Shanshan Liu
Ph.D. Student in Economics
Research Projects
Health Economics
Hospital Mergers and Quality of Care: Evidence from Heart Attack Patients and Pregnancy Outcomes in Pennsylvania​
We study the effects of hospital mergers on the quality of health outcomes for acute myocardial infarction (AMI) patients, patients receiving coronary artery bypass grafting (CABG) surgery and pregnant women in Pennsylvania during the period 1994-2010. We measure the quality of outcomes as risk-adjusted mortality and readmission for both AMI and CABG patients and as the incidence of preventable complications for pregnant patients. We also use the total charges to measure the resource utilization for each patient. Using propensity scores to match hospitals involved in mergers with hospitals that have never been involved in a merger, we find that mergers that occurred in concentrated markets are associated with increased probability of in-hospital mortality and higher readmission rates for AMI patients and with increased probability of preventable complications and reduced resource use for pregnant patients. However, we find no evidence that mergers in more concentrated areas are associated with worse outcomes for CABG patients. Finally, we find that the effects of a merger on health outcomes may last for years.
Impact of the Minimum Wage on Youth Labor Markets​
This paper examines the impact of state-level minimum wages on employment outcomes in local labor markets for youth. We use county-level Quarterly Workforce Indicators (QWI) data for 2003-2007 in a panel regression to analyze the effects of state variation in the minimum wage on employment levels, earnings, and job flows. Controlling for county fixed effects and general time fixed effects, and using a single Census Region and economic area time effects to control for spatial heterogeneity, we find a negative relationship between the minimum wage and the level of employment for those age 14-18 and 19-21. However, we find a positive employment effect for workers age 22-24 suggesting the possibility of substitution towards more experienced workers in higher minimum wage jurisdictions. We also find that the minimum wage is correlated with reduced job turnover for all age groups and faster net job growth for youth between the ages of 22 and 24.
Recession and Stress-related Health Outcomes​
This paper examines how economic recessions affect the aggregate health outcomes of a population living in the same community. I examine inpatient data from the Pennsylvania Health Care Cost Containment Council (PHC4) for the 2000-2011 period, during which people experienced two recessions. I use unemployment rate in the labor market area as the primary indicator of recession and analyze the effects of recessions on the percentage of total population in a community that are hospitalized for certain stress-related diseases, while controlling for the community's sociodemographic characteristics, such as income, poverty, crime rate, and crowded housing, and for insurance penetration. The hypotheses are that recessions may decrease the probability of hospitalization at the community level for the stress-related diseases, such as myocardial infarction, stroke, alcohol-related diagnoses, obesity, and injuries from self-harm. Finally, my study examines not only how contemporaneous recessions affect people's health at the community level but also the persistency of these effects.
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