This paper studies how Medicare payment policy shapes hospital quality and patient welfare. I build a structural model of hospital quality choice and hospital–insurer bargaining in which quality increases demand from Medicare and commercial patients, affects negotiated commercial prices, and raises hospitals' costs. I estimate the model using Massachusetts Medicare and commercial claims. I find that Medicare and commercial demand respond similarly to quality, but commercial margins are much larger and negotiated commercial prices rise with quality about 17 times more than Medicare's quality adjustment. At the average hospital, commercial patients account for 81 percent of the marginal return to quality. Therefore, increases in Medicare's share, through population aging or lowering the age of eligibility, decrease equilibrium quality and average patient welfare. I show that making Medicare rates more responsive to quality can prevent this decline, but payments and quality gains concentrate at the highest-quality, highest-margin hospitals.

This paper studies the impact of mergers and acquisitions on prices and markups in the Mexico City retail gasoline market following price deregulation. Using a difference-in-differences design, I find that merging stations significantly increased prices and markups relative to non-merging stations. To understand what drives these changes, I estimate a structural model of spatial competition in which stations are differentiated by location along consumers' commuting routes and firms compete on prices. I use the model to decompose price changes into three channels: increased market concentration, changes in marginal costs, and changes in product quality. My counterfactuals reveal that increased concentration accounts for only a small fraction of the observed increases. Instead, stations that switched upstream suppliers after a merger lowered their wholesale costs, accounting for part of the higher markups. The remaining price increases are consistent with improvements in unobserved station quality. These findings highlight that post-merger price increases need not reflect market power, particularly when ownership changes coincide with other operational changes.

We study how criminally accused candidates win three times more often than non-criminals upon nomination using data from four recent parliamentary elections in India. We write a simple model of party nomination choice, which predicts that criminals are nominated only when they are needed to win and not otherwise. Using local linear regressions, we confirm this prediction in the data. In particular, we find that the predicted probability from the ex post decision to nominate a criminal has an inverse-U relationship with a party's ex ante margin of victory. This may explain why criminal candidates are more successful than non-criminal candidates upon nomination: they are selected by political parties to do so.