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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. 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

  5. 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

  6. 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

  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. 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.

  9. 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…

  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

    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…

  12. 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

  13. Generalized Multilevel Structural Equation Modeling

    ERIC Educational Resources Information Center

    Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

    2004-01-01

    A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent

  14. 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.

  15. 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 students ability to correctly identify any of the 17 features. Conclusions A structured questionnaire significantly improves a medical students 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

  16. 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

  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. 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).…

  19. 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…

  20. 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

  1. Revisiting the Factor Structure of the Questionnaire on Smoking Urges

    ERIC Educational Resources Information Center

    Toll, Benjamin A.; McKee, Sherry A.; Krishnan-Sarin, Suchitra; O'Malley, Stephanie S.

    2004-01-01

    This study assessed the factor structure of the Questionnaire on Smoking Urges (QSU), a commonly used assessment of cravings for cigarettes, with a sample of smokers presenting for treatment in a smoking cessation trial. On the basis of previous research, three confirmatory factor analytic models were tested. Model 1 hypothesized a 26-item,

  2. 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).

  3. 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

  4. Validity, reliability, and factor structure of the Anorectic Cognitions Questionnaire.

    PubMed

    Mizes, J S; Klesges, R C

    1989-01-01

    Several authors have hypothesized cognitive distortion as central to the psychopathology of anorexia nervosa and bulimia. However, there have been few investigations of these hypotheses. Equally as important, psychometrically sound devices for assessing these cognitions are notably lacking. The purpose of this investigation is to examine the psychometric characteristics of the Anorectic Cognitions Questionnaire (MAC). This study reports on initial item development, initial concurrent validity, factor structure, initial item refinement, and internal consistency. Results indicated that the MAC has good concurrent validity, three theoretically defined factors were empirically supported, and the scale is internally consistent. PMID:2589139

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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…

  11. 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

  12. 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.

  13. 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].

  14. 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,

  15. 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

  16. Composite Reliability in Structural Equations Modeling.

    ERIC Educational Resources Information Center

    Bacon, Donald R.; And Others

    1995-01-01

    The potential for bias in reliability estimation and for errors in item selection when alpha or unit-weighted omega coefficients are used is explored under simulated conditions. Results suggest that composite reliability may be an assessment tool but should not be an item selection tool in structural equations. (SLD)

  17. Confirmation Bias in Structural Equation Modeling.

    ERIC Educational Resources Information Center

    Robles, Jaime

    1996-01-01

    A theoretical and philosophical revision of the concept of fit in structural equation modeling and its relation to a confirmation bias is developed. The neutral character of fit indexes regarding this issue is argued, concluding that protection against confirmation bias relies on model modification strategy and scientist behavior. (SLD)

  18. 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.

  19. 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

  20. Generalized Ideal Gas Equations for Structureful Universe

    NASA Astrophysics Data System (ADS)

    Afridi, Shahid N.; Khan, Khalid

    2006-09-01

    We have derived generalized ideal gas equations for a structureful universe consistingof all forms of matters. We have assumed a universe that contains superclusters. Superclusters arethen made of clusters. Each cluster can be further divided into smaller ones and so on. We havederived an expression for the entropy of such a universe. Our model is rather independent of thegeometry of the intermediate clusters. Our calculations are valid for a non-interacting universewithin non-relativistic limits. We suggest that structure formation can reduce the expansion rateof the universe.

  1. 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

  2. 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

  3. Testing Structural Invariance of the Achievement Goal Questionnaire in American, Chinese, and Dutch College Students

    ERIC Educational Resources Information Center

    Sun, Huaping; Hernandez, Diley

    2012-01-01

    This study investigates the structural invariance of the Achievement Goal Questionnaire (AGQ) in American, Chinese, and Dutch college students. Using confirmatory factor analyses (CFA), the authors found evidence for the four-factor structure of achievement goals in all three samples. Subsequent multigroup CFAs supported structural invariance of

  4. 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…

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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…

  10. 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

  11. 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

  12. 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

  13. How does severe brachycephaly affect dog's lives? Results of a structured preoperative owner questionnaire.

    PubMed

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

    2013-12-01

    Brachycephalic syndrome (BS) is a complex canine disease, which is characterized by diverse clinical signs primarily involving the respiratory and gastrointestinal systems. Through a structured owner questionnaire, the present study investigated how owners perceived the frequency and severity of a broad spectrum of welfare-relevant impairments caused by this hereditary disease. One hundred owners of brachycephalic dogs (Pugs and French bulldogs) referred for surgical treatment of BS completed the questionnaire. As a basis for comparison, 20 owners of mesocephalic dogs also completed part of the questionnaire. Questionnaire responses revealed that in addition to the well-known respiratory signs, brachycephalic dogs experienced severe exercise intolerance and prolonged recovery time after physical exercise (88%), significant heat sensitivity (more severe signs at temperatures above 19C; 50%) and a variety of sleep problems (56%). To our knowledge, this is the first study using a structured owner questionnaire specifically to investigate a broad range of problems caused by selective breeding for brachycephaly. In particular, decreased exercise tolerance, increased recovery time due to heat intolerance and the extent of sleep problems have either been underestimated in the past, or have severely worsened over recent generations of dogs. The extent and severity of clinical signs and their impact on quality of life greatly exceeded our expectations. This study emphasizes the major impact that selective breeding for extreme brachycephalic features has on animal welfare. PMID:24176279

  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. 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

  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 and Measurement Invariance of the Cognitive Failures Questionnaire across the Adult Life Span

    ERIC Educational Resources Information Center

    Rast, Philippe; Zimprich, Daniel; Van Boxtel, Martin; Jolles, Jellemer

    2009-01-01

    The Cognitive Failures Questionnaire (CFQ) is designed to assess a person's proneness to committing cognitive slips and errors in the completion of everyday tasks. Although the CFQ is a widely used instrument, its factor structure remains an issue of scientific debate. The present study used data of a representative sample (N = 1,303, 24-83 years

  18. 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…

  19. Effect of questionnaire structure on recall of drug utilization in a population of university students

    PubMed Central

    2009-01-01

    Background Self-reported data are a common source of information about drug exposure. Modes of data collection differ considerably and the questionnaire's structure may affect prevalence estimates. We compared the recall of medication use evaluated by means of two questionnaires differing in structure and length. Methods Drug utilization was assessed by two alternative versions of a questionnaire (A 4 pages, including specific questions for 12 indications/pharmacological groups and one question for "other medicines"; B 1 page, including 1 open-ended question to cover overall drug consumption). Each of 32 classes in a private University in Maputo, Mozambique, was randomly assigned questionnaire A (233 participants) or B (276 participants). Logistic regression (allowing for clustering by classroom) was used to compare the two groups in terms of socio-demographic characteristics and medication used during the previous month. Results Overall, 67.4% of the subjects had used at least one drug during the previous month. The following prevalences were greater among participants completing questionnaire A: use of drugs from two or more pharmacological groups (60.5% vs. 34.4%, p < 0.001), use of two or more drugs (66.2% vs. 43.0%, p < 0.001), and use of antibiotics (14.6% vs. 6.9%, p = 0.001), antifungals (9.4% vs. 4.0%, p = 0.013), antiparasitics (5.6% vs. 1.8%, p = 0.031) and antacids (8.6% vs. 3.6%, p = 0.024). Information about duration of treatment and medical advice was more complete with version A. Conclusion The indication/drug-specific questions (questionnaire A) revealed a significantly higher prevalence of use of medicines antibiotics, antifungals, antiparasitics and antacids without compromising the completeness of the information. PMID:19563651

  20. Generalized Appended Product Indicator Procedure for Nonlinear Structural Equation Analysis.

    ERIC Educational Resources Information Center

    Wall, Melanie M.; Amemiya, Yasuo

    2001-01-01

    Considers the estimation of polynomial structural models and shows a limitation of an existing method. Introduces a new procedure, the generalized appended product indicator procedure, for nonlinear structural equation analysis. Addresses statistical issues associated with the procedure through simulation. (SLD)

  1. 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…

  2. Two Rules of Identification for Structural Equation Models

    ERIC Educational Resources Information Center

    Bollen, Kenneth A.; Davis, Walter R.

    2009-01-01

    Identification of structural equation models remains a challenge to many researchers. Although empirical tests of identification are readily available in structural equation modeling software, these examine local identification and rely on sample estimates of parameters. Rules of identification are available, but do not include all models

  3. 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

  4. 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)

  5. 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

  6. 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.

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

    PubMed

    Raffan, Eleanor; 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. 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

  9. 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

  10. 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…

  11. 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.

  12. 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

  13. 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

  14. Internal consistency and factor structure of 12-item general health questionnaire in visually impaired students

    PubMed Central

    Bakhla, Ajay Kumar; Verma, Vijay; Hembram, Mahesh; Praharaj, Samir Kumar; Sinha, Vinod Kumar

    2013-01-01

    Background: As there are no instruments to measure psychological wellness or distress in visually impaired students, we studied internal consistency and factor structure of GHQ-12 in visually impaired children. Materials and Methods: Internal consistency analysis (Cronbach's alpha and item total correlation) and exploratory factor analysis (principal component analysis) were carried out to identify factor structure of 12-item general health questionnaire (GHQ-12). Results: All items of GHQ-12 were significantly associated with each other and the Cronbach's alpha coefficient for the scale was 0.7. On analysis of principal component, three-factor solution was found that accounted for 47.92% of the total variance. The factors included, general well-being, depression and cognitive, with Cronbach's alpha coefficients being 0.70, 0.59, and 0.34, respectively. Conclusion: Our study findings suggest GHQ-12 is a reliable with adequate internal consistency scale and multidimensional factor structure in visually impaired students. PMID:25013310

  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. 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

  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. 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…

  20. 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…

  1. Examination of the factor structure of the Schizotypal Personality Questionnaire among British and Trinidadian adults.

    PubMed

    Barron, David; Swami, Viren; Towell, Tony; Hutchinson, Gerard; Morgan, Kevin D

    2015-01-01

    Much debate in schizotypal research has centred on the factor structure of the Schizotypal Personality Questionnaire (SPQ), with research variously showing higher-order dimensionality consisting of two to seven dimensions. In addition, cross-cultural support for the stability of those factors remains limited. Here, we examined the factor structure of the SPQ among British and Trinidadian adults. Participants from a White British subsample (n = 351) resident in the UK and from an African Caribbean subsample (n = 284) resident in Trinidad completed the SPQ. The higher-order factor structure of the SPQ was analysed through confirmatory factor analysis, followed by multiple-group analysis for the model of best fit. Between-group differences for sex and ethnicity were investigated using multivariate analysis of variance in relation to the higher-order domains. The model of best-fit was the four-factor structure, which demonstrated measurement invariance across groups. Additionally, these data had an adequate fit for two alternative models: (a) 3-factor and (b) modified 4-factor model. The British subsample had significantly higher scores across all domains than the Trinidadian group, and men scored significantly higher on the disorganised domain than women. The four-factor structure received confirmatory support and, importantly, support for use with populations varying in ethnicity and culture. PMID:25699263

  2. 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

  3. The Otitis Media-6 questionnaire: psychometric properties with emphasis on factor structure and interpretability

    PubMed Central

    2013-01-01

    Background The Otitis Media-6 questionnaire (OM-6) is the most frequently used instrument to measure health related quality of life in children with otitis media. The main objectives of this study are 1) to translate and cross-culturally adapt the OM-6 into Danish, and 2) to assess important psychometric properties including structural validity and interpretability of the OM-6 in a Danish population of children suffering from otitis media. Methods The OM-6 was translated and cross-culturally adapted according to international guidelines. A longitudinal validation study enrolled 491 children and their families, and the measurement properties of the OM-6 were evaluated using the Cosmin taxonomy. The properties assessed were construct and structural validity (confirmatory factor analysis) including internal consistency, reproducibility (test-retest reliability and smallest detectable change), responsiveness and interpretability. Results A total of 435 children were eligible to participate in the study. Analyses of structural validity and internal consistency indicated that parent appraisal of hearing and speech problems may be problematic. Both scales showed similarly good test-retest reliability and construct validity, were able to discriminate between diagnostic subgroups and responsive to change. Cut-off values of 16.7 and 30.0 were found to represent minimal important change for the patients. Conclusions The Danish version of the OM-6 is a reliable, valid, responsive and interpretable questionnaire to measure quality of life in children with otitis media. This study sheds light on possible weaknesses of the instrument that needs to be acknowledged in the utilization of the instrument. However, despite these issues our results support the continuing use of OM-6 as a 1-factor functional health scale with a separate global health rating. Furthermore, indications of values representing minimal important change as perceived by the respondent are presented. PMID:24257471

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

    PubMed

    Pichardo, Carmen; Justicia, Fernando; de la Fuente, Jess; Martnez-Vicente, Jos Manuel; Berbn, 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

  5. On third Poisson structure of KdV equation

    SciTech Connect

    Gorsky, A.; Marshakov, A.; Orlov, A.

    1995-12-01

    The third Poisson structure of the KdV equation in terms of canonical {open_quote}free fields{close_quote} and the reduced WZNW model is discussed. We prove that it is {open_quotes}diagonalized{close_quotes} in the Lagrange variables which were used before in the formulation of 2d gravity. We propose a quantum path integral for the KdV equation based on this representation.

  6. Eating Disorder Examination-Questionnaire Factor Structure and Construct Validity In Bariatric Surgery Candidates

    PubMed Central

    Grilo, Carlos M.; Henderson, Kathryn E.; Bell, Robert L.; Crosby, Ross D.

    2012-01-01

    Objective The Eating Disorder Examination-Questionnaire (EDE-Q) is increasingly used in studies with bariatric surgery patients although little is known about psychometric properties of this self-report measure in this clinical group. The current study evaluated the factor structure and construct validity of the EDE-Q in bariatric surgery candidates. Methods Participants were a consecutive series of 174 obese bariatric surgery candidates 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 obese samples. CFA supported a 7-item, 3-factor structure; the three factors were interpreted as dietary restraint, shape/weight overvaluation, and body dissatisfaction. The three factors converged with other relevant collateral measures. Conclusions These factor analytic findings, which replicate recent findings from studies with diverse obese samples, demonstrated convergent validity. Implications of these findings for clinical assessment and research with bariatric surgery patients are discussed. PMID:23229951

  7. 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

  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. 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

  10. Consistent Partial Least Squares for nonlinear structural equation models.

    PubMed

    Dijkstra, Theo K; Schermelleh-Engel, Karin

    2014-10-01

    Partial Least Squares as applied to models with latent variables, measured indirectly by indicators, is well-known to be inconsistent. The linear compounds of indicators that PLS substitutes for the latent variables do not obey the equations that the latter satisfy. We propose simple, non-iterative corrections leading to consistent and asymptotically normal (CAN)-estimators for the loadings and for the correlations between the latent variables. Moreover, we show how to obtain CAN-estimators for the parameters of structural recursive systems of equations, containing linear and interaction terms, without the need to specify a particular joint distribution. If quadratic and higher order terms are included, the approach will produce CAN-estimators as well when predictor variables and error terms are jointly normal. We compare the adjusted PLS, denoted by PLSc, with Latent Moderated Structural Equations (LMS), using Monte Carlo studies and an empirical application. PMID:24306555

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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

  16. A Structural Equation Model of Conceptual Change in Physics

    ERIC Educational Resources Information Center

    Taasoobshirazi, Gita; Sinatra, Gale M.

    2011-01-01

    A model of conceptual change in physics was tested on introductory-level, college physics students. Structural equation modeling was used to test hypothesized relationships among variables linked to conceptual change in physics including an approach goal orientation, need for cognition, motivation, and course grade. Conceptual change in physics

  17. 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…

  18. 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…

  19. People Are Variables Too: Multilevel Structural Equations Modeling

    ERIC Educational Resources Information Center

    Mehta, Paras D.; Neale, Michael C.

    2005-01-01

    The article uses confirmatory factor analysis (CFA) as a template to explain didactically multilevel structural equation models (ML-SEM) and to demonstrate the equivalence of general mixed-effects models and ML-SEM. An intuitively appealing graphical representation of complex ML-SEMs is introduced that succinctly describes the underlying model and

  20. 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,

  1. 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

  2. Asymptotic Biases in Exploratory Factor Analysis and Structural Equation Modeling

    ERIC Educational Resources Information Center

    Ogasawara, Haruhiko

    2004-01-01

    Formulas for the asymptotic biases of the parameter estimates in structural equation models are provided in the case of the Wishart maximum likelihood estimation for normally and nonnormally distributed variables. When multivariate normality is satisfied, considerable simplification is obtained for the models of unstandardized variables. Formulas

  3. 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…

  4. 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…

  5. 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

  6. 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

  7. 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)

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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…

  13. Multilevel Analysis of Structural Equation Models via the EM Algorithm.

    ERIC Educational Resources Information Center

    Jo, See-Heyon

    The question of how to analyze unbalanced hierarchical data generated from structural equation models has been a common problem for researchers and analysts. Among difficulties plaguing statistical modeling are estimation bias due to measurement error and the estimation of the effects of the individual's hierarchical social milieu. This paper

  14. Effects of Employing Ridge Regression in Structural Equation Models.

    ERIC Educational Resources Information Center

    McQuitty, Shaun

    1997-01-01

    LISREL 8 invokes a ridge option when maximum likelihood or generalized least squares are used to estimate a structural equation model with a nonpositive definite covariance or correlation matrix. Implications of the ridge option for model fit, parameter estimates, and standard errors are explored through two examples. (SLD)

  15. 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

  16. 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…

  17. Dysfunctional Cognitions in Personality Pathology: The Structure and Validity of the Personality Belief Questionnaire

    PubMed Central

    Fournier, Jay C.; DeRubeis, Robert J.; Beck, Aaron T.

    2013-01-01

    Background This study examines the structure of the Personality Belief Questionnaire (PBQ), a self-report instrument designed to assess dysfunctional beliefs associated with personality pathology, as proposed by the cognitive theory of personality dysfunction. Methods The PBQ was examined using exploratory factor analysis with responses from 438 depressed outpatients, and confirmatory factor analysis with responses from 683 treatment-seeking psychiatric outpatients. All participants were assessed for personality disorder using a standard clinical interview. The validity of the resulting factor structure was assessed in the combined sample (N=1121) by examining PBQ scores for patients with and without personality disorder diagnoses. Results Exploratory and confirmatory analyses converged to indicate that the PBQ is best described by 7 empirically identified factors: 6 assess dysfunctional beliefs associated with forms of personality pathology recognized in DSM-IV. Validity analyses revealed that those diagnosed with a personality disorder evidenced a higher average score on all factors, relative to those without these disorders. Subsets of patients diagnosed with specific DSM-IV personality disorders scored higher, on average, on the factor associated with their respective diagnosis, relative to all other factors. Conclusions The pattern of results has implications for the conceptualization of personality pathology. To our knowledge, no formal diagnostic or assessment system has yet systematically incorporated the role of dysfunctional beliefs into its description of personality pathology. The identification of dysfunctional beliefs may not only aid in case conceptualization, but may provide unique targets for psychological treatment. Recommendations for future personality pathology assessment systems are provided. PMID:21910933

  18. 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.

  19. 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.…

  20. 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

  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. 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

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

    PubMed Central

    Cecchini, Jose A.; Fernndez-Rio, Javier; Mndez-Gimnez, 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

  6. 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.

  7. 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

  8. 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

  9. 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…

  10. 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

  11. 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…

  12. 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

  13. A Validation Study of the Dutch Childhood Trauma Questionnaire-Short Form: Factor Structure, Reliability, and Known-Groups Validity

    ERIC Educational Resources Information Center

    Thombs, Brett D.; Bernstein, David P.; Lobbestael, Jill; Arntz, Arnoud

    2009-01-01

    Objective: The 28-item Childhood Trauma Questionnaire-Short Form (CTQ-SF) has been translated into at least 10 different languages. The validity of translated versions of the CTQ-SF, however, has generally not been examined. The objective of this study was to investigate the factor structure, internal consistency reliability, and known-groups

  14. 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,

  15. 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

  16. 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

  17. General health questionnaire - 12: psychometric properties and factor structure among Indian women living in the United kingdom.

    PubMed

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

    1997-07-01

    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

  18. 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

  19. Crystal structure optimisation using an auxiliary equation of state

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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.

  20. Model fit evaluation in multilevel structural equation models

    PubMed Central

    Ryu, Ehri

    2014-01-01

    Assessing goodness of model fit is one of the key questions in structural equation modeling (SEM). Goodness of fit is the extent to which the hypothesized model reproduces the multivariate structure underlying the set of variables. During the earlier development of multilevel structural equation models, the standard approach was to evaluate the goodness of fit for the entire model across all levels simultaneously. The model fit statistics produced by the standard approach have a potential problem in detecting lack of fit in the higher-level model for which the effective sample size is much smaller. Also when the standard approach results in poor model fit, it is not clear at which level the model does not fit well. This article reviews two alternative approaches that have been proposed to overcome the limitations of the standard approach. One is a two-step procedure which first produces estimates of saturated covariance matrices at each level and then performs single-level analysis at each level with the estimated covariance matrices as input (Yuan and Bentler, 2007). The other level-specific approach utilizes partially saturated models to obtain test statistics and fit indices for each level separately (Ryu and West, 2009). Simulation studies (e.g., Yuan and Bentler, 2007; Ryu and West, 2009) have consistently shown that both alternative approaches performed well in detecting lack of fit at any level, whereas the standard approach failed to detect lack of fit at the higher level. It is recommended that the alternative approaches are used to assess the model fit in multilevel structural equation model. Advantages and disadvantages of the two alternative approaches are discussed. The alternative approaches are demonstrated in an empirical example. PMID:24550882

  1. 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…

  2. 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

  3. Factor Structure and Predictive Validity of Questionnaire Reports on Family Problem Solving.

    ERIC Educational Resources Information Center

    Vuchinich, Samuel; De Baryshe, Barbara

    1997-01-01

    Examines mother, father, and youth questionnaire reports on family problem solving in 55 Asian American and Pacific Island American families. Results indicate that perceptions linked to the respondent's family role best accounted for the ratings' pattern. Predictive validity depended on family role: mothers' perceptions predicted delinquency and

  4. 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

  5. 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.

  6. 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…

  7. 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).…

  8. 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).

  9. Reliability of Scales with General Structure: Point and Interval Estimation Using a Structural Equation Modeling Approach.

    ERIC Educational Resources Information Center

    Raykov, Tenko; Shrout, Patrick E.

    2002-01-01

    Discusses a method for obtaining point and interval estimates of reliability for composites of measures with a general structure. The approach is based on fitting a correspondingly constrained structural equation model and generalizes earlier covariance structure analysis methods for scale reliability estimation with congeneric tests. (SLD)

  10. The Importance of Structure Coefficients in Structural Equation Modeling Confirmatory Factor Analysis.

    ERIC Educational Resources Information Center

    Thompson, Bruce

    A general linear model (GLM) framework is used to suggest that structure coefficients ought to be interpreted in structural equation modeling confirmatory factor analysis (CFA) studies in which factors are correlated. The computation of structure coefficients in explanatory factor analysis and CFA is explained. Two heuristic data sets are used to

  11. 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

  12. A semiparametric Bayesian approach for structural equation models.

    PubMed

    Song, Xin-Yuan; Pan, Jun-Hao; Kwok, Timothy; Vandenput, Liesbeth; Ohlsson, Claes; Leung, Ping-Chung

    2010-06-01

    In the development of structural equation models (SEMs), observed variables are usually assumed to be normally distributed. However, this assumption is likely to be violated in many practical researches. As the non-normality of observed variables in an SEM can be obtained from either non-normal latent variables or non-normal residuals or both, semiparametric modeling with unknown distribution of latent variables or unknown distribution of residuals is needed. In this article, we find that an SEM becomes nonidentifiable when both the latent variable distribution and the residual distribution are unknown. Hence, it is impossible to estimate reliably both the latent variable distribution and the residual distribution without parametric assumptions on one or the other. We also find that the residuals in the measurement equation are more sensitive to the normality assumption than the latent variables, and the negative impact on the estimation of parameters and distributions due to the non-normality of residuals is more serious. Therefore, when there is no prior knowledge about parametric distributions for either the latent variables or the residuals, we recommend making parametric assumption on latent variables, and modeling residuals nonparametrically. We propose a semiparametric Bayesian approach using the truncated Dirichlet process with a stick breaking prior to tackle the non-normality of residuals in the measurement equation. Simulation studies and a real data analysis demonstrate our findings, and reveal the empirical performance of the proposed methodology. A free WinBUGS code to perform the analysis is available in Supporting Information. PMID:20533410

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Reliability and factorial structure of the Chinese version of the General Health Questionnaire.

    PubMed

    Shek, D T

    1987-11-01

    The Chinese version of the General Health Questionnaire (GHQ) was administered to 2,150 Chinese secondary school students. The GHQ was found to have high internal consistency as a scale and high item-total correlations for most of the items. Factor analysis with a five-factor solution showed that five factors were abstracted from the scale, namely, anxiety, depression, inadequate coping, interpersonal dysfunctioning, and sleep disturbances. By randomly splitting the total sample into two subsamples, these five factors could be reproduced reliably, and high coefficients of congruence were found. The psychometric properties of the Chinese version of the GHQ and the implications of the findings were discussed. PMID:3693557

  19. The algebraic structure behind the derivative nonlinear Schrdinger equation

    NASA Astrophysics Data System (ADS)

    Frana, G. S.; Gomes, J. F.; Zimerman, A. H.

    2013-08-01

    The Kaup-Newell (KN) hierarchy contains the derivative nonlinear Schrdinger equation (DNLSE) amongst others interesting and important nonlinear integrable equations. In this paper, a general higher grading affine algebraic construction of integrable hierarchies is proposed and the KN hierarchy is established in terms of an \\hat{s\\ell }_2 Kac-Moody algebra and principal gradation. In this form, our spectral problem is linear in the spectral parameter. The positive and negative flows are derived, showing that some interesting physical models arise from the same algebraic structure. For instance, the DNLSE is obtained as the second positive, while the Mikhailov model as the first negative flows. The equivalence between the latter and the massive Thirring model is also explicitly demonstrated. The algebraic dressing method is employed to construct soliton solutions in a systematic manner for all members of the hierarchy. Finally, the equivalence of the spectral problem introduced in this paper with the usual one, which is quadratic in the spectral parameter, is achieved by setting a particular automorphism of the affine algebra, which maps the homogeneous into principal gradation.

  20. 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

  1. 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.

  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. Coagulation-diffusion systems: Derivation and existence of solutions for the diffuse interface structure equations

    NASA Astrophysics Data System (ADS)

    Slemrod, M.

    1990-12-01

    This paper considers an infinite system of partial differential equations, the coagulation-diffusion equations, which add spatial diffusion to the classical coagulation equations. The main emphasis is placed on deriving an infinite system of ordinary differential equations which described the structured interface between reacting coagulation and dilute concentration. Existence of solutions to interfacial equaitons is proven under spatial boundary conditions.

  5. 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

  6. 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…

  7. 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.

  8. Two-vortex structure of electron, nonlocality and Dirac equation

    NASA Astrophysics Data System (ADS)

    Tiwari, S. C.

    2012-02-01

    The dimensionless electromagnetic coupling constant ?=e2/planckc may have three interpretations: as the well-known ratio between the electron charge radius e2/mc2 and the Compton wavelength of an electron ?c=planck/mc, as the ratio of two angular momenta since the Planck constant has the dimension of angular momentum and as the ratio of two flux quanta e and hc/e . The anomalous part of the electron magnetic moment together with the unified picture of the three interpretations of ? is suggested to have deep physical significance. The electric charge is proposed to be a new quantum of flux that leads to a new model of the electron envisaging a two-vortex structure. In analogy with quantum conditions, we postulate sub-quantum conditions applicable in a region of the order of ?c replacing planck by a universal constant f=e2/2?c and we apply it to the Dirac equation in internal space that gives rise to the anomalous magnetic moment of an electron. The Dirac spinor and two-spinor representations for the vortex structure of an electron in the single-particle Dirac framework are discussed. The role of sub-quantum rules and internal variables in developing the present ideas is also discussed. A critical discussion of past attempts at giving fundamental importance to magnetism and flux quantum is presented in order to delineate the new ideas in the present work.

  9. A First Look at the Structured Clinical Interview for "DSM-IV" Personality Disorders Screening Questionnaire: More Than Just a Screener?

    ERIC Educational Resources Information Center

    Piedmont, Ralph L.; Sherman, Martin F.; Sherman, Nancy C.; Williams, Joseph E. G.

    2003-01-01

    This study examined the psychometrics of the Structured Clinical Interview for DSM-IV Personality Disorders Personality Questionnaire (SCID-IIP) self-report personality questionnaire. The responses to the instrument were found reliable and evidenced good self-other convergence. Correlations with external criteria showed the SCID-IIP to contain

  10. 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

  11. Structural Equation Modeling for Analyzing Erythrocyte Fatty Acids in Framingham

    PubMed Central

    Pottala, James V.; Djira, Gemechis D.; Espeland, Mark A.; Larson, Martin G.; Harris, William S.

    2014-01-01

    Research has shown that several types of erythrocyte fatty acids (i.e., omega-3, omega-6, and trans) are associated with risk for cardiovascular diseases. However, there are complex metabolic and dietary relations among fatty acids, which induce correlations that are typically ignored when using them as risk predictors. A latent variable approach could summarize these complex relations into a few latent variable scores for use in statistical models. Twenty-two red blood cell (RBC) fatty acids were measured in Framingham (N = 3196). The correlation matrix of the fatty acids was modeled using structural equation modeling; the model was tested for goodness-of-fit and gender invariance. Thirteen fatty acids were summarized by three latent variables, and gender invariance was rejected so separate models were developed for men and women. A score was developed for the polyunsaturated fatty acid (PUFA) latent variable, which explained about 30% of the variance in the data. The PUFA score included loadings in opposing directions among three omega-3 and three omega-6 fatty acids, and incorporated the biosynthetic and dietary relations among them. Whether the PUFA factor score can improve the performance of risk prediction in cardiovascular diseases remains to be tested. PMID:24959197

  12. Initial validation of the Spanish childhood trauma questionnaire-short form: factor structure, reliability and association with parenting.

    PubMed

    Hernandez, Ana; Gallardo-Pujol, David; Pereda, Noem; Arntz, Arnoud; Bernstein, David P; Gaviria, Ana M; Labad, Antonio; Valero, Joaqun; Gutirrez-Zotes, Jose Alfonso

    2013-05-01

    The present study examines the internal consistency and factor structure of the Spanish version of the Childhood Trauma Questionnaire-Short Form (CTQ-SF) and the association between the CTQ-SF subscales and parenting style. Cronbach's ? and confirmatory factor analyses (CFA) were performed in a female clinical sample (n = 185). Kendall's ? correlations were calculated between the maltreatment and parenting scales in a subsample of 109 patients. The Spanish CTQ-SF showed adequate psychometric properties and a good fit of the 5-factor structure. The neglect and abuse scales were negatively associated with parental care and positively associated with overprotection scales. The results of this study provide initial support for the reliability and validity of the Spanish CTQ-SF. PMID:23266990

  13. Factor structure of the Eating Disorder Examination Questionnaire (EDE-Q) in male and female college athletes.

    PubMed

    Darcy, Alison M; Hardy, Kristina K; Crosby, Ross D; Lock, James; Peebles, Rebecka

    2013-06-01

    The study explored the psychometric properties of the Eating Disorder Examination Questionnaire (EDE-Q) among 1637 university students. Participants were divided into male (n=432) and female (n=544) competitive athletes, and male (n=229) and female (n=429) comparison groups comprised of individuals who had not engaged in competitive sports for at least one year. All groups were subjected to confirmatory factor analysis (CFA) to test the fit of the published factor structure in this population, and then exploratory FA (EFA). A three-factor solution was the best fit for three out of four groups, with a two-factor solution providing best fit for the male comparison group. The first factor for all groups resembled a combined Shape and Weight Concern subscale. The factor structure among male and female competitive athletes was remarkably similar; however, non-competitive athletic/low activity males appear qualitatively different from other groups. PMID:23453695

  14. 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…

  15. On the band gap structure of Hill's equation

    NASA Astrophysics Data System (ADS)

    Allaire, G.; Orive, R.

    2005-06-01

    We revisit the old problem of finding the stability and instability intervals of a second-order elliptic equation on the real line with periodic coefficients (Hill's equation). It is well known that the stability intervals correspond to the spectrum of the Bloch family of operators defined on a single period. Here we propose a characterization of the instability intervals. We introduce a new family of non-self-adjoint operators, formally equivalent to the Bloch ones but with an imaginary Bloch parameter, that we call exponential. We prove that they admit a countable infinite number of eigenvalues which, when they are real, completely characterize the intervals of instability of Hill's equation.

  16. 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

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

    PubMed

    Le Tortorec, Eric; Helle, Samuli; Kyhk, 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

  18. From Questionnaire to Conversation: A Structural Intervention to Improve HIV Test Counseling

    PubMed Central

    Sheon, Nicolas; Lee, Seung-Hee; Facente, Shelley

    2010-01-01

    Objectives We describe the effects of structural intervention to enhance the quality of HIV test counseling interaction with men who have sex with men (MSM) in San Francisco. Methods Audio recordings of 28 rapid HIV test sessions by seven counselors were collected in two phases: before and after implementation of a waiting room intervention prior to the session. The sessions were analyzed using sequence maps to visualize and compare the sequence and distribution of four activities: counseling, information delivery, data collection, and sample collection. Results Prior to the intervention, counselors and clients often oriented to data collection about the clients past risk as if it were a survey. In sessions recorded after the intervention, questions about past risk were dispersed throughout the session and embedded within an elaborated discussion of the clients particular life circumstances. Conclusion Direct observation with the aid of sequence maps illuminates the ways that counselors and clients collaboratively orient to various tasks. Practice Implications We demonstrated the feasibility of a structural intervention that improved the quality of both counseling and the accuracy of client risk data without requiring additional session time or counselor training. PMID:20888723

  19. 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

  20. [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

  1. 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.

  2. 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

  3. 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

  4. 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…

  5. 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.

  6. 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

  7. 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)…

  8. On bi-Hamiltonian structure of two-component Novikov equation

    NASA Astrophysics Data System (ADS)

    Li, Nianhua; Liu, Q. P.

    2013-01-01

    In this Letter, we present a bi-Hamiltonian structure for the two-component Novikov equation. We also show that proper reduction of this bi-Hamiltonian structure leads to the Hamiltonian operators found by Hone and Wang for the Novikov equation.

  9. 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)

  10. 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

  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. 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.

  13. 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

  14. 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

  15. The Factor Structure and Factorial Invariance of the 12-Item General Health Questionnaire (GHQ-12) across Time: Evidence from Two Community-Based Samples

    ERIC Educational Resources Information Center

    Makikangas, Anne; Feldt, Taru; Kinnunen, Ulla; Tolvanen, Asko; Kinnunen, Marja-Liisa; Pulkkinen, Lea

    2006-01-01

    This study provides new knowledge about the factor structure of the 12-item General Health Questionnaire (GHQ-12; D. Goldberg, 1972) through the application of confirmatory factor analysis to longitudinal data, thereby enabling investigation of the factor structure, its invariance across time, and the rank-order stability of the factors. Two

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. Structural Equation Modeling of Paired-Comparison and Ranking Data

    ERIC Educational Resources Information Center

    Maydeu-Olivares, Albert; Bockenholt, Ulf

    2005-01-01

    L. L. Thurstone's (1927) model provides a powerful framework for modeling individual differences in choice behavior. An overview of Thurstonian models for comparative data is provided, including the classical Case V and Case III models as well as more general choice models with unrestricted and factor-analytic covariance structures. A flow chart

  1. 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.

  2. Different perceptions of stress, coping styles, and general well-being among pregnant Chinese women: a structural equation modeling approach.

    PubMed

    Lau, Ying; Tha, Pyai Htun; Wong, Daniel Fu Keung; Wang, Yuqiong; Wang, Ying; Yobas, Piyanee Klainin

    2016-02-01

    Few studies have examined different perceptions of stress or explored the positive aspects of well-being among pregnant Chinese women, so there is a need to explore these phenomena in order to fill the research gap. The aim of this study was to examine the relationships among the different perceptions of stress, coping styles, and general well-being using a structural equation modeling approach. We examined a hypothetical model among 755 pregnant Chinese women based on the integration of theoretical models. The Perceived Stress Scale (PSS), the Trait Coping Styles Questionnaire (TCSQ), and the General Well-Being Schedule (GWB) were used to measure perceived stress, coping styles, and general well-being, respectively. A structural equation model showed that positive and negative perceptions of stress significantly influenced positive and negative coping styles, respectively. Different perceptions of stress were significantly associated with general well-being, but different coping styles had no significant effects on general well-being. The model had a good fit to the data (IFI?=?0.910, TLI?=?0.904, CFI?=?0.910, and RMSEA?=?0.038). Different perception of stress was able to predict significant differences in coping styles and general well-being. PMID:25822710

  3. 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

  4. 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

  5. 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…

  6. 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…

  7. Risk Factors of Work-related Upper Extremity Musculoskeletal Disorders in Male Shipyard Workers: Structural Equation Model Analysis

    PubMed Central

    Park, Byung-Chan; Kim, Eun-A; Kim, Soo Geun

    2010-01-01

    Objectives This study was conducted to develop a model describing the interaction between lifestyle, job, and postural factors and parts of the upper extremities in shipyard workers. Methods A questionnaire survey was given to 2,140 workers at a shipyard in Ulsan City. The questionnaire consisted of questions regarding the subjects' general characteristics, lifestyle, tenure, physical burden, job control, posture and musculoskeletal symptoms. The overall relationship between variables was analyzed by a structural equation model (SEM). Results The positive rate of upper extremity musculoskeletal symptoms increased in employees who worked longer hours, had severe physical burden, and did not have any control over their job. Work with a more frequent unstable posture and for longer hours was also associated with an increased positive rate of musculoskeletal symptoms. Multiple logistic regression analysis showed that unstable posture and physical burden were closely related to the positive rate of musculoskeletal symptoms after controlling for age, smoking, drinking, exercise, tenure, and job control. In SEM analysis, work-related musculoskeletal disease was influenced directly and indirectly by physical and job stress factors, lifestyle, age, and tenure (p < 0.05). The strongest correlations were found between physical factors and work-related musculoskeletal disease. Conclusion The model in this study provides a better approximation of the complexity of the actual relationship between risk factors and work-related musculoskeletal disorders. Among the variables evaluated in this study, physical factors (work posture) had the strongest association with musculoskeletal disorders. PMID:22953172

  8. Review of Ballistic Limit Equations for Composite Structure Walls of Satellites

    NASA Astrophysics Data System (ADS)

    Schaefer, Frank K.*; Schneider, E.; Lambert, M.

    2004-08-01

    In this paper a review of existing ballistic limit equations for CFRP (Carbon Fibre Reinforced Plastics) structure walls of satellites is given, and two new ballistic limit equations are presented. The predictive capabilities of the equations are compared to a set of experimental hypervelocity impact test data of CFRP plates and CFRP honeycomb sandwich panels (satellite structure wall) from ENVISAT, AXAF, and a generic technology program. In the literature, three ballistic limit equations for sandwich panels (SP) made from CFRP face-sheets and Al- honeycomb (H/C) core were found and analyzed (Frost's approach, Approach using Christiansen's Whipple shield Ballistic Limit Equation (BLE), and Taylor's approach). Furthermore, in this paper, a new ballistic limit equation was proposed for CFRP H/C SP (Modified ESA Triple Wall Equation) and for composite panels (plates) with and without MLI attached to the surface. The amount of impact data on CFRP structure walls of satellites found in the literature was rather scarce. The new BLE for CFRP plates makes good predictions to the available set of test data. For the BLE for CFRP H/C SP, it was found that Frost's approach and application of Christiansen's BLE to CFRP H/C SP lead to an overprediction of the ballistic limit diameters for ENVISAT structure walls and the samples of the generic technology program. Taylor's approach and the newly designed MET ballistic limit equation have both yielded good predictions for all samples except for the AXAF samples that had rather thin-walled face-sheets and a thin Al H/C core: for these samples the predictions were conservative. Thus, for use in risk analysis tools for satellites (e. g. ESA's ESABASE/DEBRIS tool or NASA's BUMPER code), it is recommended to use either the MET or Taylor equation.

  9. Structural model updating using frequency response function and quasi-linear sensitivity equation

    NASA Astrophysics Data System (ADS)

    Esfandiari, A.; Bakhtiari-Nejad, F.; Rahai, A.; Sanayei, M.

    2009-10-01

    A method is presented for structural mass and stiffness estimation including damping effects and using vibration data. It uses the frequency response function (FRF) and natural frequencies data for finite element model updating. The FRF data are compiled using the measured displacement, velocity or acceleration of the damaged structure. A least-square algorithm method with appropriate normalization is used for solving the over-determined system of equations with noise-polluted data. Sensitivity equation normalization and proper selection of measured frequency points improved the accuracy and convergence in finite element model updating. Using simulated measurements shows that this method can detect, locate and quantify the severity of damage within structures.

  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. 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

  12. 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,…

  13. 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

  14. 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…

  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. 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,

  17. 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…

  18. 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

  19. 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

  20. 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

  1. 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…

  2. 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…

  3. 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

  4. On the multi-symplectic structure of the SerreGreenNaghdi equations

    NASA Astrophysics Data System (ADS)

    Chhay, Marx; Dutykh, Denys; Clamond, Didier

    2016-01-01

    In this short note, we present a multi-symplectic structure of the SerreGreenNaghdi (SGN) equations modelling nonlinear long surface waves in shallow water. This multi-symplectic structure allow the use of efficient finite difference or pseudo-spectral numerical schemes preserving exactly the multi-symplectic form at the discrete level.

  5. 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…

  6. 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.

  7. 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.,…

  8. 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.,

  9. Factor Structure and Reliability of the Childhood Trauma Questionnaire and Prevalence Estimates of Trauma for Male and Female Street Youth

    ERIC Educational Resources Information Center

    Forde, David R.; Baron, Stephen W.; Scher, Christine D.; Stein, Murray B.

    2012-01-01

    This study examines the psychometric properties of the Childhood Trauma Questionnaire short form (CTQ-SF) with street youth who have run away or been expelled from their homes (N = 397). Internal reliability coefficients for the five clinical scales ranged from 0.65 to 0.95. Confirmatory Factor Analysis (CFA) was used to test the five-factor

  10. 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.…

  11. 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.

  12. 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

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

    NASA Astrophysics Data System (ADS)

    Ryan, S.; Schfer, 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

  14. First-principles prediction of the equation of state for TcC with rocksalt structure

    NASA Astrophysics Data System (ADS)

    Sun, Xiao-Wei; Chu, Yan-Dong; Liu, Zi-Jiang; Song, Ting; Tian, Jun-Hong; Wei, Xiao-Ping

    2014-10-01

    The equation of state of TcC with rocksalt structure is investigated by means of first-principles density functional theory calculations combined with the quasi-harmonic Debye model in which the phononic effects are considered. Particular attention is paid to the predictions of the compressibility, the isothermal bulk modulus and its first pressure derivative which play a central role in the formulation of approximate equations of state for the first time. The properties of TcC with rocksalt structure are summarized in the pressure range of 0-80 GPa and the temperature up to 2500 K.

  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. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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…

  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-Hernndez, Andrs; Ldtke, 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. 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

  7. 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

  8. 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

  9. 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…

  10. 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

  11. Estimation of Generalizability Coefficients via a Structural Equation Modeling Approach to Scale Reliability Evaluation

    ERIC Educational Resources Information Center

    Raykov, Tenko; Marcoulides, George A.

    2006-01-01

    A structural equation modeling approach to scale reliability evaluation can be employed to estimate generalizability theory indexes in settings where sampling of subjects and conditions is carried out. In one- and two-facet crossed designs, it is demonstrated how this method can be used to obtain estimates of relative generalizability

  12. 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…

  13. 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…

  14. 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…

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. Does Method of Handling Missing Data Affect Results of a Structural Equation Model?

    ERIC Educational Resources Information Center

    Witta, E. Lea

    The influence of method of handling missing data on estimates produced by a structural equation model of the effects of part-time work on high-school student achievement was investigated. Missing data methods studied were listwise deletion, pairwise deletion, the expectation maximization (EM) algorithm, regression, and response pattern. The 26

  1. The Use of Structural Equation Modelling to Investigate Hierarchical Organization in Learning and Cognition.

    ERIC Educational Resources Information Center

    Hill, P. W.

    1984-01-01

    The use of structural equation modeling is discussed in testing a range of theories of learning and cognition involving the concept of a hierarchy of variables of increasing complexity. To illustrate this approach, one method is applied to Bloom's taxonomy to test the theoretical assumption of hierarchical organization. (Author/MSE)

  2. Band structure analysis of an analytically solvable Hill equation with continuous potential

    NASA Astrophysics Data System (ADS)

    Morozov, G. V.; Sprung, D. W. L.

    2015-03-01

    This paper concerns analytically solvable cases of Hills equation containing a continuously differentiable periodic potential. We outline a procedure for constructing the Floquet-Bloch fundamental system, and analyze the band structure of the system. The similarities to, and differences from, the cases of a piecewise constant periodic potential and the Mathieu potential, are illuminated.

  3. Using a Structural Equation Model to Describe the Infusion of Civic Engagement in the Campus Culture

    ERIC Educational Resources Information Center

    Billings, Meredith S.; Terkla, Dawn Geronimo

    2011-01-01

    This study assesses whether Tufts University's campus culture was successful at infusing civic-mindedness in all undergraduates. A structural equation model was developed, and findings revealed that the campus environment had a significant positive impact on civic values and beliefs and a positive indirect effect on civic engagement activities.

  4. 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…

  5. 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…

  6. 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,…

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

    ERIC Educational Resources Information Center

    Nevitt, Jonathan; Hancock, Gregory R.

    2004-01-01

    Through Monte Carlo simulation, small sample methods for evaluating overall data-model fit in structural equation modeling were explored. Type I error behavior and power were examined using maximum likelihood (ML), Satorra-Bentler scaled and adjusted (SB; Satorra & Bentler, 1988, 1994), residual-based (Browne, 1984), and asymptotically

  8. 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)

  9. 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…

  10. 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…

  11. 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…

  12. 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);

  13. A Demonstration of a Systematic Item-Reduction Approach Using Structural Equation Modeling

    ERIC Educational Resources Information Center

    Larwin, Karen; Harvey, Milton

    2012-01-01

    Establishing model parsimony is an important component of structural equation modeling (SEM). Unfortunately, little attention has been given to developing systematic procedures to accomplish this goal. To this end, the current study introduces an innovative application of the jackknife approach first presented in Rensvold and Cheung (1999). Unlike

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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…

  20. 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…

  1. 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…

  2. Structural Equation Modeling of Multitrait-Multimethod Data: Different Models for Different Types of Methods

    ERIC Educational Resources Information Center

    Eid, Michael; Nussbeck, Fridtjof W.; Geiser, Christian; Cole, David A.; Gollwitzer, Mario; Lischetzke, Tanja

    2008-01-01

    The question as to which structural equation model should be selected when multitrait-multimethod (MTMM) data are analyzed is of interest to many researchers. In the past, attempts to find a well-fitting model have often been data-driven and highly arbitrary. In the present article, the authors argue that the measurement design (type of methods

  3. Structural Equation Models of Latent Interactions: Clarification of Orthogonalizing and Double-Mean-Centering Strategies

    ERIC Educational Resources Information Center

    Lin, Guan-Chyun; Wen, Zhonglin; Marsh, Herbert W.; Lin, Huey-Shyan

    2010-01-01

    The purpose of this investigation is to compare a new (double-mean-centering) strategy to estimating latent interactions in structural equation models with the (single) mean-centering strategy (Marsh, Wen, & Hau, 2004, 2006) and the orthogonalizing strategy (Little, Bovaird, & Widaman, 2006; Marsh et al., 2007). A key benefit of the

  4. 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

  5. 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…

  6. 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…

  7. 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

  8. 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

  9. 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

  10. 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…

  11. 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…

  12. Group Climate, Cohesion, Alliance, and Empathy in Group Psychotherapy: Multilevel Structural Equation Models

    ERIC Educational Resources Information Center

    Johnson, Jennifer E.; Burlingame, Gary M.; Olsen, Joseph A.; Davies, D. Robert; Gleave, Robert L.

    2005-01-01

    This study examined the definitional and statistical overlap among 4 key group therapeutic relationship constructs--group climate, cohesion, alliance, and empathy--across member-member, member-group, and member-leader relationships. Three multilevel structural equation models were tested using self-report measures completed by 662 participants

  13. 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

  14. 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

  15. 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…

  16. 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

  17. 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,

  18. 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

  19. 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.…

  20. 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…

  1. 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):

  2. 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

  3. 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

  4. 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

  5. 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…

  6. 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…

  7. 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…

  8. 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

  9. 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

  10. 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…

  11. Structure-dependent dc conductivity and relaxation time in the Debye-Stokes-Einstein equation.

    PubMed

    Power, G; Vij, J K; Johari, G P

    2007-09-27

    The basis for a modification of the Debye-Stokes-Einstein (DSE) equation between the dc conductivity, sigma(dc), and dielectric relaxation time, tau, has been examined by using broad-band dielectric spectroscopy of LiClO4 solutions in 5-methyl-2-hexanol and 1-propanol and of pure liquids. According to the DSE equation, the log sigma(dc)-log tau plots should have a slope of -1. We find that sigma(dc) begins to depend upon the structure of an electrolytic solution when a variation of solvent's equilibrium dielectric permittivity, epsilon(s), with temperature causes the ion population to vary. As a consequence of this intrinsic dependence, the log sigma(dc)-log tau plots do not obey the DSE equation. Inclusion of the effect of change in epsilon(s) on the DSE equation may be useful in analyzing the measured quantities in terms of Brownian diffusion of both ions and molecules in ultraviscous liquids. Proton translocation along a hydrogen bond contributes little to sigma(dc), which appears to be predominantly determined by the ion population in the two alcohols and the solutions. The effect is briefly discussed in the potential energy landscape paradigm of structure fluctuations, and it is suggested that the high-frequency shear modulus measurements of ionic solutions would help reveal the temperature-dependent deviation from the DSE equation. PMID:17764166

  12. 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."

  13. 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

  14. 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.

  15. 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 equatione.g., of the form ?? + m2? + g?p = 0admits 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

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. Global Bifurcation Structure and Parameter Dependence of the Hodgkin-Huxley Equations

    NASA Astrophysics Data System (ADS)

    Pan, Zhenxing; Doi, Shinji

    The Hodgkin-Huxley (HH) equations of a squid giant axon are the most important mathematical model in electrophysiology and biology, and are also important in the development of various biologically inspired intelligent devices such as artificial neuron device and neural networks. The HH equations, however, include various constants or parameters whose values were determined based on physiological experiments, and thus the values possess inherent ambiguities. Also, the constants are not really constant but change temporally. Thus, in this paper, we study the effects of the change of the constants or parameters on the dynamics of the HH equations and consider the parameter dependence and sensitivity of the equations; we study the bifurcation structure of the HH equations by changing their various parameters. In particular, we take the voltage-dependency of the dynamics of so-called gating variables as typical bifurcation parameters and show that the HH dynamics is very sensitive to the steady-state functions but not sensitive to the time constants of gating variables.

  3. 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.

  4. Influence of Psychosocial Classroom Environment on Students' Motivation and Self-Regulation in Science Learning: A Structural Equation Modeling Approach

    NASA Astrophysics Data System (ADS)

    Velayutham, Sunitadevi; Aldridge, Jill M.

    2013-04-01

    The primary aim of this study was two-fold: 1) to identify salient psychosocial features of the classroom environment that influence students' motivation and self-regulation in science learning; and 2) to examine the effect of the motivational constructs of learning goal orientation, science task value and self-efficacy in science learning on students' self-regulation in science classrooms. Data collected from 1360 science students in grades 8, 9 and 10 in five public schools in Perth, Western Australia were utilized to validate the questionnaires and to investigate the hypothesized relationships. Structural Equation Modeling analysis suggested that student cohesiveness, investigation and task orientation were the most influential predictors of student motivation and self-regulation in science learning. In addition, learning goal orientation, task value and self-efficacy significantly influenced students' self-regulation in science. The findings offer potential opportunities for educators to plan and implement effective pedagogical strategies aimed at increasing students' motivation and self-regulation in science learning.

  5. A tutorial on structural equation modeling for analysis of overlapping symptoms in co-occurring conditions using MPlus.

    PubMed

    Gunzler, Douglas D; Morris, Nathan

    2015-10-30

    Structural equation modeling (SEM) is a very general approach to analyzing data in the presence of measurement error and complex causal relationships. In this tutorial, we describe SEM, with special attention to exploratory factor analysis, confirmatory factor analysis, and multiple indicator multiple cause modeling. The tutorial is motivated by a problem of symptom overlap routinely faced by clinicians and researchers, in which symptoms or test results are common to two or more co-occurring conditions. As a result of such overlap, diagnoses, treatment decisions, and inferences about the effectiveness of treatments for these conditions can be biased. This problem is further complicated by increasing reliance on patient-reported outcomes, which introduces systematic error based on an individual's interpretation of a test questionnaire. SEM provides flexibility in handling this type of differential item functioning and disentangling the overlap. Scales and scoring approaches can be revised to be free of this overlap, leading to better care. This tutorial uses an example of depression screening in multiple sclerosis patients in which depressive symptoms overlap with other symptoms, such as fatigue, cognitive impairment, and functional impairment. Details of how MPlus (Muthn & Muthn, Los Angeles,?CA, USA) software can be used to address the symptom overlap problem, including data requirements, code and output are described in this tutorial. PMID:26045102

  6. Validating the theoretical structure of the Treatment Self-Regulation Questionnaire (TSRQ) across three different health behaviors.

    PubMed

    Levesque, Chantal S; Williams, Geoffrey C; Elliot, Diane; Pickering, Michael A; Bodenhamer, Bradley; Finley, Phillip J

    2007-10-01

    Nearly 40% of mortality in the United States is linked to social and behavioral factors such as smoking, diet and sedentary lifestyle. Autonomous self-regulation of health-related behaviors is thus an important aspect of human behavior to assess. In 1997, the Behavior Change Consortium (BCC) was formed. Within the BCC, seven health behaviors, 18 theoretical models, five intervention settings and 26 mediating variables were studied across diverse populations. One of the measures included across settings and health behaviors was the Treatment Self-Regulation Questionnaire (TSRQ). The purpose of the present study was to examine the validity of the TSRQ across settings and health behaviors (tobacco, diet and exercise). The TSRQ is composed of subscales assessing different forms of motivation: amotivation, external, introjection, identification and integration. Data were obtained from four different sites and a total of 2731 participants completed the TSRQ. Invariance analyses support the validity of the TSRQ across all four sites and all three health behaviors. Overall, the internal consistency of each subscale was acceptable (most alpha values >0.73). The present study provides further evidence of the validity of the TSRQ and its usefulness as an assessment tool across various settings and for different health behaviors. PMID:17138613

  7. 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.

  8. 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.

  9. On the minimal set of conservation laws and the Hamiltonian structure of the Whitham equations

    NASA Astrophysics Data System (ADS)

    Maltsev, A. Ya.

    2015-02-01

    We consider the questions connected with the Hamiltonian properties of the Whitham equations in case of several spatial dimensions. An essential point of our approach here is a connection of the Hamiltonian structure of the Whitham system with the finite-dimensional Poisson bracket defined on the space of periodic or quasi-periodic solutions. From our point of view, this approach gives a possibility to construct the Hamiltonian structure of the Whitham equations under minimal requirements on the properties of the initial system. The Poisson bracket for the Whitham system can be considered here as a deformation of the finite-dimensional bracket with the aid of the Dubrovin-Novikov procedure of bracket averaging. At the end, we consider the examples where the constructions of the paper play an essential role for the construction of the Poisson bracket for the Whitham system.

  10. Second order scheme for Maxwell's equations with discontinuous dielectric permittivity on structured meshes

    NASA Astrophysics Data System (ADS)

    Ismagilov, Timur Z.

    2013-10-01

    A second order finite volume scheme for numerical solution of Maxwell's equations with discontinuous dielectric permittivity on structured meshes is suggested. The scheme is based on approaches of Godunov, Lax-Wendroff and Van Leer. The distinctive feature of the suggested scheme is calculation and limitation of derivatives that ensures second order of approximation even in the cells adjacent to dielectric permittivity discontinuity. Numerical tests for problems with linear and curvilinear dielectric permittivity discontinuities confirm second order of approximation.

  11. 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.

  12. 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…

  13. Trichotomous goals of elementary school students learning English as a foreign language: a structural equation model.

    PubMed

    He, Tung-Hsien; Chang, Shan-Mao; Chen, Shu-Hui Eileen; Gou, Wen Johnny

    2012-02-01

    This study applied structural equation modeling (SEM) techniques to define the relations among trichotomous goals (mastery goals, performance-approach goals, and performance-avoidance goals), self-efficacy, use of metacognitive self-regulation strategies, positive belief in seeking help, and help-avoidance behavior. Elementary school students (N = 105), who were learning English as a foreign language, were surveyed using five self-report scales. The structural equation model showed that self-efficacy led to the adoption of mastery goals but discouraged the adoption of performance-approach goals and performance-avoidance goals. Furthermore, mastery goals increased the use of metacognitive self-regulation strategies, whereas performance-approach goals and performance-avoidance goals reduced their use. Mastery goals encouraged positive belief in help-seeking, but performance-avoidance goals decreased such belief. Finally, performance-avoidance goals directly led to help-avoidance behavior, whereas positive belief assumed a critical role in reducing help-avoidance. The established structural equation model illuminated the potential causal relations among these variables for the young learners in this study. PMID:22582685

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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…

  1. The Strengths and Difficulties Questionnaire (SDQ)--Self-Report. An Analysis of Its Structure in a Multiethnic Urban Adolescent Sample

    ERIC Educational Resources Information Center

    Richter, Jorg; Sagatun, Ase; Heyerdahl, Sonja; Oppedal, Brit; Roysamb, Espen

    2011-01-01

    Background: The SDQ is currently one of the internationally most frequently used screening instruments for child and adolescent mental health purposes. However, its structure, cross-cultural equivalence, and its applicability in ethnic minority groups is still a matter of discussion. Methods: SDQ self-report data of 5,379 ethnic Norwegian and 865

  2. Reassessment of the Psychometric Characteristics and Factor Structure of the Perceived Stress Questionnaire (PSQ): Analysis in a Sample of Dental Students

    PubMed Central

    Montero-Marin, Jess; Piva Demarzo, Marcelo Marcos; Pereira, Joao Paulo; Olea, Marina; Garca-Campayo, Javier

    2014-01-01

    Background The training to become a dentist can create psychological distress. The present study evaluates the structure of the Perceived Stress Questionnaire (PSQ), its internal consistency model and interrelatedness with burnout, anxiety, depression and resilience among dental students. Methods The study employed a cross-sectional design. A sample of Spanish dental students (n?=?314) completed the PSQ, the Goldberg Anxiety and Depression Scale (GADS), Connor-Davidson Resilience Scale (10-item CD-RISC) and Maslach Burnout Inventory-Student Survey (MBI-SS). The structure was estimated using Parallel Analysis from polychoric correlations. Unweighted Least Squares was the method for factor extraction, using the Item Response Theory to evaluate the discriminative power of items. Internal consistency was assessed by squaring the correlation between the latent true variable and the observed variable. The relationships between the PSQ and the other constructs were analysed using Spearmans coefficient. Results The results showed a PSQ structure through two sub-factors (frustration and tenseness) with regard to one general factor (perceived stress). Items that did not satisfy discriminative capacity were rejected. The model fit were acceptable (GFI?=?0.98; RSMR?=?0.06; AGFI?=?0.98; NFI?=?0.98; RFI?=?0.98). All the factors showed adequate internal consistency as measured by the congeneric model (?0.91). High and significant associations were observed between perceived stress and burnout, anxiety, depression and resilience. Conclusions The PSQ showed a hierarchical bi-factor structure among Spanish dental students. Using the questionnaire as a uni-dimensional scale may be useful in perceived stress level discrimination, while the sub-factors could help us to refine perceived stress analysis and improve therapeutic processes. PMID:24466330

  3. 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

  4. 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.

  5. 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

  6. Beyond logistic regression: structural equations modelling for binary variables and its application to investigating unobserved confounders

    PubMed Central

    Kupek, Emil

    2006-01-01

    Background Structural equation modelling (SEM) has been increasingly used in medical statistics for solving a system of related regression equations. However, a great obstacle for its wider use has been its difficulty in handling categorical variables within the framework of generalised linear models. Methods A large data set with a known structure among two related outcomes and three independent variables was generated to investigate the use of Yule's transformation of odds ratio (OR) into Q-metric by (OR-1)/(OR+1) to approximate Pearson's correlation coefficients between binary variables whose covariance structure can be further analysed by SEM. Percent of correctly classified events and non-events was compared with the classification obtained by logistic regression. The performance of SEM based on Q-metric was also checked on a small (N = 100) random sample of the data generated and on a real data set. Results SEM successfully recovered the generated model structure. SEM of real data suggested a significant influence of a latent confounding variable which would have not been detectable by standard logistic regression. SEM classification performance was broadly similar to that of the logistic regression. Conclusion The analysis of binary data can be greatly enhanced by Yule's transformation of odds ratios into estimated correlation matrix that can be further analysed by SEM. The interpretation of results is aided by expressing them as odds ratios which are the most frequently used measure of effect in medical statistics. PMID:16539711

  7. Solution of linear systems of equations with a structural analysis code on the NAS CRAY-2

    SciTech Connect

    Poole, E.L.; Overman, A.L.

    1988-12-01

    Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted the Computational Structural Mechanics (CSM) Testbed. A description of the techniques used to integrate the two solvers into the Testbed is given. Storage schemes, memory requirements, operation counts, and reformatting procedures are discussed. Finally, results from the new methods are compared with results from the initial Testbed sparse Choleski equation solver for three structural analysis problems. The new direct solvers described achieve the highest computational rates of the methods compared. The new iterative methods are not able to achieve as high computation rates as the vectorized direct solvers but are best for well conditioned problems which require fewer iterations to converge to the solution.

  8. A structurally damped plate equation with Dirichlet-Neumann boundary conditions

    NASA Astrophysics Data System (ADS)

    Denk, Robert; Schnaubelt, Roland

    2015-08-01

    We investigate sectoriality and maximal regularity in Lp-Lq-Sobolev spaces for the structurally damped plate equation with Dirichlet-Neumann (clamped) boundary conditions. We obtain unique solutions with optimal regularity for the inhomogeneous problem in the whole space, in the half-space, and in bounded domains of class C4. It turns out that the first-order system related to the scalar equation on Rn is sectorial only after a shift in the operator. On the half-space one has to include zero boundary conditions in the underlying function space in order to obtain sectoriality of the shifted operator and maximal regularity for the case of homogeneous boundary conditions. We further show that the semigroup solving the problem on bounded domains is exponentially stable.

  9. Structure of Positive Radial Solutions to Scalar Field Equations with Harmonic Potential

    NASA Astrophysics Data System (ADS)

    Hirose, Munemitsu; Ohta, Masahito

    2002-01-01

    We study a nonlinear elliptic equation with a harmonic potential-? u+(?+|x|2) u-|u|p-1 u=0, x?Rn, (E) which is related to standing waves for a nonlinear Schrdinger equation. The existence of positive solution for (E) in some energy space can be shown by the standard variational method under n?1, ?>-n and 1structure of positive radial solutions to (E) and show the uniqueness of positive solution with finite energy when n?3.

  10. 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

  11. 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

  12. Simulation of coherent structures (topological solitons) indoors by numerical solving of hydrodynamics equations

    NASA Astrophysics Data System (ADS)

    Nosov, Victor V.; Lukin, Vladimir P.; Nosov, Evgeny V.; Torgaev, Andrey V.

    2014-11-01

    Coherent structures (topological solitons) indoors had been simulated by numerical solving of hydrodynamics equations. "Indoors" means inside the closed volume without the external direct wind influence and without the exchange of internal and external medium through the borders. Results of six boundary value problems are demonstrated: spectrograph pavilion and telescope dome of large astronomical telescopes (LSVT and BTA), cubic room, flat square cuvette, square section tube, parietal turbulence (thermals). The solitary large vortices (coherent structures, topological solitons) are observed indoors. The scenes of air motion as a result of simulation of coherent structures with identical boundary conditions are the practically same as the scenes, independently previously registered at experiments by us (indoors LSVT and BTA).

  13. 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.

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

    PubMed Central

    Sideridis, Georgios; Simos, Panagiotis; Papanicolaou, Andrew; Fletcher, Jack

    2014-01-01

    The present study assessed the impact of sample size on the power and fit of structural equation modeling applied to functional brain connectivity hypotheses. The data consisted of time-constrained minimum norm estimates of regional brain activity during performance of a reading task obtained with magnetoencephalography. Power analysis was first conducted for an autoregressive model with 5 latent variables (brain regions), each defined by 3 indicators (successive activity time bins). A series of simulations were then run by generating data from an existing pool of 51 typical readers (aged 7.5-12.5 years). Sample sizes ranged between 20 and 1,000 participants and for each sample size 1,000 replications were run. Results were evaluated using chi-square Type I errors, model convergence, mean RMSEA (root mean square error of approximation) values, confidence intervals of the RMSEA, structural path stability, and D-Fit index values. Results suggested that 70 to 80 participants were adequate to model relationships reflecting close to not so close fit as per MacCallum et al.'s recommendations. Sample sizes of 50 participants were associated with satisfactory fit. It is concluded that structural equation modeling is a viable methodology to model complex regional interdependencies in brain activation in pediatric populations. PMID:25435589

  15. 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

  16. 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

  17. Conversion of Questionnaire Data

    SciTech Connect

    Powell, Danny H; Elwood Jr, Robert H

    2011-01-01

    During the survey, respondents are asked to provide qualitative answers (well, adequate, needs improvement) on how well material control and accountability (MC&A) functions are being performed. These responses can be used to develop failure probabilities for basic events performed during routine operation of the MC&A systems. The failure frequencies for individual events may be used to estimate total system effectiveness using a fault tree in a probabilistic risk analysis (PRA). Numeric risk values are required for the PRA fault tree calculations that are performed to evaluate system effectiveness. So, the performance ratings in the questionnaire must be converted to relative risk values for all of the basic MC&A tasks performed in the facility. If a specific material protection, control, and accountability (MPC&A) task is being performed at the 'perfect' level, the task is considered to have a near zero risk of failure. If the task is performed at a less than perfect level, the deficiency in performance represents some risk of failure for the event. As the degree of deficiency in performance increases, the risk of failure increases. If a task that should be performed is not being performed, that task is in a state of failure. The failure probabilities of all basic events contribute to the total system risk. Conversion of questionnaire MPC&A system performance data to numeric values is a separate function from the process of completing the questionnaire. When specific questions in the questionnaire are answered, the focus is on correctly assessing and reporting, in an adjectival manner, the actual performance of the related MC&A function. Prior to conversion, consideration should not be given to the numeric value that will be assigned during the conversion process. In the conversion process, adjectival responses to questions on system performance are quantified based on a log normal scale typically used in human error analysis (see A.D. Swain and H.E. Guttmann, 'Handbook of Human Reliability Analysis with Emphasis on Nuclear Power Plant Applications,' NUREG/CR-1278). This conversion produces the basic event risk of failure values required for the fault tree calculations. The fault tree is a deductive logic structure that corresponds to the operational nuclear MC&A system at a nuclear facility. The conventional Delphi process is a time-honored approach commonly used in the risk assessment field to extract numerical values for the failure rates of actions or activities when statistically significant data is absent.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. The factor structure and factorial invariance of the Pain-Coping Questionnaire across age: evidence from community-based samples of children and adults.

    PubMed

    Huguet, Anna; Mir, Jordi; Nieto, Rubn

    2009-09-01

    The Pain-Coping Questionnaire was developed for children to assess pain-coping strategies. It was originally suggested as a second-order factor measure: eight first-order factors and three higher-order factors. The main objective of this study was to investigate the psychometric properties of the PCQ when used with children and adults. Two samples of 702 children and 590 adults completed the measure. Confirmatory factor analytic procedures were used to examine the factor structure, and invariance across samples. The results provided good support for a second-order structural model of seven subscales for children, for a first-order structural model of seven subscales for adults, and for between-group invariance first-order structural model. These findings suggest that data obtained on the seven first-order factors from children are directly comparable to scores from adults. The internal consistency, criterion validity and convergent validity were also confirmed in both children and adult samples. This work also reports some preliminary findings related to sex and age differences on the use of pain-coping styles. PMID:19084438

  3. 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

  4. 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

  5. Soliton structure versus singularity analysis: Third-order completely intergrable nonlinear differential equations in 1 + 1-dimensions

    NASA Astrophysics Data System (ADS)

    Fuchssteiner, Benno; Carillo, Sandra

    1989-01-01

    Bcklund transformations between all known completely integrable third-order differential equations in (1 + 1)-dimensions are established and the corresponding transformations formulas for their hereditary operators and Hamiltonian formulations are exhibited. Some of these Bcklund transformations are not injective; therefore additional non-commutative symmetry groups are found for some equations. These non-commutative symmetry groups are classified as having a semisimple part isomorphic to the affine algebra A(1)1. New completely integrable third-order integro-differential equations, some depending explicitly on x, are given. These new equations give rise to nonin equation. Connections between the singularity equations (from the Painlev analysis) and the nonlinear equations for interacting solitons are established. A common approach to singularity analysis and soliton structure is introduced. The Painlev analysis is modified in such a sense that it carries over directly and without difficulty to the time evolution of singularity manifolds of equations like the sine-Gordon and nonlinear Schrdinger equation. A method to recover the Painlev series from its constant level term is exhibit. The soliton-singularity transform is recognized to be connected to the Mbius group. This gives rise to a Darboux-like result for the spectral properties of the recursion operator. These connections are used in order to explain why poles of soliton equations move like trajectories of interacting solitons. Furthermore it is explicitly computed how solitons of singularity equations behave under the effect of this soliton-singularity transform. This then leads to the result that only for scaling degrees ? = -1 and ? = -2 the usual Painlev analysis can be carried out. A new invariance principle, connected to kernels of differential operators is discovered. This new invariance, for example, connects the explicit solutions of the Liouville equation with the Miura transform. Simple methods are exhibited which allow to compute out of N-soliton solutions of the KdV (Bargman potentials) explicit solutions of equations like the Harry Dym equation. Certain solutions are plotted.

  6. 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

  7. 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.

  8. 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,

  9. 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

  10. 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 atoms 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.

  11. 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

  12. 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.

  13. 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.

  14. Working conditions, self-perceived stress, anxiety, depression and quality of life: A structural equation modelling approach

    PubMed Central

    Rusli, Bin Nordin; Edimansyah, Bin Abdin; Naing, Lin

    2008-01-01

    Background The relationships between working conditions [job demand, job control and social support]; stress, anxiety, and depression; and perceived quality of life factors [physical health, psychological wellbeing, social relationships and environmental conditions] were assessed using a sample of 698 male automotive assembly workers in Malaysia. Methods The validated Malay version of the Job Content Questionnaire (JCQ), Depression Anxiety Stress Scales (DASS) and the World Health Organization Quality of Life-Brief (WHOQOL-BREF) were used. A structural equation modelling (SEM) analysis was applied to test the structural relationships of the model using AMOS version 6.0, with the maximum likelihood ratio as the method of estimation. Results The results of the SEM supported the hypothesized structural model (?2 = 22.801, df = 19, p = 0.246). The final model shows that social support (JCQ) was directly related to all 4 factors of the WHOQOL-BREF and inversely related to depression and stress (DASS). Job demand (JCQ) was directly related to stress (DASS) and inversely related to the environmental conditions (WHOQOL-BREF). Job control (JCQ) was directly related to social relationships (WHOQOL-BREF). Stress (DASS) was directly related to anxiety and depression (DASS) and inversely related to physical health, environment conditions and social relationships (WHOQOL-BREF). Anxiety (DASS) was directly related to depression (DASS) and inversely related to physical health (WHOQOL-BREF). Depression (DASS) was inversely related to the psychological wellbeing (WHOQOL-BREF). Finally, stress, anxiety and depression (DASS) mediate the relationships between job demand and social support (JCQ) to the 4 factors of WHOQOL-BREF. Conclusion These findings suggest that higher social support increases the self-reported quality of life of these workers. Higher job control increases the social relationships, whilst higher job demand increases the self-perceived stress and decreases the self-perceived quality of life related to environmental factors. The mediating role of depression, anxiety and stress on the relationship between working conditions and perceived quality of life in automotive workers should be taken into account in managing stress amongst these workers. PMID:18254966

  15. 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

  16. 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

  17. 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

  18. 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

  19. Assessing Epistemological Beliefs: Schommer's Questionnaire Revisited.

    ERIC Educational Resources Information Center

    Clarebout, Geraldine; Elen, Jan; Luyten, Lieve; Bamps, Hadewych

    2001-01-01

    Reviewed the literature on the questionnaire developed by M. Schommer to assess epistemological beliefs and studied the factor structure of the questionnaire in 2 studies involving 117 junior college students and 148 university students. In neither study could Schommer's factor structure be retrieved. Results reveal counter-indications to the use

  20. Solving the 3D Acoustic Wave-equation on Generalized Structured Meshes: A FDTD Approach

    NASA Astrophysics Data System (ADS)

    Shragge, J. C.

    2014-12-01

    The key computational kernel of most advanced 3D seismic imaging and inversion algorithms involves calculating solutions of the 3D acoustic wave equation, most commonly with a finite-difference time-domain (FDTD) methodology. While well suited for regularly sampled rectilinear computational domains, FDTD methods seemingly have limited applicability in scenarios involving irregular 3D domain boundary surfaces and mesh interiors that are best described by non-Cartesian geometry (e.g., surface topography). Using coordinate mapping relationships and differential geometry, a FDTD approach can be developed for generating solutions to the 3D acoustic wave equation that is applicable to generalized 3D coordinate systems and (quadrilateral-faced hexahedral) structured meshes. The developed numerical implementation is similar to established Cartesian approaches, save for a necessary introduction of weighted first- and mixed second-order partial-derivative operators that account for spatially varying geometry. The approach is validated on three different types of computational meshes: (1) an ``internal boundary'' mesh conforming to a dipping water bottom; (2) analytical ``semi-orthogonal cylindrical" coordinates; and (3) analytic semi-orthogonal and numerically specified ``topographic" coordinate meshes. Impulse response tests and numerical analysis demonstrate the viability of the approach for kernel computations for 3D seismic imaging and inversion experiments for non-Cartesian geometry scenarios.

  1. 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.

  2. Structural equation modeling: a framework for ocular and other medical sciences research.

    PubMed

    Christ, Sharon L; Lee, David J; Lam, Byron L; Zheng, D Diane

    2014-02-01

    Structural equation modeling (SEM) is a modeling framework that encompasses many types of statistical models and can accommodate a variety of estimation and testing methods. SEM has been used primarily in social sciences but is increasingly used in epidemiology, public health, and the medical sciences. SEM provides many advantages for the analysis of survey and clinical data, including the ability to model latent constructs that may not be directly observable. Another major feature is simultaneous estimation of parameters in systems of equations that may include mediated relationships, correlated dependent variables, and in some instances feedback relationships. SEM allows for the specification of theoretically holistic models because multiple and varied relationships may be estimated together in the same model. SEM has recently expanded by adding generalized linear modeling capabilities that include the simultaneous estimation of parameters of different functional form for outcomes with different distributions in the same model. Therefore, mortality modeling and other relevant health outcomes may be evaluated. Random effects estimation using latent variables has been advanced in the SEM literature and software. In addition, SEM software has increased estimation options. Therefore, modern SEM is quite general and includes model types frequently used by health researchers, including generalized linear modeling, mixed effects linear modeling, and population average modeling. This article does not present any new information. It is meant as an introduction to SEM and its uses in ocular and other health research. PMID:24467557

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. A Structural Equation Model of HIV-Related Stigma, Depressive Symptoms, and Medication Adherence

    PubMed Central

    Rao, Deepa; Feldman, Betsy J.; Fredericksen, Rob J.; Crane, Paul K.; Simoni, Jane M.; Kitahata, Mari M.; Crane, Heidi M.

    2011-01-01

    HIV-related stigma has a damaging effect on health outcomes among people living with HIV (PLWH), as studies have associated it with poor HIV medication adherence and depressive symptoms. We investigated whether depressive symptoms mediate the relationship between stigma and medication adherence. In a cross-sectional study, 720 PLWH completed instruments measuring HIV-related stigma, depressive symptoms, and HIV medication adherence. We used structural equation modeling (SEM) to investigate associations among these constructs. In independent models, we found that poorer adherence was associated with higher levels of stigma and depressive symptoms. In the simultaneous model that included both stigma and depressive symptoms, depression had a direct effect on adherence, but the effect of stigma on adherence was not statistically significant. This pattern suggested that depressive symptoms at least partially mediated the association between HIV-related stigma and HIV medication adherence. These findings suggest that interconnections between several factors have important consequences for adherence. PMID:21380495

  10. A Structural Equation Model of Perievent Panic and Posttraumatic Stress Disorder After a Community Disaster

    PubMed Central

    Adams, Richard E.; Boscarino, Joseph A.

    2012-01-01

    Studies suggest that perievent panic attacks are predictive of future posttraumatic stress disorder (PTSD). Using a population of New York City residents interviewed after the World Trade Center Disaster, the authors measured event exposure, perievent panic, potential confounding, mediating variables, and PTSD. When they estimated a structural equation model, with other stressor events, psychological resources, and Year 1 and Year 2 PTSD as latent variables and adjusted for confounders, the association between perievent panic and Year 2 PTSD was not significant. Results revealed that perievent panic was predictive of Year 1 PTSD, but not Year 2 PTSD. Year 2 stressors and Year 2 psychosocial resources were the best predictors of Year 2 PTSD. PMID:21351165

  11. Quantified Choice of RMSEAs for Evaluation and Power Analysis of Small Differences between Structural Equation Models

    PubMed Central

    Li, Libo; Bentler, Peter M.

    2011-01-01

    MacCallum, Browne, and Cai (2006) proposed a new framework for evaluation and power analysis of small differences between nested structural equation models (SEMs). In their framework, the null and alternative hypotheses for testing a small difference in fit and its related power analyses were defined by some chosen root-mean-square error of approximation (RMSEA) pairs. In this article, we develop a new method that quantifies those chosen RMSEA pairs and allows a quantitative comparison of them. Our method proposes the use of single RMSEA values to replace the choice of RMSEA pairs for model comparison and power analysis, thus avoiding the differential meaning of the chosen RMSEA pairs inherent in the approach of MacCallum et al. (2006). With this choice, the conventional cutoff values in model overall evaluation can directly be transferred and applied to the evaluation and power analysis of model differences. PMID:21341916

  12. 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

  13. 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

  14. Attentional and emotional mechanisms of pain processing and their related factors: A structural equations approach

    PubMed Central

    Huber, Claudia; Kunz, Miriam; Artelt, Cordula; Lautenbacher, Stefan

    2010-01-01

    BACKGROUND/OBJECTIVE: It is known that maladaptive attentional and emotional mechanisms of pain processing as indicated by constructs such as pain hypervigilance, pain-related anxiety and pain catastrophizing play an important role in the development and maintenance of chronic pain conditions. However, little is known to date about the potential risk factors for these forms of maladaptive processing. The aim of the present study was to shed more light on this issue. A very comprehensive set of predictor variables was examined in healthy pain-free subjects. METHOD: Participants were 92 young and healthy subjects (mean [ SD] age 26.996.90 years; 47 men, 45 women). Maladaptive attentional and emotional mechanisms of pain processing were assessed by self-report measures of pain hypervigilance, pain-related anxiety and pain catastrophizing, as well as by a dot-probe task. The comprehensive set of predictor variables included measures of affective and bodily distress (depression, anxiety and somatization), experimental pain sensitivity, and cortisol reactivity. Directed relationships were estimated by using structural equation modelling. RESULTS: Structural equation modelling revealed a significant path from affective and bodily distress to self-reported maladaptive attentional and emotional pain processing. In contrast, the paths from pain sensitivity and cortisol reactivity did not reach the level of significance. CONCLUSION: These results support the position that anxiety and depression, as well as somatization, contribute to the aberrance of attentional and emotional mechanisms of pain processing. Surprisingly, the assumption of a close relationship between these maladaptive mechanisms of pain processing and pain sensitivity could not be confirmed. PMID:20808968

  15. 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

  16. 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

  17. 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)

  18. 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…

  19. 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.

  20. 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

  1. 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

  2. Rapidly oscillating asymptotic solutions of the Navier-Stokes equations, coherent structures, Fomenko invariants, Kolmogorov spectrum, and flicker noise

    NASA Astrophysics Data System (ADS)

    Maslov, V. P.; Shafarevich, A. I.

    2006-12-01

    Asymptotic solutions of the Navier-Stokes equations describing three-phase coherent structures of the Taylor scale are constructed. These equations are related to topological invariants of the Liouville foliations on the three-dimensional torus into two-dimensional tori. The solutions turn out to be unstable with respect to small-scale perturbations, which finally leads to the appearance of perturbations of Kolmogorov scale. The flicker noise occurs at the corresponding frequencies.

  3. 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.

  4. 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.

  5. Parallel workflows for data-driven structural equation modeling in functional neuroimaging.

    PubMed

    Kenny, Sarah; Andric, Michael; Boker, Steven M; Neale, Michael C; Wilde, Michael; Small, Steven L

    2009-01-01

    We present a computational framework suitable for a data-driven approach to structural equation modeling (SEM) and describe several workflows for modeling functional magnetic resonance imaging (fMRI) data within this framework. The Computational Neuroscience Applications Research Infrastructure (CNARI) employs a high-level scripting language called Swift, which is capable of spawning hundreds of thousands of simultaneous R processes (R Development Core Team, 2008), consisting of self-contained SEMs, on a high performance computing system (HPC). These self-contained R processing jobs are data objects generated by OpenMx, a plug-in for R, which can generate a single model object containing the matrices and algebraic information necessary to estimate parameters of the model. With such an infrastructure in place a structural modeler may begin to investigate exhaustive searches of the model space. Specific applications of the infrastructure, statistics related to model fit, and limitations are discussed in relation to exhaustive SEM. In particular, we discuss how workflow management techniques can help to solve large computational problems in neuroimaging. PMID:19876406

  6. 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

  7. 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.

  8. Sound Velocities and Equations of State for Lower Mantle Phases: Implications for Deep Mantle Structures

    NASA Astrophysics Data System (ADS)

    Jackson, J. M.; Wolf, A. S.; Wicks, J. K.; Solomatova, N. V.; Bower, D. J.; Sun, D.; Sturhahn, W.; Dera, P.; Prakapenka, V.

    2014-12-01

    We will present recent nuclear resonant scattering and x-ray diffraction measurements on iron-bearing phases and their application towards our understanding of deep mantle structures. Specifically, we will present measurements on (Mg,Fe)O and bridgmanite-structured (Mg,Fe)SiO3 with their relevance to ultra-low velocity zones and large piles in the core-mantle boundary region. The nuclear resonant inelastic x-ray scattering method provides specific vibrational information and in combination with x-ray diffraction data permits the determination of sound velocities and thermodynamic parameters. The nuclear resonant forward scattering method, also called synchrotron Mssbauer spectroscopy, provides hyperfine interactions between the resonant nucleus and electronic environment like isomer shifts and quadrupole splittings, which provide information on valence and spin states. These methods are complementary in terms of providing important information necessary to understand Earth's interior. For example, accurate determination of the sound velocities and equations of state of deep Earth materials combined with seismic observations and dynamic modeling is essential for understanding the radial and lateral distributions of minerals. Also, knowledge of iron valences and spin states of minerals are relevant to our understanding of transport properties, mechanical behavior, and element partitioning, all of which control Earth's internal dynamics.

  9. Parallel Workflows for Data-Driven Structural Equation Modeling in Functional Neuroimaging

    PubMed Central

    Kenny, Sarah; Andric, Michael; Boker, Steven M.; Neale, Michael C.; Wilde, Michael; Small, Steven L.

    2009-01-01

    We present a computational framework suitable for a data-driven approach to structural equation modeling (SEM) and describe several workflows for modeling functional magnetic resonance imaging (fMRI) data within this framework. The Computational Neuroscience Applications Research Infrastructure (CNARI) employs a high-level scripting language called Swift, which is capable of spawning hundreds of thousands of simultaneous R processes (R Development Core Team, 2008), consisting of self-contained SEMs, on a high performance computing system (HPC). These self-contained R processing jobs are data objects generated by OpenMx, a plug-in for R, which can generate a single model object containing the matrices and algebraic information necessary to estimate parameters of the model. With such an infrastructure in place a structural modeler may begin to investigate exhaustive searches of the model space. Specific applications of the infrastructure, statistics related to model fit, and limitations are discussed in relation to exhaustive SEM. In particular, we discuss how workflow management techniques can help to solve large computational problems in neuroimaging. PMID:19876406

  10. 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

  11. 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

  12. 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,

  13. 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,…

  14. Impaired self-awareness after traumatic brain injury: inter-rater reliability and factor structure of the Dysexecutive Questionnaire (DEX) in patients, significant others and clinicians

    PubMed Central

    McGuire, Brian E.; Morrison, Todd G.; Barker, Lynne A.; Morton, Nicholas; McBrinn, Judith; Caldwell, Sheena; Wilson, Colin F.; McCann, John; Carton, Simone; Delargy, Mark; Walsh, Jane

    2014-01-01

    Aims: This study sought to address two questions: (1) what is the inter-rater reliability of the Dysexecutive Questionnaire (DEX) when completed by patients, their significant others, and clinicians; and (2) does the factor structure of the DEX vary for these three groups? Methods: We obtained DEX ratings for 113 patients with an acquired brain injury from two brain injury services in the UK and two services in Ireland. We gathered data from two groups of raterssignificant others (DEX-SO) such as partners and close family members and clinicians (DEX-C), who were psychologists or rehabilitation physicians working closely with the patient and who were able to provide an opinion about the patients level of everyday executive functioning. Intra-class correlation coefficients and their 95% confidence intervals were calculated between each of the three groups (self, significant other, clinician). Principal axis factor (PAF) analyses were also conducted for each of the three groups. Results: The factor analysis revealed a consistent one-factor model for each of the three groups of raters. However, the inter-rater reliability analyses showed a low level of agreement between the self-ratings and the ratings of the two groups of independent raters. We also found low agreement between the significant others and the clinicians. Conclusion: Although there was a consistent finding of a single factor solution for each of the three groups, the low level of agreement between significant others and clinicians raises a question about the reliability of the DEX. PMID:25346668

  15. Modelling Pathways to Rubisco Degradation: A Structural Equation Network Modelling Approach

    PubMed Central

    Ttard-Jones, Catherine; Gatehouse, Angharad M. R.; Cooper, Julia; Leifert, Carlo; Rushton, Steven

    2014-01-01

    Omics analysis (transcriptomics, proteomics) quantifies changes in gene/protein expression, providing a snapshot of changes in biochemical pathways over time. Although tools such as modelling that are needed to investigate the relationships between genes/proteins already exist, they are rarely utilised. We consider the potential for using Structural Equation Modelling to investigate protein-protein interactions in a proposed Rubisco protein degradation pathway using previously published data from 2D electrophoresis and mass spectrometry proteome analysis. These informed the development of a prior model that hypothesised a pathway of Rubisco Large Subunit and Small Subunit degradation, producing both primary and secondary degradation products. While some of the putative pathways were confirmed by the modelling approach, the model also demonstrated features that had not been originally hypothesised. We used Bayesian analysis based on Markov Chain Monte Carlo simulation to generate output statistics suggesting that the model had replicated the variation in the observed data due to protein-protein interactions. This study represents an early step in the development of approaches that seek to enable the full utilisation of information regarding the dynamics of biochemical pathways contained within proteomics data. As these approaches gain attention, they will guide the design and conduct of experiments that enable Omics modelling to become a common place practice within molecular biology. PMID:24498339

  16. Reconstruction of vibroacoustic responses of a highly nonspherical structure using Helmholtz equation least-squares method.

    PubMed

    Lu, Huancai; Wu, Sean F

    2009-03-01

    The vibroacoustic responses of a highly nonspherical vibrating object are reconstructed using Helmholtz equation least-squares (HELS) method. The objectives of this study are to examine the accuracy of reconstruction and the impacts of various parameters involved in reconstruction using HELS. The test object is a simply supported and baffled thin plate. The reason for selecting this object is that it represents a class of structures that cannot be exactly described by the spherical Hankel functions and spherical harmonics, which are taken as the basis functions in the HELS formulation, yet the analytic solutions to vibroacoustic responses of a baffled plate are readily available so the accuracy of reconstruction can be checked accurately. The input field acoustic pressures for reconstruction are generated by the Rayleigh integral. The reconstructed normal surface velocities are validated against the benchmark values, and the out-of-plane vibration patterns at several natural frequencies are compared with the natural modes of a simply supported plate. The impacts of various parameters such as number of measurement points, measurement distance, location of the origin of the coordinate system, microphone spacing, and ratio of measurement aperture size to the area of source surface of reconstruction on the resultant accuracy of reconstruction are examined. PMID:19275312

  17. The effect of community stress and problems on psychopathology: A structural equation modeling study.

    PubMed

    Lyu, Juncheng; Shi, Hong; Wang, Suzhen; Zhang, Jie

    2016-02-01

    This research aimed to estimate the effect of perceived social factors in the community stress and problems on the residents' psychopathology such as depression and suicidal behaviors. Subjects of this study were the informants (N=1618) in a psychological autopsy (PA) study with a case-control design. We interviewed two informants (a family member and a close friend) for 392 suicides and 416 living controls, which came from 16 rural counties randomly selected from three provinces of China. Community stress and problems were measured by the WHO SUPRE-MISS scale. Depression was measured by CES-D scale, and suicidal behavior was assessed by NCS-R scale. Multivariable liner and logistic regression models and the Structural Equation Modeling (SEM) were applied to probe the correlation of the depression and the suicidal behaviors with some major demographic variables as covariates. It was found that community stress and problems were directly associated with rural Chinese residents' depression (Path coefficient=0.127, P<0.001). There was no direct correlation between community stress and problem and suicidal behaviors, but community stress and problem can affect suicidal behaviors indirectly through depression. The path coefficient between depression and suicidal behaviors was 0.975. The current study predicts a new research viewpoint, that is, the depression is the intermediate between community stress and problem and suicidal behaviors. It might be an effective route to prevent depression directly and suicidal behaviors indirectly by reducing the community stress and problems. PMID:26773987

  18. Network inference of AP pattern formation system in D.melanogaster by structural equation modeling

    NASA Astrophysics Data System (ADS)

    Aburatani, S.; Toh, H.

    2014-03-01

    Within the field of systems biology, revealing the control systems functioning during embryogenesis is an important task. To clarify the mechanisms controlling sequential events, the relationships between various factors and the expression of specific genes should be determined. In this study, we applied a method based on Structural Equation Modeling (SEM), combined with factor analysis. SEM can include the latent variables within the constructed model and infer the relationships among the latent and observed variables, as a network model. We improved a method for the construction of initial models for the SEM calculation, and applied our approach to estimate the regulatory network for Antero-Posterior (AP) pattern formation in D. melanogaster embryogenesis. In this new approach, we combined cross-correlation and partial correlation to summarize the temporal information and to extract the direct interactions from the gene expression profiles. In the inferred model, 18 transcription factor genes were regulated by not only the expression of other genes, but also the estimated factors. Since each factor regulated the same type of genes, these factors were considered to be involved in maternal effects or spatial morphogen distributions. The interpretation of the inferred network model allowed us to reveal the regulatory mechanism for the patterning along the head to tail axis in D. melanogaster.

  19. Psychological contract breach and outcomes: Combining meta-analysis and structural equation models.

    PubMed

    Topa Cantisano, Gabriela; Morales Domnguez, 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

  20. 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

  1. 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 (?2(21) ?=?48.808, p<.001, CFI ?=?.995, TLI ?=?.992, RMSEA ?=?.021, 90% CI [.013.029]) and prospective analyses (?2(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

  2. 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.

  3. Nonparametric Estimates of Gene Environment Interaction Using Local Structural Equation Modeling.

    PubMed

    Briley, Daniel A; Harden, K Paige; Bates, Timothy C; Tucker-Drob, Elliot M

    2015-09-01

    Gene environment (G E) interaction studies test the hypothesis that the strength of genetic influence varies across environmental contexts. Existing latent variable methods for estimating G E interactions in twin and family data specify parametric (typically linear) functions for the interaction effect. An improper functional form may obscure the underlying shape of the interaction effect and may lead to failures to detect a significant interaction. In this article, we introduce a novel approach to the behavior genetic toolkit, local structural equation modeling (LOSEM). LOSEM is a highly flexible nonparametric approach for estimating latent interaction effects across the range of a measured moderator. This approach opens up the ability to detect and visualize new forms of G E interaction. We illustrate the approach by using LOSEM to estimate gene socioeconomic status interactions for six cognitive phenotypes. Rather than continuously and monotonically varying effects as has been assumed in conventional parametric approaches, LOSEM indicated substantial nonlinear shifts in genetic variance for several phenotypes. The operating characteristics of LOSEM were interrogated through simulation studies where the functional form of the interaction effect was known. LOSEM provides a conservative estimate of G E interaction with sufficient power to detect statistically significant G E signal with moderate sample size. We offer recommendations for the application of LOSEM and provide scripts for implementing these biometric models in Mplus and in OpenMx under R. PMID:26318287

  4. 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

  5. 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

  6. Schizophrenic outpatient perceptions of psychiatric treatment and psychotic symptomatology: an investigation using structural equation modeling.

    PubMed

    Hayashi, N; Yamashina, M; Taguchi, H; Ishige, N; Igarashi, Y

    2001-12-01

    Schizophrenic patient perceptions of treatment have clinical value and deserve detailed psychiatric investigation. The present study sought a model indicating statistically estimated cause-effect relationships of perceptions and psychotic symptomatology of outpatients with schizophrenia by applying a method of structural equation modeling. The perceptions included in this model were patient satisfaction with treatment, perceptions of their treating psychiatrists, and patient-role perception. Scores of Positive and Negative Syndrome Scale and poor insight measures were added to the model as possible influential factors. The constructed model revealed that the poor insight exerted a major influence on the patient-role perception that had small effects on the reliable therapist perception and the satisfaction. It was also shown that satisfaction was chiefly determined by the reliable therapist perception that was formed in the treatment relationship, rather independently of the other construct. These findings were valuable in terms of their implications for understanding the makeup of the perceptions and the strategy for interventions to improve them. PMID:11737791

  7. Structural equation modeling of factors contributing to quality of life in Japanese patients with multiple sclerosis

    PubMed Central

    2013-01-01

    Background To improve quality of life (QOL) in patients with multiple sclerosis (MS), it is important to decrease disability and prevent relapse. The aim of this study was to examine the causal and mutual relationships contributing to QOL in Japanese patients with MS, develop path diagrams, and explore interventions with the potential to improve patient QOL. Methods Data of 163 Japanese MS patients were obtained using the Functional Assessment of MS (FAMS) and Nottingham Adjustment Scale-Japanese version (NAS-J) tests, as well as four additional factors that affect QOL (employment status, change of income, availability of disease information, and communication with medical staff). Data were then used in structural equation modeling to develop path diagrams for factors contributing to QOL. Results The Expanded Disability Status Scale (EDSS) score had a significant effect on the total FAMS score. Although EDSS negatively affected the FAMS symptom score, NAS-J subscale scores of anxiety/depression and acceptance were positively related to the FAMS symptom score. Changes in employment status after MS onset negatively affected all NAS-J scores. Knowledge of disease information improved the total NAS-J score, which in turn improved many FAMS subscale scores. Communication with doctors and nurses directly and positively affected some FAMS subscale scores. Conclusions Disability and change in employment status decrease patient QOL. However, the present findings suggest that other factors, such as acquiring information on MS and communicating with medical staff, can compensate for the worsening of QOL. PMID:23339479

  8. 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

  9. 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 (19902005) are used for illustration. PMID:25504026

  10. 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

  11. Investigating perturbed pathway modules from gene expression data via structural equation models

    PubMed Central

    2014-01-01

    Background It is currently accepted that the perturbation of complex intracellular networks, rather than the dysregulation of a single gene, is the basis for phenotypical diversity. High-throughput gene expression data allow to investigate changes in gene expression profiles among different conditions. Recently, many efforts have been made to individuate which biological pathways are perturbed, given a list of differentially expressed genes (DEGs). In order to understand these mechanisms, it is necessary to unveil the variation of genes in relation to each other, considering the different phenotypes. In this paper, we illustrate a pipeline, based on Structural Equation Modeling (SEM) that allowed to investigate pathway modules, considering not only deregulated genes but also the connections between the perturbed ones. Results The procedure was tested on microarray experiments relative to two neurological diseases: frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U) and multiple sclerosis (MS). Starting from DEGs and dysregulated biological pathways, a model for each pathway was generated using databases information biological databases, in order to design how DEGs were connected in a causal structure. Successively, SEM analysis proved if pathways differ globally, between groups, and for specific path relationships. The results confirmed the importance of certain genes in the analyzed diseases, and unveiled which connections are modified among them. Conclusions We propose a framework to perform differential gene expression analysis on microarray data based on SEM, which is able to: 1) find relevant genes and perturbed biological pathways, investigating putative sub-pathway models based on the concept of disease module; 2) test and improve the generated models; 3) detect a differential expression level of one gene, and differential connection between two genes. This could shed light, not only on the mechanisms affecting variations in gene expression, but also on the causes of gene-gene relationship modifications in diseased phenotypes. PMID:24885496

  12. Pediatric Health-Related Quality of Life: A Structural Equation Modeling Approach

    PubMed Central

    Villalonga-Olives, Ester; Kawachi, Ichiro; Almansa, Josu; Witte, Claudia; Lange, Benjamin; Kiese-Himmel, Christiane; von Steinbchel, 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 (35 years old) participating in a follow-up study that investigates pediatric health outcomes. Results Model fit was ?2?=?5.5; df?=?6; p?=?0.48; SRMR ?=?0.01. The variance explained of Health Related Quality of Life was 15%. Health Related Quality of Life was affected by the area education (i.e. where kindergartens were located) and development status. Developmental status was affected by the area of education, socioeconomic status and individual behavior. Symptoms did not affect the model. Conclusions The goodness of fit and the overall variance explained were good. However, the results between children' and adults' tests differed and denote a conceptual gap between adult and children measures. Indeed, there is a lot of variety in pediatric Health Related Quality of Life measures, which represents a lack of a common definition of pediatric Health Related Quality of Life. We recommend that researchers invest time in the development of pediatric Health Related Quality of Life theory and theory based evaluations. PMID:25415751

  13. Wing-Body Aeroelasticity Using Finite-Difference Fluid/Finite-Element Structural Equations on Parallel Computers

    NASA Technical Reports Server (NTRS)

    Byun, Chansup; Guruswamy, Guru P.

    1993-01-01

    This paper presents a procedure for computing the aeroelasticity of wing-body configurations on multiple-instruction, multiple-data (MIMD) parallel computers. In this procedure, fluids are modeled using Euler equations discretized by a finite difference method, and structures are modeled using finite element equations. The procedure is designed in such a way that each discipline can be developed and maintained independently by using a domain decomposition approach. A parallel integration scheme is used to compute aeroelastic responses by solving the coupled fluid and structural equations concurrently while keeping modularity of each discipline. The present procedure is validated by computing the aeroelastic response of a wing and comparing with experiment. Aeroelastic computations are illustrated for a High Speed Civil Transport type wing-body configuration.

  14. Individual, social and environmental correlates of physical activity in overweight and obese African American and Hispanic women: A structural equation model analysis

    PubMed Central

    Mama, Scherezade K.; Diamond, Pamela M.; McCurdy, Sheryl A.; Evans, Alexandra E.; McNeill, Lorna H.; Lee, Rebecca E.

    2015-01-01

    Objective Ecologic frameworks account for multilevel factors related to physical activity (PA) and may be used to develop effective interventions for women. The purpose of this study was to examine the influence of individual, social and environmental factors on PA among African American and Hispanic women using structural equation modeling. Methods Overweight and obese women (N = 164, 65.9% African American) completed a 7-day accelerometer protocol, a physical assessment, and questionnaires on body image, self-efficacy, motivational readiness, social support, home environment for physical activity and perceived environment. Trained assessors evaluated each participant's neighborhood and collected objective measures of physical activity resources and the pedestrian environment. Assessments were completed between 2006 and 2008. Results Structural model fit was acceptable (RMSEA = .030). Body composition and image was negatively associated with PA, and motivational readiness had an indirect effect on PA through body composition and image. PA resources and the pedestrian environment operated through the perceived environment to positively influence neighborhood cohesion, which was positively associated with body composition and image. Conclusion PA is more heavily influenced by intrapersonal factors related to weight. Improving intrapersonal factors related to weight and perceptions of the environment may lead to increased PA in African American and Hispanic women. PMID:25692093

  15. Spatially inhomogeneous structures in the solution of Fisher-Kolmogorov equation with delay

    NASA Astrophysics Data System (ADS)

    Aleshin, S. V.; Glyzin, S. D.; Kaschenko, S. A.

    2016-02-01

    We consider the problem of density wave propagation in a logistic equation with delay and diffusion (Fisher-Kolmogorov equation with delay). A Ginzburg-Landau equation was constructed in order to study the qualitative behavior of the solution near the equilibrium state. The numerical analysis of wave propagation shows that for a sufficiently small delay this equation has a solution similar to the solution of a classical Fisher-Kolmogorov equation. The delay increasing leads to existence of the oscillatory component in spatial distribution of solutions. A further increase of delay leads to destruction of the traveling wave. That is expressed in the fact that undamped spatio-temporal fluctuations exist in a neighborhood of the initial perturbation. These fluctuations are close to the solution of the corresponding boundary value problem with periodic boundary conditions. Finally, when the delay is sufficiently large we observe intensive spatio-temporal fluctuations in the whole area of wave propagation.

  16. Do Test Design and Uses Influence Test Preparation? Testing a Model of Washback with Structural Equation Modeling

    ERIC Educational Resources Information Center

    Xie, Qin; Andrews, Stephen

    2013-01-01

    This study introduces Expectancy-value motivation theory to explain the paths of influences from perceptions of test design and uses to test preparation as a special case of washback on learning. Based on this theory, two conceptual models were proposed and tested via Structural Equation Modeling. Data collection involved over 870 test takers of

  17. Modeling the Relationships among Topical Knowledge, Anxiety, and Integrated Speaking Test Performance: A Structural Equation Modeling Approach

    ERIC Educational Resources Information Center

    Huang, Heng-Tsung Danny

    2010-01-01

    Thus far, few research studies have examined the practice of integrated speaking test tasks in the field of second/foreign language oral assessment. This dissertation utilized structural equation modeling (SEM) and qualitative techniques to explore the relationships among topical knowledge, anxiety, and integrated speaking test performance and to

  18. Review of Sample Size for Structural Equation Models in Second Language Testing and Learning Research: A Monte Carlo Approach

    ERIC Educational Resources Information Center

    In'nami, Yo; Koizumi, Rie

    2013-01-01

    The importance of sample size, although widely discussed in the literature on structural equation modeling (SEM), has not been widely recognized among applied SEM researchers. To narrow this gap, we focus on second language testing and learning studies and examine the following: (a) Is the sample size sufficient in terms of precision and power of

  19. Socioeconomic Status and Asian American and Pacific Islander Students' Transition to College: A Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Museus, Samuel D.; Vue, Rican

    2013-01-01

    The purpose of this study is to examine socioeconomic differences in the interpersonal factors that influence college access among Asian Americans and Pacific Islanders (AAPIs). Data on 1,460 AAPIs from the Education Longitudinal Study (ELS: 02/06) were analyzed using structural equation modeling techniques. Findings suggest that parental

  20. Modeling Educational Effectiveness in Classrooms: The Use of Multi-Level Structural Equations To Model Students' Progress.

    ERIC Educational Resources Information Center

    Rowe, Kenneth J.; Hill, Peter W.

    1998-01-01

    Illustrates an approach to modeling educational effectiveness in classrooms by combining multilevel analysis and structural equation modeling in a two-step process. Data from a longitudinal study of 4,558 students in 334 class groups show how progress can be accounted for by the grouping effects of students within classes and schools. (SLD)

  1. Study of Factors Preventing Children from Enrolment in Primary School in the Republic of Honduras: Analysis Using Structural Equation Modelling

    ERIC Educational Resources Information Center

    Ashida, Akemi

    2015-01-01

    Studies have investigated factors that impede enrolment in Honduras. However, they have not analysed individual factors as a whole or identified the relationships among them. This study used longitudinal data for 1971 children who entered primary schools from 1986 to 2000, and employed structural equation modelling to examine the factors…

  2. Socioeconomic Status and Asian American and Pacific Islander Students' Transition to College: A Structural Equation Modeling Analysis

    ERIC Educational Resources Information Center

    Museus, Samuel D.; Vue, Rican

    2013-01-01

    The purpose of this study is to examine socioeconomic differences in the interpersonal factors that influence college access among Asian Americans and Pacific Islanders (AAPIs). Data on 1,460 AAPIs from the Education Longitudinal Study (ELS: 02/06) were analyzed using structural equation modeling techniques. Findings suggest that parental…

  3. Maximum Likelihood Methods in Treating Outliers and Symmetrically Heavy-Tailed Distributions for Nonlinear Structural Equation Models with Missing Data

    ERIC Educational Resources Information Center

    Lee, Sik-Yum; Xia, Ye-Mao

    2006-01-01

    By means of more than a dozen user friendly packages, structural equation models (SEMs) are widely used in behavioral, education, social, and psychological research. As the underlying theory and methods in these packages are vulnerable to outliers and distributions with longer-than-normal tails, a fundamental problem in the field is the

  4. The Best of Both Worlds: Factor Analysis of Dichotomous Data Using Item Response Theory and Structural Equation Modeling

    ERIC Educational Resources Information Center

    Glockner-Rist, Angelika; Hoijtink, Herbert

    2003-01-01

    Both structural equation modeling (SEM) and item response theory (IRT) can be used for factor analysis of dichotomous item responses. In this case, the measurement models of both approaches are formally equivalent. They were refined within and across different disciplines, and make complementary contributions to central measurement problems

  5. Equation Structure and the Meaning of the Equal Sign: The Impact of Task Selection in Eliciting Elementary Students' Understandings

    ERIC Educational Resources Information Center

    Stephens, Ana C.; Knuth, Eric J.; Blanton, Maria L.; Isler, Isil; Gardiner, Angela Murphy; Marum, Tim

    2013-01-01

    This paper reports results from a written assessment given to 290 third-, fourth-, and fifth-grade students prior to any instructional intervention. We share and discuss students' responses to items addressing their understanding of equation structure and the meaning of the equal sign. We found that many students held an operational conception of

  6. The Best of Both Worlds: Factor Analysis of Dichotomous Data Using Item Response Theory and Structural Equation Modeling

    ERIC Educational Resources Information Center

    Glockner-Rist, Angelika; Hoijtink, Herbert

    2003-01-01

    Both structural equation modeling (SEM) and item response theory (IRT) can be used for factor analysis of dichotomous item responses. In this case, the measurement models of both approaches are formally equivalent. They were refined within and across different disciplines, and make complementary contributions to central measurement problems…

  7. Study of Factors Preventing Children from Enrolment in Primary School in the Republic of Honduras: Analysis Using Structural Equation Modelling

    ERIC Educational Resources Information Center

    Ashida, Akemi

    2015-01-01

    Studies have investigated factors that impede enrolment in Honduras. However, they have not analysed individual factors as a whole or identified the relationships among them. This study used longitudinal data for 1971 children who entered primary schools from 1986 to 2000, and employed structural equation modelling to examine the factors

  8. Perceived Social Relationships and Science Learning Outcomes for Taiwanese Eighth Graders: Structural Equation Modeling with a Complex Sampling Consideration

    ERIC Educational Resources Information Center

    Jen, Tsung-Hau; Lee, Che-Di; Chien, Chin-Lung; Hsu, Ying-Shao; Chen, Kuan-Ming

    2013-01-01

    Based on the Trends in International Mathematics and Science Study 2007 study and a follow-up national survey, data for 3,901 Taiwanese grade 8 students were analyzed using structural equation modeling to confirm a social-relation-based affection-driven model (SRAM). SRAM hypothesized relationships among students' perceived social relationships in

  9. Meta-Analytic Methods of Pooling Correlation Matrices for Structural Equation Modeling under Different Patterns of Missing Data

    ERIC Educational Resources Information Center

    Furlow, Carolyn F.; Beretvas, S. Natasha

    2005-01-01

    Three methods of synthesizing correlations for meta-analytic structural equation modeling (SEM) under different degrees and mechanisms of missingness were compared for the estimation of correlation and SEM parameters and goodness-of-fit indices by using Monte Carlo simulation techniques. A revised generalized least squares (GLS) method for

  10. Next Steps in Bayesian Structural Equation Models: Comments on, Variations of, and Extensions to Muthen and Asparouhov (2012)

    ERIC Educational Resources Information Center

    Rindskopf, David

    2012-01-01

    Muthen and Asparouhov (2012) made a strong case for the advantages of Bayesian methodology in factor analysis and structural equation models. I show additional extensions and adaptations of their methods and show how non-Bayesians can take advantage of many (though not all) of these advantages by using interval restrictions on parameters. By…

  11. Are Teachers' Approaches to Teaching Responsive to Individual Student Variation? A Two-Level Structural Equation Modeling

    ERIC Educational Resources Information Center

    Rosário, Pedro; Núñez, José Carlos; Vallejo, Guilermo; Paiva, Olímpia; Valle, António; Fuentes, Sonia; Pinto, Ricardo

    2014-01-01

    In the framework of teacher's approaches to teaching, this study investigates the relationship between student-related variables (i.e., study time, class absence, domain knowledge, and homework completion), students' approaches to learning, and teachers' approaches to teaching using structural equation modeling (SEM) with two…

  12. Doubly-Latent Models of School Contextual Effects: Integrating Multilevel and Structural Equation Approaches to Control Measurement and Sampling Error

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Ludtke, Oliver; Robitzsch, Alexander; Trautwein, Ulrich; Asparouhov, Tihomir; Muthen, Bengt; Nagengast, Benjamin

    2009-01-01

    This article is a methodological-substantive synergy. Methodologically, we demonstrate latent-variable contextual models that integrate structural equation models (with multiple indicators) and multilevel models. These models simultaneously control for and unconfound measurement error due to sampling of items at the individual (L1) and group (L2)

  13. Do Test Design and Uses Influence Test Preparation? Testing a Model of Washback with Structural Equation Modeling

    ERIC Educational Resources Information Center

    Xie, Qin; Andrews, Stephen

    2013-01-01

    This study introduces Expectancy-value motivation theory to explain the paths of influences from perceptions of test design and uses to test preparation as a special case of washback on learning. Based on this theory, two conceptual models were proposed and tested via Structural Equation Modeling. Data collection involved over 870 test takers of…

  14. Are Teachers' Approaches to Teaching Responsive to Individual Student Variation? A Two-Level Structural Equation Modeling

    ERIC Educational Resources Information Center

    Rosrio, Pedro; Nez, Jos Carlos; Vallejo, Guilermo; Paiva, Olmpia; Valle, Antnio; Fuentes, Sonia; Pinto, Ricardo

    2014-01-01

    In the framework of teacher's approaches to teaching, this study investigates the relationship between student-related variables (i.e., study time, class absence, domain knowledge, and homework completion), students' approaches to learning, and teachers' approaches to teaching using structural equation modeling (SEM) with two

  15. An Empirical Test of Tinto's Integration Framework for Community Colleges Using Structural Equation Modeling

    ERIC Educational Resources Information Center

    Santos-George, Arlene A.

    2012-01-01

    This dissertation empirically tested Tinto's student integration theory through structural equation modeling using a national sample of 2,847 first-time entering community college students. Tinto theorized that the more academically and socially integrated a student is to the college environment, the more likely the student will persist

  16. Filipino Nursing Students' Behavioral Intentions toward Geriatric Care: A Structural Equation Model (SEM)

    ERIC Educational Resources Information Center

    de Guzman, Allan B.; Jimenez, Benito Christian B.; Jocson, Kathlyn P.; Junio, Aileen R.; Junio, Drazen E.; Jurado, Jasper Benjamin N.; Justiniano, Angela Bianca F.

    2013-01-01

    Anchored on the key constucts of Ajzen's Theory of Planned Behavior (1985), this paper seeks to test a model that explores the influence of knowledge, attitude, and caring behavior on nursing students' behavioral intention toward geriatric care. A five-part survey-questionnaire was administered to 839 third and fourth year nursing students from a

  17. Relationship between Learning Strategies and Motivation by Using Structural Equation Modeling Approach

    ERIC Educational Resources Information Center

    Adnan, Mohamad Azrien Mohamed; Nordin, Mohd Sahari; Ibrahim, Mohd Burhan

    2013-01-01

    This paper aimed at examining the learning strategies constructs and to investigate the relationship between learning strategies and motivation in Arabic courses. The study uses a questionnaire as the information-gathering instrument, and the participants comprised students from two public universities in Peninsular Malaysia who are studying…

  18. Filipino Nursing Students' Behavioral Intentions toward Geriatric Care: A Structural Equation Model (SEM)

    ERIC Educational Resources Information Center

    de Guzman, Allan B.; Jimenez, Benito Christian B.; Jocson, Kathlyn P.; Junio, Aileen R.; Junio, Drazen E.; Jurado, Jasper Benjamin N.; Justiniano, Angela Bianca F.

    2013-01-01

    Anchored on the key constucts of Ajzen's Theory of Planned Behavior (1985), this paper seeks to test a model that explores the influence of knowledge, attitude, and caring behavior on nursing students' behavioral intention toward geriatric care. A five-part survey-questionnaire was administered to 839 third and fourth year nursing students from a…

  19. Structural equation modeling of the proximaldistal continuum of adherence drivers

    PubMed Central

    McHorney, Colleen A; Zhang, Ning Jackie; Stump, Timothy; Zhao, Xiaoquan

    2012-01-01

    Objectives Nonadherence to prescription medications has been shown to be significantly influenced by three key medication-specific beliefs: patients perceived need for the prescribed medication, their concerns about the prescribed medication, and perceived medication affordability. Structural equation modeling was used to test the predictors of these three proximal determinants of medication adherence using the proximaldistal continuum of adherence drivers as the organizing conceptual framework. Methods In Spring 2008, survey participants were selected from the Harris Interactive Chronic Illness Panel, an internet-based panel of hundreds of thousands of adults with chronic disease. Respondents were eligible for the survey if they were aged 40 years and older, resided in the US, and reported having at least one of six chronic diseases: asthma, diabetes, hyperlipidemia, hypertension, osteoporosis, or other cardiovascular disease. A final sample size of 1072 was achieved. The proximal medication beliefs were measured by three multi-item scales: perceived need for medications, perceived medication concerns, and perceived medication affordability. The intermediate sociomedical beliefs and skills included four multi-item scales: perceived disease severity, knowledge about the prescribed medication, perceived immunity to side effects, and perceived value of nutraceuticals. Generic health beliefs and skills consisted of patient engagement in their care, health information-seeking tendencies, internal health locus of control, a single-item measure of self-rated health, and general mental health. Structural equation modeling was used to model proximaldistal continuum of adherence drivers. Results The average age was 58 years (range = 4090 years), and 65% were female and 89% were white. Forty-one percent had at least a four-year college education, and just under half (45%) had an annual income of $50,000 or more. Hypertension and hyperlipidemia were each reported by about a quarter of respondents (24% and 23%, respectively). A smaller percentage of respondents had osteoporosis (17%), diabetes (15%), asthma (13%), or other cardiovascular disease (8%). Three independent variables were significantly associated with the three proximal adherence drivers: perceived disease severity, knowledge about the medication, and perceived value of nutraceuticals. Both perceived immunity to side effects and patient engagement was significantly associated with perceived need for medications and perceived medication concerns. Conclusion Testing the proximaldistal continuum of adherence drivers shed light on specific areas where adherence dialogue and enhancement should focus. Our results can help to inform the design of future adherence interventions as well as the content of patient education materials and adherence reminder letters. For long-term medication adherence, patients need to autonomously and intrinsically commit to therapy and that, in turn, is more likely to occur if they are both informed (disease and medication knowledge and rationale, disease severity, consequences of nonadherence, and side effects) and motivated (engaged in their care, perceive a need for medication, and believe the benefits outweigh the risks). PMID:23204839

  20. Species richness and soil properties in Pinus ponderosa forests: A structural equation modeling analysis

    USGS Publications Warehouse

    Laughlin, D.C.; Abella, S.R.; Covington, W.W.; Grace, J.B.

    2007-01-01

    Question: How are the effects of mineral soil properties on understory plant species richness propagated through a network of processes involving the forest overstory, soil organic matter, soil nitrogen, and understory plant abundance? Location: North-central Arizona, USA. Methods: We sampled 75 0.05-ha plots across a broad soil gradient in a Pinus ponderosa (ponderosa pine) forest ecosystem. We evaluated multivariate models of plant species richness using structural equation modeling. Results: Richness was highest at intermediate levels of understory plant cover, suggesting that both colonization success and competitive exclusion can limit richness in this system. We did not detect a reciprocal positive effect of richness on plant cover. Richness was strongly related to soil nitrogen in the model, with evidence for both a direct negative effect and an indirect non-linear relationship mediated through understory plant cover. Soil organic matter appeared to have a positive influence on understory richness that was independent of soil nitrogen. Richness was lowest where the forest overstory was densest, which can be explained through indirect effects on soil organic matter, soil nitrogen and understory cover. Finally, model results suggest a variety of direct and indirect processes whereby mineral soil properties can influence richness. Conclusions: Understory plant species richness and plant cover in P. ponderosa forests appear to be significantly influenced by soil organic matter and nitrogen, which are, in turn, related to overstory density and composition and mineral soil properties. Thus, soil properties can impose direct and indirect constraints on local species diversity in ponderosa pine forests. ?? IAVS; Opulus Press.

  1. Comparative analysis of microbiome measurement platforms using latent variable structural equation modeling

    PubMed Central

    2013-01-01

    Background Culture-independent phylogenetic analysis of 16S ribosomal RNA (rRNA) gene sequences has emerged as an incisive method of profiling bacteria present in a specimen. Currently, multiple techniques are available to enumerate the abundance of bacterial taxa in specimens, including the Sanger sequencing, the ‘next generation’ pyrosequencing, microarrays, quantitative PCR, and the rapidly emerging, third generation sequencing, and fourth generation sequencing methods. An efficient statistical tool is in urgent need for the followings tasks: (1) to compare the agreement between these measurement platforms, (2) to select the most reliable platform(s), and (3) to combine different platforms of complementary strengths, for a unified analysis. Results We present the latent variable structural equation modeling (SEM) as a novel statistical application for the comparative analysis of measurement platforms. The latent variable SEM model treats the true (unknown) relative frequency of a given bacterial taxon in a specimen as the latent (unobserved) variable and estimates the reliabilities of, and similarities between, different measurement platforms, and subsequently weighs those measurements optimally for a unified analysis of the microbiome composition. The latent variable SEM contains the repeated measures ANOVA (both the univariate and the multivariate models) as special cases and, as a more general and realistic modeling approach, yields superior goodness-of-fit and more reliable analysis results, as demonstrated by a microbiome study of the human inflammatory bowel diseases. Conclusions Given the rapid evolution of modern biotechnologies, the measurement platform comparison, selection and combination tasks are here to stay and to grow – and the latent variable SEM method is readily applicable to any other biological settings, aside from the microbiome study presented here. PMID:23497007

  2. Determinants of work injuries in mines - an application of structural equation modelling.

    PubMed

    Maiti, J; Chatterjee, S; Bangdiwala, S I

    2004-03-01

    In spite of stringent regulations and much attention towards reducing risks in the physical environment, the mining industry continues to be associated with high levels of accidents, injuries and illnesses. Only engineering solutions to accident prevention are inappropriate unless coupled with focused attention to the attitudes and behaviours of the mineworkers in coping with the inherent physical, technical and situational risks. The present study identified these various risk factors and analysed their influences on work injury in a causal framework. Data were collected from an underground coalmine of India. The pattern and strength of relationships of 16 causal factors with work injuries were assessed through structural equation modelling. The case study results showed that negatively personified individuals are of major concern for safety improvement in the mine studied. They not only fail to avoid work injuries, they are unable to extend safe work behaviours in their work. The variable safety environment is negatively affected by personality, whereas social support has a positive relationship with safety environment. The variable job hazards appeared to have a significant relationship with job involvement, which has a negative relationship with work injury. Elimination of negative behaviours must be focused and committed by the mine safety management. Long term planning through (i) identification of negative individuals, (ii) proper councelling of adverse effects of negative behaviours, and (iii) special training with psychological treatment is highly required. Identification may begin while recruiting new workers through interview. Proper allocation of jobs (right person for right job) may be a judicial solution to this end. PMID:14977503

  3. Global sensitivity of parabolic equation radar wave propagation simulation to sea state and atmospheric refractivity structure

    NASA Astrophysics Data System (ADS)

    Lentini, N. E.; Hackett, E. E.

    2015-10-01

    Inadequate representation of the environment is a limitation for prediction of radar system performance as well as for validation of propagation codes. To improve understanding of how different environmental effects/parameters compete and compare, this study examines the sensitivity of radar wave propagation to a suite of environmental parameters for low grazing angle near-surface radar systems at 3-15 GHz at horizontal and vertical polarizations. A global sensitivity analysis method is used, which accounts for parameter interactions, and propagation is modeled using the parabolic equation method. Environmental parameters examined include eight sea state parameters and eight parameters characterizing the vertical structure and character of range-independent refractivity profiles. The relative importance of parameters varies more with frequency than polarization, and parameter interactions are found to be significant. Atmospheric mixed layer parameters are found to be the most sensitive, particularly the thickness of the mixed layer. The most significant ocean surface parameter is swell period, although sea directionality is important at 3 GHz and sea surface roughness and salinity are important at 9 and 15 GHz. Because of the spatial variability of sensitivity throughout the domain, regional analysis is performed to determine the most important parameters in different regions of the domain (1000 m in altitude and 60 km in range). These regional sensitivity results, along with those for the whole domain, provide guidance on prioritization of environmental characterization in numerical weather prediction and inversion studies (e.g., refractivity from clutter studies), which are two common methods currently used to address environmental effects on propagation.

  4. A structural equation model analysis of relationships among ENSO, seasonal descriptors and wildfires.

    PubMed

    Slocum, Matthew G; Orzell, Steve L

    2013-01-01

    Seasonality drives ecological processes through networks of forcings, and the resultant complexity requires creative approaches for modeling to be successful. Recently ecologists and climatologists have developed sophisticated methods for fully describing seasons. However, to date the relationships among the variables produced by these methods have not been analyzed as networks, but rather with simple univariate statistics. In this manuscript we used structural equation modeling (SEM) to analyze a proposed causal network describing seasonality of rainfall for a site in south-central Florida. We also described how this network was influenced by the El Nio-Southern Oscillation (ENSO), and how the network in turn affected the site's wildfire regime. Our models indicated that wet and dry seasons starting later in the year (or ending earlier) were shorter and had less rainfall. El Nio conditions increased dry season rainfall, and via this effect decreased the consistency of that season's drying trend. El Nio conditions also negatively influenced how consistent the moistening trend was during the wet season, but in this case the effect was direct and did not route through rainfall. In modeling wildfires, our models showed that area burned was indirectly influenced by ENSO via its effect on dry season rainfall. Area burned was also indirectly reduced when the wet season had consistent rainfall, as such wet seasons allowed fewer wildfires in subsequent fire seasons. Overall area burned at the study site was estimated with high accuracy (R (2) score = 0.63). In summary, we found that by using SEMs, we were able to clearly describe causal patterns involving seasonal climate, ENSO and wildfire. We propose that similar approaches could be effectively applied to other sites where seasonality exerts strong and complex forcings on ecological processes. PMID:24086670

  5. A Structural Equation Model Analysis of Relationships among ENSO, Seasonal Descriptors and Wildfires

    PubMed Central

    Slocum, Matthew G.; Orzell, Steve L.

    2013-01-01

    Seasonality drives ecological processes through networks of forcings, and the resultant complexity requires creative approaches for modeling to be successful. Recently ecologists and climatologists have developed sophisticated methods for fully describing seasons. However, to date the relationships among the variables produced by these methods have not been analyzed as networks, but rather with simple univariate statistics. In this manuscript we used structural equation modeling (SEM) to analyze a proposed causal network describing seasonality of rainfall for a site in south-central Florida. We also described how this network was influenced by the El Niño-Southern Oscillation (ENSO), and how the network in turn affected the site’s wildfire regime. Our models indicated that wet and dry seasons starting later in the year (or ending earlier) were shorter and had less rainfall. El Niño conditions increased dry season rainfall, and via this effect decreased the consistency of that season’s drying trend. El Niño conditions also negatively influenced how consistent the moistening trend was during the wet season, but in this case the effect was direct and did not route through rainfall. In modeling wildfires, our models showed that area burned was indirectly influenced by ENSO via its effect on dry season rainfall. Area burned was also indirectly reduced when the wet season had consistent rainfall, as such wet seasons allowed fewer wildfires in subsequent fire seasons. Overall area burned at the study site was estimated with high accuracy (R2 score = 0.63). In summary, we found that by using SEMs, we were able to clearly describe causal patterns involving seasonal climate, ENSO and wildfire. We propose that similar approaches could be effectively applied to other sites where seasonality exerts strong and complex forcings on ecological processes. PMID:24086670

  6. A structural equation model analysis of postfire plant diversity in California shrublands

    USGS Publications Warehouse

    Grace, J.B.; Keeley, J.E.

    2006-01-01

    This study investigates patterns of plant diversity following wildfires in fire-prone shrublands of California, seeks to understand those patterns in terms of both local and landscape factors, and considers the implications for fire management. Ninety study sites were established following extensive wildfires in 1993, and 1000-m2 plots were used to sample a variety of parameters. Data on community responses were collected for five years following fire. Structural equation modeling (SEM) was used to relate plant species richness to plant abundance, fire severity, abiotic conditions, within-plot heterogeneity, stand age, and position in the landscape. Temporal dynamics of average richness response was also modeled. Richness was highest in the first year following fire, indicating postfire enhancement of diversity. A general decline in richness over time was detected, with year-to-year variation attributable to annual variations in precipitation. Peak richness in the landscape was found where (1) plant abundance was moderately high, (2) within-plot heterogeneity was high, (3) soils were moderately low in nitrogen, high in sand content, and with high rock cover, (4) fire severity was low, and (5) stands were young prior to fire. Many of these characteristics were correlated with position in the landscape and associated conditions. We infer from the SEM results that postfire richness in this system is strongly influenced by local conditions and that these conditions are, in turn, predictably related to landscape-level conditions. For example, we observed that older stands of shrubs were characterized by more severe fires, which were associated with a low recovery of plant cover and low richness. These results may have implications for the use of prescribed fire in this system if these findings extrapolate to prescribed burns as we would expect. ?? 2006 by the Ecological Society of America.

  7. 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…

  8. Effects of opacity and equation of state on solar structure and oscillations

    NASA Astrophysics Data System (ADS)

    Guzik, Joyce A.; Cox, Arthur N.

    1991-11-01

    The evolution and p-mode oscillation frequencies of several solar models are presented, highlighting the effects of uncertainties in the opacity and equation of state. The Dappen, Mihalas, Hummer, and Mihalas ('MHD') equation of state tables are incorporated into the evolution and oscillation calculations, and the results are compared with those of models calculated using the analytical Iben equation of state. The nonadiabatic low-degree p-mode oscillation frequencies derived from models using either of these equations of state agree with observations to within a few microhertz. The MHD equation of state, with more detailed treatment of envelope ionization regions, improves agreement with observations for p-modes of degree l = 40-300. For higher degree p-modes, observational uncertainties make it difficult to determine how much improvement the MHD equation of state provides over the analytical Iben procedure. Calculated p-mode oscillation frequencies favor the higher Ross-Aller opacities, which include molecular effects and more iron lines, over the older Cox-Tabor opacities in the solar envelope at temperatures below 9000 K. Thus, solar oscillations can be effectively used to constrain opacities at the solar surface and below the convection zone.

  9. Diet History Questionnaire

    Cancer.gov

    NATIONAL INSTITUTES OF HEALTH Diet History Questionnaire Today's date: MONTH DAY YEAR |___|___| 0 0 1 1 2 2 3 3 4 5 6 7 8 01 Jan 02 Feb 03 Mar 04 Apr 05 May 06 Jun 07 Jul 08 Aug 09 Sep 10 Oct 11 Nov 12

  10. 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…

  11. The Depression Coping Questionnaire.

    ERIC Educational Resources Information Center

    Kleinke, Chris L.

    College students (N=396), chronic pain patients (N=319), and schizophrenic veterans (N=43) completed the Depression Coping Questionnaire (DCQ) and the Beck Depression Inventory (BDI). Factor analysis of the DCQ identified eleven coping responses: social support, problem solving, self-blame/escape, aggression, indulgence, activities, medication,

  12. 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),…

  13. A special purpose symbolic manipulation program for the derivation of the equations of motion for large flexible structures

    NASA Technical Reports Server (NTRS)

    Hale, A. L.; Meirovitch, L.

    1977-01-01

    This paper outlines a computer program especially tailored to the task of deriving explicit equations of motion for structures with point-connected substructures. The special purpose program is written in FORTRAN and is designed for performing the specific algebraic operations encountered in the derivation of explicit equations of motion. The derivation is by the Lagrangian approach. Using an orderly kinematical procedure and a discretization and/or truncation scheme, it is possible to write the kinetic and potential energy of each substructure in a compact vector-matrix form. Then, if each element of the matrices and vectors encountered in the kinetic and potential energy is a known algebraic expression, the computer program performs the necessary operations to evaluate the kinetic and potential energy of the system explicitly. Lagrange's equations for small motions about equilibrium can be deduced directly from the explicit form of the system kinetic and potential energy.

  14. The Peer Interaction in Primary School Questionnaire: Testing for Measurement Equivalence and Latent Mean Differences in Bullying between Gender in Egypt, Saudi Arabia and the USA

    ERIC Educational Resources Information Center

    Hussein, Mohamed Habashy

    2010-01-01

    The Peer Interaction in Primary School Questionnaire (PIPSQ) was developed to assess individuals' levels of bullying and victimization. This study used the approach of latent means analysis (LMA) within the framework of structural equation modeling (SEM) to explore the factor structure and gender differences associated with the PIPSQ in a sample

  15. Equation of State and Structure of Electrostatic Colloidal Crystals: Osmotic Pressure and Scattering Study

    NASA Astrophysics Data System (ADS)

    Reus, V.; Belloni, L.; Zemb, T.; Lutterbach, N.; Versmold, H.

    1997-04-01

    Electrostatically stabilized aqueous suspensions of bromopolystyrene particles have been studied by scattering and osmotic pressure measurements. We investigated their structure and the interparticle interactions as a function of the volume fraction at very low salinity of the order of micromole/l. At slow crystallization speed we observe perfect crystals, body centrered cubic crystals by light scattering for volume fractions between 0.04 and 0.7% and face centrered cubic crystals by Ultra Small Angle X ray Scattering (USAXS) for higher volume fractions (2 12%). After shear the crystal displays other structures. At low volume fractions (0.1 0.3%), some reflexions disappear by light scattering whereas a strong diffuse prepeak" appears before the first Bragg peak for higher concentrations (2 12%) evidenced by USAXS. This prepeak" can be attributed to defects in the crystal. Osmotic pressures have been measured by difference between the hydrostatic pressure in the solution and in the reservoir separated by an hemipermeable membrane. The experimental data are very well reproduced by the Poisson Boltzmann Cell (PBC) theory which shows that the interaction between particles is purely repulsive. No attractive contribution has been experimentally detected. By calculating the mean square displacement of a particle inside its cage from the eccentric PBC model, we have verified that the Lindemann criterion for the existence of crystals (against melting) is satisfied. This study has allowed to determine the equation of state of an electrostatical colloidal crystal and is equivalent to an ultraprecise force/distance measurement between latex particles since the measured forces are of the order of 10^{-12} N for distances of the order of 4000 . Des suspensions aqueuses de particules de bromopolystyrne ont t caractrises par diffusion de lumire, diffusion de rayons X aux petits angles et par des mesures de pression osmotique. Nous avons ainsi tudi leur structure et les interactions interparticulaires en fonction de la fraction volumique salinit constante de l'ordre de la micromole/l. Lorsque la cristallisation est lente, nous observons des cristaux parfaits cubiques centrs par diffusion de lumire pour des fractions volumiques comprises entre 0,04 et 0,7 % et cubiques faces centres pax diffusion de rayons X aux petits angles pour des fractions volumiques plus leves (2 12 %). Aprs cisaillement, des dfauts apparaissent dans les cristaux ; ils sont caractriss par la disparition de certaines raies de Bragg en diffusion de lumire pour des chantillons de fraction volumique comprise entre 0,1 et 0,3 % et par la prsence d'un pr pic observ par diffusion de rayons X aux petits angles avant le premier pic de Bragg, pour des chantillons plus concentrs (2 12 %). Les pressions osmotiques ont t mesures par diffrence de pression hydrostatique entre la solution et le rservoir spars par une membrane hmipermable. Les donnes exprimentales sont bien reproduites par la thorie Poisson Boltzmann Rseau (PBR) qui montre que les interactions sont purement rpulsives. Aucune force attractive faible de longue porte n'a t dtecte exprimentalement. En calculant le dplacement moyen d'une particule l'intrieur de sa cage l'aide du modle PBR "excentr", nous avons vrifi que le critre de Lindemann tait satisfait pour tous les cristaux observs. Cette tude a permis de dterminer l'quation d'tat d'un cristal colloidal lectrostatique. Les rsultats sont quivalents une mesure de force ultraprcise puisque les forces d'interaction mesures entre particules sont de l'ordre de 10^{-12} N pour des distances centre centre de l'ordre de 4000 .

  16. The Neo Personality Inventory-Revised: Factor Structure and Gender Invariance from Exploratory Structural Equation Modeling Analyses in a High-Stakes Setting

    ERIC Educational Resources Information Center

    Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z.; Chamorro-Premuzic, Tomas

    2013-01-01

    This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM)…

  17. The Neo Personality Inventory-Revised: Factor Structure and Gender Invariance from Exploratory Structural Equation Modeling Analyses in a High-Stakes Setting

    ERIC Educational Resources Information Center

    Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z.; Chamorro-Premuzic, Tomas

    2013-01-01

    This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM)

  18. Complex interactions among biocontrol agents, pollinators, and an invasive weed: a structural equation modeling approach.

    PubMed

    Swope, Sarah M; Parker, Ingrid M

    2012-12-01

    Herbivores, seed predators, and pollinators can exert strong impacts on their host plants. They can also affect the strength of each other's impact by modifying traits in their shared host, producing super- or sub-additive outcomes. This phenomenon is especially relevant to biological control of invasive plants because most invaders are attacked by multiple agents. Unfortunately, complex interactions among agents are rarely studied. We used structural equation modeling (SEM) to quantify the effect of two biocontrol agents and generalist pollinators on the invasive weed Centaurea solstitialis, and to identify and quantify the direct and indirect interaction pathways among them. The weevil Eustenopus villosus is both a bud herbivore and a predispersal seed predator; the fly Chaetorellia succinea is also a predispersal seed predator; Apis mellifera is the primary pollinator. We conducted this work at three sites spanning the longitudinal range of C. solstitialis in California (USA) from the coast to the Sierra Nevada Mountains. SEM revealed that bud herbivory had the largest total effect on the weed's fecundity. The direct effect of bud herbivory on final seed set was 2-4 times larger in magnitude than the direct effect of seed predation by both agents combined. SEM also revealed important indirect interactions; by reducing the number of inflorescences plants produced, bud herbivory indirectly reduced the plant's attractiveness to ovipositing seed predators. This indirect, positive pathway reduced bud herbivory's direct negative effect by 11-25%. In the same way, bud herbivory also reduced pollinator visitation, although the magnitude of this pathway was relatively small. E. villosus oviposition deterred C. succinea oviposition, which is unfortunate because C. succinea is the more voracious of the seed predators. Finally, C. succinea oviposition indirectly deterred pollinator visitation, thereby enhancing its net effect on the plant. This study demonstrates the powerful insights that can be gained from the SEM approach in understanding the multiple direct and indirect interactions among agents and pollinators and their effects on an invasive weed. Such an approach may improve our ability to manage weeds with biocontrol agents by identifying pathways that could be exploited by future agents and minimizing the possibility of interference with established agents. PMID:23387114

  19. Turbulent convection and pulsation stability of stars - I. Basic equations for calculations of stellar structure and oscillations

    NASA Astrophysics Data System (ADS)

    Xiong, D. R.; Deng, L.; Zhang, C.

    2015-08-01

    Starting from hydrodynamic equations, we have established a set of hydrodynamic equations for average flow and a set of dynamic equations of auto- and cross-correlations of turbulent velocity and temperature fluctuations, following the classic Reynold's treatment of turbulence. The combination of the two sets of equations leads to a complete and self-consistent mathematical expressions ready for the calculations of stellar structure and oscillations. In this paper, non-locality and anisotropy of turbulent convection are concisely presented, together with defining and calibrating of the three convection parameters (c1, c2 and c3) included in the algorithm. With the non-local theory of convection, the structure of the convective envelope and the major characteristics of non-adiabatic linear oscillations are demonstrated by numerical solutions. Great effort has been exercised to the choice of convection parameters and pulsation instabilities of the models, the results of which show that within large ranges of all three parameters (c1, c2 and c3) the main properties of pulsation stability keep unchanged.

  20. Chinese version of the Responses to Positive Affect Questionnaire: testing the factor structure, reliability, and validity in a college student sample.

    PubMed

    Yang, Hongfei; Guo, Wenjing

    2014-10-01

    This study tested the psychometrics of the Chinese version of the Responses to Positive Affect Questionnaire among 915 Chinese college students with an average age of 20.3 yr. (SD = 1.6). The original three-factor model with the factors dampening, emotion-focused positive rumination, and self-focused rumination was supported using exploratory and confirmatory factor analyses. All subscales showed good internal reliability, as well as evidence for convergent and incremental validity with measures of ego-resiliency, life satisfaction, and mental health symptoms. Finally, a series of hierarchical regression analyses indicated that the three subscales, especially dampening, accounted for additional unique variance in psychological adjustment above and beyond resilience. These findings generally suggested that the Chinese Responses to Positive Affect Questionnaire possesses acceptable psychometric properties. Implications for counseling, limitations, and suggestions for future study were presented. PMID:25243367

  1. The factor structure of the Turkish version of the Revised Illness Perception Questionnaire (IPQ-R) in patients with diabetes and cardiovascular disease

    PubMed Central

    2012-01-01

    Background The Revised Illness Perception Questionnaire (IPQ-R) has been used extensively in the study of illness perceptions across different populations. Only few confirmatory factor analytic (CFA) studies of the questionnaire are available. This study examines the construct and discriminant validity of the Turkish IPQ-R in patients with diabetes and cardiovascular disease focusing on the hypothesized seven dimensions of personal controllability, treatment controllability, timeline acute/chronic, timeline cyclical, coherence, consequences and emotional representations. Methods 302 patients (60.6% women) with a medically confirmed diagnosis of diabetes or cardiovascular disease and a mean age of 53.9?years were recruited from out-patient clinics in Turkey and surveyed by means of standardized interviews. Direct maximum likelihood confirmatory factor analysis was conducted. Results Several areas of ill-fit were identified in the original measurement model of the IPQ-R. Four items (items 17, 19, 20, and 31) were deleted because of poor factor loadings. Also, two error covariances (between items 33 and 34 and between items 7 and 8) were added and item 6 respecified to obtain a good model fit. The modified 34-item model showed good reliability and discriminant validity. Conclusion In accordance with studies on other language adaptations of the questionnaire, we identified certain items of the IPQ-R as potential sources of poor model fit. Their inclusion should be reconsidered in future applications of the questionnaire and researchers should examine whether our reduced set of items is stable across different populations. Our modified 34-item model showed a good reliability and discriminant validity and hence could be a valuable instrument in the assessment of illness perceptions in the Turkish health care setting, provided that the model is confirmed in subsequent research. PMID:23043425

  2. Thermodynamic structure of Lanczos-Lovelock field equations from near-horizon symmetries

    SciTech Connect

    Kothawala, Dawood; Padmanabhan, T.

    2009-05-15

    It is well known that, for a wide class of spacetimes with horizons, Einstein equations near the horizon can be written as a thermodynamic identity. It is also known that the Einstein tensor acquires a highly symmetric form near static, as well as stationary, horizons. We show that, for generic static spacetimes, this highly symmetric form of the Einstein tensor leads quite naturally and generically to the interpretation of the near-horizon field equations as a thermodynamic identity. We further extend this result to generic static spacetimes in Lanczos-Lovelock gravity, and show that the near-horizon field equations again represent a thermodynamic identity in all these models. These results confirm the conjecture that this thermodynamic perspective of gravity extends far beyond Einstein's theory.

  3. The higher grading structure of the WKI hierarchy and the two-component short pulse equation

    NASA Astrophysics Data System (ADS)

    Frana, G. S.; Gomes, J. F.; Zimerman, A. H.

    2012-08-01

    A higher grading affine algebraic construction of integrable hierarchies, containing the Wadati-Konno-Ichikawa (WKI) hierarchy as a particular case, is proposed. We show that a two-component generalization of the Schfer-Wayne short pulse equation arises quite naturally from the first negative flow of the WKI hierarchy. Some novel integrable nonautonomous models are also proposed. The conserved charges, both local and nonlocal, are obtained from the Riccati form of the spectral problem. The loop-soliton solutions of the WKI hierarchy are systematically constructed through gauge followed by reciprocal Bcklund transformation, establishing the precise connection between the whole WKI and AKNS hierarchies. The connection between the short pulse equation with the sine-Gordon model is extended to a correspondence between the two-component short pulse equation and the Lund-Regge model.

  4. Bottlenecks in turbulent kinetic energy spectra predicted from structure function inflections using the Von Krmn-Howarth equation

    NASA Astrophysics Data System (ADS)

    Katul, Gabriel G.; Manes, Costantino; Porporato, Amilcare; Bou-Zeid, Elie; Chamecki, Marcelo

    2015-09-01

    The compensated three-dimensional turbulent kinetic energy spectrum exhibits a peculiar bump at wave numbers in the vicinity of the crossover from inertial to viscous regimes due to pile up in turbulent kinetic energy, a phenomenon referred to as the bottleneck effect. The origin of this bump is linked to an inflection point in the second-order structure function in physical space caused by competition between vortex stretching and viscous diffusion mechanisms. The bump location and magnitude are reasonably predicted from a novel analytical solution to the Von Krmn-Howarth equation reflecting the competition between these two mechanisms and accounting for variable structure skewness with decreasing scale.

  5. Bottlenecks in turbulent kinetic energy spectra predicted from structure function inflections using the Von Krmn-Howarth equation.

    PubMed

    Katul, Gabriel G; Manes, Costantino; Porporato, Amilcare; Bou-Zeid, Elie; Chamecki, Marcelo

    2015-09-01

    The compensated three-dimensional turbulent kinetic energy spectrum exhibits a peculiar bump at wave numbers in the vicinity of the crossover from inertial to viscous regimes due to pile up in turbulent kinetic energy, a phenomenon referred to as the bottleneck effect. The origin of this bump is linked to an inflection point in the second-order structure function in physical space caused by competition between vortex stretching and viscous diffusion mechanisms. The bump location and magnitude are reasonably predicted from a novel analytical solution to the Von Krmn-Howarth equation reflecting the competition between these two mechanisms and accounting for variable structure skewness with decreasing scale. PMID:26465558

  6. Wing-Body Aeroelasticity Using Finite-Difference Fluid/Finite-Element Structural Equations on Parallel Computers

    NASA Technical Reports Server (NTRS)

    Byun, Chansup; Guruswamy, Guru P.; Kutler, Paul (Technical Monitor)

    1994-01-01

    In recent years significant advances have been made for parallel computers in both hardware and software. Now parallel computers have become viable tools in computational mechanics. Many application codes developed on conventional computers have been modified to benefit from parallel computers. Significant speedups in some areas have been achieved by parallel computations. For single-discipline use of both fluid dynamics and structural dynamics, computations have been made on wing-body configurations using parallel computers. However, only a limited amount of work has been completed in combining these two disciplines for multidisciplinary applications. The prime reason is the increased level of complication associated with a multidisciplinary approach. In this work, procedures to compute aeroelasticity on parallel computers using direct coupling of fluid and structural equations will be investigated for wing-body configurations. The parallel computer selected for computations is an Intel iPSC/860 computer which is a distributed-memory, multiple-instruction, multiple data (MIMD) computer with 128 processors. In this study, the computational efficiency issues of parallel integration of both fluid and structural equations will be investigated in detail. The fluid and structural domains will be modeled using finite-difference and finite-element approaches, respectively. Results from the parallel computer will be compared with those from the conventional computers using a single processor. This study will provide an efficient computational tool for the aeroelastic analysis of wing-body structures on MIMD type parallel computers.

  7. Microscopic Theory of the Nuclear Equation of State and Neutron Star Structure

    NASA Astrophysics Data System (ADS)

    Baldo, Marcello; Burgio, Fiorella

    The Bethe-Brueckner-Goldstone many-body theory of the Nuclear Equation of State is reviewed in some details. In the theory, one performs an expansion in terms of the Brueckner two-body scattering matrix and an ordering of the corresponding many-body diagrams according to the number of their hole-lines. Recent results are reported, both for symmetric and for pure neutron matter, based on realistic two-nucleon interactions. It is shown that there is strong evidence of convergence in the expansion. Once three-body forces are introduced, the phenomenological saturation point is reproduced and the theory is applied to the study of neutron star properties. One finds that in the interior of neutron stars the onset of hyperons strongly softens the Nuclear Equation of State. As a consequence, the maximum mass of neutron stars turns out to be at the lower limit of the present phenomenological observation.

  8. The Hamiltonian structure of Dirac's equation in tensor form and its Fermi quantization

    NASA Technical Reports Server (NTRS)

    Reifler, Frank; Morris, Randall

    1992-01-01

    Currently, there is some interest in studying the tensor forms of the Dirac equation to elucidate the possibility of the constrained tensor fields admitting Fermi quantization. We demonstrate that the bispinor and tensor Hamiltonian systems have equivalent Fermi quantizations. Although the tensor Hamiltonian system is noncanonical, representing the tensor Poisson brackets as commutators for the Heisenberg operators directly leads to Fermi quantization without the use of bispinors.

  9. A measurement error model for physical activity level as measured by a questionnaire with application to the 1999-2006 NHANES questionnaire.

    PubMed

    Tooze, Janet A; Troiano, Richard P; Carroll, Raymond J; Moshfegh, Alanna J; Freedman, Laurence S

    2013-06-01

    Systematic investigations into the structure of measurement error of physical activity questionnaires are lacking. We propose a measurement error model for a physical activity questionnaire that uses physical activity level (the ratio of total energy expenditure to basal energy expenditure) to relate questionnaire-based reports of physical activity level to true physical activity levels. The 1999-2006 National Health and Nutrition Examination Survey physical activity questionnaire was administered to 433 participants aged 40-69 years in the Observing Protein and Energy Nutrition (OPEN) Study (Maryland, 1999-2000). Valid estimates of participants' total energy expenditure were also available from doubly labeled water, and basal energy expenditure was estimated from an equation; the ratio of those measures estimated true physical activity level ("truth"). We present a measurement error model that accommodates the mixture of errors that arise from assuming a classical measurement error model for doubly labeled water and a Berkson error model for the equation used to estimate basal energy expenditure. The method was then applied to the OPEN Study. Correlations between the questionnaire-based physical activity level and truth were modest (r = 0.32-0.41); attenuation factors (0.43-0.73) indicate that the use of questionnaire-based physical activity level would lead to attenuated estimates of effect size. Results suggest that sample sizes for estimating relationships between physical activity level and disease should be inflated, and that regression calibration can be used to provide measurement error-adjusted estimates of relationships between physical activity and disease. PMID:23595007

  10. The Toronto Empathy Questionnaire

    PubMed Central

    Spreng, R. Nathan; McKinnon, Margaret C.; Mar, Raymond A.; Levine, Brian

    2008-01-01

    In order to formulate a parsimonious tool to assess empathy, we used factor analysis on a combination of self-report measures to examine consensus and developed a brief self-report measure of this common factor. The Toronto Empathy Questionnaire (TEQ) represents empathy as a primarily emotional process. In three studies, the TEQ demonstrated strong convergent validity, correlating positively with behavioral measures of social decoding, self-report measures of empathy, and negatively with a measure of Autism symptomatology. Moreover, it exhibited good internal consistency and high test-retest reliability. The TEQ is a brief, reliable, and valid instrument for the assessment of empathy. PMID:19085285

  11. Using structural equation modeling to construct calibration equations relating PM2.5 mass concentration samplers to the federal reference method sampler

    NASA Astrophysics Data System (ADS)

    Bilonick, Richard A.; Connell, Daniel P.; Talbott, Evelyn O.; Rager, Judith R.; Xue, Tao

    2015-02-01

    The objective of this study was to remove systematic bias among fine particulate matter (PM2.5) mass concentration measurements made by different types of samplers used in the Pittsburgh Aerosol Research and Inhalation Epidemiology Study (PARIES). PARIES is a retrospective epidemiology study that aims to provide a comprehensive analysis of the associations between air quality and human health effects in the Pittsburgh, Pennsylvania, region from 1999 to 2008. Calibration was needed in order to minimize the amount of systematic error in PM2.5 exposure estimation as a result of including data from 97 different PM2.5 samplers at 47 monitoring sites. Ordinary regression often has been used for calibrating air quality measurements from pairs of measurement devices; however, this is only appropriate when one of the two devices (the "independent" variable) is free from random error, which is rarely the case. A group of methods known as "errors-in-variables" (e.g., Deming regression, reduced major axis regression) has been developed to handle calibration between two devices when both are subject to random error, but these methods require information on the relative sizes of the random errors for each device, which typically cannot be obtained from the observed data. When data from more than two devices (or repeats of the same device) are available, the additional information is not used to inform the calibration. A more general approach that often has been overlooked is the use of a measurement error structural equation model (SEM) that allows the simultaneous comparison of three or more devices (or repeats). The theoretical underpinnings of all of these approaches to calibration are described, and the pros and cons of each are discussed. In particular, it is shown that both ordinary regression (when used for calibration) and Deming regression are particular examples of SEMs but with substantial deficiencies. To illustrate the use of SEMs, the 7865 daily average PM2.5 mass concentration measurements made by seven collocated samplers at an urban monitoring site in Pittsburgh, Pennsylvania, were used. These samplers, which included three federal reference method (FRM) samplers, three speciation samplers, and a tapered element oscillating microbalance (TEOM), operated at various times during the 10-year PARIES study period. Because TEOM measurements are known to depend on temperature, the constructed SEM provided calibration equations relating the TEOM to the FRM and speciation samplers as a function of ambient temperature. It was shown that TEOM imprecision and TEOM bias (relative to the FRM) both decreased as temperature increased. It also was shown that the temperature dependency for bias was non-linear and followed a sigmoidal (logistic) pattern. The speciation samplers exhibited only small bias relative to the FRM samplers, although the FRM samplers were shown to be substantially more precise than both the TEOM and the speciation samplers. Comparison of the SEM results to pairwise simple linear regression results showed that the regression results can differ substantially from the correctly-derived calibration equations, especially if the less-precise device is used as the independent variable in the regression.

  12. The solution of linear systems of equations with a structural analysis code on the NAS CRAY-2

    NASA Technical Reports Server (NTRS)

    Poole, Eugene L.; Overman, Andrea L.

    1988-01-01

    Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted the Computational Structural Mechanics (CSM) Testbed. A description of the techniques used to integrate the two solvers into the Testbed is given. Storage schemes, memory requirements, operation counts, and reformatting procedures are discussed. Finally, results from the new methods are compared with results from the initial Testbed sparse Choleski equation solver for three structural analysis problems. The new direct solvers described achieve the highest computational rates of the methods compared. The new iterative methods are not able to achieve as high computation rates as the vectorized direct solvers but are best for well conditioned problems which require fewer iterations to converge to the solution.

  13. Probing the pair structure of supercooled fluids by integral equations: Evidence for an equilibrium liquid-ideal glass transition?

    NASA Astrophysics Data System (ADS)

    Bomont, Jean-Marc; Pastore, Giorgio; Hansen, Jean-Pierre

    2014-02-01

    We solve the hypernetted-chain (HNC) and Rogers-Young (RY) integral equations for the pair structure of a system of two weakly coupled replic of a soft-sphere fluid, in order to detect signatures of an equilibrium transition to an ideal glass. Both integral equations predict, in addition to the supercooled-liquid branch, the appearance of a new disordered state characterized by different pair correlations, over a range of temperatures. The ideal-glass transition temperature T_{{DJ}} , identified by a discontinuous jump in the inter-replica pair correlation function, is predicted to be substantially higher with RY compared to HNC theory. The internal energy is predicted to undergo a weak discontinuity at T_{{DJ}} .

  14. Multiterm solution of a generalized Boltzmann kinetic equation for electron and positron transport in structured and soft condensed matter.

    PubMed

    White, R D; Robson, R E

    2011-09-01

    In this paper, we generalize the semiclassical Boltzmann kinetic equation for dilute gases to consider highly nonequilibrium electrons and positrons in soft condensed matter, accounting rigorously for all types of interactions, including positronium formation, and allowing for both coherent and incoherent scattering processes. The limitations inherent in the seminal paper of Cohen and Lekner [M. H. Cohen and J. Lekner, Phys. Rev. 158, 305 (1967); Y. Sakai, J. Phys. D 40, R441 (2007)] are avoided by solving the kinetic equation using a "multiterm" spherical harmonic representation of the velocity distribution function, as well as formulating a necessarily nonperturbative treatment of nonconservative collisional processes such as positronium formation. Numerical calculations of transport properties are carried out for a Percus-Yevick model of a hard-sphere system, and for positrons in liquid argon. New phenomena are predicted, including structure-induced negative conductivity and anisotropic diffusion. PMID:22060346

  15. Microscopic calculation of the equation of state of nuclear matter and neutron star structure

    NASA Astrophysics Data System (ADS)

    Gandolfi, S.; Illarionov, A. Yu.; Fantoni, S.; Miller, J. C.; Pederiva, F.; Schmidt, K. E.

    2010-05-01

    We present results for neutron star models constructed with a new equation of state for nuclear matter at zero temperature. The ground state is computed using the auxiliary field diffusion Monte Carlo (AFDMC) technique, with nucleons interacting via a semiphenomenological Hamiltonian including a realistic two-body interaction. The effect of many-body forces is included by means of additional density-dependent terms in the Hamiltonian. In this Letter, we compare the properties of the resulting neutron star models with those obtained using other nuclear Hamiltonians, focusing on the relations between mass and radius, and between the gravitational mass and the baryon number.

  16. The equation of state at finite temperature: Structure and composition of protoneutron stars

    NASA Astrophysics Data System (ADS)

    Burgio, G. F.; Baldo, M.; Chen, H.; Schulze, H.-J.

    2016-01-01

    We study the hadron-quark phase transition at finite temperature in the interior of protoneutron stars, combining the equation of state obtained within the Brueckner-Hartree-Fock approach for hadronic matter with the MIT bag and the Dyson-Schwinger models for quark matter. We discuss the dependence of the results on different nuclear three-body forces and on details of the quark model. We find that a maximum mass exceeding two solar masses can be obtained with a strong three-body force and suitable parameter values in the Dyson-Schwinger model.

  17. Some Mathematical Structures Including Simplified Non-Relativistic Quantum Teleportation Equations and Special Relativity

    SciTech Connect

    Woesler, Richard

    2007-02-21

    The computations of the present text with non-relativistic quantum teleportation equations and special relativity are totally speculative, physically correct computations can be done using quantum field theory, which remain to be done in future. Proposals for what might be called statistical time loop experiments with, e.g., photon polarization states are described when assuming the simplified non-relativistic quantum teleportation equations and special relativity. However, a closed time loop would usually not occur due to phase incompatibilities of the quantum states. Histories with such phase incompatibilities are called inconsistent ones in the present text, and it is assumed that only consistent histories would occur. This is called an exclusion principle for inconsistent histories, and it would yield that probabilities for certain measurement results change. Extended multiple parallel experiments are proposed to use this statistically for transmission of classical information over distances, and regarding time. Experiments might be testable in near future. However, first a deeper analysis, including quantum field theory, remains to be done in future.

  18. Diet History Questionnaire: Suggested Citations

    Cancer.gov

    Use of the Diet History Questionnaire and Diet*Calc Analysis Software for publication purposes should contain a citation which includes version information for the software, questionnaire, and nutrient database.

  19. ATBC Study - Questionnaires and Forms

    Cancer.gov

    Skip to Main Content Home Contact Us Links Study Details Questionnaires & Forms Current Projects ATBC Study Bibliography Study Investigators & Collaborators Proposal Review & Collaboration Research Consortium Projects Questionnaires & Forms Baseline

  20. Diet History Questionnaire: International Applications

    Cancer.gov

    ARP staff adapted the Diet History Questionnaire (DHQ) for use by Canadian populations in collaboration with the Alberta Cancer Board. This questionnaire takes into account the different food fortification polices of the U.S. and Canada.