Research

I specialize in health economics and media economics. My peer-reviewed journal publications are the following:

[2019] “The effects of competition on premiums: using United Healthcare’s 2015 entry into Affordable Care Act’s marketplaces as an instrumental variable.” Health Economics, Policy and Law, 14(3), 374-399 (with Robert J. Krebs and Masato Yano).

Abstract. One goal of the Affordable Care Act is to increase insurance coverage by improving competition and lowering premiums. To facilitate this goal, the federal government enacted online marketplaces in the 395 rating areas spanning 34 states that chose not to establish their own state-run marketplaces. Few multivariate regression studies analyzing the effects of competition on premiums suffer from endogeneity, due to simultaneity and omitted variable biases. However, United Healthcare’s decision to enter these marketplaces in 2015 provides the researcher with an opportunity to address this endogeneity problem. Exploiting the variation caused by United Healthcare’s entry decision as an instrument for competition, we study the impact of competition on premiums during the first 2 years of thesemarketplaces. Combining panel data from five different sources and controlling for 12 variables, we find that one more insurer in a rating area leads to a 6.97% reduction in the second-lowest priced silver plan premium, which is larger than the estimated effects in existing literature. Furthermore, we run a threshold analysis and find that competition’s effects on premiums become statistically insignificant if there are four or more insurers in a rating area. These findings are robust to alternative measures of premiums, inclusion of a non-linear term in the regression models and a county-level analysis.

[2018] "Effects of the ACA. on preventive care disparities." Applied Health Economics and Health Policy, 16(6), 859-869 (with Jordan G. Holding).

Abstract. The Affordable Care Act (ACA) requires non-grandfathered private insurance plans, starting with plan years on or after September 23^rd, 2010, to provide certain preventive care services without any cost sharing in the form of deductibles, copayments or co-insurance. This requirement may affect racial and ethnic disparities in preventive care as it provides the largest copay reduction in preventive care. We ask whether the ACA’s free preventive care benefits are associated with a reduction in racial and ethnic disparities in the utilization of four preventive services: cholesterol screenings, colonoscopies, mammograms, and pap smears. We use a data set of over 6,000 individuals from the 2009, 2010, and 2013 Medical Expenditure Panel Surveys (MEPS). We restrict our data set only to individuals who are old enough to be eligible for each preventive service. Our difference-in-differences logistic regression model classifies privately-insured Hispanics, African Americans, and Asians as the treatment groups and 2013 as the after-policy year. Our control group consists of non-Hispanic whites on Medicaid as this program already covered preventive care services for free or at a low cost before the ACA. After controlling for income, education, marital status, preferred interview language, self-reported health status, employment, having a usual source of care, age and gender, we find that the ACA is associated with increases in the probability of the median, privately-insured Hispanic person to get a colonoscopy by 3.6% and a mammogram by 3.1%, compared to a non-Hispanic white person on Medicaid. Similarly, we find that the median, privately-insured African American person’s probability of receiving these two preventive services improved by 2.3% and 2.4% compared to a non-Hispanic white person on Medicaid. We do not find any significant improvements for any racial or ethnic group for cholesterol screenings or pap smears. Furthermore, our results do not indicate any significant changes for Asians compared to non-Hispanic whites in utilizing the four preventive services. These reductions in racial/ethnic disparities are robust to reconfigurations of time periods, previous diagnosis, and residential status. Early effects of the ACA’s provision of free preventive care are significant for Hispanics and African Americans. Further research is needed for the later years as more individuals became aware of these benefits.

[2016] “How did Medicaid expansions affect labor supply and welfare enrollment? Evidence from the early 2000s.” Health Economics Review, 6(12), 1-16.

Abstract. In the early 2000s, Arizona, Maine, New Mexico, New York, Oregon, and Vermont expanded Medicaid to cover more low-income individuals, primarily childless adults. This change provides the researcher with an opportunity to analyze the effects of these expansions on labor supply and welfare enrollment. I use a large data set of 176 counties over 7 years, including 3 years of pre-expansion period, 1 year of implementation year, and 3 years of post-expansion period. Using a difference-in-differences approach, I find the most-affected counties had a 1.4 percentage-point more decline in labor force participation rate in comparison to other counties. Furthermore, I observe a 0.32 h decrease in average weekly hours and a 1.1 % increase in average weekly wages. This indicates labor supply was affected more than labor demand. I also observe a 0.49 % increase in Supplemental Nutrition Assistance Program (SNAP) enrollment after the Medicaid expansions. These results are robust to an alternative identification of the most-affected counties, inclusion of counties from comparison states, limiting the control group to only high-poverty counties from comparison states, exclusion of county-specific time trends, and different configuration of clustered errors. My findings provide early insights on the potential effects of new Medicaid expansions of the Affordable Care Act (ACA), since 82 % of those newly eligible are expected to be childless adults.

[2015] “What Drives Media Bias? New evidence from recent newspaper closures.” Journal of Media Economics, 28(3), 123-141.

Abstract. With the advent of the Internet, many U.S. metropolitan areas have seen newspaper closures due to declining revenues. This provides the researcher with an opportunity to analyze the microeconomicsources of media bias. This paper uses a large panel data set of newspaper archives for 99 newspapers over 240 months (1990- 2009). I find that, after controlling for the unemployment rate, the change in unemployment rate, and the political preferences of surrounding metropolitan area, conservative newspapers report 17.4% more unemployment news when the President is a Democrat rather than a Republican,before the closure of a rival newspaper in the same media market. This effect is 12.8% for liberal newspapers. After the closure, these numbers are 3.5% and 1.1%, respectively. This moderation of media bias afterclosure of a rival newspaper is robust to the inclusion of newspaper size, newspaper fixed-effects or metropolitan area fixed-effects as controls. I also find that newspapers in smaller metropolitan areas have a largermoderation in their bias. My findings provide support for theories in which media-bias is demand-driven, as surviving newspapers aim to increase their sales by gaining the former readers of a closed newspaper inthe same media market.