This study investigated the effectiveness of the KiVa antibullying program in the beginning of its nationwide implementation in Finland.
At each time point, the participants included 888 schools with approximately 150,000 students in 11,200 classrooms in Grades 1–9 (8–16 years of age; 51% boys and 49% girls). Victims and bullies were identified with the global questions from the Revised Olweus Bully/Victim Questionnaire (Olweus, 1996), utilizing the criteria suggested by Solberg and Olweus (2003). The program effects were examined by calculating odds ratios based on a cohort-longitudinal design, correcting the standard errors for clustering. Results: During the first 9 months of implementation, the KiVa program reduced both victimization and bullying, with a control/intervention group odds ratio of 1.22 (95% CI [1.19, 1.24]) for victimization and 1.18 (95% CI [1.15, 1.21]) for bullying. Conclusions: Generalized to the Finnish population of 500,000 students, this would mean a reduction of approximately 7,500 bullies and 12,500 victims. (Published abstract provided)