City Year is a learning organization committed to the rigorous evaluation of its "Whole School Whole Child" model, which trains and deploys teams of AmeriCorps members to low-performing, urban schools to empower more students to reach their full potential. A third-party study by Policy Studies Associates (PSA) examined the impact of…

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.…