Regularized parameter estimation of high dimensional t distribution

We propose penalized-likelihood methods for parameter estimation of high dimensional t distribution. First, we show that a general class of commonly used shrinkage covariance matrix estimators for multivariate normal can be obtained as penalized-likelihood estimator with a penalty that is proportional to the entropy loss between the estimate and an appropriately chosen shrinkage target. Motivated by this fact, we then consider applying this penalty to multivariate t distribution. The penalized estimate can be computed efficiently using EM algorithm for given tuning parameters. It can also be viewed as an empirical Bayes estimator. Taking advantage of its Bayesian interpretation, we propose a variant of the method of moments to effectively elicit the tuning parameters. Simulations and real data analysis demonstrate the competitive performance of the new methods.     

What’s the Relationship Got to do with It? Understanding the Therapeutic Relationship in Therapeutic Foster Care

The therapeutic relationship is increasingly recognized as important to understanding how process variables contribute to treatment outcomes. In this paper, we examine the therapeutic relationship between children with serious emotional and behavioral disorders and their treatment providers in the context of an observational study of Therapeutic Foster Care (TFC). Our findings suggest that the quality of the relationship between the treatment parent and youth in a TFC setting is significantly associated with better emotional and behavioral functioning for the youth. It appears from these findings that the quality of the relationship between the youth and treatment parent in a TFC setting is at least one of the mechanism or process factors that contribute to improved functioning for the youth.     

Statistical Inference for Expectile‐based Risk Measures

Expectiles were introduced by Newey and Powell in 1987 in the context of linear regression models. Recently, Bellini et al. revealed that expectiles can also be seen as reasonable law‐invariant risk measures. In this article, we show that the corresponding statistical functionals are continuous w.r.t. the 1‐weak topology and suitably functionally differentiable. By means of these regularity results, we can derive several properties such as consistency, asymptotic normality, bootstrap consistency and qualitative robustness of the corresponding estimators in nonparametric and parametric statistical models.     

On a new positive dependence concept based on the conditional mean inactivity time order

In this paper, we introduce a new positive dependence concept between two non negative random variables which is related to a conditional version of the mean inactivity time order. A number of properties and relationship between the new notion and the concept of positive likelihood ratio dependence (PLRD) is discussed. Some results in terms of proposed notions for the Archimedean family of copulas are provided.     

Covariate‐adjusted borrowing of historical control data in randomized clinical trials

The borrowing of historical control data can be an efficient way to improve the treatment effect estimate of the current control group in a randomized clinical trial. When the historical and current control data are consistent, the borrowing of historical data can increase power and reduce Type I error rate. However, when these 2 sources of data are inconsistent, it may result in a combination of biased estimates, reduced power, and inflation of Type I error rate. In some situations, inconsistency between historical and current control data may be caused by a systematic variation in the measured baseline prognostic factors, which can be appropriately addressed through statistical modeling. In this paper, we propose a Bayesian hierarchical model that can incorporate patient‐level baseline covariates to enhance the appropriateness of the exchangeability assumption between current and historical control data. The performance of the proposed method is shown through simulation studies, and its application to a clinical trial design for amyotrophic lateral sclerosis is described. The proposed method is developed for scenarios involving multiple imbalanced prognostic factors and thus has meaningful implications for clinical trials evaluating new treatments for heterogeneous diseases such as amyotrophic lateral sclerosis.     

Stress and tobacco use among African-American adolescents: the buffering effect of cultural factors

Tobacco is a leading contributor to morbidity and mortality and a primary reason for health disparities among African Americans. In this study we explore the role of stress in smoking and cultural factors that protect against stress among African-American adolescents. Our sample consisted of 239 youth who were recruited into the study while enrolled in 8th and 12th grade. Measures of risk factors (stress, school transition stress, and community disorganization), moderator or protective factors (religious support and intergenerational connections), and 30-day tobacco use were collected. Hierarchical multiple regression analyses were conducted. Intergenerational connections moderated the effect of stress on past 30-day tobacco use. Religious support moderated the effect of neighborhood disorganization on past 30-day tobacco use. Religious support also moderated the effect of stress on past 30-day tobacco use. The findings have implications for prevention efforts to consider religious beliefs and practices and also to link youth with supportive adults in their community.     

The Effect of Different Cultural Lenses on Reliability and Validity in Observational Data: The Example of Chinese Immigrant Parent–Toddler Dinner Interactions

This study used a mixed methodology to investigate reliability, validity, and analysis level with Chinese immigrant observational data. European‐American and Chinese coders quantitatively rated 755 minutes of Chinese immigrant parent–toddler dinner interactions on parental sensitivity, intrusiveness, detachment, negative affect, positive affect, and parents' confidence. They also gave qualitative coding rationales for their quantitative ratings. Analysis of quantitative ratings indicated systematic differences associated with coder ethnicity. Such differences could threaten the reliability between coders with different ethnicities. Analysis of qualitative rationales revealed different cultural links between concepts and behavior cues, which could challenge the cross‐cultural validity of a macro‐level coding system. When a coding system is incongruous with coders' cultural schemata, even after intensive training, the effect of culture cannot be eliminated. Implications of these findings for observational cultural research are discussed.     

Health-Promoting Influences of the Family on Late Adolescent Functioning

This study examined whether potentially modifiable health-promoting family factors during mid-adolescence (age 15) predicted adaptive functioning in late adolescence (age 18) among members of a working-class community cohort. Family factors included feeling valued in the family, cohesion, and social support. Late adolescent outcomes covered developmentally salient areas: academic functioning; mental health; suicidal behavior; and social, psychological, and behavioral functioning. Our findings demonstrate that a positive adolescent family milieu is related to both adaptive outcomes and a reduced likelihood of serious difficulties, including mental and behavior problems. Although each hypothesized health-promoting factor was significantly associated with multiple areas of age 18 functioning, the patterns of association differed by type of family factor. Taken together, results suggest that the family remains an important social context during mid-adolescence and that to be most effective programs designed by practitioners aimed at strengthening families should target multiple features of the family environment.     

A critical and comparative review of the prevention of drug and alcohol abuse in Israel

The article reviews the various programs and intervention strategies of substance abuse prevention in Israel. It concentrates mainly on the stages of primary and secondary prevention among youth. School-based prevention programs, those designated for detached youth as well as community-based programs, are presented and analyzed. The prevention efforts in Israel are also compared to those in other Western countries. The discussion includes recommendations for future developments in this domain.