performance. We compare two difference-in-differences strategies: the two-way fixed effects estimator common in the literature …

we do not know whether hospital quality indicators are causal or biased. We evaluate the validity of commonly used … quality indicators, such as mortality, readmissions, inpatient costs, and length-of-stay, using a quasi-experimental design … measure whether patient outcomes improve as much as quality indicators predict when a relatively low-quality hospital closes …