The Olweus Bullying Prevention Program produced the largest effect sizes for bullying perpetration, with effectiveness varying between Norway and USA evaluations¶

Claim · All claims
Evidence · 1 study (2 entries) · quant-synthesis r2–r3 · q4
Currency · newest study 2019 · checked against its sources 2026-10-16 (automated, 2 of 2 entries) · not reviewed by a person

Subclaims¶

q4 i? Across 12 evaluations, OBPP was the most effective program for reducing bullying perpetration, including when evaluated in Norway and in the USA separately. → Hannah Gaffney 2019 q4 i? OBPP effect sizes for victimization varied significantly between evaluations conducted in Norway and in the USA. → 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 · r3

Program-specific meta-analysis (Table 4) of 12 OBPP evaluations; the Norway–USA difference in perpetration effect magnitude "was not statistically significant." Other significantly effective programs had "markedly lower" effect sizes.

"In relation to school-bullying perpetration outcomes, overall the OBPP was the most effective intervention program. In addition, evaluations of the OBPP in Norway and in the USA were the most effective individually, in comparison with other included anti-bullying programs."

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 · r2

Program-specific victimization analysis (Table 4): OBPP Norway (n = 5) OR = 1.57 versus OBPP USA (n = 6) OR = 1.17; the authors attribute the difference possibly to evaluation methodology or "cultural and societal differences."

"Effect sizes for the OBPP varied significantly between evaluations conducted in Norway and evaluations conducted in the USA."

Discussion¶

Learner Variables¶

• Safety — outcome: instruction changes it

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
• School-based anti-bullying programs reduce bullying perpetration and victimization globally — a broader claim this one bears on
• NoTrap! was the most effective program for reducing bullying victimization, while ViSC and fairplayer.manual showed non-significant negative effects — related
• Regional differences in program effectiveness: North America led for perpetration, Scandinavia for victimization, with no clear overall pattern — related
• More intensive anti-bullying programs are more effective — related
• School-based anti-bullying programs are effective overall, decreasing bullying by 20-23% on average — a broader claim this one bears on
• School-based anti-bullying programs decrease victimization by 17-20% on average — related