Almost nonparametric inference for repeated measures in mixture models

We consider ways to estimate the mixing proportions in a finite mixture distribution or to estimate the number of components of the mixture distribution without making parametric assumptions about the component distributions. We require a vector of observations on each subject. This vector is mapped into a vector of 0s and 1s and summed. The resulting distribution of sums can be modelled as a mixture of binomials. We then work with the binomial mixture. The efficiency and robustness of this method are compared with the strategy of assuming multivariate normal mixtures when, typically, the true underlying mixture distribution is different. It is shown that in many cases the approach based on simple binomial mixtures is superior.     

The Child Labor Amendment in the Social Studies Class

As part of a geography-based minority recruiting program (MRP), teachers were asked to serve as mentors for teams of high school students interested in both postsecondary education and geography as a major discipline or career path. The goal was to determine whether teacher participation in MRP programs was an effective tool to mentor underrepresented populations in geography. One component of the program evaluation examined the impact of teacher participation in a MRP by analyzing participating teachers’ classroom strategies and students’ performance in the school year following the summer program. Teachers were surveyed and participated in follow-up interviews during the school year following their participation in the MRP to determine the effects of the program's professional development components. The research hoped to reveal: (a) the participant-teachers’ function and role as mentors for students and the changes of participant-teachers’ behaviors, and (b) how any changes in their classrooms have affected their students’ understanding of geography. Data collection, reduction and analysis followed a grounded-theory approach to qualitative research. The research confirmed that participants leave professional development with an increased enthusiasm for and a better understanding of geography that they shared with their colleagues and students. Furthermore, teachers reported overcoming campus and district barriers in order to implement strategies and technologies provided during the MRP. More promising findings validate the prevailing thought that the positive energy of the MRP continues to reach into the classrooms in the following years. By understanding the impacts of professional development on participating teachers, the discipline may better recruit and retain high-achieving minority students.     

Social Psychology and the Sociology of Knowledge

Resumen

Se parte de la revisión de los tres modelos que se han formulado desde las ciencias sociales para intentar explicar la difusión de la infección de la infección por el VIH: el modelo epidemiológico-conductal, el modelo antropológico-cultural y el modelo político-económico. Se sintetizan los resultados obtenidos en tres estudios realizados en la Argentina en relación con el tema: los códigos actuales en la sexualidad de los jóvenes, el SIDA en los medios y las organizaciones no gubernamentales que actúan en el campo del SIDA. La revisión de los resultados muestra que en la Argentina, a pesar de que algunos grupos han captado la necesidad de la incorporación del modelo político-social en el trabajo preventivo en relación con el SIDA, existen grupos que persisten en el modelo epidemiológico-conductal, que no favorece la reflexión crítica sobre el sistema social, por lo que no se da pie a acciones transformadoras que permitan el “empoderamiento” de los sectores más afectados por la epidemia.     

The Effects of Childhood Sexual Abuse and Other Trauma on Drug Court Participants

Within the context of a larger study of drug court participants, this study examined the impact of traumatic experiences on psychiatric distress and on court outcomes. In the analyses, the participants (n = 229) were separated into 3 groups: childhood sexual abuse (CSA; n = 18), other trauma (n = 134), and no trauma (n = 77). The CSA group had higher mean scores on depression, anxiety, panic disorder, social phobia, somatization, and posttraumatic stress disorder than the other trauma group. Path analyses suggest that a history of trauma is a positive predictor of psychiatric distress and negative court events (positive urine screens, sanctions, etc.), with indirect effects on substance abuse severity, and failure in the drug court. These results suggest a need for the initial assessment procedure in drug courts to include a screening for trauma history, including CSA. They also suggest a need for trauma-informed care within drug courts.     

Stress From Daily Hassles in Couples: Its Effects on Intradyadic Stress,Relationship Satisfaction,and Physical and Psychological Well‐Being

According to the systemic‐transactional stress model (STM; G. Bodenmann, European Review of Applied Psychology, 1997; 47: 137), extradyadic stress from daily hassles can have a negative impact on the individual psychological and physical health and the couple's relationship. This study is the first one to test the STM propositions in a model that includes both partners’ individual and relational outcomes simultaneously. The model also includes actor and partner effects as well as the interdependence between partners’ processes. Cross‐sectional, self‐report data were collected from 110 community couples in Switzerland. Consistent with STM predictions, results from the path model analysis indicate that for actor effects extradyadic stress from daily hassles relates directly to lower psychological (increase in anxiety symptoms) and physical well‐being and only indirectly to lower relationship satisfaction through increased intradyadic stress from relationship problems and also through more depressive symptomatology in men. The female extradyadic stress and intradyadic stress had partner effects on the male intradyadic stress and the male relationship satisfaction, respectively. Limitations as well as research and clinical implications for marriage and family therapists are discussed.     

Clustered Survival Data with Left‐truncation

Left‐truncation occurs frequently in survival studies, and it is well known how to deal with this for univariate survival times. However, there are few results on how to estimate dependence parameters and regression effects in semiparametric models for clustered survival data with delayed entry. Surprisingly, existing methods only deal with special cases. In this paper, we clarify different kinds of left‐truncation and suggest estimators for semiparametric survival models under specific truncation schemes. The large‐sample properties of the estimators are established. Small‐sample properties are investigated via simulation studies, and the suggested estimators are used in a study of prostate cancer based on the Finnish twin cohort where a twin pair is included only if both twins were alive in 1974.     

Semiparametric regression for restricted mean residual life under right censoring

A mean residual life function (MRLF) is the remaining life expectancy of a subject who has survived to a certain time point. In the presence of covariates, regression models are needed to study the association between the MRLFs and covariates. If the survival time tends to be too long or the tail is not observed, the restricted mean residual life must be considered. In this paper, we propose the proportional restricted mean residual life model for fitting survival data under right censoring. For inference on the model parameters, martingale estimating equations are developed, and the asymptotic properties of the proposed estimators are established. In addition, a class of goodness-of-fit test is presented to assess the adequacy of the model. The finite sample behavior of the proposed estimators is evaluated through simulation studies, and the approach is applied to a set of real life data collected from a randomized clinical trial.     

“U.S. Pharmaceutical Gray Markets: Why Do They Persist—and What to Do about Them?”

This article illustrates how a traditional U.S. pharmaceutical industry supply chain operates, beginning with pharmaceutical compounds and ending at patient‐dispensing hospitals or pharmacies. Furthermore, to place the problem of U.S. drug shortages in historical perspective, a review of the annual volume of such shortages over the last decade is undertaken. Following this review of recent drug shortages is an analysis of the market forces and business decisions that drive the creation of a pharmaceutical gray market, its attendant “price gouging” and product integrity issues, and the alterations in the traditional pharmaceutical industry supply chain model. In response to persistent drug shortages, the U.S. Food and Drug Administration (FDA) has recently been empowered by the executive and legislative branches of the U.S. government to actively address this issue. To reflect these FDA challenges, a thorough review of these new agency charges and responsibilities is undertaken. Lastly, an analysis of the results of recent FDA public policy actions on mitigating drug shortages, as well as recommendations tor market‐based solutions to the gray market problem that pharmaceutical manufacturers, hospitals and pharmacies could institute as industry‐wide standards of business practice, are discussed in the conclusion.