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.…

The Knowledge is Power Program (KIPP) charter schools' consistently positive impacts on student achievement (detailed in Volume I of this report) have prompted efforts to scale up the KIPP model to serve more students. According to the KIPP model, highly qualified and autonomous principals, supported by national and regional staff, drive the…