Difference-in-Differences and Treatment x Pretest Interactions: A Critique of Dual-Centered ANCOVA
This paper critically examines dual-centered ANCOVA, proposed by Lin and Larzelere (2020) and Larzelere and Lin (2025), which is claimed to accommodate a Treatment X Pretest interaction while preserving the difference-in-differences (DiD) estimate. We take issue with their claims on four grounds. First, DiD without an...