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.…

American Institutes for Research (AIR) conducted an evaluation of the effect on struggling readers of implementing the READ 180 reading intervention in five participating schools in Milwaukee Public Schools (MPS) under a Striving Readers grant from the U.S. Department of Education. The evaluation used an experimental design in order to produce a…