🤖 AI Summary
This study addresses the challenges posed by clustered sampling in regression discontinuity designs, where conventional cluster-robust standard errors may be inconsistent or overly conservative in finite samples. The authors develop a general model-based framework that establishes the asymptotic normality of local linear regression discontinuity estimators under clustering. Building on this foundation, they propose a novel nearest-neighbor-type variance estimator designed to improve inference accuracy. This approach provides the first systematic theoretical justification for clustered regression discontinuity analysis and accommodates a range of empirical settings—including those with growing cluster sizes—while demonstrating superior accuracy and reliability in small-sample simulations.
📝 Abstract
Clustered sampling is prevalent in empirical regression discontinuity (RD) designs, but it has not received much attention in the theoretical literature. In this paper, we introduce a general model-based framework for such settings and derive high-level conditions under which the standard local linear RD estimator is asymptotically normal. We verify that our high-level assumptions hold across a wide range of empirical designs, including settings of growing cluster sizes. We further show that clustered standard errors that are currently used in practice can be either inconsistent or overly conservative in finite samples. To address these issues, we propose a novel nearest-neighbor-type variance estimator and illustrate its properties in a diverse set of empirical applications.