What works in anti-bullying programs? Analysis of effective intervention components.

Previous research has shown that many school-based anti-bullying programs are effective. A prior meta-analysis (Gaffney, Ttofi, & Farrington, 2019) found that intervention programs are effective in reducing school-bullying perpetration by approximately 19-20% and school-bullying victimization by approximately 15-16%. Using data from this prior meta-analysis, the aim of the current study was to examine the relationship between effectiveness estimates and specific elements of anti-bullying programs. Specific intervention components in line with a socio-ecological framework were coded as present or absent. Components were coded on the following levels: school, classroom, teacher, parent, peer, individual, and intervention. Meta-analytical subgroup comparisons analogous to ANOVA were computed to examine the relationship between the presence of specific components and the effectiveness in reducing bullying perpetration (n = 82) and victimization (n = 86). Results indicated that the presence of a number of intervention components (e.g., whole-school approach, anti-bullying policies, classroom rules, information for parents, informal peer involvement, and work with victims) were significantly associated with larger effect sizes for school-bullying perpetration outcomes. The presence of informal peer involvement and information for parents were associated with larger effect sizes for school-bullying victimization outcomes. Meta-regression analyses showed no significant relationship between effectiveness and the number of intervention components included in a program. The present report contributes to the understanding of 'what works' in reducing school-bullying perpetration and victimization. The impact of these findings on future anti-bullying research is discussed.