This study demonstrates that regression discontinuity designs will arrive at biased estimates when attributes related to outcomes predict heaping in the running variable. We discuss several approaches to diagnosing and correcting for this type of problem. Our primary example focuses on the use...

Throughout the years spanned by the U.S. Vital Statistics Linked Birth and Infant Death Data (1983-2002), birth weights are measured most precisely for children of white and highly educated mothers. As a result, less healthy children, who are more likely to be of low socioeconomic status, are...