RCT Testing Bystander Effectiveness to Reduce Violence

Am J Prev Med. 2017 May;52(5):566-578. doi: 10.1016/j.amepre.2017.01.020. Epub 2017 Mar 6.


Introduction: Bystander-based programs have shown promise to reduce interpersonal violence at colleges, yet limited rigorous evaluations have addressed bystander intervention effectiveness in high schools. This study evaluated the Green Dot bystander intervention to reduce sexual violence and related forms of interpersonal violence in 26 high schools over 5 years.

Design: A cluster RCT was conducted.

Setting/participants: Kentucky high schools were randomized to intervention or control (wait list) conditions.

Intervention: Green Dot-trained educators conducted schoolwide presentations and recruited student popular opinion leaders to receive bystander training in intervention schools beginning in Year 1.

Main outcome measures: The primary outcome was sexual violence perpetration, and related forms of interpersonal violence victimization and perpetration were also measured using anonymous student surveys collected at baseline and annually from 2010 to 2014. Because the school was the unit of analysis, violence measures were aggregated by school and year and school-level counts were provided.

Results: A total of 89,707 students completed surveys. The primary, as randomized, analyses conducted in 2014-2016 included linear mixed models and generalized estimating equations to examine the condition-time interaction on violence outcomes. Slopes of school-level totals of sexual violence perpetration (condition-time, p<0.001) and victimization (condition-time, p<0.001) were different over time. During Years 3-4, when Green Dot was fully implemented, the mean number of sexual violent events prevented by the intervention was 120 in Intervention Year 3 and 88 in Year 4. For Year 3, prevalence rate ratios for sexual violence perpetration in the intervention relative to control schools were 0.83 (95% CI=0.70, 0.99) in Year 3 and 0.79 (95% CI=0.67, 0.94) in Year 4. Similar patterns were observed for sexual violence victimization, sexual harassment, stalking, and dating violence perpetration and victimization.

Conclusions: Implementation of Green Dot in Kentucky high schools significantly decreased not only sexual violence perpetration but also other forms of interpersonal violence perpetration and victimization.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Bullying / prevention & control*
  • Bullying / statistics & numerical data
  • Bystander Effect*
  • Cluster Analysis
  • Crime Victims / statistics & numerical data
  • Female
  • Humans
  • Kentucky / epidemiology
  • Linear Models
  • Male
  • Prevalence
  • Primary Prevention / education*
  • Risk Assessment
  • Self Report
  • Sex Offenses / prevention & control*
  • Sex Offenses / statistics & numerical data
  • Students / psychology*
  • Violence / prevention & control*
  • Violence / statistics & numerical data