Most interventions designed to prevent HIV/STI/pregnancy risk behaviours in young people have multiple components based on psychosocial theories (e.g. social cognitive theory) dictating sets of mediating variables to influence to achieve desired changes in behaviours. Mediation analysis is a method for investigating the extent to which a variable…

Introduction: Group-randomized trials (GRTs) are one of the most rigorous methods for evaluating the effectiveness of group-based health risk prevention programs. Efficiently designing GRTs with a sample size that is sufficient for meeting the trial's power and precision goals while not wasting resources exceeding them requires estimates of the…

Background: During the 2004-2005 school year, the Mississippi Department of Education, Office of Child Nutrition, initiated a pilot program to distribute free fruit and vegetable snacks to students during the school day. This article describes the first-year implementation of the Mississippi Fruit and Vegetable Pilot Program. Methods: The process…

This study evaluated All4You!, a theoretically based curriculum designed to reduce sexual risk behaviors associated with HIV, other STDs, and unintended pregnancy among students in alternative schools. The study featured a randomized controlled trial involving 24 community day schools in northern California. A cohort of 988 students was assessed…