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.…

We examined the risk of disability identification associated with individual and school variables. The sample included 18,000 students in 39 schools of an urban K-12 school system. Descriptive analysis showed racial minority risk varied across 7 disability categories, with males and students from low-income backgrounds at highest risk in most…