Meta-analysis methods for synthesizing treatment effects in multisite studies: hierarchical linear modeling (HLM) perspective

The objectives of the present mixed-effects meta-analytic application are to provide practical guidelines to: (a) Calculate..treatment effect sizes from multiple sites; (b) Calculate the overall mean of the site effect sizes and their variances; (c)..Model the heterogeneity in these site treatment effects as a function of site and program characteristics plus..unexplained random error using Hierarchical Linear Modeling (HLM); (d) Improve the ability of multisite evaluators..and policy makers to reach sound conclusions about the effectiveness of educational and social interventions based on..multisite evaluations; and (e) Illustrate the proposed methodology by applying these methods to real multi-site research..data