The Influence of Pioneer Investigators on Technology Adoption: Evidence from New Cancer Drugs
With Leila Agha
The Review of Economics and Statistics, March 2018
NBER working paper #20878 | NIH Public Access PMC5947964 | View abstract

Abstract: Local opinion leaders may play a key role in easing information frictions associated with technology adoption. This paper analyzes the influence of physician investigators who lead clinical trials for new cancer drugs. By comparing diffusion patterns across 21 new cancer drugs, we separate correlated regional demand for new technology from information spillovers. Patients in the lead investigator's region are initially 36% more likely to receive the new drug, but utilization converges within four years. We also find that "superstar" physician authors, measured by trial role or citation history, have broader influence than less prominent authors.

The Evolution of Physician Practice Styles: Evidence from Cardiologist Migration
American Economic Journal: Economic Policy, February 2018
NBER working paper #22478 | NIH Public Access PMC5876705 | View abstract

Abstract: Physician treatment choices for observably similar patients vary dramatically across regions. This paper exploits cardiologist migration to disentangle the role of physician- specific factors such as preferences and learned behavior versus environment-level factors such as hospital capacity and productivity spillovers on physician behavior. Physicians starting in the same region and subsequently moving to dissimilar regions practice similarly before the move. After the move, physician behavior in the first year changes by 0.6-0.8 percentage points for each percentage point change in practice environment, with no further changes over time. This suggests environment factors explain between 60-80 percent of regional disparities in physician behavior.

Working Papers

Does When You Die Depend on Where You Live? Evidence from Hurricane Katrina
With Tatyana Deryugina
View abstract

Abstract: Hurricane Katrina devastated the Gulf Coast in 2005, displacing over 1 million people. We follow Medicare cohorts over time and space to estimate the hurricane's long-run mortality effects on elderly and disabled victims who were initially living in New Orleans. We estimate that the hurricane reduced long-run mortality: inclusive of the initial shock, victims are 1.75 percentage points more likely to be alive eight years after the storm. Two patterns indicate that migration to lower-mortality regions drives this mortality reduction. First, victims in flooded neighborhoods migrated at much higher rates and experienced greater mortality reductions. Second, although migrants who moved to regions with lower mortality look similar at baseline to those who moved to higher-mortality regions, migrants' subsequent mortality is 0.98-1.12 percentage points lower for each percentage-point reduction in local mortality. By contrast, movers' subsequent mortality is unrelated to local Medicare spending. On average, Hurricane Katrina victims relocated to lower-mortality areas, which explains 56-79 percent of the overall mortality reductions we find.

What Do Workplace Wellness Programs Do? Evidence from the Illinois Workplace Wellness Study
With Damon Jones and Julian Reif
Study website | NBER working paper #24229 | View abstract

Abstract: Workplace wellness programs cover over 50 million workers and are intended to reduce medical spending, increase productivity, and improve well-being. Yet, limited evidence exists to support these claims. We designed and implemented a comprehensive workplace wellness program for a large employer with over 12,000 employees, and randomly assigned program eligibility and financial incentives at the individual level. Over 56 percent of eligible (treatment group) employees participated in the program. We find strong patterns of selection: during the year prior to the intervention, program participants had lower medical expenditures and healthier behaviors than non-participants. However, we do not find significant causal effects of treatment on total medical expenditures, health behaviors, employee productivity, or self-reported health status in the first year. Our 95% confidence intervals rule out 78 percent of previous estimates on medical spending and absenteeism. Our selection results suggest these programs may act as a screening mechanism: even in the absence of any direct savings, differential recruitment or retention of lower-cost participants could result in net savings for employers.

External summaries: The NBER Digest, J-PAL North America
Adaptation and the Mortality Effects of Temperature across US Climate Regions
With Garth Heutel and Nolan Miller
NBER working paper #23271 | View abstract

Abstract: We study heterogeneity in the relationship between temperature and mortality across U.S. climate regions and its implications for climate adaptation. Using exogenous variation in temperature and data on all elderly Medicare beneficiaries from 1992 – 2011, we show that the mortality effect of hot days is much larger in cool ZIP codes than in warm ones and that the opposite is true for cold days. We attribute this heterogeneity to historical climate adaptation. As one adaptive mechanism, air conditioning penetration explains nearly all of the regional heterogeneity in heat-driven morality but not cold-driven mortality. Combining these results with projected changes in local temperature distributions by the end of the century, we show that failure to incorporate climate heterogeneity in temperature effects can lead to mortality predictions that are wrong in sign for both cool and warm climates. Allowing regions to adapt to future climate according to the degree of climate adaptation currently observed across climates yields mortality impacts of climate change that are much lower than those estimated without allowing for adaptation, and possibly even negative.

The Mortality and Medical Costs of Air Pollution: Evidence from Changes in Wind Direction
With Tatyana Deryugina, Garth Heutel, Nolan Miller, and Julian Reif
NBER working paper #22796 | View abstract

Abstract: We estimate the causal effects of acute fine particulate matter (PM 2.5) exposure on mortality and health care use among the US elderly using Medicare administrative data and a novel instrument for air pollution: changes in the local wind direction. We then develop a new methodology that uses machine learning to estimate the number of life-years lost due to PM 2.5. We find that, while unhealthy individuals are disproportionately vulnerable to air pollution, the largest aggregate burden is borne by those with medium life expectancy, who are both vulnerable and comprise a large share of the elderly population.

Work in Progress

Smoked Out: The Effect of Wildfire Smoke on Labor Market Outcomes
With Mark Borgschulte and Eric Zou
Blowing Smoke: Health Impacts of Wildfire Plume Dynamics
With Nolan Miller and Eric Zou

Other Writing