There have now been many controlled studies of preventive mental health interventions for young people. For these studies to be useful, practitioners need to know whether the effects shown for a particular intervention are modest, moderate, or large.
Emily Tanner-Smith and colleagues summarized more than 400 mean effect size estimates from 74 meta-analyses that synthesized findings from many trials. All the trials were of programs aimed at preventing problematic behavior or emotional problems for young people aged 5-18. The results, published in Prevention Science, indicate that:
- With few exceptions, the median average effect sizes on various outcomes fell within the range of +0.07 to +0.16.
- Prevention programs yielded larger effects on knowledge than on actual behavior.
- Providing information to increase knowledge (e.g., about the risks of drug use) is an important component of many programs, but knowledge does not always correlate strongly with actual behavior.
The authors advise that the effect sizes indicate the level of improvement that has been achieved to date and can serve as a benchmark for assessing the value of new findings.
Source:Tanner-Smith, E. E., Durlak, J. A., & Marx, R. A. (2018). Empirically based mean effect size distributions for universal prevention programs targeting school-aged youth: A review of meta-analyses. Prevention Science. Advance online publication. doi: 10.1007/s11121-018-0942-1.