Scholars have explored ways in which school shooting events have impacted students' perception of safety. However, less is known on whether the effects of school shootings are stable across time and event. This study uses data collected through the Delaware School Survey before and after three school shootings, Columbine (1999), Virginia Tech…

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.…