Antisocial Behavior of Adoptees and Nonadoptees: Prediction from Early History and Adolescent Relationships

This study examined the contribution of demographic characteristics, early maltreatment, and peer and family relationships during adolescence to the prediction of aggressive and nonaggressive antisocial behavior (AASB and NAASB, respectively) during young adulthood; and determined whether adoption status has additional ability to predict ASB, once background, early experience, peer, and family variables were controlled. Data from adolescent and parent interviews were used from Waves 1 (predictors) and 3 (outcomes) of the National Longitudinal Study of Adolescent Health (Add Health). The sample included 337 adopted and 10,339 nonadopted adolescents whose mean ages were 15.8 at W1 and 21.7 at W3. Although AASB and NAASB were predicted by background characteristics, early maltreatment, peer relations, and family relationships, adoption status had little to no additional predictive power once the other variables were controlled.     

Effects of urbanization and land use on fish communities in Valley Creek watershed, Chester County, Pennsylvania

Valley Creek watershed, located in southeastern Pennsylvania, is a small, fourth-order stream that empties into the Schuylkill River at Valley Forge National Historic Park, thirty-five kilometers northwest of Philadelphia. The 64 km² watershed has been under extreme urbanization pressure over the past 30 years, resulting in rapidly increasing impervious surface cover and decreasing open space. The purpose of this study was to document some of the effects of urbanization on fish assemblages by quantifying the fish communities at fifteen sites throughout the watershed. Long-term effects of continued urbanization were identified, as data from the present study were compared to similar work completed nearly ten years earlier. There has been a shift in species composition from intolerant, coldwater species to more tolerant, eurythermal species. Currently, Valley Creek is supporting a naturally reproducing population of brown trout, but there has been a marked decline in relative abundance and range since 1993. Increased stream temperature from urban run-off is one of the primary issues in Valley Creek. Species composition was unique at each of the 15 stations owing to the effect of local land use in each station’;s drainage area. Fish assemblages revealed a patchy, non-continuous pattern of fish distribution.     

D-optimal weighted paired comparison designs

As a generalization of the paired comparison designs, the experimental design which considers the weighted difference between responses is studied. D-optimal designs are constructed for a model with main effects and first-order interactions. The experimental region is a hypercube or a hypersphere.     

Robust estimation in generalized linear mixed models

Generalized linear mixed models (GLMMs) are widely used to analyse non-normal response data with extra-variation, but non-robust estimators are still routinely used. We propose robust methods for maximum quasi-likelihood and residual maximum quasi-likelihood estimation to limit the influence of outlying observations in GLMMs. The estimation procedure parallels the development of robust estimation methods in linear mixed models, but with adjustments in the dependent variable and the variance component. The methods proposed are applied to three data sets and a comparison is made with the nonparametric maximum likelihood approach. When applied to a set of epileptic seizure data, the methods proposed have the desired effect of limiting the influence of outlying observations on the parameter estimates. Simulation shows that one of the residual maximum quasi-likelihood proposals has a smaller bias than those of the other estimation methods. We further discuss the equivalence of two GLMM formulations when the response variable follows an exponential family. Their extensions to robust GLMMs and their comparative advantages in modelling are described. Some possible modifications of the robust GLMM estimation methods are given to provide further flexibility for applying the method.     

Transforming national health policy: The significance of the stratification system

Policy formulation and decision-making occur within a continually changing sociopolitical environment. Presently, our national health policy lacks coherence and direction. It also is in a state of transition as evidenced by the recent restricted proposal to expand Medicare coverage to catastrophic illness. A comprehensive strategy for balancing escalating medical, hospital, and insurance costs as well as those associated with long-term care while extending access has not been devised. One of the most salient reasons for this is the failure of policy makers to grasp the complexities of the multifaceted stratification system. Its diverse, interrelated strata based on age, sex, economic status, and race are not incorporated in the process of shaping vitally needed and rational health policy. Doris Y. Wilkinson, a professor of sociology at the University of Kentucky, is a co-principal investigator on an intervention project funded by the National Cancer Institute. She recently received the Master of Public Health in Health Policy and Management from Johns Hopkins University.     

Conditional and unconditional tests with historical controls

Score statistics utilizing historical control data have been proposed to test for increasing trend in tumour occurrence rates in laboratory carcinogenicity studies. Novel invariance arguments are used to confirm, under slightly weaker conditions, previously established asymptotic distributions (mixtures of normal distributions) of tests unconditional on the tumor response rate in the concurrent control group. Conditioning on the control response rate, an ancillary statistic, leads to a new conditional limit theorem in which the test statistic converges to an unknown random variable. Because of this, a subasymptotic approximation to the conditional limiting distribution is also considered. The adequacy of these large-sample approximations in finite samples is evaluated using computer simulation. Bootstrap methods for use in finite samples are also proposed. The application of the conditional and unconditional tests is illustrated using bioassay data taken from the literature. The results presented in this paper are used to formulate recommendations for the use of tests for trend with historical controls in practice.     

Spot observation: Advantages and disadvantages for household time use research

The spot observation method of estimating time use is described in this article. Procedures for using this method in developing countries, where household activities are relatively easily observed, are contrasted with procedures used in countries characterized by very private living units and highly separated employment, educational, and household settings. Characteristics of various methods for collecting time use data are compared so that researchers can evaluate the trade-offs they can expect from selecting a particular method. A case example of using the spot observation method in a study of women's household and agricultural activities in the Njoro Region of Kenya is presented.Her research interests are household time allocation and women's economic status in developing countries.Her research interests include the time allocation of rural women and women in international development. She received her Ph.D. from the University of Illinois in 1995.The study of women's and children's time use reported in this paper was supported in part by the Center for African Studies, University of Illinois at Urbana-Champaign and by the Office of the Deputy Vice Chancellor for Academic Affairs, Egerton University, Njoro, Kenya.