Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
US policy increasingly ties payments for providers to performance on quality measures, though little empirical evidence guides the design of such incentives. I deploy administrative data to study a large federal program that penalizes hospitals with high readmissions rates. Using policy-driven variation in the penalty incentive across hospitals for identification, I find that hospital responses to the penalty account for two-thirds of the observed decrease in readmissions over this period, as well as a decrease in heart attack mortality. Quality improvement accounts for about one-half of the decrease in readmissions; the remainder is explained by selective admission of returning patients.