The BioSS Challenge - A demonstration of sampling bias

A sampling problem is described which was given to the general public to illustrate the problems of bias and the need for randomisation when sampling.     

School-based model for preventing teenage pregnancy

Social workers in the schools can take positive and immediate action to address teenage pregnancy through the use of interventive models that help teenagers avoid the risk of unwanted pregnancy. The present article describes and empirically supports 1 such school-based model. The author 1st delineates the major problems associated with teenage pregnancy and then relates the preventive model to prior research and details its implementation in school settings. A discussion of reslults from the model's field evaluation is followed with implications for school social workers. The model reported here is directed to all adolescents rather than focusing on a "high-risk" population. The risk of pregnancy is assumed to be a normal part of adolescent development. Grounded in an intterpersonal conceptualization of teenage pregnancy and in related empirical research, the school-based model helps young men and women acquire the requisite skills for preventing unwanted pregnancy. The program requires school social workers to meet with 12-18 teenage students of both sexes and to provide them with basic information on human sexuality, reproduction and contraception. These topics are covered by lectures, demostrations, discussion and audiovisual presentations. Through instruction, feedback and reinforcement, student learn how to talk about sensitive topics, stand up for their rights and be convincing and effective when carrying out decisions. Homework assignments are designed to develop the students'skills in interactions with dating partners, parents and friends. The clinical applicability and effectiveness of this prevention training model is documented through a study conducted in an urban high school. 36 informed and consenting sophomores of both sexes were randomly assigned either to an interventive group or to a non-treatment control group. Compared to the latter, the former had more accurate knowledge of human reproduction and contraception after the intervention. Buttressing these and other positive results, the students' enthusiastic feedback left little doubt that they enjoyed the group process and were interested in the training. Moreover, analyses of follow-up data on coital activity, the use of contraceptives, and family planning decisions revealed that the training had produced striking effects. Decision making tests, behavioral performance tests, follow-up questionnaires and videotaping of behavior during stressful interpersonal situations were among the evaluation techniques used.     

Peer-Collaborator Preferences of African American and White Sixth-Graders in Mathematics Classrooms

Abstract

This study focused on academic and social correlates of collaborator preferences of African American and White sixth-graders in mathematics classrooms in fall and spring. Students’ appraisals of emotional risk were examined as a moderator. Nomination procedures identified collaborator preferences, group affiliations, and social centrality; students self-reported engagement and emotional risk; school records provided achievement scores. Results indicated students preferred group affiliates, but not exclusively, as collaborators. Students with greater centrality, achievement, and engagement received more nominations. In the fall, high achievers received more nominations when appraisals of risk were high; whereas, engaged students whose appraisals of risk were low received more nominations. Results are interpreted in relation to coordinating social and academic factors in peer collaboration.     

The Louisville Twin Study: developmental synchronies in behavior

The Louisville Twin Study includes nearly 500 pairs of twins and their siblings who have participated in a longitudinal study of mental development, beginning in infancy and extending to adolescence. The results show that individual differences beginning in infancy and extending to adolescence. The results show that individual differences in intelligence progressively stabilized by school age, and each child followed a distinctive pattern of spurts and lags in mental development. Monozygotic twins became increasingly concordant over ages and matched each other closely for developmental trends. By contrast, dizygotic twins regressed to an intermediate level of concordance, comparable with that found for siblings and parent-offspring sets. A comprehensive home assessment was performed to identify the home/family variables that contributed to mental development. The overall results pointed to a strong developmental thrust in the growth of intelligence, which was principally guided by an intrinsic genetic ground plan. Qualitative features of home and family did, however, add significantly to prediction of offspring IQ. The results are interpreted in the context of Waddington's developmental model, and some recent advances in neurobiology and genetics are surveyed for their implications for developmental behavior genetics.