Regional differences in program effectiveness: North America led for perpetration, Scandinavia for victimization, with no clear overall pattern¶

Claim · All claims
Evidence · 1 study (2 entries) · quant-synthesis r2–r3 · q4
Currency · newest study 2019 · checked against its sources 2026-10-20 (automated, 2 of 2 entries) · not reviewed by a person

Subclaims¶

q4 i? For perpetration, North American evaluations were most effective, followed by Scandinavian and then European studies. → Hannah Gaffney 2019 q4 i? Combined European and Scandinavian evaluations were significantly more effective at reducing victimization than North American studies. → Hannah Gaffney 2019 (2)

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

Regional moderator analysis (Table 3) of weighted mean effect sizes across seven geographical regions for the 100 evaluations.

"In regard to school-bullying perpetration outcomes, evaluations conducted in North America were the most effective, followed by Scandinavian studies, and then European studies."

Hannah Gaffney 2019 (2)¶

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 · r3

Regional comparison for victimization outcomes; the authors report that for perpetration, the North American effect size "was not significantly different from the weighted mean for European and Scandinavian studies."

"When weighted mean effect sizes were estimated for European and Scandinavian countries collectively, they were significantly more effective in reducing bullying victimization outcomes than North American studies."

Discussion¶

Related Claims¶

• Program effectiveness varies by country: Greece led for perpetration, Italy for victimization — related
• Effectiveness of anti-bullying programs varies significantly across evaluations (heterogeneity) — a broader claim this one bears on
• The Olweus Bullying Prevention Program produced the largest effect sizes for bullying perpetration, with effectiveness varying between Norway and USA evaluations — related
• School-based anti-bullying programs reduce bullying perpetration and victimization globally — related
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• School-based anti-bullying programs are effective overall, decreasing bullying by 20-23% on average — related
• The magnitude of sex differences in mathematics varies across geographical regions, with larger estimated effects in Central Europe (d = 0.164) and Central and South America (d = 0.153) than in North America (d = 0.047) — related
• Anti-bullying intervention effects are weak, and RCT designs show even smaller effects than earlier meta-analyses suggested — related