This study examined the effects of testing accommodations on eighth-grade students' performance on large-scale achievement tests and also on their attitudes and reactions to the tests. Findings revealed significant differences in the ways students with and without disabilities experienced testing and how testing accommodations affected students'…

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.…