Authors: Sean Demack, Bronwen Maxwell, Mike Coldwell, Anna Stevens, Claire Wolstenholme, Sarah Reaney-Wood,Bernadette Stiell (Sheffield Institute of Education, Sheffield Hallam University)
and Hugues Lortie-Forgues (University of York).

This report presents findings from exploratory, descriptive meta-analyses of effect sizes reported by the first 82 EEF evaluations that used a Randomised Controlled Trial (RCT) or Clustered RCT impact evaluation design published up to January 2019, as well as findings from trial-level descriptive analyses of intervention cost-effectiveness and overall pupil-level attrition. The review used a theoretical framework derived from literature with five overarching themes to group explanatory variables: Intervention characteristics; Implementation & Fidelity; Theory & Evidence; Context; and Evaluation Design. It is not appropriate to draw causal conclusions from the results of this review, since theyare based on bivariate analyses. However, the review presents associations that may be a starting point for further investigation and an innovative review framework that can support future research.