Empirically Based Mean Effect Size Distributions for Universal Prevention Programs Targeting School-Aged Youth: A...

Area of Science:

• Psychology
• Public Health
• Education

Background:

• Universal mental health promotion and prevention programs are crucial for school-age youth.
• Existing benchmarks for effect sizes may not accurately reflect the impact of these programs.
• A need exists for empirically derived standards to assess program effectiveness.

Purpose of the Study:

• To establish evidence-based mean effect size distributions for universal youth mental health programs.
• To provide updated standards for judging the relative impact of prevention and promotion initiatives.
• To compare new distributions with existing conventions (e.g., Cohen's).

Main Methods:

• Conducted a review of reviews, synthesizing findings from 74 meta-analyses.
• Included over 1100 controlled outcome studies with more than 490,000 participants (ages 5-18).
• Analyzed effect size distributions across various program targets and outcome types.

Main Results:

• Significant variability in mean effect sizes was observed across different program targets and outcomes.
• The derived distributions differ substantially from Cohen's traditional benchmarks.
• Established new, empirically based distributions for effect size interpretation.

Conclusions:

• The updated effect size distributions offer more appropriate standards for researchers, practitioners, and funders.
• These benchmarks facilitate a more accurate assessment of universal prevention program effects in youth.
• Identified limitations in current data and suggested directions for future research.