Billions of dollars have been spent on pilot programs searching for ways to reduce health care costs. I study one such program, in which hospitals pay doctors bonuses for reducing the total hospital costs of admitted Medicare patients. Doctors respond to the bonuses by becoming more likely to admit patients whose treatment can generate high bonuses and sorting healthier patients into participating hospitals. Conditional on patient health, however, doctors do not reduce costs or change procedure use. These results highlight the ability of doctors to game incentive schemes and the risks of basing nationwide health care reforms on pilot programs.

We link the county-level rollout of stay-at-home orders during the COVID-19 pandemic to anonymized cell phone records and consumer spending data. We document three patterns. First, stay-at-home orders caused people to stay home: county-level measures of mobility declined 6% to 7% within two days of when the stay-at-home order went into effect. Second, stay-at-home orders caused large reductions in spending in sectors associated with mobility: small businesses and large retail chains. Third, we estimate fairly uniform responses to stay-at-home orders across the country; effects do not vary by county-level income, political leanings, or urban/rural status.

In 2008, Volkswagen introduced a new generation of “Clean Diesel” cars and heavily marketed them to environmentally conscious US consumers. Unknown to the public, these cars were anything but clean, emitting pollutants up to 150 times the level of comparable gas-fuelled cars. We study the rollout of these emissions-cheating diesel cars across the United States from 2008 to 2015 as a natural experiment to examine the impact of moderate levels of car pollution on infant and child health in the general population. Using the universe of vehicle registrations, we find that an additional cheating diesel car per 1,000 cars increases \mathrmPM_2.5, \mathrmPM_10, and ozone by 2, 2.2, and 1.3%, respectively, while the low birth weight rate and infant mortality rate increase by 1.9 and 1.7%, respectively. Similar impacts are found for acute asthma attacks in children. These health impacts occur at all pollution levels and across the socioeconomic spectrum.