Self‐Mutilation and Homeless Youth: The Role of Family Abuse,Street Experiences,and Mental Disorders

Self‐mutilation, which is the act of deliberately harming oneself, has been overlooked in studies of homeless and runaway youth. Given their high rates of abuse and mental health disorders, which are associated with self‐mutilation, homeless and runaway youth provide an ideal sample in which to investigate factors associated with self‐mutilation among a nonclinical population. Based on interviews with 428 homeless and runaway youth aged 16 to 19 years in 4 Midwestern states, the current study revealed widespread prevalence of self‐mutilation among these young people. Multivariate analyses indicated that sexual abuse, ever having stayed on the street, deviant subsistence strategies, and meeting diagnostic criteria for depression were positively associated with self‐mutilation. The findings are interpreted using stress theory and affect‐regulation models.     

THE SOCIAL REALITY OF PERSPECTIVES: ON G.H. MEAD'S POTENTIAL RELEVANCE FOR THE ANALYSIS OF CONTEMPORARY SOCIETIES

Mead's rarely explored notion of an “objective reality of perspectives” serves as a point of departure for a discussion of the implications of his work for general sociological theory and the analysis of contemporary societies. The epistemological background is explored to the point where sociology can be viewed as pragmatist mode of response to the inevitable relativity of knowledge. Mead's well known theory of identity formation plays an essential role in this context. The concept of perspective may serve as bridge for a generalization of the notion of identity in order to demonstrate the genuine sociological character of Mead's work. Illustrations are provided of the potential inherent in Mead's thought for research and to the study of contemporary societies. Finally sociology itself is conceived as a special kind of perspective, concerned with the inevitable perspectivity of human behavior.     

Unaffiliated voters

According to the conventional wisdom, political parties are hurt by unaffiliated voters (those who are not registered as Democrats or Republicans). These independents are irresponsible and unpredictable. Recent election law reforms throughout the country have encouraged affiliation by restricting voting in a primary to party members. This study examines the effect of the closed primary system in Connecticut. Research found that since the advent of the primary, the proportion of voters registered as unaffiliated has undergone a steady decline. But the decline in the proportion unaffiliated, however, does not appear to have strengthened partisan commitments. Rather it has changed the meaning of unaffiliated registration. In the past unaffiliated voters tended to be Democrats. Today they are equally likely to be either party.     

Sufficiency,generalized likelihood function and exponential family

The problem of characterizing an exponential family by sufficiency of certain statistics is considered. In distinction to most of the papers on this subject we do not want to characterize an exponential family of order less than or equal to k by the existence of a-dimensional sufficient statis tics in.GepenoenX' oi inc sample size. Since such a characterization is only valid under regularity assumptions, which is shown in the paper, we consider a stronger property of an exponential family which turns out to be a characteristic one. At this the concept of generalized likelihood functions will play an important role.     

A new variable importance measure for random forests with missing data

Random forests are widely used in many research fields for prediction and interpretation purposes. Their popularity is rooted in several appealing characteristics, such as their ability to deal with high dimensional data, complex interactions and correlations between variables. Another important feature is that random forests provide variable importance measures that can be used to identify the most important predictor variables. Though there are alternatives like complete case analysis and imputation, existing methods for the computation of such measures cannot be applied straightforward when the data contains missing values. This paper presents a solution to this pitfall by introducing a new variable importance measure that is applicable to any kind of data—whether it does or does not contain missing values. An extensive simulation study shows that the new measure meets sensible requirements and shows good variable ranking properties. An application to two real data sets also indicates that the new approach may provide a more sensible variable ranking than the widespread complete case analysis. It takes the occurrence of missing values into account which makes results also differ from those obtained under multiple imputation.     

On conjugate families and Jeffreys priors for von Mises–Fisher distributions

This paper discusses characteristics of standard conjugate priors and their induced posteriors in Bayesian inference for von Mises–Fisher distributions, using either the canonical natural exponential family or the more commonly employed polar coordinate parameterizations. We analyze when standard conjugate priors as well as posteriors are proper, and investigate the Jeffreys prior for the von Mises–Fisher family. Finally, we characterize the proper distributions in the standard conjugate family of the (matrix-valued) von Mises–Fisher distributions on Stiefel manifolds.     

Reports of Conferences,Institutes, and Seminars

This quarter's column features a report from the NISO/NASIG Webinar: Playing the Numbers: Best Practices in Acquiring, Interpreting and Applying Usage Statistics, offered online May 21, 2014; and the American Library Association Annual Conference, held in Las Vegas, Nevada, June 26-July 1, 2014.