Hospital mergers are a common phenomenon in the healthcare industry, and much attention has been paid to estimating price effects post-merger. Less attention has been shown towards potential non-price effects of hospital mergers, such as changes in patient care access and potential hospital steering of patients toward different departments (i.e. inpatient versus emergency), which may have differential impacts on patients by insurance type. Using data on the near-universe of US hospitals and detailed claim data from 5 states from 2008-2019, I estimate using a stacked difference-in-differences design the impact of hospital mergers on different measures of patient volumes by insurer and proxies for care quality. To examine differential effects by the intensity of concentration changes, I also employ an IV design using simulated HHI differences. I find no evidence of any differential effect on patient volumes or care quality by insurance type, suggesting that hospitals do not allocate care differently by insurance type post-merger.
This paper examines how state-level taxation and local agglomeration affect the productivity of star inventors in the United States. I merge inventor-level patent data from COMETS (Zucker and Darby, 2014) with historical tax rates from (Akcigit et al., 2021) to build an inventor-year panel spanning 1975–2005, and study both patent quantity and quality outcomes. To address endogeneity and measurement error, I employ an instrumental variables design that leverages variation in federal tax changes and the number of external firm inventors. The results show that higher personal marginal tax rates reduce the number of patents filed by star inventors but substantially increase their economic value. IV estimates indicate that a 1% increase in the personal MTR lowers patent counts by about 1.15% while raising average patent value by roughly 4.81%. These effects are not driven by positive selection in patenting and are not accompanied by large-scale migration or exit of star inventors. In contrast, once taxes are considered, agglomeration exerts only limited influence. Overall, the findings suggest that inventors in high-tax areas may accept lower output in exchange for higher-value patents, offering new evidence that taxation can enhance innovation quality even as it dampens quantity.