Joint modeling of hierarchically clustered and overdispersed non‐gaussian continuous outcomes for comet assay data

Multivariate longitudinal or clustered data are commonly encountered in clinical trials and toxicological studies. Typically, there is no single standard endpoint to assess the toxicity or efficacy of the compound of interest, but co‐primary endpoints are available to assess the toxic effects or the working of the compound. Modeling the responses jointly is thus appealing to draw overall inferences using all responses and to capture the association among the responses. Non‐Gaussian outcomes are often modeled univariately using exponential family models. To accommodate both the overdispersion and hierarchical structure in the data, Molenberghs et al. A family of generalized linear models for repeated measures with normal and conjugate random effects. Statistical Science 2010; 25:325–347 proposed using two separate sets of random effects. This papers considers a model for multivariate data with hierarchically clustered and overdispersed non‐Gaussian data. Gamma random effect for the over‐dispersion and normal random effects for the clustering in the data are being used. The two outcomes are jointly analyzed by assuming that the normal random effects for both endpoints are correlated. The association structure between the response is analytically derived. The fit of the joint model to data from a so‐called comet assay are compared with the univariate analysis of the two outcomes. Copyright © 2012 John Wiley & Sons, Ltd.     

The school-to-work transition of 2<Superscript>nd</Superscript> generation immigrants in Denmark

2^nd generation immigrants from less developed countries have less education and a lower employment frequency compared to the native Danish youth. We analyse the school-to-work transition of these groups using panel data for the years 1985–1997. The educational gap between 2^nd generation immigrants and the Danish youth is to some extent explained by age structure, while age does not explain the native-immigrant gap concerning the duration of waiting time until first job and the duration of first employment spell. Instead parental capital and neighbourhood effects seem to play a major role. We find large gender differences among 2^nd generation immigrants in the school-to-work transition.All Correspondence to Nina Smith. Thanks to Thomas Haugaard Jensen, Anne-Sofie Reng Rasmussen and Mette Skak-Nielsen who have done part of the computational work. We also want to thank two anynomous referees and participants in the ESF-conference on Migration and Development in Naples 2000 and the ESPE conference in Athens 2001 for many valuable comments. The project has been financed by the Danish Social Science Research Council (FREJA), the Danish Ministry of Labour and TSER. Furthermore, Helena Skyt Nielsen has been supported financially by the Danish Social Science Research Council (SSF), while this work was undertaken. Responsible editors: David Card and Christopher M. Schmidt.     

Promoting Coexistence by Means of Conflict Education: The MACBE Model

This article presents a conflict education program designed to restore relationships among adversaries experiencing protracted, seemingly intractable intergroup conflict. It is designed on the basis of a systems model. The underlying assumption is that breaking the escalation cycle and ameliorating the adversaries' relationships requires a comprehensive intervention. Consequently, the curriculum imparts knowledge about conflict dynamics and teaches constructive conflict resolution skills, enhancing the probability of behavior and attitude change. The program is deemed relevant to efforts of improving Arab-Jewish relations in Israel. Implementation of the intervention requires ample resources, cooperation of local communities, and forbearance of program initiators and participants, which rarely exist in tandem. Nonetheless, even partial implementation can contribute to peaceful coexistence of Arabs and Jews.     

Understanding the Socioeconomic Status of International Immigrants in Chile Through Hierarchical Cluster Analysis: a Population‐Based Study

Immigration to Chile is not large (just under 2% of the total population) but has increased in recent years. This study aimed to analyse the socioeconomic status (SES) of immigrants in Chile and compare it with the Chilean‐born, by secondary data analysis of an anonymous nationally representative survey (CASEN, 2006). Immigrants are categorized into Low, Medium and High SES through hierarchical cluster analysis. Around 1 per cent of the total sample are international immigrants; an additional 0.7 per cent did not report their migration status. Self‐reported immigrants show great variability in their SES. Immigrants in the Low SES cluster appeared to be significantly younger than those in Medium and High SES, also more likely to be children, women and belong to an ethnic minority. Immigrants in the Low SES cluster appeared similar to the unemployed, poorest Chilean‐born but are more than eight years younger on average and more likely to be female. Immigrants to Chile are a unique group, with socio‐demographic characteristics that differ significantly from the Chilean‐born population, but there is great heterogeneity and complexity within this group. Cluster analysis provided a meaningful interpretation of the multidimensional concept of SES and allowed the identification of a vulnerable group of Low SES immigrants to Chile.