Hierarchical Generalized Linear Models and Frailty Models with Bayesian Nonparametric Mixing

This paper proposes Bayesian nonparametric mixing for some well-known and popular models. The distribution of the observations is assumed to contain an unknown mixed effects term which includes a fixed effects term, a function of the observed covariates, and an additive or multiplicative random effects term. Typically these random effects are assumed to be independent of the observed covariates and independent and identically distributed from a distribution from some known parametric family. This assumption may be suspect if either there is interaction between observed covariates and unobserved covariates or the fixed effects predictor of observed covariates is misspecified. Another cause for concern might be simply that the covariates affect more than just the location of the mixed effects distribution. As a consequence the distribution of the random effects could be highly irregular in modality and skewness leaving parametric families unable to model the distribution adequately. This paper therefore proposes a Bayesian nonparametric prior for the random effects to capture possible deviances in modality and skewness and to explore the observed covariates' effect on the distribution of the mixed effects.     

A Bayesian nonparametric estimator based on left censored data

Summary This paper introduces a Bayesian nonparametric estimator for an unknown distribution function based on left censored observations. Hjort (1990)/Lo (1993) introduced Bayesian nonparametric estimators derived from beta/beta-neutral processes which allow for right censoring. These processes are taken as priors from the class ofneutral to the right processes (Doksum, 1974). The Kaplan-Meier nonparametric product limit estimator can be obtained from these Bayesian nonparametric estimators in the limiting case of a vague prior. The present paper introduces what can be seen as the correspondingleft beta/beta-neutral process prior which allow for left censoring. The Bayesian nonparametyric estimator is obtained as in the corresponding product limit estimator based on left censored data.     

Class,work and family in women's lives

Interviews with white, working professional and working class mothers suggest that these women share values about work, family and on-the-job sociality. Respondents draw from a common value system, and many of the statements voiced by one group are echoed in the other. Work and motherhood are important paths to the development of individual identity for both working class and professional women. Differences in jobs, however, lead to differences in the actualization of values in their lives. Professional women are pulled in two directions and face continuing dilemmas in balancing careers which extract strong commitments from them and the demands of motherhood. Working class women's jobs do not require the same intensity of commitment, and they find it easier to meet their families' demands on their time. But conceptualizing their work as meaningful becomes more difficult than it is for professional women. Sociality is the third area of concern. Women in this study emphasized sociality because it allowed them to complete their work more effectively. It also served expressive functions; some women made friends at work. Some de-emphasized sociality if it interfered with their work identities. The importance of sociality was not necessarily dependent upon respondents' class location.I would like to thank Harold Bershady, Charles Bosk, and Robin Leidner for their comments and encouragement during the research and writing of this project. I would also like to thank M. E. Hughes, several anonymous reviewers, andQualitative Sociology for their helpful comments on earlier version of this article.     

The effect of public policies on recent Swedish fertility behavior

In the literature the recent upsurge in period birth rates is seen as evidence of a pronatalist effect of Sweden's extensive social insurance programs. Yet, these explanations can not account for the downturn in birth rates in the 1970s, the delay in childbearing, and the constancy of cohort birth rates which characterize recent Swedish fertility behavior. To summarize the effect of Sweden's economic and policy environment on the observed fertility patterns, I use a neoclassical economic framework to develop the shadow price of fertility. Although strong simplifying assumptions are imposed, the estimated price series exhibit a negative relationship with period fertility rates and the change in the estimated relative prices of fertility over the life cycle lend modest support for the delayed childbearing.The first draft of this paper was written while I was a National Fellow at the Hoover Institution. The research was supported by grants number HD-19226 and HD-28685 from the National Institute of Child Health and Development. I thank Glen Cain, John Kerman, Tom MaCurdy, Duncan Thomas, Michael Tilkin, and seminar participants at University of Illinois, Hoover Institution, and University of Wisconsin for useful comments.     

The prevalence of problem and pathological gambling: A critical analysis

Prevalence of pathological gambling refers to the percentage of cases of pathological gambling occurring in the community at a given time. Prevalence studies conducted in different principalities throughout the world are reviewed, and it is found that none of them conforms to this definition of prevalence. The major error in all but the most recent surveys conducted is identified as the use of questions which ask whether gambling-related problems have ever occurred rather than whether they are currently occurring. This error will lead to an over-estimation of the prevalence of pathological gambling in society. The second major error identified in nearly all studies involves the accuracy of the screens being used to assess whether or not an individual is a pathological gambler. Concerns about the efficiency of the South Oaks Gambling Screen have not yet been satisfactorily resolved. None-the-less, the widespread use of the South Oaks Gambling Screen has made a valuable contribution to international comparisons of prevalence studies. Future work that explores the emerging relationship between levels of personal expenditure on gambling, types of gambling product and gambling-related problems are recommended.     

Climate change knowledge influences attitude to mitigation via efficacy beliefs

Theories proposing climate change apathy is explained by inadequate knowledge do not account for why many informed and concerned Americans fail to act. While correlations between knowledge, efficacy for climate change, and attitude to mitigation have been observed, few studies have examined efficacy for climate change as a mediator. This study aimed to investigate the influence of specific climate change knowledge on attitude to mitigation via efficacy beliefs. A cross-sectional survey of 205 US adults recruited from Amazon's Mechanical Turk assessed participants’ climate change knowledge, efficacy for climate change, and attitude to mitigation. Indirect effects of self-efficacy for climate change were observed in three mediation models, suggesting efficacy for climate change explains some of the relationship between specific climate change knowledge and attitude to mitigation. The findings suggest risk communication can motivate pro-environmental attitudes with interventions that deliver information about climate change and develop efficacy for mitigation behavior.     

Bivariate modelling of longitudinal measurements of two human immunodeficiency type 1 disease progression markers in the presence of informative drop-outs

Summary.  The main statistical problem in many epidemiological studies which involve repeated measurements of surrogate markers is the frequent occurrence of missing data. Standard likelihood-based approaches like the linear random-effects model fail to give unbiased estimates when data are non-ignorably missing. In human immunodeficiency virus (HIV) type 1 infection, two markers which have been widely used to track progression of the disease are CD4 cell counts and HIV–ribonucleic acid (RNA) viral load levels. Repeated measurements of these markers tend to be informatively censored, which is a special case of non-ignorable missingness. In such cases, we need to apply methods that jointly model the observed data and the missingness process. Despite their high correlation, longitudinal data of these markers have been analysed independently by using mainly random-effects models. Touloumi and co-workers have proposed a model termed the joint multivariate random-effects model which combines a linear random-effects model for the underlying pattern of the marker with a log-normal survival model for the drop-out process. We extend the joint multivariate random-effects model to model simultaneously the CD4 cell and viral load data while adjusting for informative drop-outs due to disease progression or death. Estimates of all the model's parameters are obtained by using the restricted iterative generalized least squares method or a modified version of it using the EM algorithm as a nested algorithm in the case of censored survival data taking also into account non-linearity in the HIV–RNA trend. The method proposed is evaluated and compared with simpler approaches in a simulation study. Finally the method is applied to a subset of the data from the 'Concerted action on seroconversion to AIDS and death in Europe' study.     

Associations Between Friendship,Sympathy, and Prosocial Behavior Toward Friends

The current study examined the associations between multiple aspects of the friend relationship (connection, companionship, psychological control) and global prosocial behavior toward friends. Participants included 467 early adolescents (M age of child = 13.32, SD = 1.05, 49% female, 69% European American), and data were collected at two time points, roughly 1 year apart. Structural equation modeling suggested that friend psychological control was negatively associated with prosocial behavior toward friends, while friend connection was positively associated (via adolescent sympathy). Discussion focuses on the friend relationship as an important influence on adolescent sympathy and prosocial behavior toward friends.