Communities That Care (CTC) is a prevention system designed to reduce adolescent substance use and delinquency through the selection of effective preventive interventions tailored to a community's specific profile of risk and protection. A community-randomized trial of CTC, the Community Youth Development Study, is currently being conducted in 24…

Factors that influence the sample size necessary for longitudinal evaluations include the nature of the evaluation questions, nature of available comparison groups, consistency of the treatment in different sites, effect size, attrition rate, significance level for statistical tests, and statistical power. (Author/GDC)

This article presents a synopsis of each of seven presentations given at a conference on design and analysis in community trial studies. Papers identify problems with community trials and discuss strengths and weaknesses associated with design and analysis strategies. Areas of consensus are summarized. (SLD)

Electricity conservation programs were implemented in matched pairs of office-classroom-laboratory buildings and dormitories. The methodological problems of predicting consumption levels, interpreting why changes in consumption occurred, and estimating initial waste levels are discussed along with their implications for the conduct of behavioral…

Simple methods for detecting attrition (nonresponse) in longitudinal evaluations are reviewed, focusing on regression-based analyses of data from a longitudinal evaluation. The approaches are illustrated with data from the Fort Bragg Evaluation, an evaluation of a major demonstration in children's mental health services. (SLD)

Evidence is presented that strengthens the argument against comparison group research strategies. Results from a study of youth attitudes related to the California Conservation Corps involving 528 participants and 668 comparisons indicate that the comparison group may not adequately represent the nontreatment state. (SLD)