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.…

This study explored the relationships among the components of the Arizona Department of Education's new teacher evaluation model, with a particular focus on the extent to which ratings from the state model's teacher observation instrument differentiated higher and lower performance. The study used teacher-level evaluation data collected by the…