Weibull and generalised exponential overdispersion models with an application to ozone air pollution

We consider the problem of estimating the mean and variance of the time between occurrences of an event of interest (inter-occurrences times) where some forms of dependence between two consecutive time intervals are allowed. Two basic density functions are taken into account. They are the Weibull and the generalised exponential density functions. In order to capture the dependence between two consecutive inter-occurrences times, we assume that either the shape and/or the scale parameters of the two density functions are given by auto-regressive models. The expressions for the mean and variance of the inter-occurrences times are presented. The models are applied to the ozone data from two regions of Mexico City. The estimation of the parameters is performed using a Bayesian point of view via Markov chain Monte Carlo (MCMC) methods.     

Recoverable robust timetabling for single delay: Complexity and polynomial algorithms for special cases

In this paper, we study the problem of planning a timetable for passenger trains considering that possible delays might occur due to unpredictable circumstances. If a delay occurs, a timetable could not be able to manage it unless some extra time has been scheduled in advance. Delays might be managed in several ways and the usual objective function considered for such purpose is the minimization of the overall waiting time caused to passengers. We analyze the timetable planning problem in terms of the recoverable robustness model, where a timetable is said to be recoverable robust if it is able to absorb small delays by possibly applying given limited recovery capabilities. The quality of a robust timetable is measured by the price of robustness that is the ratio between the cost of the recoverable robust timetable and that of a non-robust optimal one.     

Adapting The Revised Self-Leadership Questionnaire to The Portuguese Context

This study aimed to adapt the Revised Self-Leadership Questionnaire (RSLQ) (Houghton and Neck in J Manag Psychol 17(8):672?C691, 2002) for the Portuguese population. 720 professionals, and university and post-graduate students participated in this study. The RSLQ factorial structure was accessed through exploratory and multi group confirmatory factor analysis. From the 9 sub dimensional and 34 items original scale, only 7 sub dimensions and 21 items were preserved. The model tested through cross-validation multigroup analysis proved to be totally invariant across the groups, suggesting good model fit.     

Social and academic profile of the university student of social work a comparative study in Spain,Argentina, and Venezuela

ABSTRACT

The article presents the results of an empirical investigation that aimed to analyze comparative socio-demographic characteristics, motivational aspects and professional role of students who attend universities. The contexts of research were University of Mar de Plata (Argentina), University of Murcia (Spain) and University of Zulia (Venezuela). The universe of research was 304 students, with the participation of a total of 253 (TR 83,2%), 109 from University of Murcia—Spain—100 from University of Mar del Plata—Argentina and 44 from University of Zulia—Venezuela. Two hundred and forty-four measuring instruments were checked favorably. The results of the research allowed to highlight significant coincidences in most of the variables studied. In the analysis of self-perceived personality styles, there is high coincidence both in style (attributed qualification) and score (assigned quantification). At the three universities, the docent–student relationship is a positive variable that affects the favorable self-perception beyond academic success. Design and implementation of programs based on the described characteristics are recommended.     

Developing a Family Risk Assessment Tool in Adolescent Offenders: An Exploratory Study

The quality of family relations it is a relevant risk or protective factor in the adolescent criminal involvement, being the interplay between family and adolescent individual features, fundamental issues in the understanding of the adolescent risk and strengths assessment. This study aims to contribute to the validation of the Structured Interview of Family Assessment Risk (SIFAR) tool for the adolescent offenders’ family, based in nine family living items as risk factors and four protective factors. In an exploratory design, the structural consistency of SIFAR was analyzed using Cronbach’s alpha, mean inter-item correlation and exploratory factor analysis over risk items, because of the protective items dichotomous scale. The participants were a sample of 130 male adolescent delinquents detained in Portuguese facilities of the Directorate-general of Social Rehabilitation and Imprisonment, and their parents, paired analyzed. The SIFAR presents a structured professional judgment design for adolescent offender’s family protective and risk assessment. A reliability value of .75 was obtained for the risk items education, employment, housing/transport, legal problems, social dissonance, poverty, social net, social security and parenting, and an .79 was registered to the protective items family involvement, high discipline, low physical punishment and low parental stress. The risk items revealed a two-factor structure (social-economics and social conformity factors) explaining 48.15 % of the total variance. Results show the potential usefulness of SIFAR in the assessment the family protective and risk factors of adolescent offenders, presenting adequate structural reliability and construct validity. However further investigation it is necessary to the validation process of this tool.     

Bivariate beta regression models: joint modeling of the mean,dispersion and association parameters

In this paper a bivariate beta regression model with joint modeling of the mean and dispersion parameters is proposed, defining the bivariate beta distribution from Farlie–Gumbel–Morgenstern (FGM) copulas. This model, that can be generalized using other copulas, is a good alternative to analyze non-independent pairs of proportions and can be fitted applying standard Markov chain Monte Carlo methods. Results of two applications of the proposed model in the analysis of structural and real data set are included.     

FAMILY VALUES AND THE REGULATION OF LABOR

To be efficient, flexible labor markets require geographically mobile workers. Otherwise firms can take advantage of workers' immobility and extract rents at their expense. In cultures with strong family ties, moving away from home is costly. Thus, to limit the rents of firms and to avoid moving, individuals with strong family ties rationally choose regulated labor markets, even though regulation generates higher unemployment and lower incomes. Empirically, we find that individuals who inherit stronger family ties are less mobile, have lower wages and higher unemployment, and support more stringent labor market regulations. We find a positive association between labor market rigidities at the beginning of the 21st century and family values prevailing before World War II, and between family structures in the Middle Ages and current desire for labor market regulation. Both results suggest that labor market regulations have deep cultural roots.     

La Experiencia personal como origen de estilos atributivos diferenciales

Resumen

En este estudio se analizan los estilos atribucionales, para dos situaciones concretas y cotidianas—el desempleo y el fracaso escolar—, según el grado de implicación personal para ambos hechos.

Considerando variables dependientes, no habituales en la investigación de Teoría de Atribución, se confirma la existencia de un proceso de variabilidad en la realización de atribuciones, tomando como criterio distintivo la experiencia personal que los sujetos tienen en las situaciones propuestas. Se sugieren, por último, algunas hipótesis que pueden explicar estas diferencias.