Meta-analytic approaches for examining complexity and heterogeneity in studies of adolescent development.

Introduction: In the field of adolescent development, meta-analysis offers valuable tools for synthesizing and assessing cumulative research evidence on the effectiveness of programs, practices, and policies intended to promote healthy adolescent development. When examining the impact of a program implemented across multiple primary studies, variation is often observed in the methodological attributes of those primary studies, such as their implementation methods, program components, participant characteristics, outcome measurement, and the systems in which programs are deployed. Differences in methodological attributes of primary studies represented in a meta-analysis, referred to as complexity, can yield variation in true effects across primary studies, which is described as heterogeneity.