Unbiased Regression-Adjusted Estimation of Average Treatment Effects in Randomized Controlled Trials (opens in new tab)

arXiv:2511.03236v2 Announce Type: replace-cross Abstract: This article introduces a leave-one-out regression adjustment (LOORA) for estimating average treatment effects in randomized controlled trials. In finite samples, LOORA removes the bias of conventional regression adjustment and yields exact variance formulas for regression-adjusted Horvitz-Thompson and difference-in-means estimators. Ridge regularization curbs the influence of high-leverage observations, improving stability and precisi...