The goal of this article is to improve the practice and reporting of cost estimates of prevention programs. It reviews the steps in estimating the costs of an intervention and the principles that should guide estimation. The authors then review prior efforts to estimate intervention costs using...

This study investigates the relationship of panel accretion to panel attrition and examines its impact on threats to external validity in adolescent substance use research. Panel accretion involves the addition of new participants to a panel design after initial baseline data has been obtained....