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Results for “Structural equation modeling”

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PubMed2001

The impact of psychological disturbances on immediate memory.

The current study tested the hypothesis that attention mediates the impact of psychological disturbances (i.e. depression, loss of self-control, and bizarre thinking) on immediate memory. A hypothesized model, in which psychological disturbances indirectly impacted immediate memory via attention, was tested using structural equations modeling (EQS). The participants included heterogeneous groups of brain-damaged and psychiatric subjects both with and without age-corrected observed variables. These groups did not vary with regard to the relationships within the model, and all models had good fit indices [comparative fit index (CFI)>0.98]. Competing models with paths directly from psychological disturbances to verbal, spatial, and general immediate memory were not significant, and these competing models did not result in a better fitting model. Therefore, the best fitting, most parsimonious model was the hypothesized one. These results corroborate the hypothesis of an indirect relationship between psychological disturbances and immediate memory via attention.

Journal Article↗

PubMedDate not supplied

An organizational tool to describe and evaluate group performance in the health care setting.

OBJECTIVE: To develop and test a tool for evaluating the performance of working groups in the institutional health care setting and to discuss its utility for pharmacists and other health care providers. DESIGN: A model for understanding how groups make decisions in health care settings was developed based on theories derived from organizational research. Our general group decision-making model was based on data collected from a national survey of members of hospital pharmacy and therapeutics (P&T) committees. Members were asked to describe how they interacted when making decisions regarding whether to add or delete drugs from their hospital's formulary. The relationships were examined using structural equation modeling. SETTING: Large teaching hospitals. PARTICIPANTS: Key members of P&T committees. MAIN OUTCOME MEASURES: Committee members' responses about committee structure, organizational environment, quality of their interactions with each other, and the committee's decision-making abilities. Individual responses were aggregated into group measures to improve reliability and validity. RESULTS: Responses were received from 114 of the 222 hospitals surveyed (51.3%), and analysis was conducted on 95 hospitals (42.8%) for which three or more group members responded. Positive interactions among group members had the greatest influence on the group's decision-making abilities (beta = 0.92). These interactions were facilitated by a well-designed group (gamma = 0.71) and the support of the environment within which the committee operates (gamma = 0.29). CONCLUSION: The general group decision-making model tested in this study may be useful in understanding how the internal processes of health care groups such as P&T committees influence group performance and, hence, group outputs. Health care providers who apply a systematic approach to assessing group performance will find this model useful because it provides a starting point for examining the process, a way to show interrelationships among various group activities, and a guide to which strategies may be most effective for improving the decision-making process.

Decision Making↗

PubMedDate not supplied

Modeling incomplete longitudinal and cross-sectional data using latent growth structural models.

In this paper we describe some mathematical and statistical models for identifying and dealing with changes over age. We concentrate specifically on the use of a latent growth structural equation model approach to deal with issues of: (1) latent growth models of change, (2) differences in longitudinal and cross-sectional results, and (3) differences due to longitudinal attrition. This is a methodological paper using simulated data, but we base our models on practical and conceptual principles of modeling change in developmental psychology. Our results illustrate both benefits and limitations using structural models to analyze incomplete longitudinal data.

Aging↗

PubMed2006

[An explanatory model for health-promoting behaviors in patients living at home who have post stroke hemiplegia].

PURPOSE: A structural equation model was analyzed to explore the determinants of health-promoting behaviors in patients living at home in Korea who had post stroke hemiplegia. METHOD: Demographic characteristics, activities of daily living, religiosity, family support, self-efficacy, acceptance of disability, perceived barriers to health-promoting activities, depression, and health-promoting behavioral data was collected from 239 patients using self-report questionnaires. RESULT: Variables that have a direct effect on health-promoting behaviors were self-efficacy and family support. Depression, acceptance of disability, perceived barriers, activities of daily living and religiosity also influenced health-promoting behaviors in an indirect way. CONCLUSION: It is imperative to explore strategies for patients with post stroke hemiplegia to identify and maximize their resources, develop their self-efficacy, improve their emotional state, and enhance their physical activity and spiritual growth, which would maximize health-promoting behaviors.

Adult↗

PubMed2002

Confirmatory factor analysis of internet use and addiction.

The ever-changing nature of the Internet continues to fuel questions as to its benefits and possible drawbacks. One issue that is particularly problematic is the validity of claims that the Internet is addictive. The present study used a confirmatory factor analysis (CFA) on a data set of 527 participants using the same survey developed by Pratarelli et al. (1) We propose a theoretical model of the relationship between (1) Internet addiction, (2) a sexual factor, and (3) an Internet use factor. These three factors were tested using two structural equation models generated on LISREL. The CFA revealed that the three factors are not orthogonal to each other, but instead are related to some degree as one would expect if a supposed Internet addicted individual exhibited behaviors related to each factor. We next tested whether the addiction was the causal factor leaving the sex and User factors as endogenous (i.e., resulting from the addiction). The second structural equation tested the contrasting possibility that sex and User related activities were exogenous to the addiction factor (i.e., the addiction resulted from these two activities). The analysis revealed that model 1, where the addiction is the causal factor behind the sex and User factors, had a stronger model fit index. On the basis of these current data it appears that Internet addiction may involve an addictive performance profile which in turn leads to excessive behaviors that involve (1) use of the Internet for sexual purposes and (2) its functional usefulness for a variety of professional and personal goals.

Adolescent↗

PubMed2006

The SCREEN I (Seniors in the Community: Risk Evaluation for Eating and Nutrition) index adequately represents nutritional risk.

OBJECTIVE: Nutrition risk is a difficult and complex construct to define and measure. Exploratory factor analysis has been completed on SCREEN I, a nutrition risk screening index for community-living seniors. This analysis was completed to confirm this structure and further validate the index as a plausible measure of nutritional risk. STUDY DESIGN AND SETTING: As part of the Bringing Nutrition Screening to Seniors demonstration project, 1,218 seniors completed SCREEN I. Using structural equation modeling (Amos version 5 software), the original and alternative two-, three-, and four-factor structures were modeled and compared. RESULTS: The best-fitting model was a four-factor structure based on the original exploratory model. Unlike the original model, however, several SCREEN I items cross-loaded on more than one factor, demonstrating the complexity of the construct 'nutritional risk.' CONCLUSION: SCREEN I appears to represent adequately the construct 'nutritional risk' with four factors: Food Intake, Physiologic, Adaptation, and Functional. Further work should be conducted to further elucidate the complex nature of 'nutritional risk' by identifying indirect and direct relationships among the screen items and this construct.

Aged↗

PubMed2005

Psychometric properties of the Toronto Alexithymia Scale (TAS-20) for substance users.

OBJECTIVE: To determine the psychometric properties of the Toronto Alexithymia Scale (TAS-20), an established self-report measure of alexithymia, for a substance user sample participating in a clinical trial of outpatient cognitive-behavioral therapies (N=230). METHODS: Confirmatory and exploratory factor analyses were used to determine the number and nature of the factors underlying the TAS-20 in a sample of substance users. Structural equation modeling was used to determine the predictive validity of the TAS-20. RESULTS: A factor structure comparable, but not identical, with TAS-20 psychometric results with other populations was found; alpha coefficients were .88 for the feelings factor, .62 for the external thinking factor, and .87 for the total score. Although, on average, the substance users did not appear to have elevated alexithymia scores compared with the undergraduate students, alexithymia predicted less treatment engagement, i.e., fewer sessions attended and weaker helping alliance. Alexithymia also predicted alcohol use outcomes but not drug use outcomes. The relation between alexithymia and drinking outcome was conditional on whether the patient was using solely alcohol at baseline. CONCLUSION: The TAS-20 has reasonably good psychometric properties in this sample, which might be improved by dropping several marginal questionnaire items. Alexithymia appears to attenuate substance abuse treatment engagement. More clinical and research experience with this construct and specific instrument in substance user samples is needed.

Adult↗

PubMed1999

A model of war zone stressors and posttraumatic stress disorder.

We present a theoretical model of field placement, war zone stressors (fighting, death and injury of others, threat of death or injury to oneself, killing others, participating in atrocities, harsh physical conditions and insufficiency of resources in the environment) and posttraumatic stress disorder (PTSD). Theater veterans from the National Vietnam Veterans Readjustment Study were divided randomly into two subsamples of 599 each. The model was developed on the first subsample and cross-validated on the second using structural equation modeling. The model provides a theoretically and empirically satisfactory description of the anatomy of war zone stressors and their role in the etiology of PTSD, but it leaves unanswered important questions regarding the etiological role of insufficiency of resources in the environment.

Adult↗

PubMed2005

An introduction to latent growth models: analysis of repeated measures physical performance data.

The purpose of this paper is to introduce the Latent Growth Model (LGM) to researchers in exercise and sport science. Although the LGM has several merits over traditional analysis techniques in analyzing change and was first introduced almost 20 years ago, it is still underused in exercise and sport science research. This statistical model can be applied to any repeated measures data, but it is most useful when one has an a priori hypothesis about the patterns of change. The strengths of latent growth modeling include: (a) both individual and group levels of change are estimated, (b) either a linear or a curvilinear trajectory can represent individual change, (c) occasions of measurement need not be equally spaced, (d) the statistical model can account for measurement errors, (e) the model can easily include multiple predictors or correlates of change, and (f) as in general structural equation models, statistical models are flexible and allow one to extend the basic idea in several ways, such as comparing changes between groups and examining the change in multivariate latentfactors. In this paper, the basics and an extension of latent growth modeling are explained, and examples with longitudinal physical performance data are presented, along with detailed analysis procedures and considerations.

British Columbia↗

PubMed1997

The effects of positive and negative social exchanges on aging adults.

This study tested various models of the effects of positive and negative exchanges on positive and negative affect using structural equation modeling. Based on a probability sample of middle-aged and older adults, the relationships between social exchanges and psychological well-being were examined both within the total sample and within subgroups of individuals who had experienced few vs many life events. Within the general population, the Domain Specific Model resulted in the best fit. That is, positive exchanges were associated with positive affect, and negative exchanges were associated with negative affect. However, among the subgroup that had experienced more life events, there was a significantly stronger relationship between negative exchanges and negative affect. These findings suggest that, to understand the effects of social exchanges, it is important to consider the context of life events.

Adaptation, Psychological↗

PubMed2005

Images of smokers and willingness to smoke among African American pre-adolescents: an application of the prototype/willingness model of adolescent health risk behavior to smoking initiation.

OBJECTIVE: This study used the prototype/willingness model of adolescent health risk behavior to examine factors related to onset of smoking. METHODS: Two waves of data were collected from a panel of 742 African American children (mean age=10.5 at Wave 1) and their primary caregivers. Measures included cognitions outlined by the prototype model as well as self-reports of smoking by the parent and child. RESULTS: Structural equation modeling revealed a pattern consistent with expectations generated by the prototype model. The relation between contextual, familial, and dispositional factors-including neighborhood risk, parental smoking, and children's academic orientation-and the initiation of smoking at Wave 2, two years later, was mediated by the children's cognitions. Primary among these cognitions were the children's images of smokers and children's willingness to smoke. CONCLUSIONS: Smoking cognitions mediate the impact of important distal factors (such as context, family environment, and disposition) on the onset of smoking in children. Perhaps more important, it is possible to predict onset of smoking in African American children as young as age 10 by assessing the cognitive factors suggested by the prototype model.

Achievement↗

PubMed1983

A causal model for physician utilization: analysis of Norwegian data.

This article contains a causal model for physician utilization in Norway. The model relates enabling factors, predisposing factors, and perceived illness to physician utilization in a linear structural equation model. Our aim has been to study the effect of variables other than perceived illness on physician utilization. The results of the analysis indicate that the number of disability days because of illness and psychologic well-being are almost exclusively the only important variables in the explanation of physician utilization in Norway.

Costs and Cost Analysis↗

PubMedDate not supplied

Contribution of early and adult factors to socioeconomic variation in blood pressure: thirty-four-year follow-up study of school children.

OBJECTIVE: To prospectively examine the role of childhood and adulthood factors in the association between socioeconomic status (SES) and adult systolic and diastolic blood pressure (SBP, DBP). METHODS: One hundred and five boys and 101 girls who were 8 years of age at entry into the study were observed for 34 years in the Jyväskylä Longitudinal Study of Personality and Social Development, Finland. Data were gathered on educational attainment and occupational status, as indicators of SES, and potential explanatory factors related to 0, (14), 27, 36, and 42 years of age. SBP and DBP were assessed at 15 and 42 years of age. RESULTS: In a structural equation model adjusted for sex and childhood SBP, educational attainment was inversely associated with adult SBP (structural coefficient -0.17, p<.05). Incorporating the effects of parental SES and adult body mass index into the model attenuated this association so that it was no longer significant. Variation in birth weight, unemployment, smoking, alcohol consumption, and use of antihypertensive medication had marginal or no impact on the education-SBP association. No socioeconomic variation was found for DBP or occupational status. CONCLUSIONS: Prospective evidence suggests a weak association between low educational attainment and development of high SBP. Parental SES and adult BMI were the key explanatory factors for this association.

Adolescent↗

PubMed2004

Single-subject research designs and data analyses for assessing elite athletes' conditioning.

Research in conditioning (all the processes of preparation for competition) has used group research designs, where multiple athletes are observed at one or more points in time. However, empirical reports of large inter-individual differences in response to conditioning regimens suggest that applied conditioning research would greatly benefit from single-subject research designs. Single-subject research designs allow us to find out the extent to which a specific conditioning regimen works for a specific athlete, as opposed to the average athlete, who is the focal point of group research designs. The aim of the following review is to outline the strategies and procedures of single-subject research as they pertain to the assessment of conditioning for individual athletes. The four main experimental designs in single-subject research are: the AB design, reversal (withdrawal) designs and their extensions, multiple baseline designs and alternating treatment designs. Visual and statistical analyses commonly used to analyse single-subject data, and advantages and limitations are discussed. Modelling of multivariate single-subject data using techniques such as dynamic factor analysis and structural equation modelling may identify individualised models of conditioning leading to better prediction of performance. Despite problems associated with data analyses in single-subject research (e.g. serial dependency), sports scientists should use single-subject research designs in applied conditioning research to understand how well an intervention (e.g. a training method) works and to predict performance for a particular athlete.

Australia↗

PubMed2005

A strict test of the phonological loop hypothesis with Libyan data.

In Arabic, there are two ways, differing in length, of pronouncing each digit. This feature of word pairs that are conceptually identical but of different length allows for a stricter test of the phonological loop hypothesis than has been reported previously. Libyan schoolchildren, both boys and girls, of two grades took part in a quasi-experimental study in which shorter and longer digits and shorter and longer words were presented in recall and pronunciation tasks. The results confirmed the validity of the phonological loop model in that memory span was longer for shorter stimuli. Analysis of the data with structural equation modeling showed that only 17% of the individual-level variation in memory span could be explained by pronunciation speed. In an analysis of covariance, it was determined that pronunciation speed could account for a substantial proportion of the variation found across age (8-year-olds vs. 10-year-olds), stimulus modality (digits vs. words), and stimulus length (short vs. long), but not for gender differences.

Child↗

PubMed2007

The continuum model of obligatory exercise: a preliminary investigation.

OBJECTIVE: The aim of this study was to carry out a preliminary study of the proposed Continuum Model of Obligatory Exercise, which states that obligatory exercise lies on a continuum--a continuum that is characterized not only by differences in severity, but by qualitative differences in the way the syndrome manifests, as the behaviour changes from mildly obsessive attitudes to exercise, to extremely disordered attitudes to exercise, which are accompanied by an eating disorder. METHOD: Structural equation modelling (SEM) was used to investigate the Continuum Model of Obligatory Exercise utilizing data from a longitudinal study of female triathletes. RESULTS: The structural model specifying the hypothesized causal pathways confirmed many of the postulates of the Continuum Model of Obligatory Exercise, including the role of weight and shape preoccupation in predicting food restriction, eating disorder behaviour, and increased obligatory exercise behaviour, as well as the role of obsessive-compulsiveness and increased physical activity in predicting eating disorder behaviour in exercisers. CONCLUSION: The structural model investigated is reasonable and can serve as a starting point for a theory-based empirical exploration of the notion that obligatory exercise behaviour lies on a continuum.

Adult↗

PubMed2005

Mediator effects in the social development model: an examination of constituent theories.

BACKGROUND: The social development model (SDM) provides an explanatory framework for the progression of antisocial behaviour in children and adolescents. Although previous research has assessed the predictive validity of the model, alternative associations based on the SDM's constituent theories have not been examined. METHOD: Using structural equation modelling, a series of direct paths was examined for mediation by SDM constructs. Data for the study consisted of teacher-, parent- and self-report of 1016 fourth- and fifth-grade students from the Raising Healthy Children project, a longitudinal etiological study with an embedded preventive intervention. RESULTS: Four of the seven paths examined were partially or totally mediated by SDM constructs. Specifically, the relationship between prosocial bonding and adolescent antisocial behaviour, as hypothesized by social control theory, was fully mediated by prosocial beliefs. As hypothesized by social learning theory, students' socioemotional and cognitive skills significantly predicted antisocial behaviour, independent of partial mediation through rewards, bonding and beliefs. As hypothesized by differential association theory, involvement with both prosocial and antisocial persons was directly associated with respective prosocial and antisocial beliefs, independent of partial mediation through rewards and bonding. CONCLUSIONS: These findings suggest additional associations that are not currently specified in the SDM and underscore the importance of re-examining hypotheses from constituent theories when integrating developmental models of antisocial behaviour.

Antisocial Personality Disorder↗

PubMed2003

The heritability of cause-specific mortality: a correlated gamma-frailty model applied to mortality due to respiratory diseases in Danish twins born 1870-1930.

The genetic influence on susceptibility to diseases of the respiratory system and all-cause mortality was studied using data for identical (MZ) and fraternal (DZ) twins. Data from the Danish Twin Register include 1344 MZ and 2411 DZ male twin pairs and 1470 MZ and 2730 DZ female twin pairs born between 1870 and 1930, where both individuals were alive on 1 011943. We used the correlated gamma-frailty model. Proportions of variance in frailty attributable to genetic and environmental factors were assessed using the structural equation model approach. For all-cause mortality the correlation coefficients of frailty for MZ twins tend to be higher than for DZ twins. For mortality with respect to respiratory diseases this effect was only seen in females, whereas males showed the opposite effect. Five standard biometric models are fitted to the data to evaluate the magnitude and nature of genetic and environmental factors on mortality. Using the best fitting biometric model heritability for cause of death was found to be 0.58 (0.07) for all-cause mortality (AE-model) and zero for diseases of the respiratory system for males. Heritability was 0.63 (0.11) for all-cause mortality (DE-model) and 0.18 (0.09) for diseases of the respiratory system (DE-model) for females. The analysis confirms the presence of a strong genetic influence on individual frailty associated with all-cause mortality. For respiratory diseases, no genetic influence was found in males and only weak genetic influence in females. The nature of genetic influences on frailty with respect to all-cause mortality is probably additive in males and dominant in females, whereas for frailty with respect to deaths caused by respiratory diseases in females, there are genetic factors present which are caused by dominance. Environmental influences are non-shared with exception of frailty with respect to respiratory diseases in males, where the shared environment plays an important role.

Aged↗