Methods: Multilevel, multi-group structural equation modeling was used to evaluate the hypotheses. Specifically, longitudinal panel models were tested. Analyses included 7,741 4th – 6th grade students (50.6 % were girls; average age was 11.2 years) from 78 schools who were randomly assigned to either an intervention or control condition. Students in the program were assessed at three measurement occasions over the course of a single year.
Results: The preliminary results revealed key characteristics at the individual- and classroom-level that accelerated KiVa's beneficial effects. Significant differences between the intervention and control conditions allowed us examine natural developmental changes occurring in both groups and test for intervention effects. Results revealed, for example, younger students in the intervention group evidenced greater improvements in attitudes and perceptions and more significant reductions bullying and victimization. Perceptions of teachers' anti-bullying attitudes and competence in intervening also played an important role in accelerating KiVa's beneficial effects, most notably for anti-bullying perceptions and bystander defending behaviors. That is, the more students perceived their teachers as holding anti-bullying attitudes and effectively intervening in bullying situations, the faster victimization was reduced for intervention participants. Key classroom-level variables, such as class size and multi-grade classrooms, also showed reliable facilitative effects. All models demonstrated acceptable fit according to commonly used fit indices.
Conclusions and Implications: It is important not only to understand if interventions work but also under what conditions interventions work best. This exploratory investigation revealed key student- and classroom-level characteristics that accelerated positive program effects. In line with previous research, younger students reported greater improvements on several key outcomes. The question of intervention timing has been discussed extensively in the prevention field. It appears that effects in preventing or reducing bullying are largest for programs targeting children in elementary school settings. The results of this study also suggest that teachers play an important role in influencing positive changes in students' attitudes and behaviors. Therefore, interventions must incorporate strategies during implementation to support teachers in their abilities to not only implement evidence-based interventions with high fidelity but also develop their own capacities. Implications for implementing school-based bullying prevention programs in light of these findings are further discussed.