01

    Prospective studies and intervention evaluations that examine change over time assume that measurement tools measure the same construct at each occasion. In the area of parent-child feeding practices, longitudinal measurement properties of the questionnaires used are rarely verified. To ascertain that measured change in feeding practices reflects true change rather than change in the assessment, structure, or conceptualisation of the constructs over time, this study examined longitudinal measurement invariance of the Feeding Practices and Structure Questionnaire (FPSQ) subscales (9 constructs; 40 items) across 3 time points. Mothers participating in the NOURISH trial reported their feeding practices when children were aged 2, 3.7, and 5 years (N = 404). Confirmatory Factor Analysis (CFA) within a structural equation modelling framework was used. Comparisons of initial cross-sectional models followed by longitudinal modelling of subscales, resulted in the removal of 12 items, including two redundant or poorly performing subscales. The resulting 28-item FPSQ-28 comprised 7 multi-item subscales: Reward for Behaviour, Reward for Eating, Persuasive Feeding, Overt Restriction, Covert Restriction, Structured Meal Setting and Structured Meal Timing. All subscales showed good fit over 3 time points and each displayed at least partial scalar (thresholds equal) longitudinal measurement invariance. We recommend the use of a separate single item indicator to assess the family meal setting. This is the first study to examine longitudinal measurement invariance in a feeding practices questionnaire. Invariance was established, indicating that the subscales of the shortened FPSQ-28 can be used with mothers to validly assess change in 7 feeding constructs in samples of children aged 2-5 years of age. PMID:26911263

  14. The Factor Structure and Dimensional Scoring of the Generalized Anxiety Disorder Questionnaire for "DSM-IV"

    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…

  15. Revisiting the Factor Structure of the Strengths and Difficulties Questionnaire: United States, 2001.

    ERIC Educational Resources Information Center

    Dickey, Wayne C.; Blumberg, Stephen J.

    2004-01-01

    Objective: The Strengths and Difficulties Questionnaire is a 25-item instrument developed to assess emotional and behavioral problems. The current study attempted to replicate previous European structural analyses and to describe the latent dimensions that underlie responses to the parent-reported version of the Strengths and Difficulties…

  16. Factor Structure of the Children's Behavior Questionnaire in Children with Williams Syndrome

    ERIC Educational Resources Information Center

    Leyfer, Ovsanna; John, Angela E.; Woodruff-Borden, Janet; Mervis, Carolyn B.

    2012-01-01

    To examine the factor structure of temperament in 5-10-year-olds with Williams syndrome, an exploratory factor analysis was conducted on the responses of parents of 192 children on the children's behavior questionnaire. Four factors were identified. Two corresponded to factors reported for typically developing children: effortful control and…

  17. Factor Structure of the Children's Behavior Questionnaire in Children with Williams Syndrome

    ERIC Educational Resources Information Center

    Leyfer, Ovsanna; John, Angela E.; Woodruff-Borden, Janet; Mervis, Carolyn B.

    2012-01-01

    To examine the factor structure of temperament in 5-10-year-olds with Williams syndrome, an exploratory factor analysis was conducted on the responses of parents of 192 children on the children's behavior questionnaire. Four factors were identified. Two corresponded to factors reported for typically developing children: effortful control and

  18. Temperament factor structure in fragile X syndrome: the children's behavior questionnaire.

    PubMed

    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

  19. The Factorial Structure of the Expectations about Counseling Questionnaire-Brief Form: Some Serious Questions.

    ERIC Educational Resources Information Center

    Aegisdottir, Stefania; Gerstein, Lawrence H.; Gridley, Betty E.

    2000-01-01

    Examines responses of Americans and Icelanders to the Expectations About Counseling Questionnaire-Brief Form (EAC-B) through confirmatory factor analyses. Investigates the validity of and expresses concern for the underlying factor structure of the EAC-B. Argues that a four-factor solution for the EAC-B is too complex and does not fit the student…

  20. Examination of the Factor Structure and Agreement of Three Questionnaires for Identifying Young Children at Risk for Autism Spectrum Disorders

    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…

  1. Factor structure of the Minnesota Satisfaction Questionnaire short form for restaurant employees.

    PubMed

    Hancer, Mura; George, R Thomas

    2004-02-01

    The factor structure of the Minnesota Satisfaction Questionnaire short form for nonsupervisory restaurant employees was explored in questions among 2000 employees of three full-service restaurant chains operating in midwestern United States. A total of 2000 surveys were distributed to hourly employees of the three chains. From the mailing, 924 surveys were returned and found useable, a 46.2% response rate. Principal factors analysis identified a four-factor structure for the employees, in contrast to the original two-factor structure, but as in other studies the structure was multifactorial. PMID:15077790

  2. The Use of Structural Equation Models in Interpreting Regression Equations Including Suppressor and Enhancer Variables.

    ERIC Educational Resources Information Center

    McFatter, Robert M.

    1979-01-01

    The usual interpretation of suppressor effects in a multiple regression equation assumes that the correlations among variables have been generated by a particular structural model. How such a regression equation is interpreted is shown to be dependent on the structural model deemed appropriate. (Author/JKS)

  3. [The OPD Structure Questionnaire (OPD-SQ): first results on reliability and validity].

    PubMed

    Ehrenthal, Johannes C; Dinger, Ulrike; Horsch, Lena; Komo-Lang, Miriam; Klinkerfuss, Mathias; Grande, Tilman; Schauenburg, Henning

    2012-01-01

    The concept of psychic structure plays a central role in the Operationalised Psychodynamic Diagnosis (OPD) system. Until recently, its reliable and valid assessment had to be based on expert ratings of clinical interviews, limiting the use of the OPD in routine measurements and research, and excluding the patients' perspective. The current study describes the development and evaluation of a questionnaire on the OPD structure axis (OPD-SQ) in several clinical and non-clinical samples (N = 1 112). The questionnaire demonstrated good internal consistency for all the sub-scales of the OPD-SQ. Differences in mean values between the samples and between patients with vs. without personality disorders were as expected. We also found correlations with other relevant aspects of personality (attachment security, neuroticism). There were no to minimal effect of age and gender. The OPD-SQ is a helpful tool for a broad use in clinical routine as well as research projects. PMID:22271173

  4. Psychometric properties and factor structure of an L2 reading motivation questionnaire.

    PubMed

    Kim, Hee-jung; Choi, Sunhee

    2014-01-01

    The purpose of this study is to investigate the psychometric properties and factor structure of a popular second language reading motivation questionnaire developed by Mori (2002). 550 first year high school students in Korea answered the 30-item questionnaire which consists of statements indicating different degrees of English reading motivation. Exploratory factor analysis was conducted with principal axis factoring and promax rotation, which yielded a four-factor solution. The factors included 'Intercultural and Intellectual Orientation', 'Reading Efficacy', 'Intrinsic Motivation', and 'Negative Attitudes'. The results supported the multidimensionality of the construct of L2 reading motivation, but could not replicate the nine factor structure which was originally proposed by Mori. The implications for further research on L2 reading motivation and development of a more valid L2 reading scale are discussed. PMID:24704649

  5. Shock wave structure for generalized Burnett equations

    NASA Astrophysics Data System (ADS)

    Bobylev, A. V.; Bisi, M.; Cassinari, M. P.; Spiga, G.

    2011-03-01

    Stationary shock wave solutions for the generalized Burnett equations (GBE) [A. V. Bobylev, "Generalized Burnett hydrodynamics," J. Stat. Phys. 132, 569 (2008)] are studied. Based on the results of Bisi et al. ["Qualitative analysis of the generalized Burnett equations and applications to half-space problems," Kinet. Relat. Models 1, 295 (2008)], we choose a unique (optimal) form of GBE and solve numerically the shock wave problem for various Mach numbers. The results are compared with the numerical solutions of Navier-Stokes equations and with the Mott-Smith approximation for the Boltzmann equation (all calculations are done for Maxwell molecules) since it is believed that the Mott-Smith approximation yields better results for strong shocks. The comparison shows that GBE yield certain improvement of the Navier-Stokes results for moderate Mach numbers.

  6. Analysis of consumers' preferences and behavior with regard to horse meat using a structured survey questionnaire.

    PubMed

    Oh, Woon Yong; Lee, Ji Woong; Lee, Chong Eon; Ko, Moon Seok; Jeong, Jae Hong

    2009-12-01

    In this study, a structured survey questionnaire was used to determine consumers' preferences and behavior with regard to horse meat at a horse meat restaurant located in Jeju, Korea, from October 1 to December 24, 2005. The questionnaire employed in this study consisted of 20 questions designed to characterize six general attributes: horse meat sensory property, physical appearance, health condition, origin, price, and other attributes. Of the 1370 questionnaires distributed, 1126 completed questionnaires were retained based on the completeness of the answers, representing an 82.2% response rate. Two issues were investigated that might facilitate the search for ways to improve horse meat production and marketing programs in Korea. The first step was to determine certain important factors, called principal components, which enabled the researchers to understand the needs of horse meat consumers via principal component analysis. The second step was to define consumer segments with regard to their preferences for horse meat, which was accomplished via cluster analysis. The results of the current study showed that health condition, price, origin, and leanness were the most critical physical attributes affecting the preferences of horse meat consumers. Four segments of consumers, with different demands for horse meat attributes, were identified: origin-sensitive consumers, price-sensitive consumers, quality and safety-sensitive consumers, and non-specific consumers. Significant differences existed among segments of consumers in terms of age, nature of work, frequency of consumption, and general level of acceptability of horse meat. PMID:20163664

  7. Development, factor structure and application of the Dog Obesity Risk and Appetite (DORA) questionnaire

    PubMed Central

    Smith, Stephen P.; O’Rahilly, Stephen; Wardle, Jane

    2015-01-01

    Background. Dogs are compelling models in which to study obesity since the condition shares many characteristics between humans and dogs. Differences in eating behaviour are recognised to contribute to obesity susceptibility in other species but this has not been systematically studied in dogs. Aim. To develop and validate an owner-reported measure of canine eating behaviour and owner or dog related factors which can alter the development of obesity. Further, to then test variation in food-motivation in dogs and its association with obesity and owner management. Methods. Owner interviews, a literature review and existing human appetite scales were used to identify relevant topics and generate items for the questionnaire. Following a pilot phase, a 75 item online questionnaire was distributed via social media. Responses from 302 dog/owner dyads were analysed and factor structure and descriptive statistics calculated. Results were compared with descriptions of dog behaviour and management from a subset of respondents during semi-structured interviews. The optimum questions were disseminated as a 34 item final questionnaire completed by 213 owners, with a subset of respondents repeating the questionnaire 3 weeks later to assess test–retest reliability. Results. Analysis of responses to the final questionnaire relating to 213 dog/owner dyads showed a coherent factor structure and good test–retest reliability. There were three dog factors (food responsiveness and satiety, lack of selectivity, Interest in food), four owner factors (owner motivation to control dog weight, owner intervention to control dog weight, restriction of human food, exercise taken) and two dog health factors (signs of gastrointestinal disease, current poor health). Eating behaviour differed between individuals and between breed groups. High scores on dog factors (high food-motivation) and low scores on owner factors (less rigorous control of diet/exercise) were associated with obesity. Owners of more highly food-motivated dogs exerted more control over their dogs’ food intake than those of less food-motivated dogs. Conclusions. The DORA questionnaire is a reliable and informative owner-reported measure of canine eating behaviour and health and management factors which can be associated with obesity development. The tool will be applicable to study of the canine obesity model and to clinical veterinarians. Results revealed eating behaviour to be similarly associated with obesity as exercise and owners giving titbits. PMID:26468435

  8. Model Specification Searches in Structural Equation Modeling Using Tabu Search.

    ERIC Educational Resources Information Center

    Marcoulides, George A.; Drezner, Zvi; Schumacker, Randall E.

    1998-01-01

    Introduces an alternative structural equation modeling (SEM) specification search approach based on the Tabu search procedure. Using data with known structure, the procedure is illustrated, and its capabilities for specification searches in SEM are demonstrated. (Author/SLD)

  9. 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)

  10. A Structural Equation Modeling Analysis of Influences on Juvenile Delinquency

    ERIC Educational Resources Information Center

    Barrett, David E.; Katsiyannis, Antonis; Zhang, Dalun; Zhang, Dake

    2014-01-01

    This study examined influences on delinquency and recidivism using structural equation modeling. The sample comprised 199,204 individuals: 99,602 youth whose cases had been processed by the South Carolina Department of Juvenile Justice and a matched control group of 99,602 youth without juvenile records. Structural equation modeling for the…

  11. Evaluation of adherence to oral antiviral hepatitis B treatment using structured questionnaires

    PubMed Central

    Giang, Leesa; Selinger, Christian P; Lee, Alice Unah

    2012-01-01

    AIM: To assess adherence rates to nucleos(t)ide analogues (NUCs) therapy in patients with chronic hepatitis B virus infection and determine factors associated with adherence. METHODS: The questionnaire study was conducted in the liver clinics at Concord Repatriation General Hospital. All patients who were currently taking one or more NUCs were asked to complete a structured, self-administered 32-item questionnaire. Adherence was measured using visual analogue scales. The patient’s treating clinician was also asked to assess their patient’s adherence via a structured questionnaire. RESULTS: A total of 80 patients completed the questionnaire. Sixty six percent of the patients (n = 49) reported optimal adherence whilst 25 (33.8%) graded their adherence to NUCs as suboptimal. Thirty four (43%) patients reported to have omitted taking their NUCs sometime in the past. Recent non-adherence was uncommon. Amongst the patients who reported skipping medications, the most common reason cited was ”forgetfulness“ (n = 27, 56.25%). Other common reasons included: ran out of medications (n = 5, 10.42%), being too busy (n = 4, 8.33%) and due to a change in daily routine (n = 5, 10.42%). Patients who reported low adherence to other prescription pills were also more likely to miss taking NUCs (P = 0.04). Patients who were under the care of a language-discordant clinician were also more likely to report suboptimal adherence to NUCs (P = 0.04). CONCLUSION: Adherence rates were much less than that expected by the physician and has potential adverse affect on long term outcome. Communication and education appear central and strategies need to be implemented to improve ongoing adherence. PMID:22400085

  12. Sensitivity of rocky planet structures to the equation of state

    SciTech Connect

    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.

  13. Validation of the factor structure of the Greek adaptation of the Sociocultural Attitudes Towards Appearance Questionnaire (SATAQ-3).

    PubMed

    Argyrides, Marios; Kkeli, Natalie; Kendeou, Panayiota

    2014-06-01

    The current study aimed to confirm the factor structure and reliability of the newly translated Greek version of the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3) among 1753 Greek-Cypriot high school students. Results of the structural equation modeling indicated a very good fit with the original four-factor structure of the SATAQ-3 for both males and females. The Cronbach's alpha coefficients for the four subscales were .92 for 'Internalization-General', .82 for 'Internalization-Athlete', .94 for 'Pressure' and .88 for 'Information'. Further analyses showed no significant differences between BMI categories with respect to the Internalization-General, Internalization-Athlete and Information factors but there were significant differences on the Pressure factor. The findings of the current study support the existence of the original four-factor structure of the SATAQ-3. The validity and reliability results of the Greek version of the SATAQ-3 support its use in Greek-speaking countries or populations. PMID:24958653

  14. French validation of the overexcitability questionnaire 2: psychometric properties and factorial structure.

    PubMed

    Botella, Marion; Fürst, Guillaume; Myszkowski, Nils; Storme, Martin; Pereira Da Costa, Maria; Luminet, Olivier

    2015-01-01

    Overexcitability corresponds to an overall response to stimulations in 5 domains: psychomotor, sensual, intellectual, imaginational, and emotional. The aim of this study was to develop a French version of the Overexcitability Questionnaire 2 (OEQ2) and to expand its psychometric properties. Two studies were conducted: one with a sample of 474 adolescents and another with a sample of 436 adults. Internal consistency, factorial structure, and validity (correlations with intelligence, personality, and alexithymia) were examined. The French OEQ2 showed satisfactory psychometric properties, thus advocating for its use in further research on overexcitability and in clinical practice. PMID:25090583

  15. Measuring Integrated Socioemotional Guidance at School: Factor Structure and Reliability of the Socioemotional Guidance Questionnaire (SEG-Q)

    ERIC Educational Resources Information Center

    Jacobs, Karen; Struyf, Elke

    2013-01-01

    Socioemotional guidance of students has recently become an integral part of education, however no instrument exists to measure integrated socioemotional guidance. This study therefore examines the factor structure and reliability of the Socioemotional Guidance Questionnaire. Psychometric properties of the Socioemotional Guidance Questionnaire and…

  16. Regression Levels of Selected Affective Factors on Science Achievement: A Structural Equation Model with TIMSS 2011 Data

    ERIC Educational Resources Information Center

    Akilli, Mustafa

    2015-01-01

    The aim of this study is to demonstrate the science success regression levels of chosen emotional features of 8th grade students using Structural Equation Model. The study was conducted by the analysis of students' questionnaires and science success in TIMSS 2011 data using SEM. Initially, the factors that are thought to have an effect on science…

  17. Structural comparison of a translated dental attitude questionnaire: a factor analytic study.

    PubMed

    Timmerman, E M; Hoogstraten, J; Nauta, M; Meijer, K

    1996-08-01

    In 1984 the Dental Attitude Questionnaire (DAQ), an instrument for assessing various aspects of a person's attitude toward oral health care, was presented by STOCKWELL & BANTING. The DAQ consists of six content scales, Cynicism, Health Concern, Motivation, Oral Function, Social Aesthetic and Susceptibility, and two validity scales, Halo and Infrequency. A Dutch translation was presented in 1986 by HOOGSTRATEN & BROERS. In order to replicate the factor analysis on the original DAQ as reported by STOCKWELL & BANTING, the present study was undertaken. The results show a change in factor structure from a three factor solution to a two factor solution. A confirmatory factor analysis shows that the original three factor structure of the DAQ is not present in the data collected with the translated version. To account for this change, some possible reasons are discussed. PMID:8871029

  18. Exploring the factor structure of the Food Cravings Questionnaire-Trait in Cuban adults

    PubMed Central

    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

  19. A general non-linear multilevel structural equation mixture model

    PubMed Central

    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

  20. The relativistic equations of stellar structure and evolution

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.

    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.

  1. USING STRUCTURAL EQUATION MODELING TO INVESTIGATE RELATIONSHIPS AMONG ECOLOGICAL VARIABLES

    EPA Science Inventory

    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...

  2. Case Residuals in Structural Equation Modeling

    ERIC Educational Resources Information Center

    Cardinale, John

    2011-01-01

    From the beginning, lead methodologists in psychometrics and quantitative psychology have been well aware of the problems of fitting structural and confirmatory factor models. The question we approach in our research is how to best detect this misfit and how to identify specific sources of misfit by scrutinizing the data at the case level. Since…

  3. Freshman Academic Achievement: A Structural Equation Model.

    ERIC Educational Resources Information Center

    Zhang, Zhicheng; RiCharde, R. Stephen

    The causal structure between academic achievement and cognitive, psychological, and facilitative variables during the freshman year in college was studied. Data from 455 freshmen were used in the analysis. Participants completed measures of student goals, facilitative skills, and learning and thinking styles. Pre-college and freshman achievement…

  4. Examination of the Factor Structure of the Schizotypal Personality Questionnaire among British and Trinidadian Adults

    PubMed Central

    Barron, David; Swami, Viren; Hutchinson, Gerard

    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

  5. Factor structure of the Self-Regulation Questionnaire (SRQ) at Spanish universities.

    PubMed

    Pichardo, Carmen; Justicia, Fernando; de la Fuente, Jesús; Martínez-Vicente, José Manuel; Berbén, Ana B G

    2014-01-01

    The Self-Regulation Questionnaire (SRQ) has been used in psychology research during the last decade. The instrument has been used in a variety of life domains: psychological well-being, dispositional happiness, depressive symptoms and career adaptability. This investigation studies the factor structure and internal consistency of the SRQ, extracting a short version in the Spanish context and examining its relation to academic variables (self-regulated learning and grades). The analysis started from a version with 63 items, representing seven conceptual dimensions. This version was administered to a sample of 834 students from Education and Psychology. The data from the above-mentioned sample were randomly divided into two sets, each containing 50% of the students (n = 417): exploratory and confirmatory. In the exploratory sample, exploratory factor analysis findings suggested a more parsimonious measurement model, with 17 items and 4 first-order factors. The confirmatory sample was used in the confirmatory factor analysis. The results show evidence for the internal consistency of the Short Self-Regulation Questionnaire (SSRQ) in the Spanish context, with indices greater than .90 and errors around .05. Regarding academic variables, both versions are related to self-regulated learning (r = .40, p < .01) and students' grades (r = .15, p < .01). Differences from other studies done in North America are discussed, as well as similarities to a study from North-West University (in South Africa). PMID:26054362

  6. Factor Structure of the Children’s Behavior Questionnaire in Children with Williams Syndrome

    PubMed Central

    Leyfer, Ovsanna; John, Angela E.; Woodruff-Borden, Janet; Mervis, Carolyn B.

    2012-01-01

    To examine the factor structure of temperament in 5 – 10-year-olds with Williams syndrome (WS), an exploratory factor analysis was conducted on the responses of parents of 192 children on the Children’s Behavior Questionnaire (CBQ). Four factors were identified. Two corresponded to factors reported for typically developing children: Effortful Control and Extraversion/Surgency and two corresponded to the temperament constructs of withdrawal/inhibition and irritability/frustration and activity, observed in typically-developing infants. Parents of 109 of the 192 participants also completed the Anxiety Disorders Interview Schedule, Parent version. Children with an anxiety disorder other than specific phobia differed significantly from children without an anxiety disorder on all factors except Extraversion/Surgency. Children with ADHD differed significantly from children without ADHD on Effortful Control and Extraversion/Surgency. PMID:22371147

  7. Factor structure of the Children's Behavior Questionnaire in children with Williams syndrome.

    PubMed

    Leyfer, Ovsanna; John, Angela E; Woodruff-Borden, Janet; Mervis, Carolyn B

    2012-11-01

    To examine the factor structure of temperament in 5-10-year-olds with Williams syndrome, an exploratory factor analysis was conducted on the responses of parents of 192 children on the children's behavior questionnaire. Four factors were identified. Two corresponded to factors reported for typically developing children: effortful control and extraversion/surgency and two corresponded to the temperament constructs of withdrawal/inhibition and irritability/frustration and activity, observed in typically developing infants. Parents of 109 of the 192 participants also completed the anxiety disorders interview schedule, parent version. Children with an anxiety disorder other than specific phobia differed significantly from children without an anxiety disorder on all factors except extraversion/surgency. Children with attention deficit hyperactivity disorder (ADHD) differed significantly from children without ADHD on effortful control and extraversion/surgency. PMID:22371147

  8. The Knowledge of Memory Aging Questionnaire: Factor Structure and Correlates in a Lifespan Sample

    PubMed Central

    Calamia, Matthew; Reese-Melancon, Celinda; Cherry, Katie E.; Hawley, Karri S.; Jazwinski, S. Michal

    2016-01-01

    The authors examined the factor structure of the Knowledge of Memory Aging Questionnaire (KMAQ) [1] using confirmatory factor analysis in a lifespan sample of 933 individuals who ranged in age from 18 to 101. Participants were college students at Louisiana State University and adults from the community enrolled in the Louisiana Healthy Aging Study (LHAS). A two-factor solution was expected, consistent with the normal and pathological memory aging dimensions that comprise the KMAQ. A bi-factor solution with items loading on a general response bias factor and either a normal or pathological knowledge-specific factor showed good model fit. Knowledge scores were correlated with demographic and cognitive performance variables. Implications of these data for clinical settings and research are considered.

  9. An examination of the factor structure of the Sociocultural Attitudes Towards Appearance Questionnaire-3 in Malaysia.

    PubMed

    Swami, Viren

    2009-03-01

    The present study examined the factor structure of a Malay translation of the Sociocultural Attitudes Towards Appearance Questionnaire-3 among a community sample of 554 Malaysian women. Results of an exploratory factor analysis revealed the existence of four factors, two of which (Information and Internalization-Athlete) mirrored those found among Western samples. An additional factor was an amalgamation of two factors reported in the West, namely Pressure and Internalization-General. A fourth factor consisted of six items, four of which cross-loaded onto previous factors, and was consequently dropped from analyses. Cronbach's alpha coefficients for the three retained factors were all above .82, and the three factors were significantly correlated with each other and with participants' body mass index. The results of this study stress the need for locally developed scales in the study of body image and a shift away from reliance on scales developed in the West. PMID:19249260

  10. Examining the factor structures of the five facet mindfulness questionnaire and the self-compassion scale.

    PubMed

    Williams, Matthew J; Dalgleish, Tim; Karl, Anke; Kuyken, Willem

    2014-06-01

    The five facet mindfulness questionnaire (FFMQ; Baer, Smith, Hopkins, Krietemeyer, & Toney, 2006) and the self-compassion scale (SCS; Neff, 2003) are widely used measures of mindfulness and self-compassion in mindfulness-based intervention research. The psychometric properties of the FFMQ and the SCS need to be independently replicated in community samples and relevant clinical samples to support their use. Our primary aim was to establish the factor structures of the FFMQ and SCS in individuals with recurrent depression in remission, since mindfulness-based cognitive therapy (MBCT) was developed as a treatment for preventing depressive relapse. In order to determine the consistency across populations, we examined the factor structures of the FFMQ and SCS in 3 samples: (1) a convenience sample of adults, (2) a sample of adults who practice meditation, and (3) a sample of adults who suffer from recurrent depression and were recruited to take part in a trial of MBCT. Confirmatory factor analyses (CFAs) showed that a 4-factor hierarchical model of the FFMQ best fits the community sample and the clinical sample but that a 5-factor hierarchical model of the FFMQ best fits the meditator sample. CFA did not endorse the SCS 6-factor hierarchical structure in any of the 3 samples. Clinicians and researchers should be aware of the psychometric properties of the FFMQ to measure mindfulness when comparing meditators and nonmeditators. Further research is needed to develop a more psychometrically robust measure of self-compassion. PMID:24490681

  11. 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…

  12. 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…

  13. 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

  14. 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…

  15. Paraconformal structures, ordinary differential equations and totally geodesic manifolds

    NASA Astrophysics Data System (ADS)

    Kryński, Wojciech

    2016-05-01

    We construct point invariants of ordinary differential equations of arbitrary order that generalise the Tresse and Cartan invariants of equations of order two and three, respectively. The vanishing of the invariants is equivalent to the existence of a totally geodesic paraconformal structure which consists of a paraconformal structure, an adapted GL(2 , R) -connection and a two-parameter family of totally geodesic hypersurfaces on the solution space. The structures coincide with the projective structures in dimension 2 and with the Einstein-Weyl structures of Lorentzian signature in dimension 3. We show that the totally geodesic paraconformal structures in higher dimensions can be described by a natural analogue of the Hitchin twistor construction. We present a general example of Veronese webs that generalise the hyper-CR Einstein-Weyl structures in dimension 3. The Veronese webs are described by a hierarchy of integrable systems.

  16. 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…

  17. Examining the Structural Validity of the Strengths and Difficulties Questionnaire (SDQ) in a U.S. Sample of Custodial Grandmothers

    ERIC Educational Resources Information Center

    Palmieri, Patrick A.; Smith, Gregory C.

    2007-01-01

    The authors examined the structural validity of the parent informant version of the Strengths and Difficulties Questionnaire (SDQ) with a sample of 733 custodial grandparents. Three models of the SDQ's factor structure were evaluated with confirmatory factor analysis based on the item covariance matrix. Although indices of fit were good across all…

  18. A Confirmatory Approach to Examining the Factor Structure of the Strengths and Difficulties Questionnaire (SDQ): A Large Scale Cohort Study

    ERIC Educational Resources Information Center

    Niclasen, Janni; Skovgaard, Anne Mette; Andersen, Anne-Marie Nybo; Somhovd, Mikael Julius; Obel, Carsten

    2013-01-01

    The aim of this study was to examine the factor structure of the Strengths and Difficulties Questionnaire (SDQ) using a Structural Confirmatory Factor Analytic approach. The Danish translation of the SDQ was distributed to 71,840 parents and teachers of 5-7 and 10-12-year-old boys and girls from four large scale cohorts. Three theoretical models

  19. Validating the Children's Behavior Questionnaire in Dutch Children: Psychometric Properties and a Cross-Cultural Comparison of Factor Structures

    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…

  20. Factor Structure of a Brief Version of the Ways of Coping (WOC) Questionnaire: A Study with Veterinary Medicine Students.

    ERIC Educational Resources Information Center

    Brown, Sharon L.

    1994-01-01

    Explored structure of brief version of Ways of Coping (WOC) Questionnaire and coping strategies employed by students enrolled in stressful academic programs. Findings from 207 veterinary medicine students lend support to view that there are relatively stable underlying coping structures across samples or groups within specified coping situations.…

  1. A Confirmatory Approach to Examining the Factor Structure of the Strengths and Difficulties Questionnaire (SDQ): A Large Scale Cohort Study

    ERIC Educational Resources Information Center

    Niclasen, Janni; Skovgaard, Anne Mette; Andersen, Anne-Marie Nybo; Somhovd, Mikael Julius; Obel, Carsten

    2013-01-01

    The aim of this study was to examine the factor structure of the Strengths and Difficulties Questionnaire (SDQ) using a Structural Confirmatory Factor Analytic approach. The Danish translation of the SDQ was distributed to 71,840 parents and teachers of 5-7 and 10-12-year-old boys and girls from four large scale cohorts. Three theoretical models…

  2. Factor structure of the Parent Emotional Reaction Questionnaire: analysis and validation

    PubMed Central

    Holt, Tonje; Cohen, Judith A.; Mannarino, Anthony

    2015-01-01

    Background Although many children experience violence and abuse each year, there is a lack of instruments measuring parents’ emotional reactions to these events. One instrument, the Parent Emotional Reaction Questionnaire (PERQ), allows researchers and clinicians to survey a broad spectrum of parents’ feelings directly related to their children's traumatic experiences. The objectives of this study were: (1) to examine the factor structure and the internal consistency of the PERQ; (2) to evaluate the discriminant validity of the instrument; and (3) to measure whether potential subscales are sensitive to change. Method A Norwegian sample of 120 primary caregivers of a clinical sample of 120 traumatized children and youths (M age=14.7, SD=2.2; 79.8% girls) were asked to report their emotional reactions to their child's self-reported worst trauma. Exploratory factor analysis was used to explore the underlying factor structure of the data. Results The analysis of the PERQ showed a three-factor structure, conceptualized as PERQdistress, PERQshame, and PERQguilt. The internal consistencies of all three subscales were satisfactory. The correlations between the PERQ subscales and two other parental measurements revealed small to moderate effect sizes, supporting the discriminant validity of the PERQ subscales. The differences in sum scores of the PERQ subscales before and after a therapeutic intervention suggest that all of the subscales were sensitive to change. Conclusions Study findings support the validity of conceptualizing the PERQ as three separate subscales that capture clinically meaningful features of parents’ feelings after their children have experienced trauma. However, the subscales need to be further evaluated using a larger sample size and a confirmatory factor analytic approach. PMID:26333541

  3. Development of a structure-validated Family Relationship Questionnaire (FRQ) with Chinese university students.

    PubMed

    Chen, Liuxi; Xu, Kai; Fu, Lingyun; Xu, Shaofang; Gao, Qianqian; Wang, Wei

    2015-01-01

    Consistent results have shown a relationship between the psychological world of children and their perceived parental bonding or family attachment style, but to date there is no single measure covering both styles. The authors designed a statement matrix with 116 items for this purpose and compared it with the Parental Bonding Instrument (PBI) in a study with 718 university students. After exploratory and confirmatory factor analyses, five factors (scales)--namely, Paternal/Maternal Encouragement (5 items each), Paternal/Maternal Abuse (5 items each), Paternal/Maternal Freedom Release (5 items each), General Attachment (5 items), and Paternal/Maternal Dominance (4 items each)--were defined to form a Family Relationship Questionnaire (FRQ). The internal alphas of the factors ranged from .64 to .83, and their congruency coefficients were .93 to .98 in samples regarding father and mother. Women scored significantly higher on FRQ General Attachment and Maternal Encouragement and lower on Paternal Abuse than men did; only children scored significantly higher on Paternal and Maternal Encouragements than children with siblings did. Women also scored significantly higher on PBI Paternal Autonomy Denial; only children scored significantly higher on Paternal and Maternal Cares and Maternal Autonomy Denial. All intercorrelations between FRQ scales were low to medium, and some correlations between FRQ and PBI scales were medium to high. This study demonstrates that the FRQ has a structure of five factors with satisfactory discriminant and convergent validities, which might help to characterize family relationships in healthy and clinical populations. PMID:26366981

  4. Analyzing Mixed-Dyadic Data Using Structural Equation Models

    ERIC Educational Resources Information Center

    Peugh, James L.; DiLillo, David; Panuzio, Jillian

    2013-01-01

    Mixed-dyadic data, collected from distinguishable (nonexchangeable) or indistinguishable (exchangeable) dyads, require statistical analysis techniques that model the variation within dyads and between dyads appropriately. The purpose of this article is to provide a tutorial for performing structural equation modeling analyses of cross-sectional

  5. On Desirability of Parsimony in Structural Equation Model Selection.

    ERIC Educational Resources Information Center

    Raykov, Tenko; Marcoulides, George A.

    1999-01-01

    Discusses issues in structural-equation-model selection that pertain to the general utility of the principle of parsimony. Provides an example using data generated by the relatively nonparsimonious simplex model and fitted rather well by a parsimonious growth-curve model belonging to a different class of models. (Author/SLD)

  6. Multiplicity Control in Structural Equation Modeling: Incorporating Parameter Dependencies

    ERIC Educational Resources Information Center

    Smith, Carrie E.; Cribbie, Robert A.

    2013-01-01

    When structural equation modeling (SEM) analyses are conducted, significance tests for all important model relationships (parameters including factor loadings, covariances, etc.) are typically conducted at a specified nominal Type I error rate ([alpha]). Despite the fact that many significance tests are often conducted in SEM, rarely is…

  7. Analyzing Mixed-Dyadic Data Using Structural Equation Models

    ERIC Educational Resources Information Center

    Peugh, James L.; DiLillo, David; Panuzio, Jillian

    2013-01-01

    Mixed-dyadic data, collected from distinguishable (nonexchangeable) or indistinguishable (exchangeable) dyads, require statistical analysis techniques that model the variation within dyads and between dyads appropriately. The purpose of this article is to provide a tutorial for performing structural equation modeling analyses of cross-sectional…

  8. 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…

  9. 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…

  10. 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…

  11. 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…

  12. 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…

  13. 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…

  14. Bootstrap Estimation of Sample Statistic Bias in Structural Equation Modeling.

    ERIC Educational Resources Information Center

    Thompson, Bruce; Fan, Xitao

    This study empirically investigated bootstrap bias estimation in the area of structural equation modeling (SEM). Three correctly specified SEM models were used under four different sample size conditions. Monte Carlo experiments were carried out to generate the criteria against which bootstrap bias estimation should be judged. For SEM fit indices,…

  15. A Bayesian Approach for Analyzing Longitudinal Structural Equation Models

    ERIC Educational Resources Information Center

    Song, Xin-Yuan; Lu, Zhao-Hua; Hser, Yih-Ing; Lee, Sik-Yum

    2011-01-01

    This article considers a Bayesian approach for analyzing a longitudinal 2-level nonlinear structural equation model with covariates, and mixed continuous and ordered categorical variables. The first-level model is formulated for measures taken at each time point nested within individuals for investigating their characteristics that are dynamically…

  16. Local Influence Analysis of Nonlinear Structural Equation Models

    ERIC Educational Resources Information Center

    Lee, Sik-Yum; Tang, Nian-Sheng

    2004-01-01

    By regarding the latent random vectors as hypothetical missing data and based on the conditional expectation of the complete-data log-likelihood function in the EM algorithm, we investigate assessment of local influence of various perturbation schemes in a nonlinear structural equation model. The basic building blocks of local influence analysis…

  17. The relativistic equations of stellar structure and evolution

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.

    1975-01-01

    The general relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. A general relativistic version of the mixing-length formalism for convection is presented. It is argued that in work on spherical systems, general relativity theorists have identified the wrong quantity as total mass-energy inside radius r.

  18. Latent Growth Curves within Developmental Structural Equation Models.

    ERIC Educational Resources Information Center

    McArdle, J. J.; Epstein, David

    1987-01-01

    Uses structural equation modeling to combine traditional ideas from repeated-measures ANOVA with some traditional ideas from longitudinal factor analysis. The model describes a latent growth curve model that permits the estimation of parameters representing individual and group dynamics. (Author/RH)

  19. 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…

  20. 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

  1. A Structural Equation Model of Expertise in College Physics

    ERIC Educational Resources Information Center

    Taasoobshirazi, Gita; Carr, Martha

    2009-01-01

    A model of expertise in physics was tested on a sample of 374 college students in 2 different level physics courses. Structural equation modeling was used to test hypothesized relationships among variables linked to expert performance in physics including strategy use, pictorial representation, categorization skills, and motivation, and these…

  2. Play Context, Commitment, and Dating Violence: A Structural Equation Model

    ERIC Educational Resources Information Center

    Gonzalez-Mendez, Rosaura; Hernandez-Cabrera, Juan Andres

    2009-01-01

    This study develops a structural equation model to describe the effect of two groups of factors (type of commitment and play context) on the violence experienced during intimate partner conflict. After contrasting the model in adolescents and university students, we have confirmed that aggressive play and the simulation of jealousy and anger…

  3. The General Linear Model as Structural Equation Modeling

    ERIC Educational Resources Information Center

    Graham, James M.

    2008-01-01

    Statistical procedures based on the general linear model (GLM) share much in common with one another, both conceptually and practically. The use of structural equation modeling path diagrams as tools for teaching the GLM as a body of connected statistical procedures is presented. A heuristic data set is used to demonstrate a variety of univariate…

  4. Structural Equation Modeling Reporting Practices for Language Assessment

    ERIC Educational Resources Information Center

    Ockey, Gary J.; Choi, Ikkyu

    2015-01-01

    Studies that use structural equation modeling (SEM) techniques are increasingly encountered in the language assessment literature. This popularity has created the need for a set of guidelines that can indicate what should be included in a research report and make it possible for research consumers to judge the appropriateness of the…

  5. 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…

  6. 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

  7. 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…

  8. A Primer of Model Fit Indices in Structural Equation Modeling.

    ERIC Educational Resources Information Center

    Smith, Tracy D.; McMillan, Bradley F.

    This paper reviews the theoretical background, optimal levels, strengths, weaknesses, and additional considerations of the most frequently used structural equation modeling (SEM) fit statistics in an effort to enable researchers to make better, more informative judgments regarding their models. Fit indices evaluate model fit for the data being…

  9. 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…

  10. 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…

  11. Structural Equation Modeling Diagnostics Using R Package Semdiag and EQS

    ERIC Educational Resources Information Center

    Yuan, Ke-Hai; Zhang, Zhiyong

    2012-01-01

    Yuan and Hayashi (2010) introduced 2 scatter plots for model and data diagnostics in structural equation modeling (SEM). However, the generation of the plots requires in-depth understanding of their underlying technical details. This article develops and introduces an R package semdiag for easily drawing the 2 plots. With a model specified in EQS…

  12. 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.

  13. Assessment of identity disturbance: Factor structure and validation of the Personality Structure Questionnaire in an Italian sample.

    PubMed

    Berrios, Raul; Kellett, Stephen; Fiorani, Christina; Poggioli, Marisa

    2016-04-01

    There are few brief measures of identity disturbance for use in clinical practice that have been subject to any cross-cultural validation. This study investigated the construct validity of the Personality Structure Questionnaire (PSQ) in Italian clinical (N = 237) and community (N = 296) samples. Confirmatory factor analysis was conducted to investigate the internal structure of the PSQ. A 3-factor structure (i.e., differing self-states, mood variability, and behavioral loss of control) including a second-order factor provided the best fit to the data. This structure was demonstrated to be invariant across sex and clinical diagnosis, with clinical diagnosis significantly predicting increased PSQ scores. A global PSQ score of between 26 and 28 was found to be an appropriate cutoff for assisting in diagnostic processes. The clinical implication of the study is that quantitative assessment of identity disturbance can be rapidly achieved via the PSQ, usefully supplementing necessary diagnostic and formulation work. (PsycINFO Database Record PMID:26389598

  14. Local structure-preserving algorithms for the "good" Boussinesq equation

    NASA Astrophysics Data System (ADS)

    Cai, Jiaxiang; Wang, Yushun

    2013-04-01

    In this paper, we derive a series of local structure-preserving algorithms for the "good" Boussinesq equation, including multisymplectic geometric structure-preserving algorithms, local energy-preserving algorithms and local momentum-preserving algorithms. The outstanding advantage of the proposed algorithms is that they conserve these local structures in any time-space region exactly. For example, the proposed local energy-preserving algorithms preserve the local energy conservation law in any local domain. Therefore, the local structure-preserving algorithms overcome the shortage of global structure-preserving algorithms on the boundary conditions. Especially, with suitable boundary conditions such as periodic or homogeneous boundary conditions, the local structure-preserving algorithms will be global structure-preserving algorithms. Numerical results verify the theoretical analysis.

  15. On equations of motion of a nonlinear hydroelastic structure

    NASA Astrophysics Data System (ADS)

    Plotnikov, P. I.; Kuznetsov, I. V.

    2008-07-01

    Formal derivation of equations of a nonlinear hydroelastic structure, which is a volume of an ideal incompressible fluid covered by a shell, is proposed. The study is based on two assumptions. The first assumption implies that the energy stored in the shell is completely determined by the mean curvature and by the elementary area. In a three-dimensional case, the energy stored in the shell is chosen in the form of the Willmore functional. In a two-dimensional case, a more generic form of the functional can be considered. The second assumption implies that the equations of motionhave a Hamiltonian structure and can be obtained from the Lagrangian variational principle. In a two-dimensional case, a condition for the hydroelastic structure is derived, which relates the external pressure and the curvature of the elastic shell.

  16. Shock-wave structure using nonlinear model Boltzmann equations.

    NASA Technical Reports Server (NTRS)

    Segal, B. M.; Ferziger, J. H.

    1972-01-01

    The structure of strong plane shock waves in a perfect monatomic gas was studied using four nonlinear models of the Boltzmann equation. The models involved the use of a simplified collision operator with velocity-independent collision frequency, in place of the complicated Boltzmann collision operator. The models employed were the BGK and ellipsoidal models developed by earlier authors, and the polynomial and trimodal gain function models developed during the work. An exact set of moment equations was derived for the density, velocity, temperature, viscous stress, and heat flux within the shock. This set was reduced to a pair of coupled nonlinear integral equations and solved using specially adapted numerical techniques. A new and simple Gauss-Seidel iteration was developed during the work and found to be as efficient as the best earlier iteration methods.

  17. Measurement Structure of the Coping Strategies Questionnaire-24 in a Sample of Individuals with Musculoskeletal Pain: A Confirmatory Factor Analysis

    ERIC Educational Resources Information Center

    Chiu, Chung-Yi; Jochman, Joseph; Fujikawa, Mayu; Strand, David; Cheing, Gladys; Lee, Gloria; Chan, Fong

    2014-01-01

    Purpose: To examine the factorial structure of the "Coping Strategy Questionnaire"-24 (CSQ-24) in a sample of Canadians with chronic musculoskeletal pain. Method: The sample included 171 workers' compensation clients (50.9% men) recruited from outpatient rehabilitation facilities in Canada. Mean age of participants was 42.45 years…

  18. Factor Structure and Psychometric Properties of the Children's Negative Cognitive Error Questionnaire with a Clinically Depressed Adolescent Sample

    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,…

  19. Brief Report: The Ego Identity Process Questionnaire--Factor Structure, Reliability, and Convergent Validity in Dutch-Speaking Late Adolescents

    ERIC Educational Resources Information Center

    Luyckx, Koen; Goossens, Luc; Beyers, Wim; Soenens, Bart

    2006-01-01

    The reliability and validity of a Dutch version of the Ego Identity Process Questionnaire (EIPQ) were evaluated. In Study 1, the instrument was found to exhibit a clear factor structure and acceptable reliability. Using Confirmatory Factor Analysis, both a model with two process factors (Commitment, Exploration) and a model with four content…

  20. The Strengths and Difficulties Questionnaire (SDQ): The Factor Structure and Scale Validation in U.S. Adolescents

    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

  1. Measurement Structure of the Coping Strategies Questionnaire-24 in a Sample of Individuals with Musculoskeletal Pain: A Confirmatory Factor Analysis

    ERIC Educational Resources Information Center

    Chiu, Chung-Yi; Jochman, Joseph; Fujikawa, Mayu; Strand, David; Cheing, Gladys; Lee, Gloria; Chan, Fong

    2014-01-01

    Purpose: To examine the factorial structure of the "Coping Strategy Questionnaire"-24 (CSQ-24) in a sample of Canadians with chronic musculoskeletal pain. Method: The sample included 171 workers' compensation clients (50.9% men) recruited from outpatient rehabilitation facilities in Canada. Mean age of participants was 42.45 years

  2. The Strengths and Difficulties Questionnaire (SDQ): The Factor Structure and Scale Validation in U.S. Adolescents

    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…

  3. The Construct Validity of Scores on the Ways of Coping Questionnaire: Confirmatory Analysis of Alternative Factor Structures.

    ERIC Educational Resources Information Center

    Edwards, Jeffrey R.; O'Neill, Regina M.

    1998-01-01

    Confirmatory factor analysis was used to evaluate alternative factor structures, based on previous exploratory factor analyses and coping dimensions derived from the theory of R. Lazarus, for the Ways of Coping Questionnaire (S. Folkman and R. Lazarus, 1988). Results from responses of 654 college graduates provide little support for the factor

  4. GENERAL HEALTH QUESTIONNAIRE - 12: PSYCHOMETRIC PROPERTIES AND FACTOR STRUCTURE AMONG INDIAN WOMEN LIVING IN THE UNITED KINGDOM

    PubMed Central

    Jacob, K.S.; Bhugra, D.; Mann, A.H.

    1997-01-01

    The psychometric properties and factor structure of the 12 item General Health Questionnaire used in a sample of women of ethnic Indian origin living in the United Kingdom is described. The Cronbach's alpha was 0.89 and the split half reliability was 0.91. Principal component analysis revealed 2 significant components which accounted for 75.2% of variance. The psychometric properties and factor structure of the Hindi and English versions were similar.The psychometric properties and factor structure of the 12 item General Health Questionnaire used in a sample of women of ethnic Indian origin living in the United Kingdom is described. The Cronbach's alpha was 0.89 and the split half reliability was 0.91. Principal component analysis revealed 2 significant components which accounted for 75.2% of variance. The psychometric properties and factor structure of the Hindi and English versions were similar. PMID:21584074

  5. Connecting Athletes' Self-Perceptions and Metaperceptions of Competence: a Structural Equation Modeling Approach.

    PubMed

    Cecchini, Jose A; Fernández-Rio, Javier; Méndez-Giménez, Antonio

    2015-06-27

    This study explored the relationships between athletes' competence self-perceptions and metaperceptions. Two hundred and fifty one student-athletes (14.26 ± 1.89 years), members of twenty different teams (basketball, soccer) completed a questionnaire which included the Perception of Success Questionnaire, the Competence subscale of the Intrinsic Motivation Inventory, and modified versions of both questionnaires to assess athletes' metaperceptions. Structural equation modelling analysis revealed that athletes' task and ego metaperceptions positively predicted task and ego self-perceptions, respectively. Competence metaperceptions were strong predictors of competence self-perceptions, confirming the atypical metaperception formation in outcome-dependent contexts such as sport. Task and ego metaperceptions positively predicted athletes' competence metaperceptions. How coaches value their athletes' competence is more influential on what the athletes think of themselves than their own self-perceptions. Athletes' ego and task metaperceptions influenced their competence metaperceptions (how coaches rate their competence). Therefore, athletes build their competence metaperceptions using all information available from their coaches. Finally, only task-self perfections positively predicted athletes' competence self-perceptions. PMID:26240662

  6. Connecting Athletes’ Self-Perceptions and Metaperceptions of Competence: a Structural Equation Modeling Approach

    PubMed Central

    Cecchini, Jose A.; Fernández-Rio, Javier; Méndez-Giménez, Antonio

    2015-01-01

    This study explored the relationships between athletes’ competence self-perceptions and metaperceptions. Two hundred and fifty one student-athletes (14.26 ± 1.89 years), members of twenty different teams (basketball, soccer) completed a questionnaire which included the Perception of Success Questionnaire, the Competence subscale of the Intrinsic Motivation Inventory, and modified versions of both questionnaires to assess athletes’ metaperceptions. Structural equation modelling analysis revealed that athletes’ task and ego metaperceptions positively predicted task and ego self-perceptions, respectively. Competence metaperceptions were strong predictors of competence self-perceptions, confirming the atypical metaperception formation in outcome-dependent contexts such as sport. Task and ego metaperceptions positively predicted athletes’ competence metaperceptions. How coaches value their athletes’ competence is more influential on what the athletes think of themselves than their own self-perceptions. Athletes’ ego and task metaperceptions influenced their competence metaperceptions (how coaches rate their competence). Therefore, athletes build their competence metaperceptions using all information available from their coaches. Finally, only task-self perfections positively predicted athletes’ competence self-perceptions. PMID:26240662

  7. Annotated bibliography of structural equation modelling: technical work.

    PubMed

    Austin, J T; Wolfle, L M

    1991-05-01

    Researchers must be familiar with a variety of source literature to facilitate the informed use of structural equation modelling. Knowledge can be acquired through the study of an expanding literature found in a diverse set of publishing forums. We propose that structural equation modelling publications can be roughly classified into two groups: (a) technical and (b) substantive applications. Technical materials focus on the procedures rather than substantive conclusions derived from applications. The focus of this article is the former category; included are foundational/major contributions, minor contributions, critical and evaluative reviews, integrations, simulations and computer applications, precursor and historical material, and pedagogical textbooks. After a brief introduction, we annotate 294 articles in the technical category dating back to Sewall Wright (1921). PMID:1873237

  8. Validation of a structured questionnaire for COPD and prevalence of COPD in rural area of Mysore: A pilot study

    PubMed Central

    Mahesh, P. A.; Jayaraj, B. S.; Prahlad, S. T.; Chaya, S. K.; Prabhakar, A. K.; Agarwal, A. N.; Jindal, S. K.

    2009-01-01

    Background: The prevalence of chronic obstructive pulmonary disease (COPD) is increasing in India and there is a need to study the prevalence of COPD, particularly in the rural areas, which may be most affected due to their lifestyle. Materials and Methods: First stage: Validation of the questionnaire–105 consecutive patients underwent administration of the structured questionnaire and spirometry was used as a gold standard for the diagnosis of COPD. Second stage: Adults above 40 years (n = 900) in two villages of Mysore district were administered with the validated questionnaire, Knowledge and Attitude questionnaire and Fagerstorm questionnaire, to assess nicotine dependency. Results: The questionnaire was found to have a sensitivity of 62.5% and specificity of 87.6% to diagnose COPD. Of the total 900 adults surveyed (Males: 453, Females: 447), the total prevalence of COPD was 7.1%. Males had a higher prevalence (11.1%) compared to females (4.5%). The prevalence of smoking was very high among men at 71.9% and all the women were nonsmokers. The prevalence of COPD was 14.7% in smokers, 19.3% had mild to moderate nicotine dependency and 12.8% were highly dependent. Of the women exposed to regular biomass fuels, the prevalence of COPD was 3.9%, which increased to 4.8% on addition of regular passive smoking. In smoking, male gender and age were significantly associated with COPD (P < 0.05). Conclusion: The structured questionnaire is a useful tool for the screening of COPD in field studies. Smoking and biomass fuel exposure are important risk factors for COPD. PMID:20442838

  9. 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.

  10. Understanding discipline in families of children with attention-deficit/hyperactivity disorder: a structural equation model.

    PubMed

    Miranda, Ana; Grau, Dolores; Rosel, Jesús; Meliá, Amanda

    2009-11-01

    One hundred and fifty-five mothers of children with attention deficit/hyperactivity disorder (ADHD) completed a semi-structured interview, the Parenting Stress Index Questionnaire (Abidin, 1990), to evaluate parenting stress. The Parenting Scale (Arnold, O'Leary, Wolff & Acker, 1993) was also administered to measure dysfunctional discipline strategies. Structural equation modeling was used to test a model in which the independent variables were the Child's Characteristics and the Socio-Educational Status of his or her family; intermediate variables were Parenting Stress concerning the Child Domain and concerning the Parent Domain; and the dependent variable was Parental Discipline. The results confirm our hypotheses. Interventions in these families should therefore incorporate a component focused on Parenting Stress (in both the Child Domain and the Parent Domain), as a determinant of Parental Discipline. PMID:19899651

  11. The Structure of Perceived Emotional Control: Psychometric Properties of a Revised Anxiety Control Questionnaire

    ERIC Educational Resources Information Center

    Brown, Timothy A.; White, Kamila S.; Forsyth, John P.; Barlow, David H.

    2004-01-01

    The psychometric properties of the Anxiety Control Questionnaire (ACQ) were evaluated in 1,550 outpatients with DSM-IV anxiety and mood disorders and 360 nonclinical participants. Counter to prior findings, exploratory factor analyses produced a 3-factor solution (Emotion Control, Threat Control, Stress Control) based on 15 of the ACQ's original…

  12. The Home Situations Questionnaire-PDD Version: Factor Structure and Psychometric Properties

    ERIC Educational Resources Information Center

    Chowdhury, M.; Aman, M. G.; Scahill, L.; Swiezy, N.; Arnold, L. E.; Lecavalier, L.; Johnson, C.; Handen, B.; Stigler, K.; Bearss, K.; Sukhodolsky, D.; McDougle, C. J.

    2010-01-01

    Background: The Home Situations Questionnaire (HSQ) is a caregiver-rated scale designed to assess behavioural non-compliance in everyday settings that has been used in several studies in typically developing children. Currently there is no accepted measure of behavioural non-compliance in children with pervasive developmental disorders (PDDs).…

  13. Psychometric Evidence for the Leisure Interest Questionnaire and Analyses of the Structure of Leisure Interests

    ERIC Educational Resources Information Center

    Hansen, Jo-Ida C.; Scullard, Mark G.

    2002-01-01

    This study provides evidence of reliability and validity for the Leisure Interest Questionnaire (LIQ; J. C. Hansen, 1998). Undergraduate students completed the LIQ and Strong Interest Inventory (SII; E. K. Strong Jr., 1927) at Time 1 and the LIQ 5 weeks later. The internal consistency and test-retest reliability of the LIQ scales were calculated.…

  14. The Social Coping Questionnaire: An Examination of Its Structure with an American Sample of Gifted Adolescents

    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…

  15. Factor Structure and Reliability of the Childhood Trauma Questionnaire in a Canadian Undergraduate Student Sample

    ERIC Educational Resources Information Center

    Paivio, Sandra, C.; Cramer, Kenneth, M.

    2004-01-01

    Objective: The aims of this study were to examine (1) the psychometric properties of the Childhood Trauma Questionnaire [CTQ; Bernstein, D., Fink, L., Handelsman, L., Foote, J., Lovejoy, M., Wenzel, K., Sapareto, E., & Ruggiero, J. (1994). Initial reliability and validity of a new retrospective measure of child abuse and neglect. American Journal…

  16. The Adult Reading History Questionnaire (ARHQ) in Icelandic: Psychometric Properties and Factor Structure

    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…

  17. Convergence among Data Sources, Response Bias, and Reliability and Validity of a Structured Job Analysis Questionnaire.

    ERIC Educational Resources Information Center

    Smith, Jack E.; Hakel, Milton D.

    1979-01-01

    Examined are questions pertinent to the use of the Position Analysis Questionnaire: Who can use the PAQ reliably and validly? Must one rely on trained job analysts? Can people having no direct contact with the job use the PAQ reliably and validly? Do response biases influence PAQ responses? (Author/KC)

  18. Component Structure, Reliability, and Stability of Lawrence's Self-Esteem Questionnaire (LAWSEQ)

    ERIC Educational Resources Information Center

    Rae, Gordon; Dalto, Georgia; Loughrey, Dolores; Woods, Caroline

    2011-01-01

    Lawrence's Self-Esteem Questionnaire (LAWSEQ) was administered to 120 Year 1 pupils in six schools in Belfast, Northern Ireland. A principal components analysis indicated that the scale items were unidimensional and that the reliability of the scores, as estimated by Cronbach's alpha, was satisfactory ([alpha] = 0.73). There were no differences…

  19. Teaching Behavior Questionnaire: Verifying Factor Structure and Investigating Depressive Symptoms in Catholic Middle and High Schools

    ERIC Educational Resources Information Center

    Pittard, Caroline M.; Pössel, Patrick; Smith, Rosamond J.

    2015-01-01

    Teaching behavior impacts student psychopathology. This study explored the associations between teaching behavior types and depressive symptoms in students. The Teaching Behavior Questionnaire (TBQ) and the Center for Epidemiological Studies Depression Scale (CES-D) were completed by 763 middle and 976 high school students from private Catholic…

  20. The Home Situations Questionnaire-PDD Version: Factor Structure and Psychometric Properties

    ERIC Educational Resources Information Center

    Chowdhury, M.; Aman, M. G.; Scahill, L.; Swiezy, N.; Arnold, L. E.; Lecavalier, L.; Johnson, C.; Handen, B.; Stigler, K.; Bearss, K.; Sukhodolsky, D.; McDougle, C. J.

    2010-01-01

    Background: The Home Situations Questionnaire (HSQ) is a caregiver-rated scale designed to assess behavioural non-compliance in everyday settings that has been used in several studies in typically developing children. Currently there is no accepted measure of behavioural non-compliance in children with pervasive developmental disorders (PDDs).

  1. Factor structure and measurement invariance of the Health Education Impact Questionnaire: Does the subjectivity of the response perspective threaten the contextual validity of inferences?

    PubMed Central

    Elsworth, Gerald R; Nolte, Sandra

    2015-01-01

    Objective: On-going evidence is required to support the validity of inferences about change and group differences in the evaluation of health programs, particularly when self-report scales requiring substantial subjectivity in response generation are used as outcome measures. Following this reasoning, the aim of this study was to replicate the factor structure and investigate the measurement invariance of the latest version of the Health Education Impact Questionnaire, a widely used health program evaluation measure. Methods: An archived dataset of responses to the most recent version of the English-language Health Education Impact Questionnaire that uses four rather than six response options (N = 3221) was analysed using exploratory structural equation modelling and confirmatory factor analysis appropriate for ordered categorical data. Metric and scalar invariance were studied following recent recommendations in the literature to apply fully invariant unconditional models with minimum constraints necessary for model identification. Results: The original eight-factor structure was replicated and all but one of the scales (Self Monitoring and Insight) was found to consist of unifactorial items with reliability of ⩾0.8 and satisfactory discriminant validity. Configural, metric and scalar invariance were established across pre-test to post-test and population sub-groups (sex, age, education, ethnic background). Conclusion: The results support the high level of interest in the Health Education Impact Questionnaire, particularly for use as a pre-test/post-test measure in experimental studies, other pre–post evaluation designs and system-level monitoring and evaluation. PMID:26770785

  2. Crystal structure optimisation using an auxiliary equation of state.

    PubMed

    Jackson, Adam J; Skelton, Jonathan M; Hendon, Christopher H; Butler, Keith T; Walsh, Aron

    2015-11-14

    Standard procedures for local crystal-structure optimisation involve numerous energy and force calculations. It is common to calculate an energy-volume curve, fitting an equation of state around the equilibrium cell volume. This is a computationally intensive process, in particular, for low-symmetry crystal structures where each isochoric optimisation involves energy minimisation over many degrees of freedom. Such procedures can be prohibitive for non-local exchange-correlation functionals or other "beyond" density functional theory electronic structure techniques, particularly where analytical gradients are not available. We present a simple approach for efficient optimisation of crystal structures based on a known equation of state. The equilibrium volume can be predicted from one single-point calculation and refined with successive calculations if required. The approach is validated for PbS, PbTe, ZnS, and ZnTe using nine density functionals and applied to the quaternary semiconductor Cu2ZnSnS4 and the magnetic metal-organic framework HKUST-1. PMID:26567640

  3. Equations of Motion for Test Particles with Internal Structure

    NASA Astrophysics Data System (ADS)

    Fuchs, Helmut

    The general structure of equations of motion for test particles is considered with the help of a Lagrangian principle postulating a minimal coupling between internal and external variables. As an example the case of the Lorentz group as the basic internal group is considered in more detail. The connection with the Mathisson-Papapetrou equations is established.Translated AbstractBewegungsgleichungen für Test-Teilchen mit innerer StrukturWir untersuchen die allgemeine Struktur von Bewegungsgleichungen mit Hilfe eines Lagrange-Prinzips mit minimaler Kopplung zwischen inneren und äußeren Variablen. Der Fall, für den die zugrunde liegende innere Gruppe die Lorentz-Gruppe ist, wird genauer betrachtet und der Zusammenhang mit den Gleichungen von Mathisson und Papapetrou dargestellt.

  4. Factor structure and psychometric properties of the revised Home Situations Questionnaire for autism spectrum disorder: The Home Situations Questionnaire-Autism Spectrum Disorder.

    PubMed

    Chowdhury, Monali; Aman, Michael G; Lecavalier, Luc; Smith, Tristram; Johnson, Cynthia; Swiezy, Naomi; McCracken, James T; King, Bryan; McDougle, Christopher J; Bearss, Karen; Deng, Yanhong; Scahill, Lawrence

    2016-07-01

    Previously, we adapted the Home Situations Questionnaire to measure behavioral non-compliance in everyday settings in children with pervasive developmental disorders. In this study, we further revised this instrument for use in autism spectrum disorder and examined its psychometric properties (referred to as the Home Situations Questionnaire-Autism Spectrum Disorder). To cover a broader range of situations and improve reliability, we prepared seven new items describing situations in which children with autism spectrum disorder might display non-compliance. Parents completed ratings of 242 children with autism spectrum disorder with accompanying disruptive behaviors (ages 4-14 years) participating in one of two randomized clinical trials. Results from an exploratory factor analysis indicated that the Home Situations Questionnaire-Autism Spectrum Disorder consists of two 12-item factors: Socially Inflexible (α = 0.84) and Demand Specific (α = 0.89). One-to-two-week test-retest reliability was statistically significant for all scored items and also for subscale totals. The pattern of correspondence between the Home Situations Questionnaire-Autism Spectrum Disorder and parent-rated problem behavior, clinician-rated repetitive behavior, adaptive behavior, and IQ provided evidence for concurrent and divergent validity of the Home Situations Questionnaire-Autism Spectrum Disorder. Overall, the results suggest that the Home Situations Questionnaire-Autism Spectrum Disorder is an adequate measure for assessing non-compliance in a variety of situations in this population, and use of its two subscales will likely provide a more refined interpretation of ratings. PMID:26187059

  5. The Role of Internet-Specific Epistemic Beliefs and Self-Regulation in High School Students' Online Academic Help Seeking: A Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Cheng, Kun-Hung; Liang, Jyh-Chong; Tsai, Chin-Chung

    2013-01-01

    Three instruments (i.e., Internet-specific epistemic beliefs, self-regulation, and online academic help seeking questionnaires) were administered to 319 high school students with the aim of understanding the role of Internet specific epistemic beliefs and self-regulation in their online academic help seeking. Through a structure equation modeling…

  6. Testing Multivariable Covariance Structure and Means Hypotheses via Structural Equation Modeling.

    ERIC Educational Resources Information Center

    Raykov, Tenko

    2001-01-01

    Presents a didactic collection of covariance and mean structure hypotheses that can be tested using a widely applicable and easy to use structural equation modeling approach. The method is useful when the goal is to examine the observed multivariable structure or test hypotheses regarding interrelationships in measures and when large samples are…

  7. Religion, forgiveness, hostility and health: a structural equation analysis.

    PubMed

    Lutjen, Laura J; Silton, Nava R; Flannelly, Kevin J

    2012-06-01

    Religious participation has been shown to increase certain factors thought to be protective of health, including social support and positive health habits. The current study considers whether religious participation may likewise have a positive influence on health by increasing forgiveness and diminishing hostility. A structural equation analysis of data collected from a national survey of 1,629 participants supported the hypothesized model that (a) religiosity is related to greater forgiveness, (b) greater forgiveness, in turn, is related to reduced hostility and finally, (c) reduced hostility is related to better subjective health. PMID:21691897

  8. The Sleep Disorders Questionnaire. I: Creation and multivariate structure of SDQ.

    PubMed

    Douglass, A B; Bornstein, R; Nino-Murcia, G; Keenan, S; Miles, L; Zarcone, V P; Guilleminault, C; Dement, W C

    1994-03-01

    The development of the Sleep Disorders Questionnaire (SDQ) from the Sleep Questionnaire and Assessment of Wakefulness (SQAW) of Stanford University is described in detail. The extraction of the best question items from the SQAW and their subsequent rewording in the SDQ to insure greater completion rates are described. Two item test-retest reliability studies are reported on 71 controls and on 130 sleep-disorder patients, which confirmed adequate reliability. To create multivariate scoring scales, SDQ was then given in a multicenter study to 519 persons, 435 of whom were sleep-disorder patients with full polysomnography. Canonical Discriminant Function Analysis was employed, which resulted in four clinical-diagnostic scales: SA for sleep apnea, NAR for narcolepsy, PSY for psychiatric sleep disorder and PLM for periodic limb movement disorder. Each was adjusted for male and female responses and transformed to a percentile using the observed distribution of raw scores. Using Receiver Operating Characteristics analysis, cutoff points were determined for each scale to maximize its sensitivity and specificity. Positive and negative predictive values were also calculated. The SA and NAR scales proved to be the most discriminating. PMID:8036370

  9. Parental feeding styles and adolescents' healthy eating habits. Structure and correlates of a Costa Rican questionnaire.

    PubMed

    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

  10. Fluid-structural interactions using Navier-Stokes flow equations coupled with shell finite element structures

    NASA Technical Reports Server (NTRS)

    Guruswamy, Guru P.; Byun, Chansup

    1993-01-01

    A computational procedure is presented to study fluid-structural interaction problems for three-dimensional aerospace structures. The flow is modeled using the three-dimensional unsteady Euler/Navier-Stokes equations and solved using the finite-difference approach. The three dimensional structure is modeled using shell/plate finite-element formulation. The two disciplines are coupled using a domain decomposition approach. Accurate procedures both in time and space are developed to combine the solutions from the flow equations with those of the structural equations. Time accuracy is maintained using aeroelastic configuration-adaptive moving grids that are computed every time step. The work done by aerodynamic forces due to structural deformations is preserved using consistent loads. The present procedure is validated by computing the aeroelastic response of a wing and comparing with experiment. Results are illustrated for a typical wing-body configuration.

  11. Kadomtsev-Petviashvili II equation: Structure of asymptotic soliton webs

    NASA Astrophysics Data System (ADS)

    Horowitz, Shai; Zarmi, Yair

    2015-04-01

    A wealth of observations, recently supported by rigorous analysis, indicate that, asymptotically in time, most multi-soliton solutions of the Kadomtsev-Petviashvili II equation self-organize in webs comprised of solitons and soliton-junctions. Junctions are connected in pairs, each pair-by a single soliton. The webs expand in time. As distances between junctions grow, the memory of the structure of junctions in a connected pair ceases to affect the structure of either junction. As a result, every junction propagates at a constant velocity, which is determined by the wave numbers that go into its construction. One immediate consequence of this characteristic is that asymptotic webs preserve their morphology as they expand in time. Another consequence, based on simple geometric considerations, explains why, except in special cases, only 3-junctions (" Y-shaped", involving three wave numbers) and 4-junctions (" X-shaped", involving four wave numbers) can partake in the construction of an asymptotic soliton web.

  12. Structural Equation Modeling: Applications in ecological and evolutionary biology research

    USGS Publications Warehouse

    Pugesek, Bruce H.; von Eye, Alexander; Tomer, Adrian

    2003-01-01

    This book presents an introduction to the methodology of structural equation modeling, illustrates its use, and goes on to argue that it has revolutionary implications for the study of natural systems. A major theme of this book is that we have, up to this point, attempted to study systems primarily using methods (such as the univariate model) that were designed only for considering individual processes. Understanding systems requires the capacity to examine simultaneous influences and responses. Structural equation modeling (SEM) has such capabilities. It also possesses many other traits that add strength to its utility as a means of making scientific progress. In light of the capabilities of SEM, it can be argued that much of ecological theory is currently locked in an immature state that impairs its relevance. It is further argued that the principles of SEM are capable of leading to the development and evaluation of multivariate theories of the sort vitally needed for the conservation of natural systems. Supplementary information can be found at the authors website, http://www.jamesbgrace.com/. • Details why multivariate analyses should be used to study ecological systems • Exposes unappreciated weakness in many current popular analyses • Emphasizes the future methodological developments needed to advance our understanding of ecological systems.

  13. Spectral analysis and structure preserving preconditioners for fractional diffusion equations

    NASA Astrophysics Data System (ADS)

    Donatelli, Marco; Mazza, Mariarosa; Serra-Capizzano, Stefano

    2016-02-01

    Fractional partial order diffusion equations are a generalization of classical partial differential equations, used to model anomalous diffusion phenomena. When using the implicit Euler formula and the shifted Grünwald formula, it has been shown that the related discretizations lead to a linear system whose coefficient matrix has a Toeplitz-like structure. In this paper we focus our attention on the case of variable diffusion coefficients. Under appropriate conditions, we show that the sequence of the coefficient matrices belongs to the Generalized Locally Toeplitz class and we compute the symbol describing its asymptotic eigenvalue/singular value distribution, as the matrix size diverges. We employ the spectral information for analyzing known methods of preconditioned Krylov and multigrid type, with both positive and negative results and with a look forward to the multidimensional setting. We also propose two new tridiagonal structure preserving preconditioners to solve the resulting linear system, with Krylov methods such as CGNR and GMRES. A number of numerical examples show that our proposal is more effective than recently used circulant preconditioners.

  14. Reporting Multiple-Group Mean and Covariance Structure across Occasions with Structural Equation Modeling

    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…

  15. A New Look at the Big Five Factor Structure through Exploratory Structural Equation Modeling

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Ludtke, Oliver; Muthen, Bengt; Asparouhov, Tihomir; Morin, Alexandre J. S.; Trautwein, Ulrich; Nagengast, Benjamin

    2010-01-01

    NEO instruments are widely used to assess Big Five personality factors, but confirmatory factor analyses (CFAs) conducted at the item level do not support their a priori structure due, in part, to the overly restrictive CFA assumptions. We demonstrate that exploratory structural equation modeling (ESEM), an integration of CFA and exploratory…

  16. A Y-like structure in Jupiter's equator

    NASA Astrophysics Data System (ADS)

    Barrado-Izagirre, N.; Legarreta, J.; Garca-Melendo, E.; Snchez-Lavega, A.; Gmez-Forrellad, J. M.

    2015-10-01

    In this work we are presenting a study of peculiar Y-shaped structures that appeared in the equatorial zone of Jupiter between September and December 2012.These low albedo structures (named Y1 and Y2) were oriented along the equator and centered on it (at latitude 0.5to 1N). By using images acquired by a worldwide network of observers contributing to the PVOL-IOPW database [3] and operating small telescopes,we have analyzed the morphology of the structures and the surrounding area as well as the dynamical evolution during their lifetime 90 and 60 days respectively. In this period of time convective activity was registered near the vertex of these structures. We have complemented the study with a set of images in ultraviolet and near infrared wavelengths obtained by the Hubble Space Telescope (HST) for this epoch. The features were not visible at 255 nm wavelengths which indicate that they were vertically thin and placed in altitude between the upper Equatorial hazes and the main cloud deck. In addition, they move faster than their surroundings. Finally, we interpret the phenomenon as the manifestation of a transient equatorially trapped Kelvin wave.

  17. The Adult Reading History Questionnaire (ARHQ) in Icelandic: Psychometric Properties and Factor Structure.

    PubMed

    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

  18. Structural equation modeling: building and evaluating causal models: Chapter 8

    USGS Publications Warehouse

    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.

  19. Bayesian structural equation modeling in sport and exercise psychology.

    PubMed

    Stenling, Andreas; Ivarsson, Andreas; Johnson, Urban; Lindwall, Magnus

    2015-08-01

    Bayesian statistics is on the rise in mainstream psychology, but applications in sport and exercise psychology research are scarce. In this article, the foundations of Bayesian analysis are introduced, and we will illustrate how to apply Bayesian structural equation modeling in a sport and exercise psychology setting. More specifically, we contrasted a confirmatory factor analysis on the Sport Motivation Scale II estimated with the most commonly used estimator, maximum likelihood, and a Bayesian approach with weakly informative priors for cross-loadings and correlated residuals. The results indicated that the model with Bayesian estimation and weakly informative priors provided a good fit to the data, whereas the model estimated with a maximum likelihood estimator did not produce a well-fitting model. The reasons for this discrepancy between maximum likelihood and Bayesian estimation are discussed as well as potential advantages and caveats with the Bayesian approach. PMID:26442771

  20. Structural precursor to freezing: An integral equation study

    NASA Astrophysics Data System (ADS)

    Brader, Joseph M.

    2008-03-01

    Recent simulation studies have drawn attention to the shoulder which forms in the second peak of the radial distribution function of hard spheres at densities close to freezing and which is associated with local crystalline ordering in the dense fluid. We address this structural precursor to freezing using an inhomogeneous integral equation theory capable of describing local packing constraints to a high level of accuracy. The addition of a short-range attractive interaction leads to a well known broadening of the fluid-solid coexistence region as a function of attraction strength. The appearance of a shoulder in our calculated radial distribution functions is found to be consistent with the broadened coexistence region for a simple model potential, thus demonstrating that the shoulder is not exclusively a high density packing effect.

  1. Approaches to Testing Interaction Effects Using Structural Equation Modeling Methodology.

    PubMed

    Li, F; Harmer, P; Duncan, T E; Duncan, S C; Acock, A; Boles, S

    1998-01-01

    Use of structural equation modeling (SEM) methodology to study interactive relationships among latent variables began with the work of Kenny and Judd (1984) who developed a method of testing interactions involving continuous latent variables by forming products of multiple indicator variables. Until recently, there has been considerable difficulty implementing the method in SEM programs. This article reviews a single indicator approach (Joreskog & Yang, 1996) and multiple indicator approaches (Jaccard & Wan, 1995; Ping, 1996) that simplify Kenny and Judd's method. An illustrative application using an empirical example examining the interactive effect of perceptions of competence and perceptions of autonomy on exercise intrinsic motivation is presented. Practical issues surrounding the use of these different approaches are discussed. PMID:26771752

  2. Structural equation models of VMT growth in US urbanised areas.

    USGS Publications Warehouse

    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.

  3. Malignant Potential of Gastrointestinal Cancers Assessed by Structural Equation Modeling

    PubMed Central

    Onodera, Kei; Takahashi, Hiroaki; Okahara, Satoshi; Kodaira, Junichi; Oohashi, Hirokazu; Isshiki, Hiroyuki; Kawakami, Kentaro; Yamashita, Kentaro; Shinomura, Yasuhisa; Hosokawa, Masao

    2016-01-01

    Background Parameters reported in pathologic reviews have been failing to assess exactly the malignant potential of gastrointestinal cancers. We hypothesized that malignant potential could be defined by common latent variables (hypothesis I), but there are substantial differences in the associations between malignant potential and pathologic parameters according to the origin of gastrointestinal cancers (hypothesis II). We shed light on these issues by structural equation modeling. Materials and Methods We conducted a cross-sectional survey of 217 esophageal, 192 gastric, and 175 colorectal cancer patients who consecutively underwent curative surgery for their pathologic stage I cancers at Keiyukai Sapporo Hospital. Latent variables identified by factor analysis and seven conventional pathologic parameters were introduced in the structural equation modeling analysis. Results Because latent variables were disparate except for their number, 'three' in the examined gastrointestinal cancers, the first hypothesis was rejected. Because configural invariance across gastrointestinal cancers was not approved, the second hypothesis was verified. We could trace the three significant paths on the causal graph from latent variables to lymph node metastasis, which were mediated through depth, lymphatic invasion, and matrilysin expression in esophageal cancer, whereas only one significant path could be traced in both gastric and colorectal cancer. Two of the three latent variables were exogenous in esophageal cancer, whereas one factor was exogenous in the other gastrointestinal cancers. Cancer stemness promoted viability in esophageal cancer, but it was suppressed in others. Conclusion These results reflect the malignant potential of esophageal cancer is higher than that of the other gastrointestinal cancers. Such information might contribute to refining clinical treatments for gastrointestinal cancers. PMID:26889682

  4. Relationships among structural empowerment, psychological empowerment, intent to stay and burnout in nursing field in mainland China-based on a cross-sectional questionnaire research.

    PubMed

    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 χ(2)  = 58.580, P > 0.05, χ(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

  5. Shock wave structure using nonlinear model Boltzmann equations

    NASA Technical Reports Server (NTRS)

    Segal, Ben Maurice

    1971-01-01

    The structure of a strong plane shock wave in a monatomic rarefied perfect gas is one of the simplest problems able to be posed in kinetic theory, and one of the hardest to solve. Its simplicity lies in the absence of solid boundaries, geometrical complications, or internal molecular energy. Its difficulty arises from the great departure of the gas from equilibrium within the shock, which invalidates many of the techniques used successfully elsewhere in kinetic theory. In addition to this theoretical challenge, the modern development of ballistics and hypersonic flight has helped to stimulate extensive theoretical and experimental interest in the shock problem. The experimenters in turn have encountered great difficulties on account of the very small physical dimensions of shocks. In fact, until very recently indeed, any close comparisons of theoretical and experimental shock structure results have been rather unprofitable due to the inadequacies of both theory and experiment. During the last few years this situation has been appreciably improved by development of the Monte Carlo method. This allows idealized 'experiments' to be performed on large computers instead of in wind tunnels, using a known intermolecular force law. The most developed of these methods has been shown to be equivalent theoretically to the Boltzmann equation and to give results which agree extremely closely with measurements of high accuracy. Thus Monte Carlo results not only form the soundest basis for our present theoretical knowledge of shock wave structure, but, for purposes of developing other theories, can also be considered a very valuable experimental resource. However, such results remain very expensive to obtain. In this thesis we develop more economical kinetic theory methods for the approximate prediction of shock structure, and compare our results with those of the Monte Carlo method.

  6. 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.

  7. Bayesian Analysis of Structural Equation Models with Nonlinear Covariates and Latent Variables

    ERIC Educational Resources Information Center

    Song, Xin-Yuan; Lee, Sik-Yum

    2006-01-01

    In this article, we formulate a nonlinear structural equation model (SEM) that can accommodate covariates in the measurement equation and nonlinear terms of covariates and exogenous latent variables in the structural equation. The covariates can come from continuous or discrete distributions. A Bayesian approach is developed to analyze the…

  8. Factor structure of the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3) among adolescent boys in China.

    PubMed

    Jackson, Todd; Chen, Hong

    2010-09-01

    There is considerable evidence that mass media portrayals of body image contribute to body dissatisfaction, yet the assessment of perceived media influences has been examined fleetingly in highly populated, non-Western cultures, particularly among young males. This research examined the factor structure of the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3) among adolescent boys in China. In an initial exploratory factor analysis (N=719), a four factor solution emerged with components reflecting General Pressure-Internalization, Sources of Appearance Information, Pressure-Internalization of an Athletic Ideal, and Pressure to be Thin. Subsequently, confirmatory factor analyses in a new sample (n=749) assessed fits of the derived four factor model, a three factor variant, and alternatives reflecting "Western" and "Malay" SATAQ-3 solutions. The derived four factor solution had the most acceptable structure across several fit indices. Patterns of correlation with other self-report measures also provided preliminary support for the validity of the derived solution. PMID:20800561

  9. The Strengths and Difficulties Questionnaire (SDQ): Factor Structure and Gender Equivalence in Norwegian Adolescents

    PubMed Central

    Hysing, Mari; Skogen, Jens Christoffer; Breivik, Kyrre

    2016-01-01

    Although frequently used with older adolescents, few studies of the factor structure, internal consistency and gender equivalence of the SDQ exists for this age group, with inconsistent findings. In the present study, confirmatory factor analysis (CFA) was used to evaluate the five-factor structure of the SDQ in a population sample of 10,254 16–18 year-olds from the youth@hordaland study. Measurement invariance across gender was assessed using multigroup CFA. A modestly modified five-factor solution fitted the data acceptably, accounting for one cross loading and some local dependencies. Importantly, partial measurement non-invariance was identified, with differential item functioning in eight items, and higher correlations between emotional and conduct problems for boys compared to girls. Implications for use clinically and in research are discussed. PMID:27138259

  10. On the specification of structural equation models for ecological systems

    USGS Publications Warehouse

    Grace, J.B.; Michael, Anderson T.; Han, O.; Scheiner, S.M.

    2010-01-01

    The use of structural equation modeling (SEM) is often motivated by its utility for investigating complex networks of relationships, but also because of its promise as a means of representing theoretical concepts using latent variables. In this paper, we discuss characteristics of ecological theory and some of the challenges for proper specification of theoretical ideas in structural equation models (SE models). In our presentation, we describe some of the requirements for classical latent variable models in which observed variables (indicators) are interpreted as the effects of underlying causes. We also describe alternative model specifications in which indicators are interpreted as having causal influences on the theoretical concepts. We suggest that this latter nonclassical specification (which involves another variable type-the composite) will often be appropriate for ecological studies because of the multifaceted nature of our theoretical concepts. In this paper, we employ the use of meta-models to aid the translation of theory into SE models and also to facilitate our ability to relate results back to our theories. We demonstrate our approach by showing how a synthetic theory of grassland biodiversity can be evaluated using SEM and data from a coastal grassland. In this example, the theory focuses on the responses of species richness to abiotic stress and disturbance, both directly and through intervening effects on community biomass. Models examined include both those based on classical forms (where each concept is represented using a single latent variable) and also ones in which the concepts are recognized to be multifaceted and modeled as such. To address the challenge of matching SE models with the conceptual level of our theory, two approaches are illustrated, compositing and aggregation. Both approaches are shown to have merits, with the former being preferable for cases where the multiple facets of a concept have widely differing effects in the system and the latter being preferable where facets act together consistently when influencing other parts of the system. Because ecological theory characteristically deals with concepts that are multifaceted, we expect the methods presented in this paper will be useful for ecologists wishing to use SEM. ?? 2010 by the Ecological Society of America.

  11. Evaluation of model fit in nonlinear multilevel structural equation modeling

    PubMed Central

    Schermelleh-Engel, Karin; Kerwer, Martin; Klein, Andreas G.

    2013-01-01

    Evaluating model fit in nonlinear multilevel structural equation models (MSEM) presents a challenge as no adequate test statistic is available. Nevertheless, using a product indicator approach a likelihood ratio test for linear models is provided which may also be useful for nonlinear MSEM. The main problem with nonlinear models is that product variables are non-normally distributed. Although robust test statistics have been developed for linear SEM to ensure valid results under the condition of non-normality, they have not yet been investigated for nonlinear MSEM. In a Monte Carlo study, the performance of the robust likelihood ratio test was investigated for models with single-level latent interaction effects using the unconstrained product indicator approach. As overall model fit evaluation has a potential limitation in detecting the lack of fit at a single level even for linear models, level-specific model fit evaluation was also investigated using partially saturated models. Four population models were considered: a model with interaction effects at both levels, an interaction effect at the within-group level, an interaction effect at the between-group level, and a model with no interaction effects at both levels. For these models the number of groups, predictor correlation, and model misspecification was varied. The results indicate that the robust test statistic performed sufficiently well. Advantages of level-specific model fit evaluation for the detection of model misfit are demonstrated. PMID:24624110

  12. The role of burnout syndrome as a mediator for the effect of psychosocial risk factors on the intensity of musculoskeletal disorders: a structural equation modeling approach.

    PubMed

    Gholami, Tahereh; Pahlavian, Ahmad Heidari; Akbarzadeh, Mahdi; Motamedzade, Majid; Moghaddam, Rashid Heidari

    2016-01-01

    This study examined the hypothesis that burnout syndrome mediates effects of psychosocial risk factors and intensity of musculoskeletal disorders (MSDs) among hospital nurses. The sample was composed of 415 nurses from various wards across five hospitals of Iran's Hamedan University of Medical Sciences. Data were collected through three questionnaires: job content questionnaire, Maslach burnout inventory and visual analogue scale. Results of structural equation modeling with a mediating effect showed that psychosocial risk factors were significantly related to changes in burnout, which in turn affects intensity of MSDs. PMID:27075269

  13. 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…

  14. Hard ellipses: Equation of state, structure, and self-diffusion.

    PubMed

    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 ≤ φ ≤ 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 φ, 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

  15. [Transformational and transactional leadership: An analysis of the factor structure of the Multifactor Leadership Questionnaire (MLQ) in a Spanish sample].

    PubMed

    Molero Alonso, Fernando; Recio Saboya, Patricia; Cuadrado Guirado, Isabel

    2010-08-01

    The Multifactor Leadership Questionnaire (MLQ) has been one of the most commonly used instruments to assess leadership in organizational settings for the last two decades. However, the factor structure proposed by the MLQ authors has received some criticism. The aim of this work is to examine the fit indices of several alternative factor models suggested by the literature. In order to accomplish this objective, we conducted confirmatory factor analyses in a sample of 954 participants using a Spanish version of the MLQ. Results show that the model that produces the better fit with the data consists of four factors: transformational leadership, developmental/transactional leadership, corrective leadership and avoidant/passive leadership. This model is parsimonious and consistent with the MLQ literature. PMID:20667281

  16. The relationship between quality management practices and organisational performance: A structural equation modelling approach

    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.

  17. Applications of Multilevel Structural Equation Modeling to Cross-Cultural Research

    ERIC Educational Resources Information Center

    Cheung, Mike W.-L.; Au, Kevin

    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 begun 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 collecting data…

  18. Applications of Multilevel Structural Equation Modeling to Cross-Cultural Research

    ERIC Educational Resources Information Center

    Cheung, Mike W.-L.; Au, Kevin

    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 begun 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 collecting data

  19. Habitat fragmentation and reproductive success: a structural equation modelling approach.

    PubMed

    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

  20. Inferring causal phenotype networks using structural equation models

    PubMed Central

    2011-01-01

    Phenotypic traits may exert causal effects between them. For example, on the one hand, high yield in dairy cows may increase the liability to certain diseases and, on the other hand, the incidence of a disease may affect yield negatively. Likewise, the transcriptome may be a function of the reproductive status in mammals and the latter may depend on other physiological variables. Knowledge of phenotype networks describing such interrelationships can be used to predict the behavior of complex systems, e.g. biological pathways underlying complex traits such as diseases, growth and reproduction. Structural Equation Models (SEM) can be used to study recursive and simultaneous relationships among phenotypes in multivariate systems such as genetical genomics, system biology, and multiple trait models in quantitative genetics. Hence, SEM can produce an interpretation of relationships among traits which differs from that obtained with traditional multiple trait models, in which all relationships are represented by symmetric linear associations among random variables, such as covariances and correlations. In this review, we discuss the application of SEM and related techniques for the study of multiple phenotypes. Two basic scenarios are considered, one pertaining to genetical genomics studies, in which QTL or molecular marker information is used to facilitate causal inference, and another related to quantitative genetic analysis in livestock, in which only phenotypic and pedigree information is available. Advantages and limitations of SEM compared to traditional approaches commonly used for the analysis of multiple traits, as well as some indication of future research in this area are presented in a concluding section. PMID:21310061

  1. Brooding and pondering: isolating the active ingredients of depressive rumination with exploratory factor analysis and structural equation modeling.

    PubMed

    Armey, Michael F; Fresco, David M; Moore, Michael T; Mennin, Douglas S; Turk, Cynthia L; Heimberg, Richard G; Kecmanovic, Jelena; Alloy, Lauren B

    2009-12-01

    Depressive rumination, as assessed by Nolen-Hoeksema's Response Styles Questionnaire (RSQ), predicts the onset, chronicity, and duration of depressed mood. However, some RSQ items contain depressive content and result in a heterogeneous factor structure. After the a priori elimination of items potentially confounded with depressed item content, Treynor, Gonzalez, and Nolen-Hoeksema identified two factors within the remaining RSQ rumination sub-scale that were differentially related to depression: brooding and pondering. However, Treynor et al. used a nonstandard form and administration of the RSQ. The present study sought to address these methodological idiosyncrasies and replicate the factor structure of Treynor et al. through exploratory factor analysis and structural equation modeling. Findings support the brooding and pondering solution and demonstrate that brooding relates more strongly to depression and anxiety than does pondering. PMID:19667138

  2. Investigating the factorial invariance of the 28-item DBQ across genders and age groups: an Exploratory Structural Equation Modeling study.

    PubMed

    Mattsson, Markus

    2012-09-01

    The Driver Behaviour Questionnaire (DBQ) is perhaps the most widely used questionnaire instrument in traffic psychology with 174 studies published by late 2010. The instrument was developed based on a plausible cognitive ergonomic theory (the Generic Error Modeling System, GEMS), but the factor structure obtained in the original study (Reason et al., 1990) did not mirror the theory's conceptual structure. This led to abandoning GEMS and adopting the obtained factor structure as a starting point for further DBQ research. This article argues that (1) certain choices in the original study, concerning statistical methodology and the wording of individual question items, may have contributed to the ways the obtained factor structure deviated from the underlying theory and (2) the analysis methods often used in DBQ studies, principal components (PC) analysis and maximum likelihood (ML) factor analysis, are not optimal choices for the non-normally distributed categorical data that is obtained using the instrument. This is because ML produces biased results when used with this type of data, while PC is by definition unable to uncover latent factors as it summarizes all variation in the measured variables. (3) Even though DBQ factor scores have been routinely compared in subgroups of men and women and respondents of different ages, DBQ's factorial invariance in these groups has not been rigorously tested. These concerns are addressed in this article by framing the results of certain previous DBQ studies as a structural equation model (SEM) and an Exploratory Structural Equation Model (ESEM) and testing measurement model fit in subgroups of respondents. The SEM analyses indicate that the model does not fit data from the whole sample of respondents as it stands, while the ESEM analyses show that a modification of the model does. However, the ESEM analyses indicate the DBQ measures different underlying latent variables in the different subgroups. Based on the analyses and a review of recent advances in attention and memory research, an update to the theory underlying the DBQ is suggested. PMID:22664704

  3. Executive functions, impulsivity, and inhibitory control in adolescents: A structural equation model

    PubMed Central

    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

  4. Executive functions, impulsivity, and inhibitory control in adolescents: A structural equation model.

    PubMed

    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

  5. Pesticide residue transfer in Thai farmer families: using structural equation modeling to determine exposure pathways.

    PubMed

    Liu, Hanhua; Hanchenlaksh, Chalalai; Povey, Andrew C; de Vocht, Frank

    2015-01-01

    Use of pesticides in agriculture may lead to downstream exposure of farmers' families to pesticide residues inadvertently taken home. Identification of the independent contribution of different exposure pathways from the farmer to their children can provide clear targets to reduce exposure of farmers' children. Individual contributions of different pesticide transfer exposure pathways were investigated using structural equation modeling methods, and the benefits of these methods compared to standard multiple regression are described. A total of 72 Thai families, consisting of a farmer, a spouse, and a child, participated in this study. Family members completed a questionnaire and self-collected three spot morning urine samples in the spraying season. Urine samples were analyzed for diethyl phosphate, diethyl thiophosphate, diethyl dithiophosphate, dimethyl phosphate, dimethyl thiophosphate, and dimethyl dithiophosphate. A path model was developed based on an a priori hypothesized framework to examine the individual contributions of different exposure pathways that may directly or indirectly affect transfer of pesticide residues from farmers to their children. Transfer from the farmer to the child occurs indirectly, primarily through transfer to the spouse in the first instance, but also through contamination of the home environment. Clear targets for interventions are directly the reduction of farmers' take-home exposures and indirectly frequent cleaning of the home to avoid buildup of pesticide residues. PMID:25407029

  6. [Antecedents and consequences of workplace bullying: a longitudinal analysis with a structural equation model].

    PubMed

    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

  7. Predictors of Quality of Life in Portuguese Obese Patients: A Structural Equation Modeling Application

    PubMed Central

    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

  8. The impact of culture and employee-focused criteria on productivity: A structural equation modelling approach

    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.

  9. RESPONSE PATTERNS ON INTERVIEW AND QUESTIONNAIRE VERSIONS OF THE EATING DISORDER EXAMINATION AND THEIR IMPACT ON LATENT STRUCTURE ANALYSES

    PubMed Central

    Berg, Kelly C.; Swanson, Sonja A.; Stiles-Shields, E. Colleen; Eddy, Kamryn T.; Peterson, Carol B.; Le Grange, Daniel

    2013-01-01

    Objective The purpose of this investigation was to compare the latent structures of the interview (EDE) and questionnaire (EDE-Q) versions of the Eating Disorder Examination. Methods Participants were 280 children, adolescents, and young adults seeking eating disorder treatment. Two separate latent structure analyses (LSAs) were conducted; one used variables from the EDE as indicators and the other used the corresponding variables from the EDE-Q as indicators. Results The EDE and EDE-Q models both yielded four-class solutions. Three of the four classes from the EDE-Q model demonstrated moderate to high concordance with their paired class from the EDE model. Using the EDE-Q to detect the EDE, the sensitivity and specificity of measuring certain classes varied from poor (18.6%) to excellent (93.7%). The overall concordance was moderate (?=.49). Discussion These data suggest that LSAs using the EDE and EDE-Q may be directly compared; however, differences between results may represent inconsistencies in response patterns rather than true differences in psychopathology. PMID:23375185

  10. Poisson structures for lifts and periodic reductions of integrable lattice equations

    NASA Astrophysics Data System (ADS)

    Kouloukas, Theodoros E.; Tran, Dinh T.

    2015-02-01

    We introduce and study suitable Poisson structures for four-dimensional maps derived as lifts and specific periodic reductions of integrable lattice equations. These maps are Poisson with respect to these structures and the corresponding integrals are in involution.

  11. A Bayesian Approach for Analyzing Hierarchical Data with Missing Outcomes through Structural Equation Models

    ERIC Educational Resources Information Center

    Song, Xin-Yuan; Lee, Sik-Yum

    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…

  12. A Bayesian Approach for Analyzing Hierarchical Data with Missing Outcomes through Structural Equation Models

    ERIC Educational Resources Information Center

    Song, Xin-Yuan; Lee, Sik-Yum

    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

  13. Evaluation of Structural Equation Mixture Models: Parameter Estimates and Correct Class Assignment

    ERIC Educational Resources Information Center

    Tueller, Stephen; Lubke, Gitta

    2010-01-01

    Structural equation mixture models (SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from 1 wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are…

  14. Estimating and Interpreting Latent Variable Interactions: A Tutorial for Applying the Latent Moderated Structural Equations Method

    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)…

  15. 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.

  16. Progress in Integrated Fluid/Structure/Controls Computations Using High Fidelity Equations

    NASA Technical Reports Server (NTRS)

    Guruswamy, Guru P.; VanDalsem, William R. (Technical Monitor)

    1995-01-01

    Aeroelasticity that 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 aircraft which can experience complex flow/structure interactions. Supersonic transports can experience vortex induced aeroelastic oscillations whereas subsonic transports 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. Using these high fidelity methods, design quantities such as structural stresses can be directly computed. Computations using these high fidelity equations require state-of-the-art large computational resources. This paper will describe the transition from potential equations to Euler/Navier-Stokes equations for fluids and from modal equations to finite element equations for structures. Complexities associated with grids for moving control surfaces will be discussed. All contents of the paper will be limited to those already presented at domestic conferences within U.S. such as those sponsored by AIAA. It will not include any materials related to HPCCP computational work.

  17. Meta-Analytic Structural Equation Modeling (MASEM): Comparison of the Multivariate Methods

    ERIC Educational Resources Information Center

    Zhang, Ying

    2011-01-01

    Meta-analytic Structural Equation Modeling (MASEM) has drawn interest from many researchers recently. In doing MASEM, researchers usually first synthesize correlation matrices across studies using meta-analysis techniques and then analyze the pooled correlation matrix using structural equation modeling techniques. Several multivariate methods of…

  18. 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…

  19. On the Likelihood Ratio Test in Structural Equation Modeling when Parameters are Subject to Boundary Constraints

    ERIC Educational Resources Information Center

    Stoel, Reinoud D.; Garre, Francisca Galindo; Dolan, Conor; van den Wittenboer, Godfried

    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…

  20. Evaluation of Structural Equation Mixture Models: Parameter Estimates and Correct Class Assignment

    ERIC Educational Resources Information Center

    Tueller, Stephen; Lubke, Gitta

    2010-01-01

    Structural equation mixture models (SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from 1 wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are

  1. Mathematical structure of tetrad equations for vacuum relativity

    SciTech Connect

    Estabrook, Frank B.

    2005-02-15

    The tetrad partial differential equations formulated by Buchman and Bardeen for vacuum gravity are shown to be well posed by calculation of the Cartan characters of an associated exterior differential system. Gauge specializations are discussed. A Cartan 4-form is found for this field theory, together with its intrinsic version the Lagrangian density.

  2. Fixed- and random-effects meta-analytic structural equation modeling: examples and analyses in R.

    PubMed

    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

  3. Factor structure of the General Health Questionnaire-28 (GHQ-28) from infertile women attending the Yazd Research and Clinical Center for Infertility

    PubMed Central

    Shayan, Zahra; Pourmovahed, Zahra; Najafipour, Fatemeh; Abdoli, Ali Mohammad; Mohebpour, Fatemeh; Najafipour, Sedighe

    2015-01-01

    Background: Nowadays, infertility problems have become a social concern, and are associated with multiple psychological and social problems. Also, it affects the interpersonal communication between the individual, familial, and social characteristics. Since women are exposed to stressors of physical, mental, social factors, and treatment of infertility, providing a psychometric screening tool is necessary for disorders of this group. Objective: The aim of this study was to determine the factor structure of the general health questionnaire-28 to discover mental disorders in infertile women. Materials and Methods: In this study, 220 infertile women undergoing treatment of infertility were selected from the Yazd Research and Clinical Center for Infertility with convenience sampling in 2011. After completing the general health questionnaire by the project manager, validity and, reliability of the questionnaire were calculated by confirmatory factor structure and Cronbach's alpha, respectively. Results: Four factors, including anxiety and insomnia, social dysfunction, depression, and physical symptoms were extracted from the factor structure. 50.12% of the total variance was explained by four factors. The reliability coefficient of the questionnaire was obtained 0.90. Conclusion: Analysis of the factor structure and reliability of General Health Questionnaire-28 showed that it is suitable as a screening instrument for assessing general health of infertile women.

  4. Factor structure of the Social Experience Questionnaire across time, sex, and grade among early elementary school children.

    PubMed

    Desjardins, Tracy; Yeung Thompson, Rachel S; Sukhawathanakul, Paweena; Leadbeater, Bonnie J; Macdonald, Stuart W S

    2013-12-01

    Ample research suggests that peer victimization predicts social and psychological maladjustment, including emotional (e.g., anxiety, low self-esteem, and depression) and behavioral (e.g., aggression) problems among children. Thus, a reliable measure of peer victimization for research with young children is needed. The Social Experience Questionnaire-Self-Report (SEQ-S) has been widely used in existing research to assess children's victimization (Crick & Grotpeter, 1996). However, empirical support for the psychometric properties of the SEQ-S is limited by the methods used to evaluate it (i.e., exploratory as opposed to confirmatory analyses), by the lack of longitudinal data, and by the limited age ranges studied. This study examined the underlying factor structure of SEQ-S ratings across 3 time points in a sample of 830 early elementary school children using confirmatory factor analysis. The hypothesized model included 3 latent factors: overt victimization, relational victimization, and receipt of prosocial acts from peers. This model provided a good fit to the data at each time point. Although it is not clear that there is invariance, results indicate that invariance across time, sex, and grade could be present. Recommendations for continued use of the SEQ-S in future research on peer victimization with young children are discussed. (PsycINFO Database Record (c) 2013 APA, all rights reserved). PMID:23730827

  5. Factor structure and reliability of the childhood trauma questionnaire and prevalence estimates of trauma for male and female street youth.

    PubMed

    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 .65 to .95. Confirmatory Factor Analysis (CFA) was used to test the five-factor structure of the scales yielding acceptable fit for the total sample. Additional multigroup analyses were performed to consider items by gender. Results provided only evidence of weak factorial invariance. Constrained models showed invariance in configuration, factor loadings, and factor covariances but failed for equality of intercepts. Mean trauma scores for street youth tended to fall in the moderate to severe range on all abuse/neglect clinical scales. Females reported higher levels of abuse and neglect. Prevalence of child maltreatment of individual forms was very high with 98% of street youth reporting one or more forms; 27.4% of males and 48.9% of females reported all five forms. Results of this study support the viability of the CTQ-SF for screening maltreatment in a highly vulnerable street population. Caution is recommended when comparing prevalence estimates for male and female street youth given the failure of the strong factorial multigroup model. PMID:21810791

  6. Structure of Helicity and Global Solutions of Incompressible Navier-Stokes Equation

    NASA Astrophysics Data System (ADS)

    Lei, Zhen; Lin, Fang-Hua; Zhou, Yi

    2015-12-01

    In this paper we derive a new energy identity for the three-dimensional incompressible Navier-Stokes equations by a special structure of helicity. The new energy functional is critical with respect to the natural scalings of the Navier-Stokes equations. Moreover, it is conditionally coercive. As an application we construct a family of finite energy smooth solutions to the Navier-Stokes equations whose critical norms can be arbitrarily large.

  7. A Test and Cross-Validation of the Revised Two-Factor Study Process Questionnaire Factor Structure among Western University Students

    ERIC Educational Resources Information Center

    Immekus, Jason C.; Imbrie, P. K.

    2010-01-01

    The Revised Two-Factor Study Process Questionnaire (R-SPQ-2F) is a measure of university students' approach to learning. Original evaluation of the scale's psychometric properties was based on a sample of Hong Kong university students' scores. The purpose of this study was to test and cross-validate the R-SPQ-2F factor structure, based on separate…

  8. Adjustment to College as Measured by the Student Adaptation to College Questionnaire: A Quantitative Review of Its Structure and Relationships with Correlates and Consequences

    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…

  9. The Structure of Self-Serving Cognitive Distortions: A Validation of the "How I Think" Questionnaire in a Sample of Italian Adolescents

    ERIC Educational Resources Information Center

    Bacchini, Dario; De Angelis, Grazia; Affuso, Gaetana; Brugman, Daniel

    2016-01-01

    This study aims to investigate the structure of self-serving cognitive distortions (CD), evaluating the psychometric properties of the How I Think Questionnaire in a sample of Italian adolescents. A confirmatory factor analysis supported the distinction between four categories of CD and the use of a single second-order dimension of CD. Reliability…

  10. Factor Structure of the Reactive-Proactive Aggression Questionnaire in Turkish Children and Gender, Grade-Level, and Socioeconomic Status Differences in Reactive and Proactive Aggression

    ERIC Educational Resources Information Center

    Uz Bas, Asli; Yurdabakan, Irfan

    2012-01-01

    The present study aimed to evaluate the factor structure of the Reactive-Proactive Aggression Questionnaire (RPQ) with Turkish children, and to investigate gender, grade-level, and socioeconomic status (SES) differences in reactive and proactive aggression. Participants consisted of 1,081 Turkish children (544 boys and 537 girls) aged 9 to 14…

  11. Adjustment to College as Measured by the Student Adaptation to College Questionnaire: A Quantitative Review of Its Structure and Relationships with Correlates and Consequences

    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

  12. Factor Structure of the Reactive-Proactive Aggression Questionnaire in Turkish Children and Gender, Grade-Level, and Socioeconomic Status Differences in Reactive and Proactive Aggression

    ERIC Educational Resources Information Center

    Uz Bas, Asli; Yurdabakan, Irfan

    2012-01-01

    The present study aimed to evaluate the factor structure of the Reactive-Proactive Aggression Questionnaire (RPQ) with Turkish children, and to investigate gender, grade-level, and socioeconomic status (SES) differences in reactive and proactive aggression. Participants consisted of 1,081 Turkish children (544 boys and 537 girls) aged 9 to 14

  13. Inverse diffraction grating of Maxwell's equations in biperiodic structures.

    PubMed

    Bao, Gang; Cui, Tao; Li, Peijun

    2014-02-24

    Consider a time-harmonic electromagnetic plane wave incident on a perfectly conducting biperiodic surface (crossed grating). The diffraction is modeled as a boundary value problem for the three-dimensional Maxwell equation. The surface is assumed to be a small and smooth deformation of a planar surface. In this paper, a novel approach is developed to solve the inverse diffraction grating problem in the near-field regime, which is to reconstruct the surface with resolution beyond Rayleigh's criterion. The method requires only a single incident field with one polarization, one frequency, and one incident direction, and is realized by using the fast Fourier transform. Numerical results show that the method is simple, efficient, and stable to reconstruct biperiodic surfaces with subwavelength resolution. PMID:24663798

  14. Constructing a Variable Coefficient Integrable Coupling Equation Hierarchy and its Hamiltonian Structure

    NASA Astrophysics Data System (ADS)

    Yu, Fajun; Feng, Shuo

    2016-03-01

    How to construct a variable coefficient integrable coupling equation hierarchy is an important problem. In this paper, we present new Lax pairs with some arbitrary functions and generate a variable coefficient integrable coupling of Ablowitz-Kaup-Newell-Segur hierarchy from a zero-curvature equation. Then the Hamiltonian structure of the variable coefficient coupling equation hierarchy is derived from the variational trace identity. It is also indicated that this method is an efficient and straightforward way to construct the variable coefficient integrable coupling equation hierarchy.

  15. System Characteristics, Satisfaction and E-Learning Usage: A Structural Equation Model (SEM)

    ERIC Educational Resources Information Center

    Ramayah, T.; Lee, Jason Wai Chow

    2012-01-01

    With the advent of the Internet, more and more public universities in Malaysia are putting in effort to introduce e-learning in their respective universities. Using a structured questionnaire derived from the literature, data was collected from 250 undergraduate students from a public university in Penang, Malaysia. Data was analyzed using AMOS…

  16. Nonlinear static and dynamic analysis of beam structures using fully intrinsic equations

    NASA Astrophysics Data System (ADS)

    Sotoudeh, Zahra

    2011-07-01

    Beams are structural members with one dimension much larger than the other two. Examples of beams include propeller blades, helicopter rotor blades, and high aspect-ratio aircraft wings in aerospace engineering; shafts and wind turbine blades in mechanical engineering; towers, highways and bridges in civil engineering; and DNA modeling in biomedical engineering. Beam analysis includes two sets of equations: a generally linear two-dimensional problem over the cross-sectional plane and a nonlinear, global one-dimensional analysis. This research work deals with a relatively new set of equations for one-dimensional beam analysis, namely the so-called fully intrinsic equations. Fully intrinsic equations comprise a set of geometrically exact, nonlinear, first-order partial differential equations that is suitable for analyzing initially curved and twisted anisotropic beams. A fully intrinsic formulation is devoid of displacement and rotation variables, making it especially attractive because of the absence of singularities, infinite-degree nonlinearities, and other undesirable features associated with finite rotation variables. In spite of the advantages of these equations, using them with certain boundary conditions presents significant challenges. This research work will take a broad look at these challenges of modeling various boundary conditions when using the fully intrinsic equations. Hopefully it will clear the path for wider and easier use of the fully intrinsic equations in future research. This work also includes application of fully intrinsic equations in structural analysis of joined-wing aircraft, different rotor blade configuration and LCO analysis of HALE aircraft.

  17. Examining Factor Structure and Validating the Persian Version of the Pregnancy’s Worries and Stress Questionnaire for Pregnant Iranian Women

    PubMed Central

    Navidpour, Fariba; Dolatian, Mahrokh; Yaghmaei, Farideh; Majd, Hamid Alavi; Hashemi, Seyed Saeed

    2015-01-01

    Background and Objectives: Pregnant women tend to experience anxiety and stress when faced with the changes to their biology, environment and personal relationships. The identification of these factors and the prevention of their side effects are vital for both mother and fetus. The present study was conducted to validate and to examine the factor structure of the Persian version of the Pregnancy’s Worries and Stress Questionnaire. Materials and Methods: The 25-item PWSQ was first translated by specialists into Persian. The questionnaire’s validity was determined using face, content, criterion and construct validity and reliability of questionnaire was examined using Cronbach’s alpha. Confirmatory factor analysis was performed in AMOS and SPSS 21. Participants included healthy Iranian pregnant women (8-39 weeks) who refer to selected hospitals for prenatal care. Hospitals included private, social security and university hospitals and selected through the random cluster sampling method. Findings: The results of validity and reliability assessments of the questionnaire were acceptable. Cronbach’s alpha calculated showed a high internal consistency of 0.89. The confirmatory factor analysis using the χ2, CMIN/DF, IFI, CFI, NFI and NNFI indexes showed the 6-factor model to be the best fitted model for explaining the data. Conclusion: The questionnaire was translated into Persian to examine stress and worry specific to Iranian pregnant women. The psychometric results showed that the questionnaire is suitable for identifying Iranian pregnant women with pregnancy-related stress. PMID:26153186

  18. The abundant symmetry structure of hierarchies of nonlinear equations obtained by reciprocal links

    NASA Astrophysics Data System (ADS)

    Carillo, Sandra; Fuchssteiner, Benno

    1989-07-01

    Explicit computation for a Kawamoto-type equation shows that there is a rich associated symmetry structure for four separate hierarchies of nonlinear integrodifferential equations. Contrary to the general belief that symmetry groups for nonlinear evolution equations in 1+1 dimensions have to be Abelian, it is shown that, in this case, the symmetry group is noncommutative. Its semisimple part is isomorphic to the affine Lie algebra A(1)1 associated to sl(2,C). In two of the additional hierarchies that were found, an explicit dependence of the independent variable occurs. Surprisingly, the generic invariance for the Kawamoto-type equation obtained in Rogers and Carillo [Phys. Scr. 36, 865 (1987)] via a reciprocal link to the Möbius invariance of the singularity equation of the Kaup-Kupershmidt (KK) equation only holds for one of the additional hierarchies of symmetry groups. Thus the generic invariance is not a universal property for the complete symmetry group of equations obtained by reciprocal links. In addition to these results, the bi-Hamiltonian formulation of the hierarchy is given. A direct Bäcklund transformation between the (KK) hierarchy and the hierarchy of singularity equation for the Caudrey-Dodd-Gibbon-Sawada-Kotera equation is exhibited: This shows that the abundant symmetry structure found for the Kawamoto equation must exist for all fifth-order equations, which are known to be completely integrable since these equations are connected either by Bäcklund transformations or reciprocal links. It is shown that similar results must hold for all hierarchies emerging out of singularity hierarchies via reciprocal links. Furthermore, general aspects of the results are discussed.

  19. A homotopy algorithm for synthesizing robust controllers for flexible structures via the maximum entropy design equations

    NASA Technical Reports Server (NTRS)

    Collins, Emmanuel G., Jr.; Richter, Stephen

    1990-01-01

    One well known deficiency of LQG compensators is that they do not guarantee any measure of robustness. This deficiency is especially highlighted when considering control design for complex systems such as flexible structures. There has thus been a need to generalize LQG theory to incorporate robustness constraints. Here we describe the maximum entropy approach to robust control design for flexible structures, a generalization of LQG theory, pioneered by Hyland, which has proved useful in practice. The design equations consist of a set of coupled Riccati and Lyapunov equations. A homotopy algorithm that is used to solve these design equations is presented.

  20. The Swedish version of the Outcome Questionnaire (OQ-45): reliability and factor structure in a substance abuse sample.

    PubMed

    Wennberg, Peter; Philips, Björn; de Jong, Kim

    2010-09-01

    This study described the psychometric properties of the Swedish version of the Outcome Questionnaire (OQ-45.2) in a substance abuse sample (N=227). The test properties were satisfactory except for somewhat low internal consistency in the social role subscale. The results were similar to those obtained in other countries but systematic international comparisons are still lacking. PMID:20021732

  1. National Survey of Sensory Features in Children with ASD: Factor Structure of the Sensory Experience Questionnaire (3.0)

    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.,…

  2. The Application of Structured Job Analysis Information Based on the Position Analysis Questionnaire (PAQ). Final Report No. 9.

    ERIC Educational Resources Information Center

    McCormick, Ernest J.

    The Position Analysis Questionnaire (PAQ) is a job analysis instrument consisting of 187 job elements organized into six divisions. The PAQ was used in the eight studies summarized in this final report. The studies were: (1) ratings of the attribute requirements of PAQ job elements, (2) a series of principal components analyses of these attribute…

  3. National Survey of Sensory Features in Children with ASD: Factor Structure of the Sensory Experience Questionnaire (3.0)

    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 2-12years 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.,

  4. Factor Structure of the Schalock and Keith Quality of Life Questionnaire (QOL-Q): Validation on Mexican and Spanish Samples

    ERIC Educational Resources Information Center

    Caballo, C.; Crespo, M.; Jenaro, C.; Verdugo, M. A.; Martinez, J. L.

    2005-01-01

    Background: The Quality of Life Questionnaire (QOL-Q) is used widely to evaluate the quality of life of persons with intellectual disability (ID). Its validity for use with Spanish-speaking cultures has been demonstrated for individuals with visual disabilities, but not for those with physical or intellectual disabilities. Such was the purpose of…

  5. Examining the Factor Structure and Discriminant Validity of the 12-Item General Health Questionnaire (GHQ-12) Among Spanish Postpartum Women

    ERIC Educational Resources Information Center

    Aguado, Jaume; Campbell, Alistair; Ascaso, Carlos; Navarro, Purificacion; Garcia-Esteve, Lluisa; Luciano, Juan V.

    2012-01-01

    In this study, the authors tested alternative factor models of the 12-item General Health Questionnaire (GHQ-12) in a sample of Spanish postpartum women, using confirmatory factor analysis. The authors report the results of modeling three different methods for scoring the GHQ-12 using estimation methods recommended for categorical and binary data.…

  6. Comparing Empirical Power of Multilevel Structural Equation Models and Hierarchical Linear Models: Understanding Cross-Level Interactions

    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:…

  7. The feeding practices and structure questionnaire: construction and initial validation in a sample of Australian first-time mothers and their 2-year olds

    PubMed Central

    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 α: 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

  8. The Lattice Structure of Connection Preserving Deformations for q-Painlevé Equations I

    NASA Astrophysics Data System (ADS)

    Ormerod, Christopher M.

    2011-05-01

    We wish to explore a link between the Lax integrability of the q-Painlevé equations and the symmetries of the q-Painlevé equations. We shall demonstrate that the connection preserving deformations that give rise to the q-Painlevé equations may be thought of as elements of the groups of Schlesinger transformations of their associated linear problems. These groups admit a very natural lattice structure. Each Schlesinger transformation induces a Bäcklund transformation of the q-Painlevé equation. Each translational Bäcklund transformation may be lifted to the level of the associated linear problem, effectively showing that each translational Bäcklund transformation admits a Lax pair. We will demonstrate this framework for the q-Painlevé equations up to and including q-PVI.

  9. 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.

  10. Discrete Kalman filtering equations of second-order form for control-structure interaction simulations

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alvin, K. F.; Belvin, W. Keith

    1991-01-01

    A second-order form of discrete Kalman filtering equations is proposed as a candidate state estimator for efficient simulations of control-structure interactions in coupled physical coordinate configurations as opposed to decoupled modal coordinates. The resulting matrix equation of the present state estimator consists of the same symmetric, sparse N x N coupled matrices of the governing structural dynamics equations as opposed to unsymmetric 2N x 2N state space-based estimators. Thus, in addition to substantial computational efficiency improvement, the present estimator can be applied to control-structure design optimization for which the physical coordinates associated with the mass, damping and stiffness matrices of the structure are needed instead of modal coordinates.

  11. Evaluation of Existing Structure and Civil Protection Management Framework in Greek Local Authorities: A Questionnaire Survey Demonstrates Why Prevention Fails

    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.

  12. 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…

  13. Direct and Indirect Effects of Parental Influence upon Adolescent Alcohol Use: A Structural Equation Modeling Analysis

    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…

  14. Multilevel Structural Equation Models for the Analysis of Comparative Data on Educational Performance

    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…

  15. OpenMx: An Open Source Extended Structural Equation Modeling Framework

    ERIC Educational Resources Information Center

    Boker, Steven; Neale, Michael; Maes, Hermine; Wilde, Michael; Spiegel, Michael; Brick, Timothy; Spies, Jeffrey; Estabrook, Ryne; Kenny, Sarah; Bates, Timothy; Mehta, Paras; Fox, John

    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 along with the philosophy behind the user interface. The OpenMx data structures are introduced--these…

  16. Application of Exploratory Structural Equation Modeling to Evaluate the Academic Motivation Scale

    ERIC Educational Resources Information Center

    Guay, Frédéric; Morin, Alexandre J. S.; Litalien, David; Valois, Pierre; Vallerand, Robert J.

    2015-01-01

    In this research, the authors examined the construct validity of scores of the Academic Motivation Scale using exploratory structural equation modeling. Study 1 and Study 2 involved 1,416 college students and 4,498 high school students, respectively. First, results of both studies indicated that the factor structure tested with exploratory…

  17. Structural Equation Modeling in Assessing Students' Understanding of the State Changes of Matter

    ERIC Educational Resources Information Center

    Stamovlasis, Dimitrios; Tsitsipis, Georgios; Papageorgiou, George

    2012-01-01

    In this study, structural equation modeling (SEM) is applied to an instrument assessing students' understanding of the particulate nature of matter, the collective properties and physical changes, such as melting, evaporation, boiling and condensation. The structural relationships among particular groups of items were investigated. In addition,…

  18. Multilevel Structural Equation Models for the Analysis of Comparative Data on Educational Performance

    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

  19. The Effect of Perceived Instructional Effectiveness on Student Loyalty: A Multilevel Structural Equation Model

    ERIC Educational Resources Information Center

    Simsek, Gulhayat Golbasi; Noyan, Fatma

    2009-01-01

    Social sciences research often entails the analysis of data with a multilevel structure. An example of multilevel data is containing measurement on university students nested within instructors. This paper concentrates on multilevel analysis of structural equation modeling with educational data. Data used in this study were gathered from 17647…

  20. Application of Exploratory Structural Equation Modeling to Evaluate the Academic Motivation Scale

    ERIC Educational Resources Information Center

    Guay, Frdric; Morin, Alexandre J. S.; Litalien, David; Valois, Pierre; Vallerand, Robert J.

    2015-01-01

    In this research, the authors examined the construct validity of scores of the Academic Motivation Scale using exploratory structural equation modeling. Study 1 and Study 2 involved 1,416 college students and 4,498 high school students, respectively. First, results of both studies indicated that the factor structure tested with exploratory

  1. Using Structural Equation Modeling to Examine Group Differences in Assessment Booklet Designs with Sparse Data

    ERIC Educational Resources Information Center

    Willse, John T.; Goodman, Joshua T.; Allen, Nancy; Klaric, John

    2008-01-01

    The current research demonstrates the effectiveness of using structural equation modeling (SEM) for the investigation of subgroup differences with sparse data designs where not every student takes every item. Simulations were conducted that reflected missing data structures like those encountered in large survey assessment programs (e.g., National…

  2. Introducing Algebraic Structures through Solving Equations: Vertical Content Knowledge for K-12 Mathematics Teachers

    ERIC Educational Resources Information Center

    Wasserman, Nicholas H.

    2014-01-01

    Algebraic structures are a necessary aspect of algebraic thinking for K-12 students and teachers. An approach for introducing the algebraic structure of groups and fields through the arithmetic properties required for solving simple equations is summarized; the collective (not individual) importance of these axioms as a foundation for algebraic

  3. 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…

  4. Application of partial differential equation modeling of the control/structural dynamics of flexible spacecraft

    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.

  5. Fitting Data to Model: Structural Equation Modeling Diagnosis Using Two Scatter Plots

    ERIC Educational Resources Information Center

    Yuan, Ke-Hai; Hayashi, Kentaro

    2010-01-01

    This article introduces two simple scatter plots for model diagnosis in structural equation modeling. One plot contrasts a residual-based M-distance of the structural model with the M-distance for the factor score. It contains information on outliers, good leverage observations, bad leverage observations, and normal cases. The other plot contrasts

  6. Introducing Algebraic Structures through Solving Equations: Vertical Content Knowledge for K-12 Mathematics Teachers

    ERIC Educational Resources Information Center

    Wasserman, Nicholas H.

    2014-01-01

    Algebraic structures are a necessary aspect of algebraic thinking for K-12 students and teachers. An approach for introducing the algebraic structure of groups and fields through the arithmetic properties required for solving simple equations is summarized; the collective (not individual) importance of these axioms as a foundation for algebraic…

  7. Structural Equation Modeling in Assessing Students' Understanding of the State Changes of Matter

    ERIC Educational Resources Information Center

    Stamovlasis, Dimitrios; Tsitsipis, Georgios; Papageorgiou, George

    2012-01-01

    In this study, structural equation modeling (SEM) is applied to an instrument assessing students' understanding of the particulate nature of matter, the collective properties and physical changes, such as melting, evaporation, boiling and condensation. The structural relationships among particular groups of items were investigated. In addition,

  8. OpenMx: An Open Source Extended Structural Equation Modeling Framework

    ERIC Educational Resources Information Center

    Boker, Steven; Neale, Michael; Maes, Hermine; Wilde, Michael; Spiegel, Michael; Brick, Timothy; Spies, Jeffrey; Estabrook, Ryne; Kenny, Sarah; Bates, Timothy; Mehta, Paras; Fox, John

    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 along with the philosophy behind the user interface. The OpenMx data structures are introduced--these

  9. Fitting Data to Model: Structural Equation Modeling Diagnosis Using Two Scatter Plots

    ERIC Educational Resources Information Center

    Yuan, Ke-Hai; Hayashi, Kentaro

    2010-01-01

    This article introduces two simple scatter plots for model diagnosis in structural equation modeling. One plot contrasts a residual-based M-distance of the structural model with the M-distance for the factor score. It contains information on outliers, good leverage observations, bad leverage observations, and normal cases. The other plot contrasts…

  10. A family of solution algorithms for nonlinear structural analysis based on relaxation equations

    NASA Technical Reports Server (NTRS)

    Park, K. C.

    1981-01-01

    A family of hierarchical algorithms for nonlinear structural equations are presented. The algorithms are based on the Davidenko-Branin type homotopy and shown to yield consistent hierarchical perturbation equations. The algorithms appear to be particularly suitable to problems involving bifurcation and limit point calculations. An important by-product of the algorithms is that it provides a systematic and economical means for computing the stepsize at each iteration stage when a Newton-like method is employed to solve the systems of equations. Some sample problems are provided to illustrate the characteristics of the algorithms.

  11. Fluid/Structure Interaction Studies of Aircraft Using High Fidelity Equations on Parallel Computers

    NASA Technical Reports Server (NTRS)

    Guruswamy, Guru; VanDalsem, William (Technical Monitor)

    1994-01-01

    Abstract 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 super computers 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 ENSAERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.

  12. Progress in Computational Aeroelasticity Using High Fidelity Flow and Structural Equations on Parallel Computers

    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.

  13. Testing strong factorial invariance using three-level structural equation modeling.

    PubMed

    Jak, Suzanne

    2014-01-01

    Within structural equation modeling, the most prevalent model to investigate measurement bias is the multigroup model. Equal factor loadings and intercepts across groups in a multigroup model represent strong factorial invariance (absence of measurement bias) across groups. Although this approach is possible in principle, it is hardly practical when the number of groups is large or when the group size is relatively small. Jak et al. (2013) showed how strong factorial invariance across large numbers of groups can be tested in a multilevel structural equation modeling framework, by treating group as a random instead of a fixed variable. In the present study, this model is extended for use with three-level data. The proposed method is illustrated with an investigation of strong factorial invariance across 156 school classes and 50 schools in a Dutch dyscalculia test, using three-level structural equation modeling. PMID:25120499

  14. A ballistic limit equation for hypervelocity impacts on CFRP Al H/C satellite structures

    NASA Astrophysics Data System (ADS)

    Ryan, S.; Schäfer, F.; Destefanis, R.; Lambert, M.

    Composite sandwich panels consisting of Carbon Fiber Reinforced Plastic facesheets bonded to Aluminum honeycomb cores CFRP Al H C SP are amongst the most commonly used structures for satellites due to their relative low mass and high thermal and mechanical stability To assess the threat of micrometeoroid orbital debris M OD on a satellite mission equations which define the limits of structural perforation in terms of impactor mass velocity and angle are required This type of equation is referred to as a Ballistic Limit Equation BLE There is presently no validated BLE existing for application in the risk assessment of CFRP Al H C SP structures During a recent experimental test campaign performed in the framework of ESA Contract 16721 e g 1 using EMI s two-stage light-gas guns the ballistic performance of multiple representative CFRP Al HC SP structural configurations GOCE Radarsat-2 Herschel Planck BeppoSax was investigated The experimental results have been used to adjust and validate a new empirical BLE derived from an existing Whipple Shield BLE which provides a significant improvement in the accuracy of ballistic performance prediction over existing techniques Additionally the equation is capable of predicting the ballistic limit of an Electronic-box representative structure located behind the structural wall Good agreement with the experimental results is achieved for the vast majority of test set-ups For some set-ups the ballistic limit was conservatively predicted however this is attributed to the additional

  15. Second-order discrete Kalman filtering equations for control-structure interaction simulations

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Belvin, W. Keith; Alvin, Kenneth F.

    1991-01-01

    A general form for the first-order representation of the continuous, second-order linear structural dynamics equations is introduced in order to derive a corresponding form of first-order Kalman filtering equations (KFE). Time integration of the resulting first-order KFE is carried out via a set of linear multistep integration formulas. It is shown that a judicious combined selection of computational paths and the undetermined matrices introduced in the general form of the first-order linear structural systems leads to a class of second-order discrete KFE involving only symmetric, N x N solution matrix.

  16. An integral equation theory for solvation effects on the molecular structural fluctuation

    NASA Astrophysics Data System (ADS)

    Matsumura, Yoshihiro; Sato, Hirofumi

    2015-07-01

    A new integral equation theory is proposed, which enables us to efficiently compute conformational distribution of a polyatomic molecule in solution phase. The solvation effect on the intramolecular correlation function is evaluated through a self-consistent procedure. In addition, the analytical expression of solvation free energy is derived, explicitly taking into account the molecular structural fluctuation. The derived equation establishes a direct route between the structural fluctuation and free energy of the molecule. The method was successfully applied to a series of n-alkanes in aqueous solutions to demonstrate the superiority of the proposed theory.

  17. Self-administered food frequency questionnaire used in the 5-year follow-up survey of the JPHC Study: questionnaire structure, computation algorithms, and area-based mean intake.

    PubMed

    Sasaki, Satoshi; Kobayashi, Minatsu; Ishihara, Junko; Tsugane, Shoichiro

    2003-01-01

    In this section we described the structure of the self-administered semiquantitative food frequency questionnaire used in the 5-year follow-up survey of the JPHC study, the computation algorithms, and the area-based mean intakes of nutrients and food groups in the subjects of the validation study. The FFQ consists of five sections: 1) semiquantitative frequency questions for rice and miso (fermented soybean paste)-soup, 2) those for alcoholic beverages, 3) those for vitamin supplements, 4) those for foods and beverages, and 5) questions on dietary and cooking behaviors. From the questions, intakes of nutrients and foods by food groups were computed. Although most of them were computed from the frequency and relative portion size indicated in the replies, together with the fixed portion size, a seasonal coefficient was added in the computation of vegetables and fruits. Only frequency of intake and fixed portion size were used for computation of beverages. Sugar and cream added in coffee and tea were computed from the frequency of coffee and tea intake. The intakes of cooking oil, cooking salt (sodium), and salt in noodle-soup were estimated from the questions of relative preference of oil, salt, and noodle-soup. PMID:12701629

  18. Thermodynamics and structure of a two-dimensional electrolyte by integral equation theory

    SciTech Connect

    Aupic, Jana; Urbic, Tomaz

    2014-05-14

    Monte Carlo simulations and integral equation theory were used to predict the thermodynamics and structure of a two-dimensional Coulomb fluid. We checked the possibility that integral equations reproduce Kosterlitz-Thouless and vapor-liquid phase transitions of the electrolyte and critical points. Integral equation theory results were compared to Monte Carlo data and the correctness of selected closure relations was assessed. Among selected closures hypernetted-chain approximation results matched computer simulation data best, but these equations unfortunately break down at temperatures well above the Kosterlitz-Thouless transition. The Kovalenko-Hirata closure produces results even at very low temperatures and densities, but no sign of phase transition was detected.

  19. Biological fitness and the Price Equation in class-structured populations.

    PubMed

    Grafen, Alan

    2015-05-21

    Price׳s extended covariance selection mathematics is applied to class-structured populations with additional assumptions, to derive the 'genetic Price Equation with class structure'. Each individual belongs to a class, and there may be overlapping generations; the equation is genetic because the trait is restricted to an arbitrary weighted sum of allele frequencies. Two special cases are then considered, a demography-like case corresponding to Fisher's fundamental theorem of natural selection, and a sex-ratio-like case corresponding to Fisher's sex ratio argument: these differ in whether it is natural to assume that the per-capita or the total reproductive values of each class are maintained from the parental to the descendant population. These cases also match the two existing attempts to eliminate from the effects of natural selection those passive changes in allele frequencies that are caused by the class structure, and suggest improvements in one of them. In each case a more specialised Price Equation, and a 'fundamental theorem of natural selection', are proved, which hold out of class-structure equilibrium, showing that passive changes can be eliminated in more than one way, and hinting at the possibility of a more general formulation. Previous class-structured Price Equations and a 'fundamental theorem' are linked to these results. The power of Price's formal approach is vividly illustrated by this lucid conspectus of otherwise self-standing theories with confusing interconnections. PMID:25701635

  20. Some Poisson structures and Lax equations associated with the Toeplitz lattice and the Schur lattice

    NASA Astrophysics Data System (ADS)

    Lemarie, Caroline

    2016-01-01

    The Toeplitz lattice is a Hamiltonian system whose Poisson structure is known. In this paper, we unveil the origins of this Poisson structure and derive from it the associated Lax equations for this lattice. We first construct a Poisson subvariety H n of GL n (C), which we view as a real or complex Poisson-Lie group whose Poisson structure comes from a quadratic R-bracket on gl n (C) for a fixed R-matrix. The existence of Hamiltonians, associated to the Toeplitz lattice for the Poisson structure on H n , combined with the properties of the quadratic R-bracket allow us to give explicit formulas for the Lax equation. Then we derive from it the integrability in the sense of Liouville of the Toeplitz lattice. When we view the lattice as being defined over R, we can construct a Poisson subvariety H n τ of U n which is itself a Poisson-Dirac subvariety of GL n R (C). We then construct a Hamiltonian for the Poisson structure induced on H n τ , corresponding to another system which derives from the Toeplitz lattice the modified Schur lattice. Thanks to the properties of Poisson-Dirac subvarieties, we give an explicit Lax equation for the new system and derive from it a Lax equation for the Schur lattice. We also deduce the integrability in the sense of Liouville of the modified Schur lattice.

  1. Discussions on equivalent solutions and localized structures via the mapping method based on Riccati equation

    NASA Astrophysics Data System (ADS)

    Xu, Ling; Cheng, Xuan; Dai, Chao-Qing

    2015-12-01

    Although the mapping method based on Riccati equation was proposed to obtain variable separation solutions many years ago, two important problems have not been studied: i) the equivalence of variable separation solutions by means of the mapping method based on Riccati equation with the radical sign combined ansatz; and ii) lack of physical meanings for some localized structures constructed by variable separation solutions. In this paper, we re-study the (2+1)-dimensional Boiti-Leon-Pempinelli equation via the mapping method based on Riccati equation and prove that nine types of variable separation solutions are actually equivalent to each other. Moreover, we also re-study localized structures constructed by variable separation solutions. Results indicate that some localized structures reported in the literature are lacking real values due to the appearance of the divergent and un-physical phenomenon for the initial field. Therefore, we must be careful with the initial field to avoid the appearance of some un-physical or even divergent structures in it when we construct localized structures for the potential field.

  2. 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.

  3. Evaluation of structural equation mixture models Parameter estimates and correct class assignment

    PubMed Central

    Tueller, Stephen; Lubke, Gitta

    2009-01-01

    Structural Equation Mixture Models(SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from one wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are investigated in a large scale simulation study. Design factors of the simulation study are (im)balanced class proportions, (im)balanced factor variances, sample size, and class separation. We compare the fit of models with correct and misspecified within-class structural relations. In addition, we investigate the potential to fit SEMMs with binary indicators. The structure of within-class distributions can be recovered under a wide variety of conditions, indicating the general potential and flexibility of SEMMs to test complex within-class models. Correct class assignment is limited. PMID:20582328

  4. The Relation among Fit Indexes, Power, and Sample Size in Structural Equation Modeling

    ERIC Educational Resources Information Center

    Kim, Kevin H.

    2005-01-01

    The relation among fit indexes, power, and sample size in structural equation modeling is examined. The noncentrality parameter is required to compute power. The 2 existing methods of computing power have estimated the noncentrality parameter by specifying an alternative hypothesis or alternative fit. These methods cannot be implemented easily and

  5. Exploring Mediating Effect of Metacognitive Awareness on Comprehension of Science Texts through Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Wang, Jing-Ru; Chen, Shin-Feng

    2014-01-01

    This study used a Chinese-language version of the Index of Science Reading Awareness (ISRA) to investigate metacognitive awareness and the Reading Comprehension of Science Test (RCST) to explore comprehension of science text by Taiwanese students. Structural equation modeling (SEM) results confirmed the validity of the underlying models of

  6. An Assessment of Practical Solutions for Structural Equation Modeling with Complex Sample Data

    ERIC Educational Resources Information Center

    Stapleton, Laura M.

    2006-01-01

    This article discusses 5 approaches that secondary researchers might use to obtain robust estimates in structural equation modeling analyses when using data that come from large survey programs. These survey programs usually collect data using complex sampling designs and estimates obtained from conventional analyses that ignore the dependencies…

  7. Estimating, Testing, and Comparing Specific Effects in Structural Equation Models: The Phantom Model Approach

    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…

  8. Women's Path into Science and Engineering Majors: A Structural Equation Model

    ERIC Educational Resources Information Center

    Camp, Amanda G.; Gilleland, Diane; Pearson, Carolyn; Vander Putten, Jim

    2009-01-01

    The intent of this study was to investigate the adequacy of Weidman's (1985, 1989) theoretical undergraduate socialization model as an empirical-based causal model pertaining to women's career path choice into a science or engineering (SE) major via structural equation modeling. Data were obtained from the Beginning Postsecondary Students…

  9. University Students' Behaviors Pertaining to Sustainability: A Structural Equation Model with Sustainability-Related Attributes

    ERIC Educational Resources Information Center

    Sahin, Elvan; Ertepinar, Hamide; Teksoz, Gaye

    2012-01-01

    The purpose of this study is to construct a structural equation model to examine the links among attitudes, values, and behaviors pertaining to sustainability, participation in outdoor recreation as well as gender and tendency to follow mass media for university students. The data were collected by on-line administration of a survey to 958…

  10. Structural Equation Models of Latent Interactions: An Appropriate Standardized Solution and Its Scale-Free Properties

    ERIC Educational Resources Information Center

    Wen, Zhonglin; Marsh, Herbert W.; Hau, Kit-Tai

    2010-01-01

    Standardized parameter estimates are routinely used to summarize the results of multiple regression models of manifest variables and structural equation models of latent variables, because they facilitate interpretation. Although the typical standardization of interaction terms is not appropriate for multiple regression models, straightforward…

  11. Testing Time-Invariance of Variable Specificity in Repeated Measure Designs Using Structural Equation Modeling

    ERIC Educational Resources Information Center

    Raykov, Tenko; Amemiya, Yasuo

    2008-01-01

    A structural equation modeling method for examining time-invariance of variable specificity in longitudinal studies with multiple measures is outlined, which is developed within a confirmatory factor-analytic framework. The approach represents a likelihood ratio test for the hypothesis of stability in the specificity part of the residual term…

  12. Evaluating Small Sample Approaches for Model Test Statistics in Structural Equation Modeling.

    ERIC Educational Resources Information Center

    Nevitt, Jonathan

    Structural equation modeling (SEM) attempts to remove the negative influence of measurement error and allows for investigation of relationships at the level of the underlying constructs of interest. SEM has been regarded as a "large sample" technique since its inception. Recent developments in SEM, some of which are currently available in popular…

  13. Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety

    ERIC Educational Resources Information Center

    Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

    2013-01-01

    Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.…

  14. 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…

  15. Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety

    ERIC Educational Resources Information Center

    Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

    2013-01-01

    Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.

  16. Structural Equation Modelling of Multiple Facet Data: Extending Models for Multitrait-Multimethod Data

    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…

  17. A Structural Equation Model at the Individual and Group Level for Assessing Faking-Related Change

    ERIC Educational Resources Information Center

    Ferrando, Pere Joan; Anguiano-Carrasco, Cristina

    2011-01-01

    This article proposes a comprehensive approach based on structural equation modeling for assessing the amount of trait-level change derived from faking-motivating situations. The model is intended for a mixed 2-wave 2-group design, and assesses change at both the group and the individual level. Theoretically the model adopts an integrative…

  18. Organizational Cynicism, School Culture, and Academic Achievement: The Study of Structural Equation Modeling

    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…

  19. 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…

  20. Using a Structural Equation Model to Examine Factors Affecting Married Individuals' Sexual Embarrassment

    ERIC Educational Resources Information Center

    Celik, Eyup; Arici, Neslihan

    2014-01-01

    This study aimed to predict the effects of levels of sexual awareness, sexual courage, and sexual self-disclosure on sexual embarrassment. Data was collected from 336 married individuals, who have students in the Sultangazi District of Istanbul. According to the structural equation model (SEM), sexual self-disclosure, directly, and sexual courage…

  1. Standards-Based Evaluation and Teacher Career Satisfaction: A Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Conley, Sharon; Muncey, Donna E.; You, Sukkyung

    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

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  3. 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…

  4. 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…

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  6. Multilevel Modeling of Two Cyclical Processes: Extending Differential Structural Equation Modeling to Nonlinear Coupled Systems

    ERIC Educational Resources Information Center

    Butner, Jonathan; Amazeen, Polemnia G.; Mulvey, Genna M.

    2005-01-01

    The authors present a dynamical multilevel model that captures changes over time in the bidirectional, potentially asymmetric influence of 2 cyclical processes. S. M. Boker and J. Graham's (1998) differential structural equation modeling approach was expanded to the case of a nonlinear coupled oscillator that is common in bimanual coordination…

  7. Comparison of Approaches to Constructing Confidence Intervals for Mediating Effects Using Structural Equation Models

    ERIC Educational Resources Information Center

    Cheung, Mike W. L.

    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…

  8. A Two-Stage Approach to Synthesizing Covariance Matrices in Meta-Analytic Structural Equation Modeling

    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…

  9. Residuals and the Residual-Based Statistic for Testing Goodness of Fit of Structural Equation Models

    ERIC Educational Resources Information Center

    Foldnes, Njal; Foss, Tron; Olsson, Ulf Henning

    2012-01-01

    The residuals obtained from fitting a structural equation model are crucial ingredients in obtaining chi-square goodness-of-fit statistics for the model. The authors present a didactic discussion of the residuals, obtaining a geometrical interpretation by recognizing the residuals as the result of oblique projections. This sheds light on the…

  10. Standards-Based Evaluation and Teacher Career Satisfaction: A Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Conley, Sharon; Muncey, Donna E.; You, Sukkyung

    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…

  11. Parsimonious Structural Equation Models for Repeated Measures Data, with Application to the Study of Consumer Preferences

    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

  12. The Relation among Fit Indexes, Power, and Sample Size in Structural Equation Modeling

    ERIC Educational Resources Information Center

    Kim, Kevin H.

    2005-01-01

    The relation among fit indexes, power, and sample size in structural equation modeling is examined. The noncentrality parameter is required to compute power. The 2 existing methods of computing power have estimated the noncentrality parameter by specifying an alternative hypothesis or alternative fit. These methods cannot be implemented easily and…

  13. Bayesian Methods for Analyzing Structural Equation Models with Covariates, Interaction, and Quadratic Latent Variables

    ERIC Educational Resources Information Center

    Lee, Sik-Yum; Song, Xin-Yuan; Tang, Nian-Sheng

    2007-01-01

    The analysis of interaction among latent variables has received much attention. This article introduces a Bayesian approach to analyze a general structural equation model that accommodates the general nonlinear terms of latent variables and covariates. This approach produces a Bayesian estimate that has the same statistical optimal properties as a

  14. Structural Equation Modeling towards Online Learning Readiness, Academic Motivations, and Perceived Learning

    ERIC Educational Resources Information Center

    Horzum, Mehmet Baris; Kaymak, Zeliha Demir; Gungoren, Ozlem Canan

    2015-01-01

    The relationship between online learning readiness, academic motivations, and perceived learning was investigated via structural equation modeling in the research. The population of the research consisted of 750 students who studied using the online learning programs of Sakarya University. 420 of the students who volunteered for the research and…

  15. 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…

  16. Level-Specific Evaluation of Model Fit in Multilevel Structural Equation Modeling

    ERIC Educational Resources Information Center

    Ryu, Ehri; West, Stephen G.

    2009-01-01

    In multilevel structural equation modeling, the "standard" approach to evaluating the goodness of model fit has a potential limitation in detecting the lack of fit at the higher level. Level-specific model fit evaluation can address this limitation and is more informative in locating the source of lack of model fit. We proposed level-specific test…

  17. Spiritual Leadership and Organizational Culture: A Study of Structural Equation Modeling

    ERIC Educational Resources Information Center

    Karadag, Engin

    2009-01-01

    The aim of this study is to test the spiritual leadership behaviors of school principles in a structural equation model. The study is designed to test causality with the assumption that causality exists between the two variables. In this study, spiritual leadership behavior of managers is treated as the independent variable whereas the…

  18. Reliability of Summed Item Scores Using Structural Equation Modeling: An Alternative to Coefficient Alpha

    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…

  19. A Confirmatory Structural Equation Model of Achievement Estimated by Dichotomous Attitudes, Interest, and Conceptual Understanding

    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):…

  20. Structural Equation Modeling versus Ordinary Least Squares Canonical Analysis: Some Heuristic Comparisons.

    ERIC Educational Resources Information Center

    Dawson, Thomas E.

    This paper describes structural equation modeling (SEM) in comparison with another overarching analysis within the general linear model (GLM) analytic family: canonical correlation analysis. The uninitiated reader can gain an understanding of SEM's basic tenets and applications. Latent constructs discovered via a measurement model are explored and…

  1. Exploratory Structural Equation Modeling, Integrating CFA and EFA: Application to Students' Evaluations of University Teaching

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Muthen, Bengt; Asparouhov, Tihomir; Ludtke, Oliver; Robitzsch, Alexander; Morin, Alexandre J. S.; Trautwein, Ulrich

    2009-01-01

    This study is a methodological-substantive synergy, demonstrating the power and flexibility of exploratory structural equation modeling (ESEM) methods that integrate confirmatory and exploratory factor analyses (CFA and EFA), as applied to substantively important questions based on multidimentional students' evaluations of university teaching…

  2. Residuals and the Residual-Based Statistic for Testing Goodness of Fit of Structural Equation Models

    ERIC Educational Resources Information Center

    Foldnes, Njal; Foss, Tron; Olsson, Ulf Henning

    2012-01-01

    The residuals obtained from fitting a structural equation model are crucial ingredients in obtaining chi-square goodness-of-fit statistics for the model. The authors present a didactic discussion of the residuals, obtaining a geometrical interpretation by recognizing the residuals as the result of oblique projections. This sheds light on the

  3. 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…

  4. Vocabulary and Grammar Knowledge in Second Language Reading Comprehension: A Structural Equation Modeling Study

    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);…

  5. Cultural, Social, and Economic Capital Constructs in International Assessments: An Evaluation Using Exploratory Structural Equation Modeling

    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…

  6. Meta-Analytic Structural Equation Modeling: A Two-Stage Approach

    ERIC Educational Resources Information Center

    Cheung, Mike W. L.; Chan, Wai

    2005-01-01

    To synthesize studies that use structural equation modeling (SEM), researchers usually use Pearson correlations (univariate r), Fisher z scores (univariate z), or generalized least squares (GLS) to combine the correlation matrices. The pooled correlation matrix is then analyzed by the use of SEM. Questionable inferences may occur for these ad hoc…

  7. Understanding the Impact of Trauma Exposure on Posttraumatic Stress Symptomatology: A Structural Equation Modeling Approach

    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…

  8. 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

  9. Performance and scaling of locally-structured grid methods forpartial differential equations

    SciTech Connect

    Colella, Phillip; Bell, John; Keen, Noel; Ligocki, Terry; Lijewski, Michael; Van Straalen, Brian

    2007-07-19

    In this paper, we discuss some of the issues in obtaining high performance for block-structured adaptive mesh refinement software for partial differential equations. We show examples in which AMR scales to thousands of processors. We also discuss a number of metrics for performance and scalability that can provide a basis for understanding the advantages and disadvantages of this approach.

  10. 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.

  11. 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…

  12. A Structural Equation Model of Burnout and Job Exit among Child Protective Services Workers.

    ERIC Educational Resources Information Center

    Drake, Brett; Yadama, Gautam N.

    1996-01-01

    Uses a structural equation model to examine the three elements of the Maslach Burnout Inventory (MBI)--emotional exhaustion, depersonalization, and personal accomplishment--in relation to job exit among child protective services workers over a 15-month period. The model was supported, showing the relevance of all three MBI elements of job exit.…

  13. Testing Mediation Using Multiple Regression and Structural Equation Modeling Analyses in Secondary Data

    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…

  14. Testing Mediation in Structural Equation Modeling: The Effectiveness of the Test of Joint Significance

    ERIC Educational Resources Information Center

    Leth-Steensen, Craig; Gallitto, Elena

    2016-01-01

    A large number of approaches have been proposed for estimating and testing the significance of indirect effects in mediation models. In this study, four sets of Monte Carlo simulations involving full latent variable structural equation models were run in order to contrast the effectiveness of the currently popular bias-corrected bootstrapping…

  15. Quasi-Maximum Likelihood Estimation of Structural Equation Models with Multiple Interaction and Quadratic Effects

    ERIC Educational Resources Information Center

    Klein, Andreas G.; Muthen, Bengt O.

    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…

  16. 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…

  17. Factors Affecting Higher Order Thinking Skills of Students: A Meta-Analytic Structural Equation Modeling Study

    ERIC Educational Resources Information Center

    Budsankom, Prayoonsri; Sawangboon, Tatsirin; Damrongpanit, Suntorapot; Chuensirimongkol, Jariya

    2015-01-01

    The purpose of the research is to develop and identify the validity of factors affecting higher order thinking skills (HOTS) of students. The thinking skills can be divided into three types: analytical, critical, and creative thinking. This analysis is done by applying the meta-analytic structural equation modeling (MASEM) based on a database of…

  18. Bias and Efficiency in Structural Equation Modeling: Maximum Likelihood versus Robust Methods

    ERIC Educational Resources Information Center

    Zhong, Xiaoling; Yuan, Ke-Hai

    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,…

  19. A Polychoric Instrumental Variable (PIV) Estimator for Structural Equation Models with Categorical Variables

    ERIC Educational Resources Information Center

    Bollen, Kenneth A.; Maydeu-Olivares, Albert

    2007-01-01

    This paper presents a new polychoric instrumental variable (PIV) estimator to use in structural equation models (SEMs) with categorical observed variables. The PIV estimator is a generalization of Bollen's (Psychometrika 61:109-121, 1996) 2SLS/IV estimator for continuous variables to categorical endogenous variables. We derive the PIV estimator…

  20. Teacher's Corner: Structural Equation Modeling with the Sem Package in R

    ERIC Educational Resources Information Center

    Fox, John

    2006-01-01

    R is free, open-source, cooperatively developed software that implements the S statistical programming language and computing environment. The current capabilities of R are extensive, and it is in wide use, especially among statisticians. The sem package provides basic structural equation modeling facilities in R, including the ability to fit…

  1. Psychological Separation, Attachment Security, Vocational Self-Concept Crystallization, and Career Indecision: A Structural Equation Analysis.

    ERIC Educational Resources Information Center

    Tokar, David M.; Withrow, Jason R.; Hall, Rosalie J.; Moradi, Bonnie

    2003-01-01

    Structural equation modeling was used to test theoretically based models in which psychological separation and attachment security variables were related to career indecision and those relations were mediated through vocational self-concept crystallization. Results indicated that some components of separation and attachment security did relate to…

  2. A Polychoric Instrumental Variable (PIV) Estimator for Structural Equation Models with Categorical Variables

    ERIC Educational Resources Information Center

    Bollen, Kenneth A.; Maydeu-Olivares, Albert

    2007-01-01

    This paper presents a new polychoric instrumental variable (PIV) estimator to use in structural equation models (SEMs) with categorical observed variables. The PIV estimator is a generalization of Bollen's (Psychometrika 61:109-121, 1996) 2SLS/IV estimator for continuous variables to categorical endogenous variables. We derive the PIV estimator

  3. Self-Esteem as a Mediator between Perfectionism and Depression: A Structural Equations Analysis.

    ERIC Educational Resources Information Center

    Rice, Kenneth G.; Ashby, Jeffrey S.; Slaney, Robert B.

    1998-01-01

    The association between adaptive and maladaptive dimensions of perfectionism was examined in relation to self-esteem and depression. Confirmatory factor analysis was used to develop and assess the measurement model used. A mediation model was tested with structural equations. Two perfectionism factors were found and outcomes distinguished by path…

  4. 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…

  5. Anti-Transgender Prejudice: A Structural Equation Model of Associated Constructs

    ERIC Educational Resources Information Center

    Tebbe, Esther N.; Moradi, Bonnie

    2012-01-01

    This study aimed to identify theoretically relevant key correlates of anti-transgender prejudice. Specifically, structural equation modeling was used to test the unique relations of anti-lesbian, gay, and bisexual (LGB) prejudice; traditional gender role attitudes; need for closure; and social dominance orientation with anti-transgender prejudice.…

  6. A Program Implementing Mardia's Multivariate Normality Test for Use in Structural Equation Modeling with Latent Variables.

    ERIC Educational Resources Information Center

    MacIntosh, Randall

    1997-01-01

    Presents KANT, a FORTRAN 77 software program that tests assumptions of multivariate normality in a data set. Based on the test developed by M. V. Mardia (1985), the KANT program is useful for those engaged in structural equation modeling with latent variables. (SLD)

  7. Relationships among Adolescents' Leisure Motivation, Leisure Involvement, and Leisure Satisfaction: A Structural Equation Model

    ERIC Educational Resources Information Center

    Chen, Ying-Chieh; Li, Ren-Hau; Chen, Sheng-Hwang

    2013-01-01

    The purpose of this cross-sectional study was to test a cause-and-effect model of factors affecting leisure satisfaction among Taiwanese adolescents. A structural equation model was proposed in which the relationships among leisure motivation, leisure involvement, and leisure satisfaction were explored. The study collected data from 701 adolescent…

  8. Parsimonious Structural Equation Models for Repeated Measures Data, with Application to the Study of Consumer Preferences

    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…

  9. Embedding IRT in Structural Equation Models: A Comparison with Regression Based on IRT Scores

    ERIC Educational Resources Information Center

    Lu, Irene R. R.; Thomas, D. Roland; Zumbo, Bruno D.

    2005-01-01

    This article reviews the problems associated with using item response theory (IRT)-based latent variable scores for analytical modeling, discusses the connection between IRT and structural equation modeling (SEM)-based latent regression modeling for discrete data, and compares regression parameter estimates obtained using predicted IRT scores and…

  10. Using Structural Equation Modeling to Assess Functional Connectivity in the Brain: Power and Sample Size Considerations

    ERIC Educational Resources Information Center

    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…

  11. 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…

  12. Understanding the Impact of Trauma Exposure on Posttraumatic Stress Symptomatology: A Structural Equation Modeling Approach

    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

  13. Exploring Mediating Effect of Metacognitive Awareness on Comprehension of Science Texts through Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Wang, Jing-Ru; Chen, Shin-Feng

    2014-01-01

    This study used a Chinese-language version of the Index of Science Reading Awareness (ISRA) to investigate metacognitive awareness and the Reading Comprehension of Science Test (RCST) to explore comprehension of science text by Taiwanese students. Structural equation modeling (SEM) results confirmed the validity of the underlying models of…

  14. Geometric structures on solutions of equations of 3-dimensional adiabatic gas motion

    NASA Astrophysics Data System (ADS)

    Yumaguzhin, Valeriy

    2014-11-01

    In this paper, we show that characteristic covectors of a system of equations of 3-dimensional adiabatic gas motion generate a geometric structure on every solution of this system. This structure consists of a hyperplane and a non degenerate cone in every cotangent space to a solution. These hyperplane and cone intersect in zero point only. We construct differential invariants of this structure: a vector field, a conformal structure, a Lorentzian metric, and a linear connection. In the case of polytropic gas motion, we calculate classes of explicit solutions possessing the linear connection with zero torsion.

  15. Personality, negative affect coping, and drinking alone: a structural equation modeling approach to examine correlates of adolescent solitary drinking

    PubMed Central

    Creswell, Kasey G.; Chung, Tammy; Wright, Aidan G. C.; Clark, Duncan B.; Black, Jessica J.; Martin, Christopher S.

    2015-01-01

    Aims This study examined the personality traits of negative emotionality and constraint and the ability to resist drinking during negative affective states as correlates of solitary drinking in adolescence. We hypothesized that higher levels of negative emotionality and lower levels of constraint would predict solitary drinking and that these relationships would be mediated by the ability to resist drinking in response to negative emotions. Design Structural equation modeling was used to fit a path model from the personality traits of negative emotionality and constraint to solitary drinking status through intermediate effects on the ability to resist drinking during negative emotions using cross-sectional data. Setting Clinical and community settings in Pennsylvania, USA. Participants The sample included 761 adolescent drinkers (mean age = 17.1). Measurements Adolescents completed the Lifetime Drinking History, the Multidimensional Personality Questionnaire, the Constructive Thinking Inventory and the Situational Confidence Questionnaire. Findings The path model provided a good fit to the data. The association between trait negative emotionality and solitary drinking was fully mediated by adolescents' ability to resist drinking during negative affective states (b = 0.05, P = 0.01). In contrast, constraint had a direct effect on solitary drinking (odds ratio (OR) = 0.79, b = –0.23, P<0.01), as well as an indirect effect through the ability to resist drinking during negative affective states (b = –0.03, P = 0.02). Conclusions The ability to resist drinking while experiencing negative feelings or emotions may be an important underlying mechanism linking trait negative emotionality (a tendency toward depression, anxiety and poor reaction to stress) and constraint (lack of impulsiveness) to adolescent solitary drinking. PMID:25664806

  16. Association between social capital, health-related quality of life, and mental health: a structural-equation modeling approach

    PubMed Central

    Hassanzadeh, Jafar; Asadi-Lari, Mohsen; Baghbanian, Abdolvahab; Ghaem, Haleh; Kassani, Aziz; Rezaianzadeh, Abbas

    2016-01-01

    Aim To explore the association(s) between demographic factors, socioeconomic status (SES), social capital, health-related quality of life (HRQoL), and mental health among residents of Tehran, Iran. Methods The pooled data (n = 31 519) were extracted from a population-based survey Urban Health Equity Assessment and Response Tool-2 (Urban HEART-2) conducted in Tehran in 2011. Mental health, social capital, and HRQoL were assessed using the 28-item General Health Questionnaire (GHQ-28), social capital questionnaire, and Short-Form Health Survey (SF-12), respectively. The study used a multistage sampling method. Social capital, HRQoL, and SES were considered as latent variables. The association between these latent variables, demographic factors, and mental health was determined by structural-equation modeling (SEM). Results The mean age and mental health score were 44.48 ± 15.87 years and 23.33 ± 11.10 (range, 0-84), respectively. The prevalence of mental disorders was 41.76% (95% confidence interval 41.21-42.30). The SEM model showed that age was directly associated with social capital (P = 0.016) and mental health (P = 0.001). Sex was indirectly related to mental health through social capital (P = 0.018). SES, HRQoL, and social capital were associated both directly and indirectly with mental health status. Conclusion This study suggests that changes in social capital and SES can lead to positive changes in mental health status and that individual and contextual determinants influence HRQoL and mental health. PMID:26935615

  17. The relativistic equations of stellar structure and evolution. Stars with degenerate neutron cores. 1: Structure of equilibrium models

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.; Zytkow, A. N.

    1976-01-01

    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. Finally, it is argued that in previous work on spherical systems general relativity theorists have identified the wrong quantity as "total mass-energy inside radius r."

  18. Online Social Presence: Score Validity of the Computer-Mediated Communication Questionnaire

    ERIC Educational Resources Information Center

    Yen, Cherng-Jyh

    2008-01-01

    The purpose of this study was to conduct a confirmatory factor analysis of the Computer-Mediated Communication Questionnaire scores, using structural equation modeling, to assess the consistency between the empirical data and the hypothesized factor structure of the CMCQ in the proposed models, which is stipulated by the theoretical framework and

  19. Online Social Presence: Score Validity of the Computer-Mediated Communication Questionnaire

    ERIC Educational Resources Information Center

    Yen, Cherng-Jyh

    2008-01-01

    The purpose of this study was to conduct a confirmatory factor analysis of the Computer-Mediated Communication Questionnaire scores, using structural equation modeling, to assess the consistency between the empirical data and the hypothesized factor structure of the CMCQ in the proposed models, which is stipulated by the theoretical framework and…

  20. Egyptian mothers’ preferences regarding how physicians break bad news about their child’s disability: A structured verbal questionnaire

    PubMed Central

    2012-01-01

    Background Breaking bad news to mothers whose children has disability is an important role of physicians. There has been considerable speculation about the inevitability of parental dissatisfaction with how they are informed of their child’s disability. Egyptian mothers’ preferences for how to be told the bad news about their child’s disability has not been investigated adequately. The objective of this study was to elicit Egyptian mothers’ preferences for how to be told the bad news about their child’s disability. Methods Mothers of 100 infants recently diagnosed with Down syndrome were interviewed regarding their preferences for how to be told bad news. Mothers were recruited through outpatient clinics of the Pediatric Genetics Department at Fayoum University Hospital (located 90 km southwest of Cairo, Egypt) from January to June 2011. Results and discussion Questionnaire analyses revealed nine themes of parental preferences for how to be told information difficult to hear. Mothers affirmed previously reported recommendations for conveying bad medical news to parents, including being told early, being told of others with a similar condition, and being informed of the prognosis. Conclusions Mothers affirmed communication themes previously discussed in the literature, such as being told early, and being informed of the prognosis. Although more research is needed in this important area, we hope that our findings will stimulate future search and help health care providers in different societies establish guidelines for effectively communicating bad news. PMID:22747832

  1. Families of solutions to the generalized Ginzburg-Landau equation and structural transitions between them

    SciTech Connect

    Ovchinnikov, Yu. N.

    2013-09-15

    Solutions to the generalized Ginzburg-Landau equations for superconductors are obtained for a Ginzburg-Landau parameter {kappa} close to unity. The families of solutions with arbitrary number n of flux quanta in a unit cell are analyzed. It is shown that under certain conditions, a cascade of phase transitions between different structures in a magnetic field appears near T{sub c}. Algebraic equations are derived for determining the boundaries of coexistence of different phases on the (T, H{sub 0}) plane.

  2. Quantization of wave equations and hermitian structures in partial differential varieties.

    PubMed

    Paneitz, S M; Segal, I E

    1980-12-01

    Sufficiently close to 0, the solution variety of a nonlinear relativistic wave equation-e.g., of the form squarevarphi + m(2)varphi + gvarphi(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

  3. The Survey Questionnaire

    ERIC Educational Resources Information Center

    Ritter, Lois A. Ed.; Sue, Valerie M., Ed.

    2007-01-01

    Internet-based surveys are still relatively new, and researchers are just beginning to articulate best practices for questionnaire design. Online questionnaire design has generally been guided by the principles applying to other self-administered instruments, such as paper-based questionnaires. Web-based questionnaires, however, have the potential…

  4. Self-assembly of nanocomponents into composite structures: Derivation and simulation of Langevin equations

    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.

  5. Investigating the Relationships among Stressors, Stress Level, and Mental Symptoms for Infertile Patients: A Structural Equation Modeling Approach

    PubMed Central

    Wang, Jong-Yi; Liang, Wen-Miin; Yang, Tung-Chuan; Lee, Young-Chang; Wang, Chia-Woei

    2015-01-01

    Objective Patients with infertility are a high risk group in depression and anxiety. However, an existing theoretically and empirically validated model of stressors, stress, and mental symptoms specific for infertile patients is still a void. This study aimed to determine the related factors and their relational structures that affect the level of depressive and anxiety symptoms among infertile patients. Methods A cross-sectional sample of 400 infertility outpatients seeking reproduction treatments in three teaching hospitals across Taiwan participated in the structured questionnaire survey in 2011. The hypothesized model comprising 10 latent variables was tested by Structural Equation Modeling using AMOS 17. Results Goodness-of-fit indexes, including χ2/DF = 1.871, PGFI = 0.746, PNFI = 0.764, and others, confirmed the modified model fit the data well. Marital stressor, importance of children, guilt-and-blame, and social stressor showed a direct effect on perceived stress. Instead of being a factor of stress, social support was directly and positively related to self-esteem. Perceived stress and self-esteem were the two major mediators for the relationships between stressors and mental symptoms. Increase in social support and self-esteem led to decrease in mental symptoms among the infertile patients. Conclusions The relational structures were identified and named as the Stressors Stress Symptoms Model, clinically applied to predict anxiety and depression from various stressors. Assessing sources and level of infertility-related stress and implementing culturally-sensitive counseling with an emphasis on positive personal value may assist in preventing the severity of depression and anxiety. PMID:26484531

  6. General features and master equations for structurization in complex dusty plasmas

    SciTech Connect

    Tsytovich, V. N.; Morfill, G. E.

    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.

  7. 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.

  8. Maximum pulsar mass, equation of state and structure of neutron-star cores

    NASA Astrophysics Data System (ADS)

    Haensel, P.; Zdunik, J. L.

    2016-01-01

    The structure of neutron stars is determined by the equation of state of dense matter in their interiors. Brief review of the equation of state from neutron star surface to its center is presented. Recent discovery of two two-solar-mass pulsars puts interesting constraints on the poorly known equation of state of neutron-star cores for densities greater than normal nuclear matter density. Namely, this equation of state has to be stiff enough to yield maximum allowable mass of neutron stars greater than two solar masses. There are many models of neutron stars cores involving exclusively nucleons that satisfy this constraint. However, for neutron-star models based on recent realistic baryon interaction, and allowing for the presence of hyperons, the hyperon softening of the equation of state yields maximum masses significantly lower than two solar masses. Proposed ways out from this ”hyperon puzzle” are presented. They require a very fine tuning of parameters of dense hadronic matter and quark matter models. Consequences for the mass-radius relation for neutron stars are illustrated. A summary of the present situation and possible perspectives/challenges, as well as possible observational tests, are given.

  9. THE PRENATAL PARENTAL REFLECTIVE FUNCTIONING QUESTIONNAIRE: EXPLORING FACTOR STRUCTURE AND CONSTRUCT VALIDITY OF A NEW MEASURE IN THE FINN BRAIN BIRTH COHORT PILOT STUDY.

    PubMed

    Pajulo, Marjukka; Tolvanen, Mimmi; Karlsson, Linnea; Halme-Chowdhury, Elina; Öst, Camilla; Luyten, Patrick; Mayes, Linda; Karlsson, Hasse

    2015-01-01

    Parental reflective functioning (PRF) is the capacity to focus on experience and feelings in oneself and in the child. Individual differences in PRF reportedly affect child attachment and socioemotional development. In this study, we report work on developing a questionnaire to assess PRF during pregnancy (Prenatal Parental Reflective Functioning Questionnaire; P-PRFQ). The factor structure of the 33-item version of the P-PRFQ was explored using pilot study data from the Finn Brain Birth Cohort Study (n = 124 mothers, n = 82 fathers). Construct validity was assessed against the Pregnancy Interview (PI; A. Slade, L. Grunebaum, L. Huganir, & M. Reeves, 1987, 2002, 2011) in a subsample of 29 mothers from the same pilot sample. Exploratory and confirmatory factor analysis resulted in a 14-item P-PRFQ, with three factors which seem to capture relevant aspects of prenatal parental mentalization-F1: "Opacity of mental states," F2: "Reflecting on the fetus-child," and F3: "The dynamic nature of the mental states." Functioning of the factor structure was further tested in the large cohort with 600 mothers and 600 fathers. Correlations with the PI result were high, both regarding total and factor scores of the P-PRFQ. Cost-effective tools to assess key areas of early parenting are needed for both research and clinical purposes. The 14-item P-PRFQ seems to be an applicable and promising new tool for assessing very early parental mentalizing capacity. PMID:26096692

  10. Dromion-like structures and stability analysis in the variable coefficients complex Ginzburg–Landau equation

    SciTech Connect

    Wong, Pring; Pang, Li-Hui; Huang, Long-Gang; Li, Yan-Qing; Lei, Ming; Liu, Wen-Jun

    2015-09-15

    The study of the complex Ginzburg–Landau equation, which can describe the fiber laser system, is of significance for ultra-fast laser. In this paper, dromion-like structures for the complex Ginzburg–Landau equation are considered due to their abundant nonlinear dynamics. Via the modified Hirota method and simplified assumption, the analytic dromion-like solution is obtained. The partial asymmetry of structure is particularly discussed, which arises from asymmetry of nonlinear and dispersion terms. Furthermore, the stability of dromion-like structures is analyzed. Oscillation structure emerges to exhibit strong interference when the dispersion loss is perturbed. Through the appropriate modulation of modified exponent parameter, the oscillation structure is transformed into two dromion-like structures. It indicates that the dromion-like structure is unstable, and the coherence intensity is affected by the modified exponent parameter. Results in this paper may be useful in accounting for some nonlinear phenomena in fiber laser systems, and understanding the essential role of modified Hirota method.

  11. Confirming the Structure of the "Why Do You Smoke?" Questionnaire: A Community Resource for Adolescent Tobacco Cessation

    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…

  12. Confirming the Structure of the "Why Do You Smoke?" Questionnaire: A Community Resource for Adolescent Tobacco Cessation

    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

  13. Prospective memory in healthy Chinese people: the latent structure of the Comprehensive Assessment of Prospective Memory Questionnaire.

    PubMed

    Chan, Raymond C K; Qing, Yonghong; Wu, Qiuping; Shum, David

    2010-06-01

    This study aimed to examine the latent structure of the Chinese version of the Comprehensive Assessment of Prospective Memory (CAPM) using confirmatory factor analysis. A total of 264 healthy Chinese participants (118 men and 146 women) took part in the study and their ages ranged from 17 to 90 years. There was no gender effect upon the frequency of prospective memory (PM) forgetting but age and education were found to be correlated significantly with these frequencies in the current sample. Results of the study also showed that the model with the best fit had a tripartite structure which consisted of a general memory factor (with all items loading on it) plus a basic activities of daily living as well as an instrumental activities of daily living factor. Furthermore, this tripartite model was robust across subgroups with respect to gender, education, and age. These findings provide support for the construct validity of the original CAPM and demonstrate its utility in another culture. PMID:20155572

  14. 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.

  15. Elliptical vortex solutions, integrable Ermakov structure, and Lax pair formulation of the compressible Euler equations.

    PubMed

    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

  16. Quantum structure emerging from the transformation design of the Dirac equation

    SciTech Connect

    Lin, De-Hone

    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.

  17. Hamiltonian structures of nonlinear evolution equations connected with a polynomial pencil

    SciTech Connect

    Gadzhiev, I.T.; Gerdzhikov, V.S.; Ivanov, M.I.

    1986-09-10

    For a generalized Zakharov-Shabat system in which the matrix potential is a polynomial in the spectral parameter a generating operator is constructed which makes it possible to compactly write out the nonlinear evolution equations (NEE) connected with the system. The eigenfunctions of the generating operator - the squares of solutions of the original system - are found. The Hamiltonian property of the NEE and the existence of a hierarchy of Hamiltonian structures are established.

  18. Hamiltonian structures of nonlinear evolution equations associated with a polynomial bundle

    SciTech Connect

    Gadzhiev, I.T.; Gerdzhikov, V.S.; Ivanov, M.I.

    1987-05-20

    For the generalized Zakharov-Shabat system with the matrix potential a polynomial in the spectral parameter, they construct a generating operator which leads to a compact representation of the nonlinear evolution equations (NEE) associated with the system. The eigenfunctions of the generating operator are obtained as the squares of the solutions of the original system. The Hamiltonian nature of the NEE and the existence of a hierarchy of Hamiltonian structures is established.

  19. Hamiltonian structures of nonlinear evolution equations connected with a polynomial pencil

    SciTech Connect

    Gadzhiev, I.T.; Gerdzhikov, V.S.; Ivanov, M.I.

    1986-09-01

    For a generalized Zakharov-Shabat system in which the matrix potential is a polynomial in the spectral parameter a generating operator is constructed which makes it possible to compactly write out the nonlinear evolution equations (NEE) connected with the system. The eigenfunctions of the generating operator - the ''squares'' of solutions of the original system - are found. The Hamiltonian property of the NEE and the existence of a hierachy of Hamiltonian structures are established.

  20. Study of the shock wave structure by regularized Grad's set of equations

    NASA Astrophysics Data System (ADS)

    Timokhin, M. Yu.; Bondar, Ye. A.; Kokhanchik, A. A.; Ivanov, M. S.; Ivanov, I. E.; Kryukov, I. A.

    2015-03-01

    In this work, we continue to study the possibility of applying moment equations for strongly nonequilibrium flows by an example of the problem of the shock wave structure in a monatomic gas in a wide range of Mach numbers for various models of molecular interaction. The object of the study is the so-called regularized 13-moment Grad's system (R13). First time, both linear and nonlinear versions of this system of equations were considered for the problem at such wide range of parameters. The Godunov method with increased accuracy is used as a numerical tool for solving the R13 system. The numerical results for the R13 system are analyzed by using data obtained by the Direct Simulation Monte Carlo (DSMC) method, experimental data, and analytical results. As a whole, the R13 system provides an adequate description of the shock wave structure in a wide range of Mach numbers. For Mach numbers around 2, good agreement with experimental and DSMC results is observed for both linear and nonlinear versions of the system. For high Mach numbers, the result strongly depends on the molecular interaction model used: shock wave structure predictions of the nonlinear R13 system are better for Maxwell molecules and worse for hard spheres as compared to the linear version. Particular attention in this work is paid to studying nonmonotonicity of the total temperature profile (temperature overshoot) in the structure of a strong shock wave. It is shown that the moment equations correctly predict the existence of the temperature overshoot. At the same time, the solution of the moment equations overpredicts the temperature overshoot at least two-fold for Mach number M = 8, and the nonlinear version of the R13 system yields a better result for this parameter than the linear version.

  1. How Structure Sense for Algebraic Expressions or Equations Is Related to Structure Sense for Abstract Algebra

    ERIC Educational Resources Information Center

    Novotna, Jarmila; Hoch, Maureen

    2008-01-01

    Many students have difficulties with basic algebraic concepts at high school and at university. In this paper two levels of algebraic structure sense are defined: for high school algebra and for university algebra. We suggest that high school algebra structure sense components are sub-components of some university algebra structure sense…

  2. Nonlinear Dynamics of Layered Structures and the Generalized Sine-Lattice Equations

    NASA Astrophysics Data System (ADS)

    Soboleva, Tatyana; Zeltser, Alexander; Kivshar, Yuri; Turitsyn, Sergei

    1995-07-01

    We analyze nonlinear waves in layered (anisotropic) structures with strong interlayer interaction. One of the important physical examples of nonlinear modes in such structures is the so-called supersolitons, localized excitations of the density of a vortex lattice propagating in a system of interacting (parallel) long Josephson junctions. We show that the dynamics of these structures may be described by the so-called sine-lattice (SL) equation first introduced by S. Takeno and S. Homma [J. Phys. Soc. Jpn. 55 (1986) 65] and its various generalizations, e.g. those which include a transverse degree of freedom or more general types of the interlayer (nonlinear) interactions described by periodic Jacobi elliptic functions. We analyze nonlinear localized waves in such generalized SL equations analytically and numerically, and show that, in general, density waves may be of three types, namely kinks, dynamical solitons, and envelope solitons. We investigate also the transverse stability of quasi-one-dimensional solitons in the framework of the effective modified Boussinesq equation valid for both small amplitudes and continuous approximation, as well as investigate numerically the effects of perturbations (dissipation or point-like impurities) on the dynamics of π -kinks.

  3. Quantization of wave equations and hermitian structures in partial differential varieties

    PubMed Central

    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 □ϕ + m2ϕ + gϕp = 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

  4. Anomalous wave structure in magnetized materials described by non-convex equations of state

    SciTech Connect

    Serna, Susana; Marquina, Antonio

    2014-01-15

    We analyze the anomalous wave structure appearing in flow dynamics under the influence of magnetic field in materials described by non-ideal equations of state. We consider the system of magnetohydrodynamics equations closed by a general equation of state (EOS) and propose a complete spectral decomposition of the fluxes that allows us to derive an expression of the nonlinearity factor as the mathematical tool to determine the nature of the wave phenomena. We prove that the possible formation of non-classical wave structure is determined by both the thermodynamic properties of the material and the magnetic field as well as its possible rotation. We demonstrate that phase transitions induced by material properties do not necessarily imply the loss of genuine nonlinearity of the wavefields as is the case in classical hydrodynamics. The analytical expression of the nonlinearity factor allows us to determine the specific amount of magnetic field necessary to prevent formation of complex structure induced by phase transition in the material. We illustrate our analytical approach by considering two non-convex EOS that exhibit phase transitions and anomalous behavior in the evolution. We present numerical experiments validating the analysis performed through a set of one-dimensional Riemann problems. In the examples we show how to determine the appropriate amount of magnetic field in the initial conditions of the Riemann problem to transform a thermodynamic composite wave into a simple nonlinear wave.

  5. Analysis of frequency band structure in one-dimensional sonic crystal using Webster horn equation

    NASA Astrophysics Data System (ADS)

    Gupta, A.; Lim, K. M.; Chew, C. H.

    2011-05-01

    Sound propagation through periodic arrangement of scatterers lead to formation of bands of frequencies, known as band gaps, where sound cannot propagate though the structure. We propose a method based on Webster horn equation, along with Floquet theorem, to predict the band gap of a one-dimensional periodic structure made of hard sound-scatterers. The method is further modified to obtain the complex wave numbers, which give the decay constants. The decay constant is used to predict the sound attenuation of the evanescent wave in the finite sonic crystal. The theoretical prediction is verified with experimental measurements.

  6. Emotional dysregulation, internalizing symptoms, and self-injurious and suicidal behavior: Structural equation modeling analysis.

    PubMed

    Kranzler, Amy; Fehling, Kara B; Anestis, Michael D; Selby, Edward A

    2016-07-01

    This study used structural equation modeling to examine the relationships between emotion dysregulation, internalizing symptoms, nonsuicidal self-injury (NSSI), and suicide. One hundred forty-eight undergraduates completed a brief structured interview and self-report measures of emotion dysregulation, internalizing symptoms, and NSSI and suicidal behaviors. Results indicated a significant indirect effect of emotion dysregulation on NSSI via internalizing symptoms and on suicide attempts via NSSI. Findings provide a more nuanced understanding of the indirect association between emotion dysregulation and NSSI and suicidal behaviors. Implications for the potential utility of targeting internalizing symptoms as well as emotion dysregulation in interventions addressing NSSI and suicidal behaviors are discussed. PMID:26808092

  7. Numerical solution of the vertical structure equation in the normal mode method. [in meteorology

    NASA Technical Reports Server (NTRS)

    Sasaki, Y. K.; Chang, L. P.

    1985-01-01

    In the present model of multilayered stability stratification, aimed at obtaining the analytic eigensolutions of the vertical structure equation, each layer is characterized by its own static stability value. By requiring continuity of pressure and vertical velocity across each interface level, and by imposing suitable upper and lower boundary conditions, matching eigensolutions are obtained in terms of the Bessel functions. Attention is given to an explicit example of a double-layered stratified atmosphere which demonstrates the mathematical manipulations involved; the resultant vertical structure functions are used to check the accuracy of the numerical solutions by the finite difference and finite element methods.

  8. An ultra-short screening version of the Recalled Parental Rearing Behavior questionnaire (FEE-US) and its factor structure in a representative German sample

    PubMed Central

    2012-01-01

    Background The Recalled Parental Rearing Behavior questionnaire (FEE, [1,2]) assesses perceived parental rearing behavior separately for each parent. An ultra-short screening version (FEE-US) with the same three scales each for the mother and the father is reported and factor-analytically validated. Methods N = 4,640 subjects aged 14 to 92 (M = 48.4 years) were selected by the random-route sampling method. The ultra-short questionnaire version was derived from the long version through item and factor analyses. In a confirmatory factor analysis framework, the hypothesized three-factorial structure was fitted to the empirical data and tested for measurement invariance, differential item functioning, item discriminability, and convergent and discriminant factorial validity. Effects of gender or age were assessed using MANOVAs. Results The a-priori hypothesized model resulted in mostly adequate overall fit. Neither gender nor age group yielded considerable effects on the factor structure, but had small effects on means of raw score sums. Factorial validities could be confirmed. Scale sums are well-suited to rank respondents along the respective latent dimension. Conclusion The structure of the long version with the factors Rejection & Punishment, Emotional Warmth, and Control & Overprotection could be replicated for both father and mother items in the ultra-short screening version using confirmatory factor analyses. These results indicate that the ultra-short screening version is a time-saving and promising screening instrument for research settings and in individual counseling. However, the shortened scales do not necessarily represent the full spectrum covered by the full-scale dimensions. PMID:23134704

  9. Kinematic assumptions and their consequences on the structure of field equations in continuum dislocation theory

    NASA Astrophysics Data System (ADS)

    Silbermann, C. B.; Ihlemann, J.

    2016-03-01

    Continuum Dislocation Theory (CDT) relates gradients of plastic deformation in crystals with the presence of geometrically necessary dislocations. Therefore, the dislocation tensor is introduced as an additional thermodynamic state variable which reflects tensorial properties of dislocation ensembles. Moreover, the CDT captures both the strain energy from the macroscopic deformation of the crystal and the elastic energy of the dislocation network, as well as the dissipation of energy due to dislocation motion. The present contribution deals with the geometrically linear CDT. More precise, the focus is on the role of dislocation kinematics for single and multi-slip and its consequences on the field equations. Thereby, the number of active slip systems plays a crucial role since it restricts the degrees of freedom of plastic deformation. Special attention is put on the definition of proper, well-defined invariants of the dislocation tensor in order to avoid any spurious dependence of the resulting field equations on the coordinate system. It is shown how a slip system based approach can be in accordance with the tensor nature of the involved quantities. At first, only dislocation glide in one active slip system of the crystal is allowed. Then, the special case of two orthogonal (interacting) slip systems is considered and the governing field equations are presented. In addition, the structure and symmetry of the backstress tensor is investigated from the viewpoint of thermodynamical consistency. The results will again be used in order to facilitate the set of field equations and to prepare for a robust numerical implementation.

  10. Postpartum Depressive Symptoms Across Time and Place: Structural Invariance of the Self-Reporting Questionnaire Among Women from the International, Multi-Site MAL-ED Study

    PubMed Central

    Pendergast, Laura L.; Scharf, Rebecca J.; Rasmussen, Zeba A.; Seidman, Jessica C.; Schaefer, Barbara A.; Svensen, Erling; Tofail, Fahmida; Koshy, Beena; Kosek, Margaret; Rasheed, Muneera A.; Roshan, Reeba; Maphula, Angelina; Shrestha, Rita; Murray-Kolb, Laura E.

    2014-01-01

    Background The Self-Reporting Questionnaire (SRQ) is a screening instrument that has been shown to be an effective measure of depression in postpartum women and is widely used in developing nations. Methods The SRQ was administered to 2,028 mothers from eight nations at two time points: one and six months postpartum. All data were obtained from the Interactions of Malnutrition and Enteric Infections: Consequences for Child Health and Development (MAL-ED) study. The sample included women from MAL-ED sites in Bangladesh, Brazil, India, Nepal, Pakistan, Peru, South Africa, and Tanzania. This study examined three aspects of validity of SRQ scores including (a) structural validity, (b) cross-cultural invariance, and (c) invariance over time. Results A 16-item, one-factor structure with items reflecting somatic symptoms removed was deemed to be superior to the original structure in this postpartum population. Although differential item functioning (DIF) across sites was evident, the one-factor model was a good fit to the data from seven sites, and the structure was invariant across the one- and six-month time points. Limitations Findings are based on data from self-report scales. No information about the clinical status of the participants was available. Conclusions Overall, findings support the validity of a modified model of the SRQ among postpartum women. Somatic symptoms (e.g., headaches, not sleeping well) may not reflect internalizing problems in a postpartum population. Implications for researchers and practitioners are discussed. PMID:24981251

  11. Energy transfer in structured and unstructured environments: Master equations beyond the Born-Markov approximations.

    PubMed

    Iles-Smith, Jake; Dijkstra, Arend G; Lambert, Neill; Nazir, Ahsan

    2016-01-28

    We explore excitonic energy transfer dynamics in a molecular dimer system coupled to both structured and unstructured oscillator environments. By extending the reaction coordinate master equation technique developed by Iles-Smith et al. [Phys. Rev. A 90, 032114 (2014)], we go beyond the commonly used Born-Markov approximations to incorporate system-environment correlations and the resultant non-Markovian dynamical effects. We obtain energy transfer dynamics for both underdamped and overdamped oscillator environments that are in perfect agreement with the numerical hierarchical equations of motion over a wide range of parameters. Furthermore, we show that the Zusman equations, which may be obtained in a semiclassical limit of the reaction coordinate model, are often incapable of describing the correct dynamical behaviour. This demonstrates the necessity of properly accounting for quantum correlations generated between the system and its environment when the Born-Markov approximations no longer hold. Finally, we apply the reaction coordinate formalism to the case of a structured environment comprising of both underdamped (i.e., sharply peaked) and overdamped (broad) components simultaneously. We find that though an enhancement of the dimer energy transfer rate can be obtained when compared to an unstructured environment, its magnitude is rather sensitive to both the dimer-peak resonance conditions and the relative strengths of the underdamped and overdamped contributions. PMID:26827205

  12. Energy transfer in structured and unstructured environments: Master equations beyond the Born-Markov approximations

    NASA Astrophysics Data System (ADS)

    Iles-Smith, Jake; Dijkstra, Arend G.; Lambert, Neill; Nazir, Ahsan

    2016-01-01

    We explore excitonic energy transfer dynamics in a molecular dimer system coupled to both structured and unstructured oscillator environments. By extending the reaction coordinate master equation technique developed by Iles-Smith et al. [Phys. Rev. A 90, 032114 (2014)], we go beyond the commonly used Born-Markov approximations to incorporate system-environment correlations and the resultant non-Markovian dynamical effects. We obtain energy transfer dynamics for both underdamped and overdamped oscillator environments that are in perfect agreement with the numerical hierarchical equations of motion over a wide range of parameters. Furthermore, we show that the Zusman equations, which may be obtained in a semiclassical limit of the reaction coordinate model, are often incapable of describing the correct dynamical behaviour. This demonstrates the necessity of properly accounting for quantum correlations generated between the system and its environment when the Born-Markov approximations no longer hold. Finally, we apply the reaction coordinate formalism to the case of a structured environment comprising of both underdamped (i.e., sharply peaked) and overdamped (broad) components simultaneously. We find that though an enhancement of the dimer energy transfer rate can be obtained when compared to an unstructured environment, its magnitude is rather sensitive to both the dimer-peak resonance conditions and the relative strengths of the underdamped and overdamped contributions.

  13. Cross-cultural adaptation of the VISA-A questionnaire, an index of clinical severity for patients with Achilles tendinopathy, with reliability, validity and structure evaluations

    PubMed Central

    Silbernagel, Karin Grävare; Thomeé, Roland; Karlsson, Jon

    2005-01-01

    Background Achilles tendinopathy is considered to be one of the most common overuse injuries in elite and recreational athletes and the recommended treatment varies. One factor that has been stressed in the literature is the lack of standardized outcome measures that can be used in all countries. One such standardized outcome measure is the Victorian Institute of Sports Assessment – Achilles (VISA-A) questionnaire, which is designed to evaluate the clinical severity for patients with Achilles tendinopathy. The purpose of this study was to cross-culturally adapt the VISA-A questionnaire to Swedish, and to perform reliability, validity and structure evaluations. Methods Cross-cultural adaptation was performed in several steps including translations, synthesis of translations, back translations, expert committee review and pre-testing. The final Swedish version, the VISA-A Swedish version (VISA-A-S) was tested for reliability on healthy individuals (n = 15), and patients (n = 22). Tests for internal consistency, validity and structure were performed on 51 patients. Results The VISA-A-S had good reliability for patients (r = 0.89, ICC = 0.89) and healthy individuals (r = 0.89–0.99, ICC = 0.88–0.99). The internal consistency was 0.77 (Cronbach's alpha). The mean [95% confidence interval] VISA-A-S score in the 51 patients (50 [44–56]) was significantly lower than in the healthy individuals (96 [94–99]). The VISA-A-S score correlated significantly (Spearman's r = -0.68) with another tendon grading system. Criterion validity was considered good when comparing the scores of the Swedish version with the English version in both healthy individuals and patients. The factor analysis gave the factors pain/symptoms and physical activity Conclusion The VISA-A-S questionnaire is a reliable and valid instrument and comparable to the original version. It measures two factors: pain/symptoms and physical activity, and can be used in both research and the clinical setting. PMID:15748297

  14. Structure and decay constant of the {rho} meson within the Bethe-Salpeter equation

    SciTech Connect

    Wang, Z. G.; Wan, S. L.

    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.

  15. Relationship between Temperament, Depression, Anxiety, and Hopelessness in Adolescents: A Structural Equation Model.

    PubMed

    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

  16. Relationship between Temperament, Depression, Anxiety, and Hopelessness in Adolescents: A Structural Equation Model

    PubMed Central

    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

  17. Factor Structure and Construct Validity of the Eating Disorder Examination-Questionnaire in College Students: Further Support for a Modified Brief Version

    PubMed Central

    Grilo, Carlos M.; Reas, Deborah L.; Hopwood, Christopher J.; Crosby, Ross D.

    2014-01-01

    Objective The Eating Disorder Examination-Questionnaire (EDE-Q) is widely used in research studies across clinical and non-clinical groups. Relatively little is known about psychometric properties of this measure and the available literature has not supported the proposed scale structure. The current study evaluated the factor structure and construct validity of the EDE-Q in a non-clinical study group of young adults. Method Participants were 801 young adults (573 females, 228 males) enrolled at a large public university in the Midwestern United States who completed the EDE-Q and a battery of behavioral and psychological measures. Results Confirmatory factor analysis (CFA) revealed an inadequate fit for the original EDE-Q structure but revealed a good fit for an alternative structure suggested by recent research with predominately overweight/obese samples. CFA supported a modified 7-item, 3-factor structure; the three factors were interpreted as dietary restraint, shape/weight overvaluation, and body dissatisfaction. Factor loadings and item intercepts were invariant across sex and overweight status. The three factors had less redundancy than the original EDE-Q scales and demonstrated improved convergent and discriminant validity in relation to relevant other measures. Discussion These factor-analytic findings, which replicate findings from studies with diverse predominately overweight/obese samples, supported a modified 7-item, 3-factor structure for the EDE-Q with improved psychometric characteristics. The findings provide further empirical support for the distinction between body dissatisfaction and overvaluation and have implications for assessment and research. These findings need to be replicated in samples of persons with eating-disorder psychopathology including those with anorexia nervosa, bulimia nervosa, and allied states. PMID:25346071

  18. Psychosocial Problems Among Truant Youth: A Multi-Group, Exploratory Structural Equation Modeling Analysis

    PubMed Central

    Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C.; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven

    2012-01-01

    Truant youth represent a critical group needing problem-oriented research and involvement in effective services. The limited number of studies on the psychosocial functioning of truant youths have focused on one or a few problem areas, rather than examining co-morbid problem behaviors. The present study addresses the need to examine the interrelationships of multiple domains of psychosocial functioning, including substance involvement, mental health, and delinquency, among truant youth. Exploratory structural equation modeling on baseline data collected on 219 truant youths identified two major factors reflecting psychosocial functioning, and found the factor structure was similar across major sociodemographic subgroups. Further analyses supported the validity of the factor structure. The research and service delivery implications of the findings are discussed. PMID:23243383

  19. Impact of empowerment on professional practice environments and organizational commitment among nurses: a structural equation approach.

    PubMed

    Yang, Jinhua; Liu, Yanhui; Huang, Chunping; Zhu, Lefeng

    2013-02-01

    A higher turnover rate was identified in Chinese staff nurses and it was highly correlated with lower commitment. Empowering work environments that support professional practice have been positively related to nurse outcomes. This study was to integrate structural empowerment theory with magnet hospital characteristics and provide empirical evidence on the relationships between structural empowerment, professional practice environments and organizational commitment. A cross-sectional design was used to examine the relationships in a sample of 750 full-time nurses employed in five Chinese hospitals in 2011. Structural equation modeling was used to test the proposed hypotheses. The results support the hypothesized model. Professional practice environments partially mediated the relationship between empowerment and organizational commitment. Our findings suggest that higher empowerment facilitates the professional practice environments and commitment of these nurses. PMID:23425379

  20. Testing the Factor Structure and Measurement Invariance Across Gender of the Big Five Inventory Through Exploratory Structural Equation Modeling.

    PubMed

    Chiorri, Carlo; Marsh, Herbert W; Ubbiali, Alessandro; Donati, Deborah

    2016-01-01

    Confirmatory factor analyses (CFAs) typically fail to support the a priori 5-factor structure of Big Five self-report instruments, due in part to the overly restrictive CFA assumptions. We show that exploratory structural equation modeling (ESEM), an integration of CFA and exploratory factor analysis, overcomes these problems in relation to responses to the 44-item Big Five Inventory (BFI) administered to a large Italian community sample. ESEM fitted the data better and resulted in less correlated factors than CFA, although ESEM and CFA factor scores correlated at near unity with observed raw scores. Tests of gender invariance with a 13-model taxonomy of full measurement invariance showed that the factor structure of the BFI is gender-invariant and that women score higher on Neuroticism, Agreeableness, Extraversion, and Conscientiousness. Through ESEM one could address substantively important issues about BFI psychometric properties that could not be appropriately addressed through traditional approaches. PMID:25932664

  1. A ballistic limit equation for hypervelocity impacts on composite honeycomb sandwich panel satellite structures

    NASA Astrophysics Data System (ADS)

    Ryan, S.; Schaefer, F.; Destefanis, R.; Lambert, M.

    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 was derived from an existing Whipple-shield BLE. This new BLE provided a good level of accuracy in predicting the ballistic performance of stand-alone sandwich panel structures. Additionally, the equation is capable of predicting the ballistic limit of a thin Al plate located at a standoff behind the sandwich panel structure. This thin plate is the representative of internal satellite systems, e.g. an Al electronic box cover, a wall of a metallic vessel, etc. Good agreement was achieved with both the experimental test campaign results and additional test data from the literature for the vast majority of set-ups investigated. For some experiments, the ballistic limit was conservatively predicted, a result attributed to shortcomings in correctly accounting for the presence of high surface density multi-layer insulation on the outer facesheet. Four existing BLEs commonly applied for application with stand-alone sandwich panels were reviewed using the new impact test data. It was found that a number of these common approaches provided non-conservative predictions for sandwich panels with CFRP facesheets.

  2. Structural equation modeling of sleep apnea, inflammation, and metabolic dysfunction in children.

    PubMed

    Waters, Karen A; Mast, Benjamin T; Vella, Silvano; de la Eva, Roland; O'Brien, Louise M; Bailey, Sherryn; Tam, Charmaine S; Wong, Melanie; Baur, Louise A

    2007-12-01

    Obstructive sleep apnea (OSA), often concomitant with obesity, increases the risk for the metabolic syndrome. One mechanism that may participate in this association is upregulation of inflammatory pathways. We used structural equation modeling to assess the interrelations between childhood obesity, OSA, inflammation, and metabolic dysfunction. One hundred and eighty-four children (127 boys, mean age: 8.5 +/- 4.1 years) had height and weight measured, underwent overnight polysomnography and had fasting blood taken. The blood was analyzed for insulin, glucose, lipids, leptin, and cytokines [interferon (IFN)-gamma, granulocyte macrophage-colony stimulating factor, interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor-alpha]. Structural equation modeling (SEM) was used to evaluate associations between the outcomes of interest including hypoxia, arousal (related to respiratory and spontaneous), obesity, metabolic dysfunction, and inflammatory markers. Two cytokine factors and one metabolic factor were derived for the SEM. These factors provided good fit in the structural equation model (chi(2)/df = 2.855; comparative fit index = 0.90, root mean squared error of approximation = 0.10) and all factor loadings were significantly different from zero (P < or = 0.01). Overall, our results indicate that while obesity (as measured by body mass index z-score) has a major influence on the metabolic dysfunction associated with OSA, arousal indices, and cytokine markers may also influence this association. Our results support the hypothesis that OSA is a contributor to the mechanisms that link sleep, systemic inflammation and insulin resistance, and show that the interrelations may begin in childhood. PMID:18036084

  3. The Structure of Preschoolers' Emotion Knowledge: Model Equivalence and Validity Using a Structural Equation Modeling Approach

    ERIC Educational Resources Information Center

    Bassett, Hideko Hamada; Denham, Susanne; Mincic, Melissa; Graling, Kelly

    2012-01-01

    Research Findings: A theory-based 2-factor structure of preschoolers' emotion knowledge (i.e., recognition of emotional expression and understanding of emotion-eliciting situations) was tested using confirmatory factor analysis. Compared to 1- and 3-factor models, the 2-factor model showed a better fit to the data. The model was found to be…

  4. Constrained hierarchical least square nonlinear equation solvers. [for indefinite stiffness and large structural deformations

    NASA Technical Reports Server (NTRS)

    Padovan, J.; Lackney, J.

    1986-01-01

    The current paper develops a constrained hierarchical least square nonlinear equation solver. The procedure can handle the response behavior of systems which possess indefinite tangent stiffness characteristics. Due to the generality of the scheme, this can be achieved at various hierarchical application levels. For instance, in the case of finite element simulations, various combinations of either degree of freedom, nodal, elemental, substructural, and global level iterations are possible. Overall, this enables a solution methodology which is highly stable and storage efficient. To demonstrate the capability of the constrained hierarchical least square methodology, benchmarking examples are presented which treat structure exhibiting highly nonlinear pre- and postbuckling behavior wherein several indefinite stiffness transitions occur.

  5. Analysis of factors affecting satisfaction level on problem based learning approach using structural equation modeling

    NASA Astrophysics Data System (ADS)

    Hussain, Nur Farahin Mee; Zahid, Zalina

    2014-12-01

    Nowadays, in the job market demand, graduates are expected not only to have higher performance in academic but they must also be excellent in soft skill. Problem-Based Learning (PBL) has a number of distinct advantages as a learning method as it can deliver graduates that will be highly prized by industry. This study attempts to determine the satisfaction level of engineering students on the PBL Approach and to evaluate their determinant factors. The Structural Equation Modeling (SEM) was used to investigate how the factors of Good Teaching Scale, Clear Goals, Student Assessment and Levels of Workload affected the student satisfaction towards PBL approach.

  6. Direct and Indirect Effects of Education on Job Satisfaction: A Structural Equation Model for the Spanish Case

    ERIC Educational Resources Information Center

    Fabra, M. Eugenia; Camison, Cesar

    2009-01-01

    Empirical literature has traditionally analyzed the effect of education on job satisfaction with single-equation models that ignore interrelationships between theoretical explanatory variables. Their results are somewhat inconclusive. We propose estimating a structural equation model to obtain both the direct effects and the set of indirect

  7. Spiritual and Non-spiritual Needs Among German Soldiers and Their Relation to Stress Perception, PTDS Symptoms, and Life Satisfaction: Results from a Structural Equation Modeling Approach.

    PubMed

    Büssing, Arndt; Recchia, Daniela R

    2016-06-01

    In an anonym cross-sectional survey (using standardized questionnaires) among 1092 German soldiers, we found that 21 % regard their faith as a "strong hold in difficult times." Only a few had specific religious needs. Rather, a consistent theme from the participants was the need to communicate their own fears, worries and desire to attain states of inner peace. "Soldiers" stress perception and posttraumatic stress disorder symptoms were associated particularly with existential and Inner Peace Needs. Structural equation modeling indicated that stress perception has a negative influence on soldiers' life satisfaction, which in turn gives rise to specific unmet spiritual needs. These specific needs may indicate psycho-emotional problems which could be supported very early to prevent health affections and service failure. PMID:26054928

  8. How does multilevel upper airway surgery influence the lives of dogs with severe brachycephaly? Results of a structured pre- and postoperative owner questionnaire.

    PubMed

    Pohl, Sabine; Roedler, Frauke S; Oechtering, Gerhard U

    2016-04-01

    Brachycephalic airway syndrome in dogs is typified by a variety of anatomical abnormalities causing a diverse spectrum of clinical signs of varying intensity. This variability makes the assessment of the surgical outcome after upper airway surgery difficult. Using a structured questionnaire, the present study investigated the dog owner-perceived severity and frequency of a broad spectrum of welfare-relevant impairments 2 weeks before and 6 months after brachycephalic dogs underwent a recently developed multi-level upper airway surgery. All dogs underwent surgical treatment of stenotic nares (ala-vestibuloplasty), the nasal cavity (laser-assisted turbinectomy, LATE), the pharynx (palatoplasty and tonsillotomy), and if indicated, laryngeal surgery (laser-assisted ablation of everted ventricles and partial cuneiformectomy). Owners of brachycephalic dogs (n = 102) referred for upper airway surgery were eligible to participate. Questionnaire data from owners of 37 Pugs and 25 French bulldogs were evaluated. In all dogs, the clinical signs associated with brachycephaly improved markedly after surgery. Most encouraging was the striking reduction in life-threatening events by 90% (choking fits decreased from 60% to 5% and collapse from 27% to 3%). The incidence of sleeping problems decreased from 55% to 3%, and the occurrence of breathing sounds declined by approximately 50%. There was a marked improvement in exercise tolerance and a modest improvement in heat tolerance. Dogs with severe brachycephaly benefitted substantially from multi-level surgery, and there were particular improvements in the incidences of severe impairment and life-threatening events. However, despite the marked improvement perceived by dog owners, these dogs remained clinically affected and continued to show welfare-relevant impairments caused by these hereditary disorders. PMID:26897434

  9. High Risk Sexual Behaviors for HIV among the In-School Youth in Swaziland: A Structural Equation Modeling Approach

    PubMed Central

    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

  10. Prolongation Structure of a Generalised Inhomogeneous Gardner Equation in Plasmas and Fluids

    NASA Astrophysics Data System (ADS)

    Xie, Xi-Yang; Tian, Bo; Sun, Wen-Rong; Wang, Yun-Po

    2016-04-01

    In this article, the prolongation structure technique is applied to a generalised inhomogeneous Gardner equation, which can be used to describe certain physical situations, such as the stratified shear flows in ocean and atmosphere, ion acoustic waves in plasmas with a negative ion, interfacial solitary waves over slowly varying topographies, and wave motion in a non-linear elastic structural element with large deflection. The Lax pairs, which are derived via the prolongation structure, are more general than the Lax pairs published before. Under the Painlevé conditions, the linear-damping coefficient equals to zero, the quadratic non-linear coefficient is proportional to the dispersive coefficient c(t), the cubic non-linear coefficient is proportional to c(t), leaving no constraints on c(t) and the dissipative coefficient d(t). We establish the prolongation structure through constructing the exterior differential system. We introduce two methods to obtain the Lax pairs: (a) based on the prolongation structure, the Lax pairs are obtained, and (b) via the Lie algebra, we can derive the Pfaffian forms and Lax pairs when certain parameters are chosen. We set d(t) as a constant to discuss the influence of c(t) on the Pfaffian forms and Lax pairs, and to discuss the influence of d(t) on the Pfaffian forms and Lax pairs, we set c(t) as another constant. Then, we get different prolongation structure, Pfaffian forms and Lax pairs.

  11. The structural equation analysis of childhood abuse, adult stressful life events, and temperaments in major depressive disorders and their influence on refractoriness

    PubMed Central

    Toda, Hiroyuki; Inoue, Takeshi; Tsunoda, Tomoya; Nakai, Yukiei; Tanichi, Masaaki; Tanaka, Teppei; Hashimoto, Naoki; Nakato, Yasuya; Nakagawa, Shin; Kitaichi, Yuji; Mitsui, Nobuyuki; Boku, Shuken; Tanabe, Hajime; Nibuya, Masashi; Yoshino, Aihide; Kusumi, Ichiro

    2015-01-01

    Background Previous studies have shown the interaction between heredity and childhood stress or life events on the pathogenesis of a major depressive disorder (MDD). In this study, we tested our hypothesis that childhood abuse, affective temperaments, and adult stressful life events interact and influence the diagnosis of MDD. Patients and methods A total of 170 healthy controls and 98 MDD patients were studied using the following self-administered questionnaire surveys: the Patient Health Questionnaire-9 (PHQ-9), the Life Experiences Survey, the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire, and the Child Abuse and Trauma Scale (CATS). The data were analyzed with univariate analysis, multivariable analysis, and structural equation modeling. Results The neglect scores of the CATS indirectly predicted the diagnosis of MDD through cyclothymic and anxious temperament scores of the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire in the structural equation modeling. Two temperaments – cyclothymic and anxious – directly predicted the diagnosis of MDD. The validity of this result was supported by the results of the stepwise multivariate logistic regression analysis as follows: three factors – neglect, cyclothymic, and anxious temperaments – were significant predictors of MDD. Neglect and the total CATS scores were also predictors of remission vs treatment-resistance in MDD patients independently of depressive symptoms. Limitations The sample size was small for the comparison between the remission and treatment-resistant groups in MDD patients in multivariable analysis. Conclusion This study suggests that childhood abuse, especially neglect, indirectly predicted the diagnosis of MDD through increased affective temperaments. The important role as a mediator of affective temperaments in the effect of childhood abuse on MDD was suggested. PMID:26316754

  12. The Defense Style Questionnaire.

    PubMed

    Andrews, G; Singh, M; Bond, M

    1993-04-01

    The Defense Style Questionnaire has proven of interest as the first questionnaire to reliably describe defense styles. The 72-item DSM-III-R-labeled Defense Style Questionnaire was administered to 388 controls and 324 patients. Eight statistical and two a priori criteria were used in choosing two items to represent each of the 20 defenses. A new 40-item Defense Style Questionnaire is published together with normative and reliability data on a normal population, patients with anxiety disorders, and child-abusing parents. The scores are unaffected by the sex of the respondent, but the endorsement of immature defense styles decreases with age. PMID:8473876

  13. Motives for marijuana use among heavy-using high school students: An analysis of structure and utility of the Comprehensive Marijuana Motives Questionnaire.

    PubMed

    Blevins, Claire E; Banes, Kelsey E; Stephens, Robert S; Walker, Denise D; Roffman, Roger A

    2016-06-01

    Motives for marijuana use are important predictors of problematic outcomes associated with marijuana use. Most measures, to date, were developed by adapting alcohol motives measures. However, the Comprehensive Marijuana Motives Questionnaire (CMMQ) was created using a bottom-up approach to evaluate twelve distinct motives for use. The CMMQ was developed and validated in a normative college population. As such, no known study has evaluated the factor structure and utility of the CMMQ in a heavy-using, high school student population. The current study utilized a sample of 252 heavy marijuana-using high school students recruited for a combination motivational enhancement/cognitive behavioral intervention. Results from baseline measures indicated that the factor structure of the CMMQ was maintained in this population. Results from multiple regression analyses revealed distinct relationships with measures of negative consequences of use, including indices of marijuana use, marijuana-related problems, self-efficacy, and internalizing and externalizing symptoms. In particular, the Coping motive was associated with several negative outcomes, which is consistent with previous marijuana and alcohol motives literature. Results suggest that the CMMQ may be useful in assessing marijuana motives among heavy marijuana-using adolescents. PMID:26878304

  14. Schizotypal personality questionnaire - brief revised (updated): An update of norms, factor structure, and item content in a large non-clinical young adult sample.

    PubMed

    Davidson, Charlie A; Hoffman, Lesa; Spaulding, William D

    2016-04-30

    This study updates and provides evidence for the dimensionality, reliability, and validity of a standard instrument for detection and measurement of schizotypy in non-clinical young adults. Schizotypy represents a set of traits on which both nonclinical and schizophrenia-spectrum populations vary meaningfully. These traits are linked to biological, cognitive, and social dimensions of serious mental illness (SMI), to clinical and subclinical variation in personal and social functioning, and to risk for SMI. Reliable and valid identification of schizotypal traits has important implications for clinical practice and research. Four consecutive independent samples of undergraduates were administered the SPQ-BR (N=2552). Confirmatory factor analyses suggested a minor item wording change improved reliability, and this Updated questionnaire was implemented for three-quarters of the sample (SPQ-BRU). A, single-order, nine-factor structure had acceptable psychometric properties. The best fitting second-order structure included four higher-order factors that distinguished Social Anxiety and Interpersonal factors. This differentiation was supported by differential relationships with treatment history. The Disorganized factor had the greatest unique relationship with personal and family treatment history. With few exceptions, factor loadings showed stability across samples. Overall, the higher-order and lower-order factors of schizotypy demonstrated reliability and convergent and discriminant validity; detailed psychometric data are presented in a supplement. PMID:27086255

  15. Brooding and Pondering: Isolating the Active Ingredients of Depressive Rumination with Exploratory Factor Analysis and Structural Equation Modeling

    ERIC Educational Resources Information Center

    Armey, Michael F.; Fresco, David M.; Moore, Michael T.; Mennin, Douglas S.; Turk, Cynthia L.; Heimberg, Richard G.; Kecmanovic, Jelena; Alloy, Lauren B.

    2009-01-01

    Depressive rumination, as assessed by Nolen-Hoeksema's Response Styles Questionnaire (RSQ), predicts the onset, chronicity, and duration of depressed mood. However, some RSQ items contain depressive content and result in a heterogeneous factor structure. After the a priori elimination of items potentially confounded with depressed item content,…

  16. Guidelines for a graph-theoretic implementation of structural equation modeling

    USGS Publications Warehouse

    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.

  17. Social-cognitive determinants of nutrition behavior among supermarket food shoppers: a structural equation analysis.

    PubMed

    Anderson, E S; Winett, R A; Wojcik, J R

    2000-09-01

    A social-cognitive model of nutrition behavior (A. Bandura, 1997) was tested using structural equation modeling of data from 307 food shoppers recruited from 5 supermarkets in Southwest Virginia. The shoppers were participating in the baseline phase of an ongoing nutrition promotion program. As part of the evaluation, data were collected on the self-efficacy and outcome-expectations components of social-cognitive theory as well as on food purchases and intake. The structural analyses presented here support the social-cognitive model. Self-efficacy, physical outcome expectations, age, socioeconomic status, and number of children were important predictors of nutrition behavior among shoppers. Implications for interventions using social-cognitive variables to improve the nutritional content of food purchases and intake are discussed. PMID:11007156

  18. Normal forms for semilinear equations with non-dense domain with applications to age structured models

    NASA Astrophysics Data System (ADS)

    Liu, Zhihua; Magal, Pierre; Ruan, Shigui

    2014-08-01

    Normal form theory is very important and useful in simplifying the forms of equations restricted on the center manifolds in studying nonlinear dynamical problems. In this paper, using the center manifold theorem associated with the integrated semigroup theory, we develop a normal form theory for semilinear Cauchy problems in which the linear operator is not densely defined and is not a Hille-Yosida operator and present procedures to compute the Taylor expansion and normal form of the reduced system restricted on the center manifold. We then apply the main results and computation procedures to determine the direction of the Hopf bifurcation and stability of the bifurcating periodic solutions in a structured evolutionary epidemiological model of influenza A drift and an age structured population model.

  19. Adjoint design sensitivity analysis of reduced atomic systems using generalized Langevin equation for lattice structures

    SciTech Connect

    Kim, Min-Geun; Jang, Hong-Lae; Cho, Seonho

    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.

  20. Job and Professional Leaving Among Newly Licensed RNs: A Structural Equation Model.

    PubMed

    Unruh, Lynn; Zhang, Ning Jackie; Chisolm, Latarsha

    2016-01-01

    With more than 50% of the nursing workforce close to retirement, it is especially important to keep younger nurses in nursing jobs and careers. This study empirically tests a structural equation model of registered nurse (RN) intent to leave the job and profession using data from a survey of newly licensed RNs (NLRNs). Job demands, difficulties and control, intent to leave the job, and intent to leave the profession were latent variables. A number of direct, indirect, and mediating relationships were modeled. Measurement models for all latent variables and the structural model had good fit. The final model showed a path from job demands, difficulties, and control to job satisfaction to intent to leave the job to intent to leave the profession. The results suggest that the process of an NLRN intending to leave the job and profession involves a number of mediators between the work environment and this intent. PMID:25433000

  1. Vector Autoregression, Structural Equation Modeling, and Their Synthesis in Neuroimaging Data Analysis

    PubMed Central

    Chen, Gang; Glen, Daniel R.; Saad, Ziad S.; Hamilton, J. Paul; Thomason, Moriah E.; Gotlib, Ian H.; Cox, Robert W.

    2011-01-01

    Vector autoregression (VAR) and structural equation modeling (SEM) are two popular brain-network modeling tools. VAR, which is a data-driven approach, assumes that connected regions exert time-lagged influences on one another. In contrast, the hypothesis-driven SEM is used to validate an existing connectivity model where connected regions have contemporaneous interactions among them. We present the two models in detail and discuss their applicability to FMRI data, and interpretational limits. We also propose a unified approach that models both lagged and contemporaneous effects. The unifying model, structural vector autoregression (SVAR), may improve statistical and explanatory power, and avoids some prevalent pitfalls that can occur when VAR and SEM are utilized separately. PMID:21975109

  2. On the relationship between modifications to the Raychaudhuri equation and the canonical Hamiltonian structures

    NASA Astrophysics Data System (ADS)

    Singh, Parampreet; Soni, S. K.

    2016-06-01

    The problem of obtaining canonical Hamiltonian structures from the equations of motion, without any knowledge of the action, is studied in the context of the spatially flat Friedmann, ‘Robertson’, and Walker models. Modifications to the Raychaudhuri equation are implemented independently as quadratic and cubic terms of energy density without introducing additional degrees of freedom. Depending on their sign, modifications make gravity repulsive above a curvature scale for matter satisfying strong energy conditions, or more attractive than in the classical theory. The canonical structure of the modified theories is determined by demanding that the total Hamiltonian be a linear combination of gravity and matter Hamiltonians. In the quadratic repulsive case, the modified canonical phase space of gravity is a polymerized phase space with canonical momentum as inverse a trigonometric function of the Hubble rate; the canonical Hamiltonian can be identified with the effective Hamiltonian in loop quantum cosmology. The repulsive cubic modification results in a ‘generalized polymerized’ canonical phase space. Both the repulsive modifications are found to yield singularity avoidance. In contrast, the quadratic and cubic attractive modifications result in a canonical phase space in which canonical momentum is nontrigonometric and singularities persist. Our results hint at connections between the repulsive/attractive nature of modifications to gravity arising from the gravitational sector and polymerized/non polymerized gravitational phase space.

  3. An extended structure-based model based on a stochastic eddy-axis evolution equation

    NASA Technical Reports Server (NTRS)

    Kassinos, S. C.; Reynolds, W. C.

    1995-01-01

    We have proposed and implemented an extension of the structure-based model for weak deformations. It was shown that the extended model will correctly reduce to the form of standard k-e models for the case of equilibrium under weak mean strain. The realizability of the extended model is guaranteed by the method of its construction. The predictions of the proposed model were very good for rotating homogeneous shear flows and for irrotational axisymmetric contraction, but were seriously deficient in the case of plane strain and axisymmetric expansion. We have concluded that the problem behind these difficulties lies in the algebraic constitutive equation relating the Reynolds stresses to the structure parameters rather than in the slow model developed here. In its present form, this equation assumes that under irrotational strain the principal axes of the Reynolds stresses remain locked onto those of the eddy-axis tensor. This is correct in the RDT limit, but inappropriate under weaker mean strains, when the non-linear eddy-eddy interactions tend to misalign the two sets of principal axes and create some non-zero theta and gamma.

  4. Pallidal index on MRI as a target organ dose of manganese: structural equation model analysis.

    PubMed

    Kim, Euna; Kim, Yangho; Cheong, Hae-Kwan; Cho, Sungil; Shin, Yong Chul; Sakong, Joon; Kim, Kyoo Sang; Yang, Jung Sun; Jin, Young-Woo; Kang, Seong-Kyu

    2005-06-01

    We have used a structural equation model (SEM) to analyze the interrelationships among exposure markers, magnetic resonance imaging (MRI) signal index, and neurobehavioral effects. Based on exposure groups, we assessed blood manganese, MRI measurements of pallidal index (PI), and neurobehavioral core test battery (WHO-NCTB) on 111 male workers occupationally exposed to manganese, including welders, smelter workers, and welding rod manufacturing workers. Latent variables were constructed to represent the neurobehavioral effects in an integrated way. The structural equation model revealed that airborne manganese and blood manganese contribute to PI significantly. Manganese exposure in the ambient air may lead to an increase in the internal dose, not only indirectly, by increasing blood manganese level, but also directly, independent of blood concentration. PI significantly contributed to a decrease in neurobehavioral test scores. We found that airborne manganese contributed to PI, and that PI is the most effective predictor of neurobehavioral performance, after adjusting for age and level of education. In conclusion, PI on MRI reflects target organ dose of occupational manganese exposure. PMID:15935207

  5. Estimating and interpreting latent variable interactions: A tutorial for applying the latent moderated structural equations method

    PubMed Central

    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) method is one that is built into Mplus software. The potential utility of this method is limited by the fact that the models do not produce traditional model fit indices, standardized coefficients, or effect sizes for the latent interaction, which renders model fitting and interpretation of the latent variable interaction difficult. This article compiles state-of-the-science techniques for assessing LMS model fit, obtaining standardized coefficients, and determining the size of the latent interaction effect in order to create a tutorial for new users of LMS models. The recommended sequence of model estimation and interpretation is demonstrated via a substantive example and a Monte Carlo simulation. Finally, extensions of this method are discussed, such as estimating quadratic effects of latent factors and interactions between latent slope and intercept factors, which hold significant potential for testing and advancing developmental theories. PMID:26478643

  6. Representing general theoretical concepts in structural equation models: The role of composite variables

    USGS Publications Warehouse

    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.

  7. A determinant-based criterion for working correlation structure selection in generalized estimating equations.

    PubMed

    Jaman, Ajmery; Latif, Mahbub A H M; Bari, Wasimul; Wahed, Abdus S

    2016-05-20

    In generalized estimating equations (GEE), the correlation between the repeated observations on a subject is specified with a working correlation matrix. Correct specification of the working correlation structure ensures efficient estimators of the regression coefficients. Among the criteria used, in practice, for selecting working correlation structure, Rotnitzky-Jewell, Quasi Information Criterion (QIC) and Correlation Information Criterion (CIC) are based on the fact that if the assumed working correlation structure is correct then the model-based (naive) and the sandwich (robust) covariance estimators of the regression coefficient estimators should be close to each other. The sandwich covariance estimator, used in defining the Rotnitzky-Jewell, QIC and CIC criteria, is biased downward and has a larger variability than the corresponding model-based covariance estimator. Motivated by this fact, a new criterion is proposed in this paper based on the bias-corrected sandwich covariance estimator for selecting an appropriate working correlation structure in GEE. A comparison of the proposed and the competing criteria is shown using simulation studies with correlated binary responses. The results revealed that the proposed criterion generally performs better than the competing criteria. An example of selecting the appropriate working correlation structure has also been shown using the data from Madras Schizophrenia Study. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26626276

  8. Development of the PMPQ: A Structural Job Analysis Questionnaire for the Study of Professional and Managerial Positions. PMPQ Report No. 1.

    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…

  9. Wesleyan University Student Questionnaire.

    ERIC Educational Resources Information Center

    Haagen, C. Hess

    This questionnaire assesses marijuana use practices in college students. The 30 items (multiple choice or free response) are concerned with personal and demographic data, marijuana smoking practices, use history, effects from smoking marijuana, present attitude toward the substance, and use of other drugs. The Questionnaire is untimed and…

  10. Questionnaire for Parents.

    ERIC Educational Resources Information Center

    Purdue Univ., Lafayette, IN. Educational Research Center.

    The 116-item parent questionnaire is designed for parents of elementary school children. It is intended to be used with the child's mother, or the person acting as the child's mother. The questionnaire consists of a section devoted to demographic variables and scales measuring 14 parent variables: (1) parent's achievement aspirations for the…

  11. Impact of noise on self-rated job satisfaction and health in open-plan offices: a structural equation modelling approach.

    PubMed

    Lee, Pyoung Jik; Lee, Byung Kwon; Jeon, Jin Yong; Zhang, Mei; Kang, Jian

    2016-02-01

    This study uses a structural equation model to examine the effects of noise on self-rated job satisfaction and health in open-plan offices. A total of 334 employees from six open-plan offices in China and Korea completed a questionnaire survey. The questionnaire included questions assessing noise disturbances and speech privacy, as well as job satisfaction and health. The results indicated that noise disturbance affected self-rated health. Contrary to popular expectation, the relationship between noise disturbance and job satisfaction was not significant. Rather, job satisfaction and satisfaction with the environment were negatively correlated with lack of speech privacy. Speech privacy was found to be affected by noise sensitivity, and longer noise exposure led to decreased job satisfaction. There was also evidence that speech privacy was a stronger predictor of satisfaction with environment and job satisfaction for participants with high noise sensitivity. In addition, fit models for employees from China and Korea showed slight differences. Practitioner Summary: This study is motivated by strong evidence that noise is the key source of complaints in open-plan offices. Survey results indicate that self-rated job satisfaction of workers in open-plan offices was negatively affected by lack of speech privacy and duration of disturbing noise. PMID:26366940

  12. Application of high precision band structure calculations to the equation of state for beryllium oxide: SESAME equation of state number 7612

    SciTech Connect

    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.

  13. Symmetric Gauss-Seidel multigrid solution of the Euler equations on structured and unstructured grids

    NASA Astrophysics Data System (ADS)

    Caughey, David A.

    2005-11-01

    The efficient symmetric Gauss-Seidel (SGS) algorithm for solving the Euler equations of inviscid, compressible flow on structured grids, developed in collaboration with Jameson of Stanford University, is extended to unstructured grids. The algorithm uses a nonlinear formulation of an SGS solver, implemented within the framework of multigrid. The earlier form of the algorithm used the natural (lexicographic) ordering of the mesh cells available on structured grids for the SGS sweeps, but a number of features of the method that are believed to contribute to its success can also be implemented for computations on unstructured grids. The present paper reviews, the features of the SGS multigrid solver for structured gr0ids, including its nonlinear implementation, its use of “absolute” Jacobian matrix preconditioning, and its incorporation of multigrid, and then describes the incorporation of these features into an algorithm suitable for computations on unstructured grids. The implementation on unstructured grids is based on the agglomerated multigrid method developed by Sørensen, which uses an explicit Runge-Kutta smoothing algorithm. Results of computations for steady, transonic flows past two-dimensional airfoils are presented, and the efficiency of the method is evaluated for computations on both structured and unstructured meshes.

  14. Development of uncertainty-based work injury model using Bayesian structural equation modelling.

    PubMed

    Chatterjee, Snehamoy

    2014-01-01

    This paper proposed a Bayesian method-based structural equation model (SEM) of miners' work injury for an underground coal mine in India. The environmental and behavioural variables for work injury were identified and causal relationships were developed. For Bayesian modelling, prior distributions of SEM parameters are necessary to develop the model. In this paper, two approaches were adopted to obtain prior distribution for factor loading parameters and structural parameters of SEM. In the first approach, the prior distributions were considered as a fixed distribution function with specific parameter values, whereas, in the second approach, prior distributions of the parameters were generated from experts' opinions. The posterior distributions of these parameters were obtained by applying Bayesian rule. The Markov Chain Monte Carlo sampling in the form Gibbs sampling was applied for sampling from the posterior distribution. The results revealed that all coefficients of structural and measurement model parameters are statistically significant in experts' opinion-based priors, whereas, two coefficients are not statistically significant when fixed prior-based distributions are applied. The error statistics reveals that Bayesian structural model provides reasonably good fit of work injury with high coefficient of determination (0.91) and less mean squared error as compared to traditional SEM. PMID:24111548

  15. The Eating Attitudes Test-26 revisited using exploratory structural equation modeling.

    PubMed

    Maïano, Christophe; Morin, Alexandre J S; Lanfranchi, Marie-Christine; Therme, Pierre

    2013-07-01

    Most previous studies have failed to replicate the original factor structure of the 26-item version of the Eating Attitudes Test (EAT-26) among community samples of adolescents. The main objective of the present series of four studies (n = 2178) was to revisit the factor structure of this instrument among mixed gender community samples of adolescents using both exploratory structural equation modeling (ESEM) and confirmatory factor analysis (CFA). First, results from the ESEM analyses provided satisfactory goodness-of-fit statistics and reliability coefficients for a six-factor model of the EAT with 18 items (EAT-18) closely corresponding to the original seven-factor structure proposed for the 40-item version of the EAT. Second, these analyses were satisfactorily replicated among a new sample of community adolescents using CFA. The results confirmed the factor loading and intercept invariance of this model across gender and age groups (i.e., early and late adolescence), as well as the complete invariance of the EAT-18 measurement model between ethnicities (i.e., European versus African origins) and across weight categories (i.e., underweight, normal weight and overweight). Finally, the last study provided support for convergent validity of the EAT-18 with the Eating Disorder Inventory and with instruments measuring global self-esteem, physical appearance, social physique anxiety and fear of negative appearance evaluation. PMID:23344702

  16. Testing the simplex assumption underlying the Sport Motivation Scale: a structural equation modeling analysis.

    PubMed

    Li, F; Harmer, P

    1996-12-01

    Self-determination theory (Deci & Ryan, 1985) suggests that motivational orientation or regulatory styles with respect to various behaviors can be conceptualized along a continuum ranging from low (a motivation) to high (intrinsic motivation) levels of self-determination. This pattern is manifested in the rank order of correlations among these regulatory styles (i.e., adjacent correlations are expected to be higher than those more distant) and is known as a simplex structure. Using responses from the Sport Motivation Scale (Pelletier et al., 1995) obtained from a sample of 857 college students (442 men, 415 women), the present study tested the simplex structure underlying SMS subscales via structural equation modeling. Results confirmed the simplex model structure, indicating that the various motivational constructs are empirically organized from low to high self-determination. The simplex pattern was further found to be invariant across gender. Findings from this study support the construct validity of the SMS and have important implications for studies focusing on the influence of motivational orientation in sport. PMID:9016481

  17. Thermodynamic and structural properties of strongly coupled plasma mixtures from the perturbative HNC-equation

    SciTech Connect

    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.

  18. Structural equation models to estimate risk of infection and tolerance to bovine mastitis

    PubMed Central

    2013-01-01

    Background One method to improve durably animal welfare is to select, as reproducers, animals with the highest ability to resist or tolerate infection. To do so, it is necessary to distinguish direct and indirect mechanisms of resistance and tolerance because selection on these traits is believed to have different epidemiological and evolutionary consequences. Methods We propose structural equation models with latent variables (1) to quantify the latent risk of infection and to identify, among the many potential mediators of infection, the few ones that influence it significantly and (2) to estimate direct and indirect levels of tolerance of animals infected naturally with pathogens. We applied the method to two surveys of bovine mastitis in the Walloon region of Belgium, in which we recorded herd management practices, mastitis frequency, and results of bacteriological analyses of milk samples. Results and discussion Structural equation models suggested that, among more than 35 surveyed herd characteristics, only nine (age, addition of urea in the rations, treatment of subclinical mastitis, presence of dirty liner, cows with hyperkeratotic teats, machine stripping, pre- and post-milking teat disinfection, and housing of milking cows in cubicles) were directly and significantly related to a latent measure of bovine mastitis, and that treatment of subclinical mastitis was involved in the pathway between post-milking teat disinfection and latent mastitis. These models also allowed the separation of direct and indirect effects of bacterial infection on milk productivity. Results suggested that infected cows were tolerant but not resistant to mastitis pathogens. Conclusions We revealed the advantages of structural equation models, compared to classical models, for dissecting measurements of resistance and tolerance to infectious diseases, here bovine mastitis. Using our method, we identified nine major risk factors that were directly associated with an increased risk of mastitis and suggested that cows were tolerant but not resistant to mastitis. Selection should aim at improved resistance to infection by mastitis pathogens, although further investigations are needed due to the limitations of the data used in this study. PMID:23496993

  19. Numerical solutions of Navier-Stokes equations for the structure of a trailing vortex

    NASA Technical Reports Server (NTRS)

    Jain, A. C.

    1977-01-01

    The structure and decay of a trailing vortex were analyzed during the numerical solutions of the full Navier-Stokes equations. Unsteady forms of the governing equations were recast in terms of circulation, vorticity, and stream function as dependent variables, and a second upwind finite difference scheme was used to integrate them with prescribed initial and boundary conditions. The boundary conditions at the outer edge and at the outflow section of the trailing vortex were considered. Different models of the flow were postulated, and solutions were obtained describing the development of the flow as integration proceeds in time. A parametric study was undertaken with a view to understanding the various phenomena that may possibly occur in the trailing vortex. Using the Hoffman and Joubert law of circulation at the inflow section, the results of this investigation were compared with experimental data for a Convair 990 wind model and a rectangular wing. With an exponentially decaying law of circulation at the inflow section and an adverse pressure gradient at the outer edge of the trailing vortex, solutions depict vortex bursting through the sudden expansion of the core and/or through the stagnation and consequent reversal of the flow on the axis. It was found that this bursting takes place at lower values of the swirl ratio as the Reynolds number increases.

  20. Parental authority questionnaire.

    PubMed

    Buri, J R

    1991-08-01

    A questionnaire was developed for the purpose of measuring Baumrind's (1971) permissive, authoritarian, and authoritative parental authority prototypes. It consists of 30 items per parent and yields permissive, authoritarian, and authoritative scores for both the mother and the father; each of these scores is derived from the phenomenological appraisals of the parents' authority by their son or daughter. The results of several studies have supported the Parental Authority Questionnaire as a psychometrically sound and valid measure of Baumrind's parental authority prototypes, and they have suggested that this questionnaire has considerable potential as a valuable tool in the investigation of correlates of parental permissiveness, authoritarianism, and authoritativeness. PMID:16370893

  1. OpenMx 2.0: Extended Structural Equation and Statistical Modeling.

    PubMed

    Neale, Michael C; Hunter, Michael D; Pritikin, Joshua N; Zahery, Mahsa; Brick, Timothy R; Kirkpatrick, Robert M; Estabrook, Ryne; Bates, Timothy C; Maes, Hermine H; Boker, Steven M

    2016-06-01

    The new software package OpenMx 2.0 for structural equation and other statistical modeling is introduced and its features are described. OpenMx is evolving in a modular direction and now allows a mix-and-match computational approach that separates model expectations from fit functions and optimizers. Major backend architectural improvements include a move to swappable open-source optimizers such as the newly written CSOLNP. Entire new methodologies such as item factor analysis and state space modeling have been implemented. New model expectation functions including support for the expression of models in LISREL syntax and a simplified multigroup expectation function are available. Ease-of-use improvements include helper functions to standardize model parameters and compute their Jacobian-based standard errors, access to model components through standard R $ mechanisms, and improved tab completion from within the R Graphical User Interface. PMID:25622929

  2. Profile Likelihood-Based Confidence Intervals and Regions for Structural Equation Models.

    PubMed

    Pek, Jolynn; Wu, Hao

    2015-12-01

    Structural equation models (SEM) are widely used for modeling complex multivariate relationships among measured and latent variables. Although several analytical approaches to interval estimation in SEM have been developed, there lacks a comprehensive review of these methods. We review the popular Wald-type and lesser known likelihood-based methods in linear SEM, emphasizing profile likelihood-based confidence intervals (CIs). Existing algorithms for computing profile likelihood-based CIs are described, including two newer algorithms which are extended to construct profile likelihood-based confidence regions (CRs). Finally, we illustrate the use of these CIs and CRs with two empirical examples, and provide practical recommendations on when to use Wald-type CIs and CRs versus profile likelihood-based CIs and CRs. OpenMx example code is provided in an Online Appendix for constructing profile likelihood-based CIs and CRs for SEM. PMID:25925009

  3. Impact of oral health on physical and psychosocial dimensions: an analysis using structural equation modeling.

    PubMed

    Silveira, Marise Fagundes; Marôco, João P; Freire, Rafael Silveira; Martins, Andréa Maria Eleutério de Barros Lima; Marcopito, Luiz Francisco

    2014-06-01

    This study aimed to estimate the prevalence of impact of oral health conditions on physical and psychosocial dimensions among adolescents and to identify factors associated with severity of impact. The impact of oral health status was assessed by the instrument Oral Health Impact Profile (OHIP-14). The covariates were: socioeconomic status, habits and health care, use of dental services, and normative conditions of oral health. Structural equation modeling was performed, and 15.6% of adolescents reported impact in at least one dimension of the OHIP-14. The dimensions that showed the highest prevalence of impact were psychological distress (11.8%) and physical pain (6.6%). The number of teeth needing dental treatment, number of filled teeth, and CPI significantly affected severity of impact. In this adolescent population, unfavorable socioeconomic conditions were associated with reduced use of dental services, associated in turn with precarious oral health conditions and increased severity of impact. PMID:25099041

  4. The Cusp Catastrophe Model as Cross-Sectional and Longitudinal Mixture Structural Equation Models

    PubMed Central

    Chow, Sy-Miin; Witkiewitz, Katie; Grasman, Raoul P. P. P.; Maisto, Stephen A.

    2015-01-01

    Catastrophe theory (Thom, 1972, 1993) is the study of the many ways in which continuous changes in a system’s parameters can result in discontinuous changes in one or several outcome variables of interest. Catastrophe theory–inspired models have been used to represent a variety of change phenomena in the realm of social and behavioral sciences. Despite their promise, widespread applications of catastrophe models have been impeded, in part, by difficulties in performing model fitting and model comparison procedures. We propose a new modeling framework for testing one kind of catastrophe model — the cusp catastrophe model — as a mixture structural equation model (MSEM) when cross-sectional data are available; or alternatively, as an MSEM with regime-switching (MSEM-RS) when longitudinal panel data are available. The proposed models and the advantages offered by this alternative modeling framework are illustrated using two empirical examples and a simulation study. PMID:25822209

  5. Time dependent Schroedinger equation on arbitrary structured grids: Application to photoionization

    SciTech Connect

    Gordon, D.F.; Hafizi, B.

    2012-08-01

    A systematic technique for conservatively discretizing the time dependent Schroedinger equation on an arbitrary structured grid is given. Spatial differencing is carried out by finite volumes, and temporal differencing is carried out semi-implicitly. It is shown that the resulting algorithm conserves probability to within a round-off error regardless of the grid geometry. The algorithm is efficient for both serial and parallel computation. The conservative nature of the algorithm, and its phase accuracy, are demonstrated for a bound state, and for a free state in an electromagnetic field. The ionization rate for a hydrogen atom in a strong electromagnetic field is computed, and compared with the rate from tunneling theory. The regime of validity of tunneling theory is clarified.

  6. Early-Life Socioeconomic Status and Physical Activity in Later Life: Evidence from Structural Equation Models

    PubMed Central

    Pudrovska, Tetyana; Aniskin, Andriy

    2014-01-01

    Objectives This study examines the association between early-life socioeconomic status (SES) at age 18 and physical activity (PA) at age 65, elucidates mechanisms explaining this association, and explores gender differences in mediating pathways. Methods Multi-group structural equation modeling is applied to the 1957–2004 data from the Wisconsin Longitudinal Study. Results Early-life SES is positively associated with exercise in later life. This association is mediated by socioeconomic resources, health problems, obesity, and depressive symptoms (women only) in 1993 and sports participation in 1957. All mediators explain over 95% of the effect of early-life SES. Discussion This study emphasizes the importance of complex multiple pathways linking early family SES to later-life PA. We identify chains of risks that need to be broken to improve PA among older adults. Our findings also suggest that interventions aimed at maintaining optimal physical functioning in old age should begin at least at midlife. PMID:23248349

  7. High Pressure Structures and Equations of State of HIO3 and HI3 O8

    NASA Astrophysics Data System (ADS)

    Zaug, Joseph; Stavrou, Elissaios; Little, Brian; Bastea, Sorin; Crowhurst, Jonathan

    Knowledge of high-pressure thermodynamic properties of iodine containing oxides and acids is important toward improving the accuracy of semi-empirical predictions of extreme condition explosive and combustive chemistry of iodine containing formulations. Here we report on the synthesis of explosive chemical products HIO3 and HI3O8 and on the structures and isotropic equations of state up to 35 and 45 GPa respectively. EOS model parameters are provided including parametrized exponential-6 interatomic potential values used to conduct thermochemical calculations of iodine containing reactants. This work was performed under the auspices of the U.S. Department of Energy jointly by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. High Pressure Structures and Equations of State of HIO3 and HIO3 O8

    NASA Astrophysics Data System (ADS)

    Zaug, Joseph; Stavrou, Elissaios; Little, Brian; Bastea, Sorin; Crowhurst, Jonathan; Chemical Energetics Collaboration

    Knowledge of high-pressure thermodynamic properties of iodine containing oxides and acids is important toward improving the accuracy of semi-empirical predictions of extreme condition explosive and combustive chemistry of iodine containing formulations. Here we report on the synthesis of explosive chemical products HIO3 and HIO3O8 and on the structures and isotropic equations of state up to 35 and 45 GPa respectively. EOS model parameters are provided including parametrized exponential-6 interatomic potential values used to conduct thermochemical calculations of iodine containing reactants. This work was performed under the auspices of the U.S. Department of Energy jointly by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. 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.

  10. From patterns to causal understanding: Structural equation modeling (SEM) in soil ecology

    USGS Publications Warehouse

    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.

  11. Students attitude towards calculus subject: A case-study using structural equation modeling

    NASA Astrophysics Data System (ADS)

    Awang, Noorehan; Hamid, Nur Nadiah Abd.

    2015-10-01

    This study was designed to assess the attitude of Bumiputera students towards mathematics. The instrument used to measure the attitude was Test of Mathematics Related Attitude (TOMRA). This test measures students' attitudes in four criteria: normality of mathematics (N), attitudes towards mathematics inquiry (I), adoption of mathematics attitude (A) and enjoyment of mathematics lessons (E). The target population of this study was all computer science and quantitative science students who enrolled in a Calculus subject at UiTM Negeri Sembilan. Confirmatory Factor Analysis was carried out and the inter-relationship among the four criteria was analyzed using Structural Equation Modeling. The students scored high in E, moderately in A and relatively low in N and I.

  12. A Comparison of Methods for Estimating Quadratic Effects in Nonlinear Structural Equation Models

    PubMed Central

    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

  13. Analyzing average and conditional effects with multigroup multilevel structural equation models

    PubMed Central

    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

  14. Perceptions of ambiguously unpleasant interracial interactions: a structural equation modeling approach.

    PubMed

    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

  15. Maternal, Infant Characteristics, Breastfeeding Techniques, and Initiation: Structural Equation Modeling Approaches

    PubMed Central

    Htun, Tha Pyai; Lim, Peng Im; Ho-Lim, Sarah

    2015-01-01

    Objectives The aim of this study was to examine the relationships among maternal and infant characteristics, breastfeeding techniques, and exclusive breastfeeding initiation in different modes of birth using structural equation modeling approaches. Methods We examined a hypothetical model based on integrating concepts of a breastfeeding decision-making model, a breastfeeding initiation model, and a social cognitive theory among 952 mother-infant dyads. The LATCH breastfeeding assessment tool was used to evaluate breastfeeding techniques and two infant feeding categories were used (exclusive and non-exclusive breastfeeding). Results Structural equation models (SEM) showed that multiparity was significantly positively associated with breastfeeding techniques and the jaundice of an infant was significantly negatively related to exclusive breastfeeding initiation. A multigroup analysis in the SEM showed no difference between the caesarean section and vaginal delivery groups estimates of breastfeeding techniques on exclusive breastfeeding initiation. Breastfeeding techniques were significantly positively associated with exclusive breastfeeding initiation in the entire sample and in the vaginal deliveries group. However, breastfeeding techniques were not significantly associated with exclusive breastfeeding initiation in the cesarean section group. Maternal age, maternal race, gestations, birth weight of infant, and postnatal complications had no significant impacts on breastfeeding techniques or exclusive breastfeeding initiation in our study. Overall, the models fitted the data satisfactorily (GFI = 0.979–0.987; AGFI = 0.951–0.962; IFI = 0.958–0.962; CFI = 0.955–0.960, and RMSEA = 0.029–0.034). Conclusions Multiparity and jaundice of an infant were found to affect breastfeeding technique and exclusive breastfeeding initiation respectively. Breastfeeding technique was related to exclusive breastfeeding initiation according to the mode of birth. This relationship implies the importance of early effective interventions among first-time mothers with jaundice infants in improving breastfeeding techniques and promoting exclusive breastfeeding initiation. PMID:26566028

  16. Integrating occupancy models and structural equation models to understand species occurrence

    PubMed Central

    Joseph, Maxwell B.; Preston, Daniel L.; Johnson, Pieter T. J.

    2016-01-01

    Understanding the drivers of species occurrence is a fundamental goal in basic and applied ecology. Occupancy models have emerged as a popular approach for inferring species occurrence because they account for problems associated with imperfect detection in field surveys. Current models, however, are limited because they assume covariates are independent (i.e., indirect effects do not occur). Here, we combined structural equation and occupancy models to investigate complex influences on species occurrence while accounting for imperfect detection. These two methods are inherently compatible because they both provide means to make inference on latent or unobserved quantities based on observed data. Our models evaluated the direct and indirect roles of cattle grazing, water chemistry, vegetation, nonnative fishes, and pond permanence on the occurrence of six pond-breeding amphibians, two of which are threatened: the California tiger salamander (Ambystoma californiense), and the California red-legged frog (Rana draytonii). While cattle had strong effects on pond vegetation and water chemistry, their overall effects on amphibian occurrence were small compared to the consistently negative effects of nonnative fish. Fish strongly reduced occurrence probabilities for four of five native amphibians, including both species of conservation concern. These results could help to identify drivers of amphibian declines and to prioritize strategies for amphibian conservation. More generally, this approach facilitates a more mechanistic representation of ideas about the causes of species distributions in space and time. As shown here, occupancy modeling and structural equation modeling are readily combined, and bring rich sets of techniques that may provide unique theoretical and applied insights into basic ecological questions. PMID:27197402

  17. Railway noise annoyance: exposure-response relationships and testing a theoretical model by structural equation analysis.

    PubMed

    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

  18. New solutions of the Jacobi equations for three-dimensional Poisson structures

    NASA Astrophysics Data System (ADS)

    Hernández-Bermejo, Benito

    2001-10-01

    A systematic investigation of the skew-symmetric solutions of the three-dimensional Jacobi equations is presented. As a result, three disjoint and complementary new families of solutions are characterized. Such families are very general, thus unifying many different and well-known Poisson structures seemingly unrelated which now appear embraced as particular cases of a more general solution. This unification is not only conceptual but allows the development of algorithms for the explicit determination of important properties such as the symplectic structure, the Casimir invariants and the Darboux canonical form, which are known only for a limited sample of Poisson structures. These common procedures are thus simultaneously valid for all the particular cases which can now be analyzed in a unified and more economic framework, instead of using a case-by-case approach. In addition, the methods developed are valid globally in phase space, thus ameliorating the usual scope of Darboux' reduction which is only of local nature. Finally, the families of solutions found present some new nonlinear superposition principles which are characterized.

  19. Structure-function hierarchies and von Kármán-Howarth relations for turbulence in magnetohydrodynamical equations.

    PubMed

    Basu, Abhik; Naji, Ali; Pandit, Rahul

    2014-01-01

    We generalize the method of A. M. Polyakov, [ Phys. Rev. E 52 6183 (1995)] for obtaining structure-function relations in turbulence in the stochastically forced Burgers equation, to develop structure-function hierarchies for turbulence in three models for magnetohydrodynamics (MHD). These are the Burgers analogs of MHD in one dimension [ Eur. Phys. J. B 9 725 (1999)], and in three dimensions (3DMHD and 3D Hall MHD). Our study provides a convenient and unified scheme for the development of structure-function hierarchies for turbulence in a variety of coupled hydrodynamical equations. For turbulence in the three sets of MHD equations mentioned above, we obtain exact relations for third-order structure functions and their derivatives; these expressions are the analogs of the von Kármán-Howarth relations for fluid turbulence. We compare our work with earlier studies of such relations in 3DMHD and 3D Hall MHD. PMID:24580182

  20. Ab initio studies of equations of state and chemical reactions of reactive structural materials

    NASA Astrophysics Data System (ADS)

    Zaharieva, Roussislava

    The motivations for the research issues addressed in this thesis are based on the needs of the aerospace structural analysis and the design community. The specific focus is related to the characterization and shock induced chemical reactions of multi-functional structural-energetic materials that are also known as the reactive structural materials and their reaction capabilities. Usually motivation for selection of aerospace structural materials is to realize required strength characteristics and favorable strength to weight ratios. The term strength implies resistance to loads experienced during the service life of the structure, including resistance to fatigue loads, corrosion and other extreme conditions. Thus, basically the structural materials are single function materials that resist loads experienced during the service life of the structure. However, it is desirable to select materials that are capable of offering more than one basic function of strength. Very often, the second function is the capability to provide functions of sensing and actuation. In this thesis, the second function is different. The second function is the energetic characteristics. Thus, the choice of dual functions of the material are the structural characteristics and energetic characteristics. These materials are also known by other names such as the reactive material structures or dual functional structural energetic materials. Specifically the selected reactive materials include mixtures of selected metals and metal oxides that are also known as thermite mixtures, reacting intermetallic combinations and oxidizing materials. There are several techniques that are available to synthesize these structural energetic materials or reactive material structures and new synthesis techniques constitute an open research area. The focus of this thesis, however, is the characterization of chemical reactions of reactive material structures that involve two or more solids (or condensed matter). The subject of studies of the shock or thermally induced chemical reactions of the two solids comprising these reactive materials, from first principles, is a relatively new field of study. The published literature on ab initio techniques or quantum mechanics based approaches consists of the ab initio or ab initio-molecular dynamics studies in related fields that contain a solid and a gas. One such study in the literature involves a gas and a solid. This is an investigation of the adsorption of gasses such as carbon monoxide (CO) on Tungsten. The motivation for these studies is to synthesize alternate or synthetic fuel technology by Fischer-Tropsch process. In this thesis these studies are first to establish the procedure for solid-solid reaction and then to extend that to consider the effects of mechanical strain and temperature on the binding energy and chemisorptions of CO on tungsten. Then in this thesis, similar studies are also conducted on the effect of mechanical strain and temperature on the binding energies of Titanium and hydrogen. The motivations are again to understand the method and extend the method to such solid-solid reactions. A second motivation is to seek strained conditions that favor hydrogen storage and strain conditions that release hydrogen easily when needed. Following the establishment of ab initio and ab initio studies of chemical reactions between a solid and a gas, the next step of research is to study thermally induced chemical reaction between two solids (Ni+Al). Thus, specific new studies of the thesis are as follows: (1) Ab initio Studies of Binding energies associated with chemisorption of (a) CO on W surfaces (111, and 100) at elevated temperatures and strains and (b) adsorption of hydrogen in titanium base. (2) Equations of state of mixtures of reactive material structures from ab initio methods. (3) Ab initio studies of the reaction initiation, transition states and reaction products of intermetallic mixtures of (Ni+Al) at elevated temperatures and strains. (4) Press-cure synthesis of Nano-nickel and nano-aluminum based reactive material structures and DTA tests to study experimentally initiation of chemical reactions, due to thermal energy input.

  1. Race/Ethnicity and Social Capital among Middle- and Upper-Middle-Class Elementary School Families: A Structural Equation Model

    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…

  2. Applying Structural Equation Modeling in the Context of the Theory of Reasoned Action: Some Problems and Solutions.

    ERIC Educational Resources Information Center

    van den Putte, Bas; Hoogstraten, Johan

    1997-01-01

    Problems found in the application of structural equation modeling to the theory of reasoned action are explored, and an alternative model specification is proposed that improves the fit of the data while leaving intact the structural part of the model being tested. Problems and the proposed alternative are illustrated. (SLD)

  3. Analysis of structural relationship among the occupational dysfunction on the psychological problem in healthcare workers: a study using structural equation modeling.

    PubMed

    Teraoka, Mutsumi; Kyougoku, Makoto

    2015-01-01

    Purpose. The purpose of this study is to demonstrate the hypothetical model based on structural relationship with the occupational dysfunction on psychological problems (stress response, burnout syndrome, and depression) in healthcare workers. Method. Three cross sectional studies were conducted to assess the following relations: (1) occupational dysfunction on stress response (n = 468), (2) occupational dysfunction on burnout syndrome (n = 1,142), and (3) occupational dysfunction on depression (n = 687). Personal characteristics were collected through a questionnaire (such as age, gender, and job category, opportunities for refreshment, time spent on leisure activities, and work relationships) as well as the Classification and Assessment of Occupational Dysfunction (CAOD). Furthermore, study 1 included the Stress Response Scale-18 (SRS-18), study 2 used the Japanese Burnout Scale (JBS), and study 3 employed the Center for Epidemiological Studies Depression Scale (CES-D). The Kolmogorov-Smirnov test, confirmatory factor analysis (CFA), exploratory factor analysis (EFA), and path analysis of structural equation modeling (SEM) analysis were used in all of the studies. EFA and CFA were used to measure structural validity of four assessments; CAOD, SRS-18, JBS, and CES-D. For examination of a potential covariate, we assessed the correlation of the total and factor score of CAOD and personal factors in all studies. Moreover, direct and indirect effects of occupational dysfunction on stress response (Study 1), burnout syndrome (Study 2), and depression (Study 3) were also analyzed. Results. In study 1, CAOD had 16 items and 4 factors. In Study 2 and 3, CAOD had 16 items and 5 factors. SRS-18 had 18 items and 3 factors, JBS had 17 items and 3 factors, and CES-D had 20 items and 4 factors. All studies found that there were significant correlations between the CAOD total score and the personal factor that included opportunities for refreshment, time spent on leisure activities, and work relationships (p < 0.01). The hypothesis model results suggest that the classification of occupational dysfunction had good fit on the stress response (RMSEA = 0.061, CFI = 0.947, and TLI = 0.943), burnout syndrome (RMSEA = 0.076, CFI = 0.919, and TLI = 0.913), and depression (RMSEA = 0.060, CFI = 0.922, TLI = 0.917). Moreover, the detected covariates include opportunities for refreshment, time spent on leisure activities, and work relationships on occupational dysfunction. Conclusion. Our findings indicate that psychological problems are associated with occupational dysfunction in healthcare workers. Reduction of occupational dysfunction might be a strategy of better preventive occupational therapies for healthcare workers with psychological problems. However, longitudinal studies will be needed to determine a causal relationship. PMID:26618078

  4. Analysis of structural relationship among the occupational dysfunction on the psychological problem in healthcare workers: a study using structural equation modeling

    PubMed Central

    Kyougoku, Makoto

    2015-01-01

    Purpose. The purpose of this study is to demonstrate the hypothetical model based on structural relationship with the occupational dysfunction on psychological problems (stress response, burnout syndrome, and depression) in healthcare workers. Method. Three cross sectional studies were conducted to assess the following relations: (1) occupational dysfunction on stress response (n = 468), (2) occupational dysfunction on burnout syndrome (n = 1,142), and (3) occupational dysfunction on depression (n = 687). Personal characteristics were collected through a questionnaire (such as age, gender, and job category, opportunities for refreshment, time spent on leisure activities, and work relationships) as well as the Classification and Assessment of Occupational Dysfunction (CAOD). Furthermore, study 1 included the Stress Response Scale-18 (SRS-18), study 2 used the Japanese Burnout Scale (JBS), and study 3 employed the Center for Epidemiological Studies Depression Scale (CES-D). The Kolmogorov–Smirnov test, confirmatory factor analysis (CFA), exploratory factor analysis (EFA), and path analysis of structural equation modeling (SEM) analysis were used in all of the studies. EFA and CFA were used to measure structural validity of four assessments; CAOD, SRS-18, JBS, and CES-D. For examination of a potential covariate, we assessed the correlation of the total and factor score of CAOD and personal factors in all studies. Moreover, direct and indirect effects of occupational dysfunction on stress response (Study 1), burnout syndrome (Study 2), and depression (Study 3) were also analyzed. Results. In study 1, CAOD had 16 items and 4 factors. In Study 2 and 3, CAOD had 16 items and 5 factors. SRS-18 had 18 items and 3 factors, JBS had 17 items and 3 factors, and CES-D had 20 items and 4 factors. All studies found that there were significant correlations between the CAOD total score and the personal factor that included opportunities for refreshment, time spent on leisure activities, and work relationships (p < 0.01). The hypothesis model results suggest that the classification of occupational dysfunction had good fit on the stress response (RMSEA = 0.061, CFI = 0.947, and TLI = 0.943), burnout syndrome (RMSEA = 0.076, CFI = 0.919, and TLI = 0.913), and depression (RMSEA = 0.060, CFI = 0.922, TLI = 0.917). Moreover, the detected covariates include opportunities for refreshment, time spent on leisure activities, and work relationships on occupational dysfunction. Conclusion. Our findings indicate that psychological problems are associated with occupational dysfunction in healthcare workers. Reduction of occupational dysfunction might be a strategy of better preventive occupational therapies for healthcare workers with psychological problems. However, longitudinal studies will be needed to determine a causal relationship. PMID:26618078

  5. On the mathematical and geometrical structure of the determining equations for shear waves in nonlinear isotropic incompressible elastodynamics

    NASA Astrophysics Data System (ADS)

    Saccomandi, Giuseppe; Vitolo, Raffaele

    2014-08-01

    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 [Acta Mechanica 3, 167-181 (1967)]. We show that a natural generalization of this class of solutions yields an infinite family of 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.

  6. Full Equations (FEQ) model for the solution of the full, dynamic equations of motion for one-dimensional unsteady flow in open channels and through control structures

    USGS Publications Warehouse

    Franz, Delbert D.; Melching, Charles S.

    1997-01-01

    The Full EQuations (FEQ) model is a computer program for solution of the full, dynamic equations of motion for one-dimensional unsteady flow in open channels and through control structures. A stream system that is simulated by application of FEQ is subdivided into stream reaches (branches), parts of the stream system for which complete information on flow and depth are not required (dummy branches), and level-pool reservoirs. These components are connected by special features; that is, hydraulic control structures, including junctions, bridges, culverts, dams, waterfalls, spillways, weirs, side weirs, and pumps. The principles of conservation of mass and conservation of momentum are used to calculate the flow and depth throughout the stream system resulting from known initial and boundary conditions by means of an implicit finite-difference approximation at fixed points (computational nodes). The hydraulic characteristics of (1) branches including top width, area, first moment of area with respect to the water surface, conveyance, and flux coefficients and (2) special features (relations between flow and headwater and (or) tail-water elevations, including the operation of variable-geometry structures) are stored in function tables calculated in the companion program, Full EQuations UTiLities (FEQUTL). Function tables containing other information used in unsteady-flow simulation (boundary conditions, tributary inflows or outflows, gate settings, correction factors, characteristics of dummy branches and level-pool reservoirs, and wind speed and direction) are prepared by the user as detailed in this report. In the iterative solution scheme for flow and depth throughout the stream system, an interpolation of the function tables corresponding to the computational nodes throughout the stream system is done in the model. FEQ can be applied in the simulation of a wide range of stream configurations (including loops), lateral-inflow conditions, and special features. The accuracy and convergence of the numerical routines in the model are demonstrated for the case of laboratory measurements of unsteady flow in a sewer pipe. Verification of the routines in the model for field data on the Fox River in northeastern Illinois also is briefly discussed. The basic principles of unsteady-flow modeling and the relation between steady flow and unsteady flow are presented. Assumptions and the limitations of the model also are presented. The schematization of the stream system and the conversion of the physical characteristics of the stream reaches and a wide range of special features into function tables for model applications are described. The modified dynamic-wave equation used in FEQ for unsteady flow in curvilinear channels with drag on minor hydraulic structures and channel constrictions determined from an equivalent energy slope is developed. The matrix equation relating flows and depths at computational nodes throughout the stream system by the continuity (conservation of mass) and modified dynamic-wave equations is illustrated for four sequential examples. The solution of the matrix equation by Newton's method is discussed. Finally, the input for FEQ and the error messages and warnings issued are presented.

  7. Structural Equation Modeling Highlights the Potential of Kim-1 as a Biomarker for Chronic Kidney Disease

    PubMed Central

    Gardiner, Lesley; Akintola, Adebayo; Chen, Gang; Catania, Jeffrey M.; Vaidya, Vishal; Burghardt, Robert C.; Bonventre, Joseph V.; Trzeciakowski, Jerome; Parrish, Alan R.

    2012-01-01

    Background Chronic kidney disease (CKD) is a major public health problem, and despite continued research in the field, there is still a need to identify both biomarkers of risk and progression, as well as potential therapeutic targets. Structural equation modeling (SEM) is a family of statistical techniques that has been utilized in the fields of sociology and psychology for many years; however, its utilization in the biological sciences is relatively novel. SEM's ability to investigate complex relationships in an efficient, single model could be utilized to understand the progression of CKD, as well as to develop a predictive model to assess kidney status in the patient. Methods Fischer 344 rats were fed either an ad libitum diet or a calorically restricted diet, and a time-course study of kidney structure and function was performed. EQS, a SEM software package, was utilized to generate five CKD models of the Fisher 344 rat and identify relationships between measured variables and estimates of kidney damage and kidney function. Results All models identified strong relationships between a biomarker for CKD, kidney injury molecule-1 (Kim-1) and kidney damage, in the Fischer 344 rat CKD model. Models also indicate a strong relationship between age and renal damage and dysfunction. Conclusion SEM can be used to model CKD and could be useful to examine biomarkers in CKD patients. PMID:22269876

  8. A structural equation model of plant species richness and its application to a coastal wetland

    USGS Publications Warehouse

    Grace, J.B.; Pugesek, B.H.

    1997-01-01

    Studies of plant species richness have often emphasized the role of either community biomass (as an indicator of density effects) or abiotic factors. In this article we present a general model that simultaneously examines the relative importance of abiotic and density effects. General and specific models were developed to examine the importance of abiotic conditions, disturbance, and community biomass on plant species richness. Models were evaluated using structural equation modeling based on data from 190 plots across a coastal marsh landscape. The accepted model was found to explain 45% of the observed variation in richness, 75% of biomass, and 65% of light penetration. Model results indicate that abiotic conditions have both direct effects on the species pool and indirect effects on richness mediated through effects on biomass and shading. Effects of disturbance were found to be indirect via biomass. Strong density effects on richness were indicated by the results, and canopy light penetration was found to be a better predictor of richness than was biomass. Overall, it appears that richness in this coastal landscape is controlled in roughly equal proportions by abiotic influences on the species pool and density effects, with disturbance playing a lesser role. The structure of the general model presented should be applicable to a wide variety of herbaceous plant communities.

  9. Sample Size Considerations in Prevention Research Applications of Multilevel Modeling and Structural Equation Modeling.

    PubMed

    Hoyle, Rick H; Gottfredson, Nisha C

    2015-10-01

    When the goal of prevention research is to capture in statistical models some measure of the dynamic complexity in structures and processes implicated in problem behavior and its prevention, approaches such as multilevel modeling (MLM) and structural equation modeling (SEM) are indicated. Yet the assumptions that must be satisfied if these approaches are to be used responsibly raise concerns regarding their use in prevention research involving smaller samples. In this article, we discuss in nontechnical terms the role of sample size in MLM and SEM and present findings from the latest simulation work on the performance of each approach at sample sizes typical of prevention research. For each statistical approach, we draw from extant simulation studies to establish lower bounds for sample size (e.g., MLM can be applied with as few as ten groups comprising ten members with normally distributed data, restricted maximum likelihood estimation, and a focus on fixed effects; sample sizes as small as N = 50 can produce reliable SEM results with normally distributed data and at least three reliable indicators per factor) and suggest strategies for making the best use of the modeling approach when N is near the lower bound. PMID:24752569

  10. A structural equation modelling approach examining the pathways between safety climate, behaviour performance and workplace slipping

    PubMed Central

    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

  11. ODEion--a software module for structural identification of ordinary differential equations.

    PubMed

    Gennemark, Peter; Wedelin, Dag

    2014-02-01

    In the systems biology field, algorithms for structural identification of ordinary differential equations (ODEs) have mainly focused on fixed model spaces like S-systems and/or on methods that require sufficiently good data so that derivatives can be accurately estimated. There is therefore a lack of methods and software that can handle more general models and realistic data. We present ODEion, a software module for structural identification of ODEs. Main characteristic features of the software are: • The model space is defined by arbitrary user-defined functions that can be nonlinear in both variables and parameters, such as for example chemical rate reactions. • ODEion implements computationally efficient algorithms that have been shown to efficiently handle sparse and noisy data. It can run a range of realistic problems that previously required a supercomputer. • ODEion is easy to use and provides SBML output. We describe the mathematical problem, the ODEion system itself, and provide several examples of how the system can be used. Available at: http://www.odeidentification.org. PMID:24467754

  12. The Dirac equation in electronic structure calculations: Accurate evaluation of DFT predictions for actinides

    SciTech Connect

    Wills, John M; Mattsson, Ann E

    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.

  13. Stability of solitary structures in the nonlinear Schrödinger equation

    NASA Astrophysics Data System (ADS)

    Rypdal, K.; Rasmussen, J. Juul

    1989-08-01

    The transverse stability of solitary wave structures to the equation iψt + ψxx + sψyy + p|ψ|2ψ = 0 is studied for the four cases; (p = 1, s = 1), (p = 1, s = -1), (p = -1, s = -1) and (p = -1, s = 1). Solitary waves in the x-direction are envelopes ψ = √2 sech(x) exp (it), for p = 1, and they are kinks; ψ = √2 tanh(x) exp (- 2it), for p = -1. For s = 1 an "energy principle" can be invoked, and instability for the envelope occurs in the range 0 < k2 < 3, and for the kink in the range 0 < k2 < 1. Here k is the wavenumber of the perturbation in the y-direction. Growth rates are estimated very simply by means of a Rayleigh-Ritz method. For s = -1, we review existing results for the envelope. It is unstable in a range 0 < k2 <= 1.17 where the upper limit must be determined numerically. For the kink, we find a continuum of unstable, non-local perturbations covering the whole range 0 < k2 < ∞. On both sides of the kink structure (|x| gg 1) these perturbations are oblique, purely growing plane waves. We conclude that both envelopes and kinks are transversely unstable for all signs of p and s.

  14. Attitudes and doping: a structural equation analysis of the relationship between athletes' attitudes, sport orientation and doping behaviour

    PubMed Central

    2007-01-01

    Background For effective deterrence methods, individual, systemic and situational factors that make an athlete or athlete group more susceptible to doping than others should be fully investigated. Traditional behavioural models assume that the behaviour in question is the ultimate end. However, growing evidence suggests that in doping situations, the doping behaviour is not the end but a means to an end, which is gaining competitive advantage. Therefore, models of doping should include and anti-doping policies should consider attitudes or orientations toward the specific target end, in addition to the attitude toward the 'tool' itself. Objectives The aim of this study was to empirically test doping related dispositions and attitudes of competitive athletes with the view of informing anti-doping policy developments and deterrence methods. To this end, the paper focused on the individual element of the drug availability – athlete's personality – situation triangle. Methods Data were collected by questionnaires containing a battery of psychological tests among competitive US male college athletes (n = 199). Outcome measures included sport orientation (win and goal orientation and competitiveness), doping attitude, beliefs and self-reported past or current use of doping. A structural equation model was developed based on the strength of relationships between these outcome measures. Results Whilst the doping model showed satisfactory fit, the results suggested that athletes' win and goal orientation and competitiveness do not play a statistically significant role in doping behaviour, but win orientation has an effect on doping attitude. The SEM analysis provided empirical evidence that sport orientation and doping behaviour is not directly related. Conclusion The considerable proportion of doping behaviour unexplained by the model suggests that other factors play an influential role in athletes' decisions regarding prohibited methods. Future research, followed by policy development, should incorporate these factors to capture the complexity of the doping phenomenon and to identify points for effective anti-doping interventions. Sport governing bodies and anti-doping organisations need to recognise that using performance enhancements may be more of a rational, outcome optimizing behaviour than deviance and consider offering acceptable alternative performance-enhancing methods to doping. PMID:17996097

  15. On the structure of the master equation for a two-level system coupled to a thermal bath

    NASA Astrophysics Data System (ADS)

    de Vega, Inés

    2015-04-01

    We derive a master equation from the exact stochastic Liouville-von-Neumann (SLN) equation (Stockburger and Grabert 2002 Phys. Rev. Lett. 88 170407). The latter depends on two correlated noises and describes exactly the dynamics of an oscillator (which can be either harmonic or present an anharmonicity) coupled to an environment at thermal equilibrium. The newly derived master equation is obtained by performing analytically the average over different noise trajectories. It is found to have a complex hierarchical structure that might be helpful to explain the convergence problems occurring when performing numerically the stochastic average of trajectories given by the SLN equation (Koch et al 2008 Phys. Rev. Lett. 100 230402, Koch 2010 PhD thesis Fakultät Mathematik und Naturwissenschaften der Technischen Universitat Dresden).

  16. Factor Structure of the Primary Scales of the Inventory of Personality Organization in a Nonclinical Sample Using Exploratory Structural Equation Modeling

    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,

  17. Factor Structure of the Primary Scales of the Inventory of Personality Organization in a Nonclinical Sample Using Exploratory Structural Equation Modeling

    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,…

  18. Integrability and structural stability of solutions to the Ginzburg-Landau equation

    NASA Technical Reports Server (NTRS)

    Keefe, Laurence R.

    1986-01-01

    The integrability of the Ginzburg-Landau equation is studied to investigate if the existence of chaotic solutions found numerically could have been predicted a priori. The equation is shown not to possess the Painleveproperty, except for a special case of the coefficients that corresponds to the integrable, nonlinear Schroedinger (NLS) equation. Regarding the Ginzburg-Landau equation as a dissipative perturbation of the NLS, numerical experiments show all but one of a family of two-tori solutions, possessed by the NLS under particular conditions, to disappear under real perturbations to the NLS coefficients of O(10 to the -6th).

  19. The Decision Making Ecology of placing a child into foster care: A structural equation model.

    PubMed

    Graham, J Christopher; Dettlaff, Alan J; Baumann, Donald J; Fluke, John D

    2015-11-01

    The Decision Making Ecology provided a framework for empirically testing the impact of Case, Caseworker and Organizational factors on the decision to place children in out-of-home care. The structural equation model we developed fit the data extremely well, indicating a complex relationship between the variables. The main findings indicate that Case factors, even as aggregated to the worker level, were of most importance: Percent Removed was increased in part by greater average Risk being assessed and more families on a worker's caseload being Low Income. Furthermore, removal rates were increased by lower proportions of Hispanic families on the caseload, as well as lower organizational support, and a perception of manageable workload and sufficient resources. Individual factors, i.e., variables characterizing the caseworkers themselves, were not found to directly influence the placement decision, including workers' own race/ethnicity, though various orders of mediated effects were indicated, and these are detailed. Interrelationships between variables that affect case, caseworker and organizational factors are discussed along with implications for practice. PMID:25861871

  20. Testing hypotheses in evolutionary ecology with imperfect detection: capture-recapture structural equation modeling.

    PubMed

    Cubaynes, Sarah; Doutrelant, Claire; Grégoire, Arnaud; Perret, Philippe; Faivre, Bruno; Gimenez, Olivier

    2012-02-01

    Studying evolutionary mechanisms in natural populations often requires testing multifactorial scenarios of causality involving direct and indirect relationships among individual and environmental variables. It is also essential to account for the imperfect detection of individuals to provide unbiased demographic parameter estimates. To cope with these issues, we developed a new approach combining structural equation models with capture-recapture models (CR-SEM) that allows the investigation of competing hypotheses about individual and environmental variability observed in demographic parameters. We employ Markov chain Monte Carlo sampling in a Bayesian framework to (1) estimate model parameters, (2) implement a model selection procedure to evaluate competing hypotheses about causal mechanisms, and (3) assess the fit of models to data using posterior predictive checks. We illustrate the value of our approach using two case studies on wild bird populations. We first show that CR-SEM can be useful to quantify the action of selection on a set of phenotypic traits with an analysis of selection gradients on morphological traits in Common Blackbirds (Turdus merula). In a second case study on Blue Tits (Cyanistes caeruleus), we illustrate the use of CR-SEM to study evolutionary trade-offs in the wild, while accounting for varying environmental conditions. PMID:22624306

  1. Bayesian model comparison of nonlinear structural equation models with missing continuous and ordinal categorical data.

    PubMed

    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

  2. Determinants of Phubbing, Which is the Sum of Many Virtual Addictions: A Structural Equation Model

    PubMed Central

    Karadağ, Engi̇n; Tosuntaş, Şule Betül; Erzen, Evren; Duru, Pinar; Bostan, Nalan; Şahi̇n, Berrak Mizrak; Çulha, İLKAY; Babadağ, 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

  3. Psychological contract breach and outcomes: Combining meta-analysis and structural equation models.

    PubMed

    Topa Cantisano, Gabriela; Morales Domínguez, J Francisco; Depolo, Marco

    2008-08-01

    In this study, meta-analytic procedures were used to examine the relationships between psychological contract perceived breach and certain outcome variables, such as organizational commitment, job satisfaction and organizational citizenship behaviours (OCB). Our review of the literature generated 41 independent samples in which perceived breach was used as a predictor of these personal and organizational outcomes. A medium effect size (ES) for desirable outcomes (job satisfaction, organizational commitment, organizational trust, OCB and performance) was obtained (r=-.35). For undesirable outcomes (neglect in role duties and intention to leave), ES were also medium (r=.31). When comparing attitudinal (job satisfaction, organizational commitment, organizational trust) and behavioural outcomes (OCB, neglect in role duties and performance), a stronger ES was found for attitudinal (r=-.24) than for behavioural outcomes (r=-.11). Potential moderator variables were examined, and it was found that they explained only a percentage of variability of primary studies. Structural equation analysis of the pooled meta-analytical correlation matrix indicated that the relationships of perceived breach with satisfaction, OCB, intention to leave and performance are fully mediated by organizational trust and commitment. Results are discussed in order to suggest theoretical and empirical implications. PMID:18674448

  4. Analysis of Roadside Air Quality in Jakarta City: A Structural Equation Approach

    NASA Astrophysics Data System (ADS)

    Nugroho, Sudarmanto Budi; Fujiwara, Akimasa; Zhang, Junyi

    Jakarta city has serious air pollution problems which largely affected by transportation activities. In this paper, a comparative analysis of ambient roadside air pollution patterns in Jakarta city was conducted by using time series data at the existing roadside monitoring stations in 2003. The complex cause-effect relationships between meteorology and pollutants, thus, differ from one season to another. This paper attempts to apply structural equation models with latent variables, which represents the above-mentioned cause-effect relationships. The effectiveness of the established models is empirically confirmed that the goodness-of-fit indices are 0.783 for the weekday wet, 0.845 for the weekday dry, 0.775 for the weekend wet, and 0.822 for the weekend dry. The models give us a better way to analyze urban air pollution due to the results of the significant interactions among meteorological factors, wind and primary pollutants, and also their different influences on surface ozone for each season.

  5. Stress and Resilience in Functional Somatic Syndromes – A Structural Equation Modeling Approach

    PubMed Central

    Fischer, Susanne; Lemmer, Gunnar; Gollwitzer, Mario; Nater, Urs M.

    2014-01-01

    Background Stress has been suggested to play a role in the development and perpetuation of functional somatic syndromes. The mechanisms of how this might occur are not clear. Purpose We propose a multi-dimensional stress model which posits that childhood trauma increases adult stress reactivity (i.e., an individual's tendency to respond strongly to stressors) and reduces resilience (e.g., the belief in one's competence). This in turn facilitates the manifestation of functional somatic syndromes via chronic stress. We tested this model cross-sectionally and prospectively. Methods Young adults participated in a web survey at two time points. Structural equation modeling was used to test our model. The final sample consisted of 3′054 participants, and 429 of these participated in the follow-up survey. Results Our proposed model fit the data in the cross-sectional (χ2(21)  = 48.808, p<.001, CFI  = .995, TLI  = .992, RMSEA  = .021, 90% CI [.013.029]) and prospective analyses (χ2(21)  = 32.675, p<.05, CFI  = .982, TLI  = .969, RMSEA  = .036, 90% CI [.001.059]). Discussion Our findings have several clinical implications, suggesting a role for stress management training in the prevention and treatment of functional somatic syndromes. PMID:25396736

  6. Identifying determinants of nations' wetland management programs using structural equation modeling: An exploratory analysis

    USGS Publications Warehouse

    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.

  7. Perievent panic attack and depression after the World Trade Center disaster: a structural equation model analysis.

    PubMed

    Adams, Richard E; Boscarino, Joseph A

    2011-01-01

    Research suggests that perievent panic attacks--panic attacks in temporal proximity to traumatic events--are predictive of later mental health status, including the onset of depression. Using a community sample of New York City residents interviewed 1 year and 2 years after the World Trade Center Disaster, we estimated a structural equation model (SEM) using pre-disaster psychological status and post-disaster life events, together with psychosocial resources, to assess the relationship between perievent panic and later onset depression. Bivariate results revealed a significant association between perievent panic and both year-1 and year-2 depression. Results for the SEM, however showed that perievent panic was predictive of year-1 depression, but not year-2 depression, once potential confounders were controlled Year-2 stressors and year-2 psychosocial resources were the best predictors of year-2 depression onset. Pre-disaster psychological problems were directly implicated in year-1 depression, but not year-2 depression. We conclude that a conceptual model that includes pre- and post-disaster variables best explains the complex causal pathways between psychological status, stressor exposure, perievent panic attacks, and depression onset two years after the World Trade Center attacks. PMID:21957721

  8. A multilevel cross-lagged structural equation analysis for reciprocal relationship between social capital and health.

    PubMed

    Yu, Ge; Sessions, John G; Fu, Yu; Wall, Martin

    2015-10-01

    We investigated the reciprocal relationship between individual social capital and perceived mental and physical health in the UK. Using data from the British Household Panel Survey from 1991 to 2008, we fitted cross-lagged structural equation models that include three indicators of social capital vis. social participation, social network, and loneliness. Given that multiple measurement points (level 1) are nested within individuals (level 2), we also applied a multilevel model to allow for residual variation in the outcomes at the occasion and individual levels. Controlling for gender, age, employment status, educational attainment, marital status, household wealth, and region, our analyses suggest that social participation predicts subsequent change in perceived mental health, and vice versa. However, whilst loneliness is found to be significantly related to perceived mental and physical health, reciprocal causality is not found for perceived mental health. Furthermore, we find evidence for reverse effects with both perceived mental and physical health appearing to be the dominant causal factor with respect to the prospective level of social network. Our findings thus shed further light on the importance of social participation and social inclusion in health promotion and aid the development of more effective public health policies in the UK. PMID:26277109

  9. Perievent Panic Attack and Depression after the World Trade Center Disaster: A Structural Equation Model Analysis

    PubMed Central

    Adams, Richard E.; Boscarino, Joseph A.

    2011-01-01

    Research suggests that perievent panic attacks – panic attacks in temporal proximity to traumatic events – are predictive of later mental health status, including the onset of depression. Using a community sample of New York City residents interviewed 1 year and 2 years after the World Trade Center Disaster, we estimated a structural equation model (SEM) using pre-disaster psychological status and post-disaster life events, together with psychosocial resources, to assess the relationship between perievent panic and later onset depression. Bivariate results revealed a significant association between perievent panic and both year-1 and year-2 depression. Results for the SEM, however, showed that perievent panic was predictive of year-1 depression, but not year-2 depression, once potential confounders were controlled. Year-2 stressors and year-2 psychosocial resources were the best predictors of year-2 depression onset. Pre-disaster psychological problems were directly implicated in year-1 depression, but not year-2 depression. We conclude that a conceptual model that includes pre- and post-disaster variables best explains the complex causal pathways between psychological status, stressor exposure, perievent panic attacks, and depression onset two years after the World Trade Center attacks. PMID:21957721

  10. Testing a theory of aircraft noise annoyance: a structural equation analysis.

    PubMed

    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

  11. A structural equation analysis of family accommodation in pediatric obsessive-compulsive disorder.

    PubMed

    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

  12. Mediation Analysis With Intermediate Confounding: Structural Equation Modeling Viewed Through the Causal Inference Lens

    PubMed Central

    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

  13. Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety

    PubMed Central

    Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

    2015-01-01

    Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb. This study used Monte Carlo data simulation techniques to evaluate sample size requirements for common applied SEMs. Across a series of simulations, we systematically varied key model properties, including number of indicators and factors, magnitude of factor loadings and path coefficients, and amount of missing data. We investigated how changes in these parameters affected sample size requirements with respect to statistical power, bias in the parameter estimates, and overall solution propriety. Results revealed a range of sample size requirements (i.e., from 30 to 460 cases), meaningful patterns of association between parameters and sample size, and highlight the limitations of commonly cited rules-of-thumb. The broad “lessons learned” for determining SEM sample size requirements are discussed. PMID:25705052

  14. Young adults' knowledge of politics: evaluating the role of socio-cognitive variables using structural equations.

    PubMed

    Brussino, Silvina; Medrano, Leonardo; Sorribas, Patricia; Rabbia, Hugo H

    2011-05-01

    The aim of this study was to create an explanatory model that allows analyzing the predictive power of a set of variables related to political knowledge; more specifically, to analyze the relationship between the education level of young adults and the variables, interest in politics and internal political efficacy. We also analyzed the combined relationship between these variables, together with age, and political knowledge. We worked with a sample group of 280 young adults between the ages of 18-30 from the city of Córdoba (Argentina). The data was subjected to a structural equation modelling SEM analysis, which allowed for the corroboration of the following hypotheses: the higher the education level, the more the interest in politics; the higher the education level, the better the perception of internal political efficacy; the higher the education level, the more the political knowledge; the more the interest in politics, the more the political knowledge; and the better the perception of internal political efficacy, the more interest in politics. Moreover, the following hypotheses could not be verified: the older an individual, the more the political knowledge; and the better the perception of internal political efficacy, the more the political knowledge. The model obtained allows for discussion of the explanatory value of these socio-cognitive variables. PMID:21568176

  15. Pediatric Health-Related Quality of Life: A Structural Equation Modeling Approach

    PubMed Central

    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 χ2 = 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

  16. Integrating affective and cognitive correlates of heart rate variability: A structural equation modeling approach.

    PubMed

    Mann, Sarah L; Selby, Edward A; Bates, Marsha E; Contrada, Richard J

    2015-10-01

    High frequency heart rate variability (HRV) is a measure of neurocardiac communication thought to reflect predominantly parasympathetic cardiac regulation. Low HRV has been associated empirically with clinical and subclinical levels of anxiety and depression and, more recently, high levels of HRV have been associated with better performance on some measures of executive functioning (EF). These findings have offered support for theories proposing HRV as an index measure of a broad, self-regulatory capacity underlying aspects of emotion regulation and executive control. This study sought to test that proposition by using a structural equation modeling approach to examine the relationships of HRV to negative affect (NA) and EF in a large sample of U.S. adults ages 30s-80s. HRV was modeled as a predictor of an NA factor (self-reported trait anxiety and depression symptoms) and an EF factor (performance on three neuropsychological tests tapping facets of executive abilities). Alternative models also were tested to determine the utility of HRV for predicting NA and EF, with and without statistical control of demographic and health-related covariates. In the initial structural model, HRV showed a significant positive relationship to EF and a nonsignificant relationship to NA. In a covariate-adjusted model, HRV's associations with both constructs were nonsignificant. Age emerged as the only significant predictor of NA and EF in the final model, showing inverse relationships to both. Findings may reflect population and methodological differences from prior research; they also suggest refinements to the interpretations of earlier findings and theoretical claims regarding HRV. PMID:26168884

  17. The Questionnaire of Lifestyle Change in Regard to Problematic Internet Use: Factor Structure and Concurrent and Cross-Year Predictive Utilities

    ERIC Educational Resources Information Center

    Yeh, Yu-Chen; Lin, Sunny S. J.; Tseng, Yin-Hsing; Hwang, Fang-Ming

    2012-01-01

    This study constructed a questionnaire, named "Lifestyle Change in Regard to Problematic Internet Use (LC-PIU)," for helping school psychologists detect early indications of PIU-related lifestyle changes in university populations. Our focus is on all university students who use the Internet, not users who already show dependent symptoms. The…

  18. Narcotics Center Questionnaire, 1968.

    ERIC Educational Resources Information Center

    Marks, John B.; And Others

    This questionnaire assesses drug knowledge, drug use practices, and attitudes toward drugs in junior high school, senior high school, and college students. The 105 items (multiple choice, yes/no, or completion) are concerned with personal and demographic data, "book" knowledge of drugs, "street" knowledge of drugs (drug argot and the like),…

  19. 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…

  20. Facilities Sharing Questionnaire Survey.

    ERIC Educational Resources Information Center

    California Community Colleges, Sacramento. Office of the Chancellor.

    In order to determine the extent to which the California community colleges share and borrow facilities, a questionnaire was sent to each California community college in January 1974. Sixty-six (96 percent) of the 69 districts responded. Analysis of the data revealed that the typical campus shared 7.5 facilities and borrowed 5.6. More than 37…