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.…

The current study examined the relations among self-esteem, approving normative beliefs about bullying, school climate, and bullying perpetration using a large, longitudinal sample of children from elementary, middle, and high school. Self-report surveys were collected at two points in time over the course of 1 year from 7,299 ethnically diverse…

Exposure to violence at school remains a significant problem for children and adolescents. This study examined the relationship between exposure to violence at school and child reports of psychological trauma symptoms and violent behavior. The sample consisted of children in grades 3 through 12 in 17 public schools from two different states. Rates…