Young Children's Prosocial and Aggressive Behaviors and Their Experiences of Being Targeted for Similar Behaviors by Peers

Children's target experiences (as recipients of prosocial peer acts and victims of peer aggression) were investigated for their concurrent and longitudinal associations with prosocial and aggressive behavior. Forty‐four children (initially 22–40 months) were observed in naturalistic interactions with peers during a two‐month period for each of three consecutive years. Results revealed no consistency over time in children's experiences as targets for aggressive or prosocial peer acts, although there was some indication that altruistic target experiences may be stable from the end of the preschool period. Early behavior appeared to affect the way children were later treated by peers, but no support was found for the idea that early target experiences influence later behavior. Prosocial behavior was concurrently and longitudinally associated with prosocial target experiences. Aggressive behavior reduced the likelihood of children being targets of prosocial peer behavior and, over time, also of their being targets of peers’ aggression.     

Pooling multivariate data under W, LR and LM tests

Two independent random samples are drawn from two multivariate normal populations with mean vectors μ1 and μ2 and a common variance-covariance matrix Σ. Ahmed and Saleh (1990) considered preliminary test maximum likelihood estimator (PMLTE) for estimating μ1 based on the Hotelling's T _N ², when it is suspected that μ1=μ2. In this paper, the PTMLE based on the Wald (W), Likelihood Ratio (LR) and Lagrangian Multiplier (LM) tests are considered. Using the quadratic risk function, the conditions of superiority of the proposed estimator for departure parameter are derived. A max-min rule for the size of the preliminary test of significance is presented. It is demonstrated that the PTMLE based on W test produces the highest minimum guaranteed efficiencies compared to UMLE among the three test procedures.     

Renyi's entropy for residual lifetime distribution

In the present paper, we introduce and study Renyi's information measure (entropy) for residual lifetime distributions. It is shown that the proposed measure uniquely determines the distribution. We present characterizations for some lifetime models. Further, we define two new classes of life distributions based on this measure. Various properties of these classes are also given.     

Grenzen der Geschichte?

The article follows Tony Becher’s suggestion, that scientific disciplines metaphorically spoken may be looked at as different tribes of different habits occupying different territories. The articles reviews then some possibilities to determine a border between the field of historical research and sociology by different methods, different theories, different research objects e. g. past vs. present and so on. The academic field of history is described as a field importing theories, methods and objects from other academic fields, many of them from sociology. The last decades’ processes of innovation and redefinition within the field of historical research diminished cognitive differences between history and sociology so significantly that — this is the main argument of the article — more or less only the borders produced by institutions remained. Nevertheless these kind of borders have major effects all of them responsible for maintaining different disciplinary identities.     

Applied state space modelling of non-Gaussian time series using integration-based Kalman filtering

The main topic of the paper is on-line filtering for non-Gaussian dynamic (state space) models by approximate computation of the first two posterior moments using efficient numerical integration. Based on approximating the prior of the state vector by a normal density, we prove that the posterior moments of the state vector are related to the posterior moments of the linear predictor in a simple way. For the linear predictor Gauss-Hermite integration is carried out with automatic reparametrization based on an approximate posterior mode filter. We illustrate how further topics in applied state space modelling, such as estimating hyperparameters, computing model likelihoods and predictive residuals, are managed by integration-based Kalman-filtering. The methodology derived in the paper is applied to on-line monitoring of ecological time series and filtering for small count data.     

Modeling heteroscedastic age-period-cohort cancer data

The extent to which cancer will be a burden on the Canadian health-care system will be determined by future cancer rates and future population levels in the high-risk age groups. Parametric models of incidence and mortality rates for various cancers may be used to obtain medium-term forecasts of rates, which then can be used in conjunction with population projections to obtain forecasts of total incidence and mortality. Age-period-cohort cancer data often exhibit marked heteroscedasticity, which complicates the modeling of the data. Methods to allow for the effects of this heteroscedasticity on residual processes are developed and discussed in the context of modeling Canadian female breast-cancer incidence data.     

Peer influence and drug use among adolescents in rural areas

A sample of 1,004 eighth and tenth grade students in twenty-three small Central/East Texas communities was assessed to determine 1) their perception of the number of their friends who use drugs, 2) the amount of information they received about drugs from their friends, and 3) the connection between those perceptions and drug use. A multiple regression model which included grade, gender, the degree to which friends are perceived to use drugs and the amount of information about drugs received from friends explained 39 percent of the variance in the degree to which rural adolescents were involved in drug use. An item specific analysis of the subcomponents of these composite variables explained 44 percent of the variance in the degree to which rural adolescents were involved in drug use. This same four-factor model accurately classified over 81 percent of non-drug-users and 67 percent of users using discriminant analysis. Students who perceived a higher degree of drug use among their friends and who received more information about drugs from their friends used drugs more frequently. Lower marijuana use in these rural areas as compared to the nation, both as a peer perception and as a fact, may protect these students to a degree from broader patterns of drug use. The findings of this study support the theory that peer pressure is related to drug abuse, even in rural areas.