title: Rejoinder: Remaining Challenges in Investigating Grade-Retention Effectiveness.
abstract: This rejoinder, in response to the commentaries of Steiner, Park, and Kim (this issue) and Reshetnyak, Cham, and Hughes (this issue), discusses remaining challenges in grade retention research. First, a same-age comparison assumes that the instruments used in different grades measure ability equally well. We discuss the importance of evaluating the properties of the scaling process to address whether this assumption has been met. Second, we discuss issues in the selection of covariates to be included in the weights. Third, we discuss the unconfoundedness assumption and the problem of remaining imbalance. Finally, we provide an empirical illustration showing that studying grade-retention effectiveness comes with multiple methodological decisions that are rooted in a bias-variance trade-off.
authors.affiliation: a Centre for Educational Effectiveness and Evaluation , University of Leuven.
authors.forename: Machteld
authors.initials: M
authors.lastname: Vandecandelaere
authors.affiliation: b Department of Applied Mathematics , Computer Science and Statistics, Ghent University.
authors.forename: Stijn
authors.initials: S
authors.lastname: Vansteelandt
keywords: Bias–variance trade-off; grade retention; marginal structural models; unconfoundedness assumption