Background:This article revisits an article published in Evaluation Review in 2005 on sample size estimation and power analysis for group-randomized trials. With help from a careful reader, we learned of an important error in the spreadsheet used to perform the calculations and generate the...

To allow appropriate allocation of prevention and care funding, HIV/AIDS surveillance data must include risk factor information, currently available for less than 70% of cases reported in the United States. The authors evaluated an intervention consisting of provider training and materials to...

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...