Longitudinal data analysis with structural equations

In this paper we review different structural equation models for the analysis of longitudinal data: (a) univariate models of observable variables, (b) multivariate models of observable variables, (c) models with latent variables, (d) models that are unconditioned or conditioned to other variables (depending on the variability of the independent variables: time-varying or time-invariant, and depending on the type of independent variables: of latent variables or of observable variables), (e) models with interaction of variables, (f) models with non-linear variables, (g) models with a constant, (h) with single level and multilevel measurement, and (i) other advances in SEM of longitudinal data (latent growth curve model, latent difference score, etc.). We have paid more attention to the interaction of variables and to non-linear transformations of variables because they are not frequently used in empirical investigation. They do, however, offer interesting possibilities to researchers who wish to verify relations between the variables they obtain. Potential applications are described, with their advantages and disadvantages

Effect of the rating source in organizational citizenship behavior: A multitrait-multimethod analysis, The

This study compares the ratings for three dimensions of organizational citizenship behaviour (OCB) provided by managers (self-ratings), their subordinates, and their colleagues (superiors and peers) in the Spanish branch of a multinational food company. Using hierarchical confirmatory factor analysis, we find strong method effects, indicating that ratings from different sources provide different information. A comparison among means shows that, in most cases, subordinate and self-ratings are significantly higher than colleague ratings. We also add to the recent research about the dimensionality of OCB by performing a correlation analysis among OCB dimensions that controls for method effects. Our results show that, when methods are taken into account, correlations among OCB dimensions are not significant.Organizational citizenship behavior; rating source; self-ratings; method effect

Bias and heteroscedastic memory error in self-reported health behavior: an investigation using covariance structure analysis

BACKGROUND: Frequent use of self-reports for investigating recent and past behavior in medical research requires statistical techniques capable of analyzing complex sources of bias associated with this methodology. In particular, although decreasing accuracy of recalling more distant past events is commonplace, the bias due to differential in memory errors resulting from it has rarely been modeled statistically. METHODS: Covariance structure analysis was used to estimate the recall error of self-reported number of sexual partners for past periods of varying duration and its implication for the bias. RESULTS: Results indicated increasing levels of inaccuracy for reports about more distant past. Considerable positive bias was found for a small fraction of respondents who reported ten or more partners in the last year, last two years and last five years. This is consistent with the effect of heteroscedastic random error where the majority of partners had been acquired in the more distant past and therefore were recalled less accurately than the partners acquired more recently to the time of interviewing. CONCLUSIONS: Memory errors of this type depend on the salience of the events recalled and are likely to be present in many areas of health research based on self-reported behavior

Relationship between three palliative care outcome scales

BACKGROUND: Various scales have been used to assess palliative outcomes. But measurement can still be problematic and core components of measures have not been identified. This study aimed to determine the relationships between, and factorial structure of, three widely used scales among advanced cancer patients. METHODS: Patients were recruited who received home or hospital palliative care services in the south of England. Hope, quality of life and palliative outcomes were assessed by patients in face to face interviews, using three previously established scales – a generic measure (EQoL), a palliative care specific measure (POS) and a measure of hope (Herth Hope Index). Analysis comprised: exploratory factor analysis of each individual scale, and all scales combined, and confirmatory factor analysis for model building and validation. RESULTS: Of 171 patients identified, 140 (81%) consented and completed first interviews; mean age was 71 years, 54% were women, 132 had cancer. In exploratory analysis of individual means, three out of the five factors in the EQoL explained 75% of its variability, four out of the 10 factors in POS explained 63% of its variability, and in the Hope Index, nine out of the 12 items explained 69% of its variability. When exploring the relative factorial structure of all three scales, five factors explained 56% of total combined variability. Confirmatory analysis reduced this to a model with four factors – self-sufficiency, positivity, symptoms and spiritual. Removal of the spiritual factor left a model with an improved goodness of fit and a measure with 11 items. CONCLUSION: We identified three factors which are important outcomes and would be simple to measure in clinical practice and research

Esquema y recomendaciones para el uso de los Modelos de Ecuaciones Estructurales || Scheme and recommendations for the use of Structural Equations Models

In the last thirty years the use of Structural Equation Modeling (SEM) has been increasing in an exponential manner. Such is this increase that we are witnessing, sometimes a use so far from the correct and appropriate practice with this type of multivariate statistical technique. In this short paper we want to make a presentation of the different stages to follow in the use of SEM, and a presentation of the most common options and recommendations to consider in those same phases.En los últimos treinta años el uso de los Modelos de Ecuaciones Estructurales (SEM) ha ido incrementándose de una manera exponencial. Tal es este incremento que asistimos, a veces, a una aplicación de la técnica estadística algo alejada de la praxis correcta y adecuada con este tipo de técnicas multivariantes. En este breve trabajo se trata de efectuar una presentación de las distintas fases a seguir en el uso de los SEM, una presentación de las opciones más habituales y de las recomendaciones a considerar en esas mismas fases

MEASUREMENT INVARIANCE: CONCEPT AND IMPLEMENTATION

An empirical evidence for independent samples of a population regarding measurement invariance implies that factor structure of a measurement tool is equal across these samples; in other words, it measures the intended psychological trait within the same structure. In this case, the evidence of construct validity would be strengthened within the frame of the scores obtained from the tool. When measurement invariance is not supported, the researchers should consider the possibility of the different factor designs for each group. Ignoring such a situation brings forward the probability about differentiation of the trait(s) measured by measurement tool for that/those group(s), so it causes to suspect the validity of the scores obtained from the tool. The aim of this study is to examine measurement invariance in the context of the conceptual foundations of multi-group confirmatory factor analysis, and discuss the subject through the results from two hypothetical data set that one supports measurement invariance, but the other does not. As a result of analysis performed in this direction, it is determined that the five-factor design derived from the first data set is equal across the groups in the majors of science, health, and social science. It is also concluded that the three-factor design obtained from the secondary data set is not equal for female and male groups. Besides, the exploratory factor analysis performed for female and male groups separately shows that the three-factor design of the tool is valid for females, but the number of factors was four in males. When the factor design for male group is examined, it is determined that the three items in the second factor separate significantly. That leads to the conclusion that it is crucial to test measurement invariance in studies regarding the determination of the psychometric properties of the tool.

The Development of a Spanish Language Version of the Worn Out Scale of the General Well-Being Questionnaire (GWBQ)

The paper describes the development of a short Spanish-language version of the General Well-Being Questionnaire (GWBQ; Cox & Gotts, 1987), based on the 12 items of its Worn Out scale. Research has shown the English-version Worn Out scale to be sensitive to aspects of the design and management of work. This study aimed to test its crosscultural consistency in a Spanish-language workplace context. The data were collected from a sample of 229 workers in Valencia (Spain). Confirmatory Factor Analyses showed the factorial validity, reliability, and concurrent validity of the new Spanish version to be adequate. The sensitivity of the new measure to safety behavior and the reporting of accidents was also assessed and shown to be good. The new questionnaire extends the usefulness of the parent questionnaire to occupational health psychology research in the Spanish language by offering a short assessment tool appropriate for workplace studies.El artículo describe el desarrollo de la versión corta en español del General Well-Being Questionnaire (GWBQ; Cox & Gotts, 1987; en español el “Cuestionario de Bienestar General”), basada en los 12 ítems de su subescala de “Agotamiento”. La investigación ha mostrado que la versión en inglés de la escala de Agotamiento es sensible a ciertos aspectos del diseño y gestión del trabajo. El propósito de este estudio fue comprobar la consistencia transcultural en un contexto de trabajo de habla española. Los datos se recogieron de una muestra de 229 trabajadores en Valencia (España). Análisis factoriales confirmatorios demostraron la adecuación de la validez factorial, la fiabilidad, y la validez concurrente de la nueva versión española. También se evaluó la sensibilidad de la nueva medida hacia la conducta de seguridad y distintas medidas de siniestralidad, comprobando asimismo su adecuación. El cuestionario nuevo amplía la utilidad del cuestionario original al frecerse como herramienta para los investigadores en psicología de la salud cupacional en lengua española, ofreciendo un nstrumento corto de evaluación apropiado para el lugar de trabajo

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

Abstract 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.</p

Las propiedades psicométricas de la versión inicial del cuestionario de orientación a la tarea y al ego (teosq) adaptado a la educación física en su traducción al castellano

El propósito de este trabajo es analizar las propiedades psicométricas de la versión inicial del cuestionario TEOSQ, en su traducción al castellano, aplicado al contexto de la educación física escolar y adaptado a tal efecto. Con ello se pretende determinar si constituye un instrumento válido y fiable para utilizar en futuras investigaciones del ámbito de la educación física escolar en el contexto español. El cuestionario se administró a 774 estudiantes valencianos de E.S.O. de edades comprendidas entre los 12 y los 16 años. El análisis factorial confirmatorio (CFA) apoyó el modelo teórico hipotetizado de dos factores ('orientación a la tarea' y 'orientación al ego') para la escala del TEOSQ. La baja correlación entre los factores demostró la independencia de los mismos y los coeficientes alfa mostraron una consistencia interna aceptable de las dos subescalas. Las pruebas t indican que existen diferencias significativas por género de tal manera que los alumnos, en comparación con las alumnas, presentan una mayor orientación al ego.The purpose of this paper is to analyse the psychometric properties of the Physical Education-Adapted Task and Ego Orientation in Sport Questionnaire (TEOSQ) in its initial Spanish language version applied within the context of and adapted to physical education in schools. The paper aims to determine whether the Questionnaire can be considered a valid and reliable instrument in future research on physical education in Spanish schools. The questionnaire was administered to 774 Valencian secondary school students between the ages of 12 and 16 years old. The Confirmatory Factor Analysis (CFA) supported the hypothesized theoretical model of two factors ('task orientation' and 'ego orientation') in the TEOSQ scale. The low correlation between factors showed their independence and alfa coefficients indicated the acceptable internal consistency of both subscales. T-tests indicated that males were more ego-oriented than females

Structural equation modelling

Over the past two decades there has been an upsurge in interest in structural equation modelling (SEM). Applications abound in the social sciences and econometrics, but the use of this multivariate technique is not so common in public health research. This dissertation discusses the methodology, the criticisms and practical problems of SEM. We examine actual applications of SEM in public health research. Comparisons are made between multiple regression and SEM and between factor analysis and SEM. A complex model investigating the utilization of antenatal care services (ANC) by migrant women in Belgium is analysed using SEM. The dissertation concludes with a discussion of the results found and on the use of SEM in public health research. Structural equation modelling is recommended as a tool for public health researchers with a warning against using the technique too casually.Mathematical SciencesM. Sc. (Statistics