This report presents findings from the Girls Shape the Future study, which was designed to evaluate the implementation and effectiveness of the Girls Incorporated® Will Power/Won’t Power® curriculum developed to reduce sexual intercourse, pregnancy, and sexually transmitted infections...

Evaluations of the patient-centered medical home, a model that redesigns primary care, should account for clustering of patients within practices. This paper describes why and how to do this, and what samples of patients and practices are needed for studies to achieve adequate statistical power.