Effectiveness of anti-bullying programs varies significantly across evaluations (heterogeneity)¶

Claim · All claims
Evidence · 1 study · quant-synthesis r2 · q4
Currency · newest study 2019 · checked against its sources 2026-10-16 (automated, 1 of 1 entry) · not reviewed by a person

Subclaims¶

q4 i? The meta-analysis found significant heterogeneity in effect sizes for both perpetration and victimization outcomes. → Hannah Gaffney 2019

Evidence¶

Hannah Gaffney 2019¶

Hannah Gaffney, David P. Farrington, & Maria M. Ttofi. (2019). Examining the Effectiveness of School-Bullying Intervention Programs Globally: a Meta-analysis. International Journal of Bullying Prevention. https://doi.org/10.1007/s42380-019-0007-4

q4 · i? · quant-synthesis · r2

Heterogeneity statistics from the same meta-analysis of 100 evaluations, which the authors attribute to "the large number of studies included in our meta-analysis, and the wide array of countries and intervention programs represented."

"there was significant heterogeneity for both bullying perpetration (Q = 323.39; p < 0.001) and bullying victimization (Q = 387.26; p < 0.001) outcomes."

Discussion¶

Learner Variables¶

• Safety — outcome: instruction changes it

Related Claims¶

• Program effectiveness varies by country: Greece led for perpetration, Italy for victimization — a narrower finding that bears on this claim
• School-based anti-bullying programs reduce bullying perpetration and victimization globally — related
• Regional differences in program effectiveness: North America led for perpetration, Scandinavia for victimization, with no clear overall pattern — a narrower finding that bears on this claim
• NoTrap! was the most effective program for reducing bullying victimization, while ViSC and fairplayer.manual showed non-significant negative effects — a narrower finding that bears on this claim
• The Olweus Bullying Prevention Program produced the largest effect sizes for bullying perpetration, with effectiveness varying between Norway and USA evaluations — a narrower finding that bears on this claim
• School-based anti-bullying programs decrease victimization by 17-20% on average — related
• Work with peers in anti-bullying programs is associated with an increase in victimization — a narrower finding that bears on this claim
• More intensive anti-bullying programs are more effective — a narrower finding that bears on this claim
• School-based anti-bullying programs are effective overall, decreasing bullying by 20-23% on average — related
• Parent meetings, firm disciplinary methods, and improved playground supervision are program elements associated with decreases in bullying and victimization — related
• Anti-bullying intervention effects are weak, and RCT designs show even smaller effects than earlier meta-analyses suggested — related