Latino adolescents are disproportionately impacted by HIV, but researchers have documented few programs to prevent and reduce HIV risk. The Storytelling for Empowerment (SFE) "HIV StoryBook" was designed with an innovative ecodevelopment approach combining empowerment, family communication, and positive cultural identity. A mixed method…

Background: Cluster-randomized experiments that assign intact groups such as schools or school districts to treatment conditions are increasingly common in educational research. Such experiments are inherently multilevel designs whose sensitivity (statistical power and precision of estimates) depends on the variance decomposition across levels.…