Covariate Selection and School Effectiveness Measures in Value-Added Models: A Systematic Review

The appropriate selection of covariates in value-added models (VAMs) remains a subject of considerable debate, particularly regarding its implications for the accuracy of school-effectiveness measures. This systematic review synthesizes evidence from 25 empirical studies conducted across multiple national contexts and published between 1996 and 2023. The findings suggest that incorporating relevant covariates can improve the accuracy of school-effectiveness measurement in VAMs. Specifically, students’ prior achievement, particularly prior achievement in the same subject, was consistently identified as a salient covariate. At the student level, demographic characteristics and socioeconomic status were also frequently identified as relevant covariates. In contrast, evidence concerning the relevance of school-level covariates was mixed. Moreover, the contribution of covariates to school-effectiveness measurement varied across subject areas, educational stages, measurement intervals, and student population characteristics. These findings provide methodological guidance for covariate specification in VAMs and offer practical implications for educational policy and school management.