In 2 experiments the authors investigated whether assigning a perspective to middle school students prior to reading a long informational text would improve their reading comprehension. Pretest-posttest control group designs were employed in both experiments, in Experiment 1 (n = 146 fifth- and sixth-grade students) and in Experiment 2 (n = 83…

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.…