Essays in Applied Microeconomics

Robert T. Omberg

Advisor: Alex T Tabarrok, PhD, Department of Economics

Committee Members: Thomas Stratmann, Sita Slavov

Online Location, Online
April 27, 2022, 11:00 AM to 01:00 PM


This dissertation consists of three evaluations of "natural experiments" using modern methods of causal inference. The first chapter, The Labor Market Impacts of Ridesharing, examines the impact of the emergence of the “gig economy” on the broader labor market by exploiting the staggered introduction of the ridesharing service Uber to American Cities between 2013 and 2018. Using difference-in-differences methods, Chaisemartin and D’Haultoeuilleas time corrected Wald estimator, Callaway and Sant’Anna’s doubly robust difference-in-differences estimator, and Abadie et al’s synthetic control method, I estimate that Uber’s arrival to a city resulted in decline in the unemployment rate by between a fifth and a half of a percentage point. This suggests that Uber allowed many workers to supplement their earnings during periods of unemployment, framing the ridesharing service as a complement to, rather than a substitute for, traditional employment. I also find some evidence that Uber had a very small positive effect on wages at the lower end of the wage distribution, suggesting that Uber may have altered worker search behavior or affected bargaining power. The second chapter, which has been published in the IZA Journal of Labor Policy, explores the impact of the minimum wage in Puerto Rico. Revisiting research from the 1990s from Castillo-Freeman and Krueger, I use the synthetic control method of Abadie et al. to estimate the impact of the most recent increase in the federal minimum wage on employment in Puerto Rico. I estimate that the employment/population ratio of various groups in Puerto Rico was significantly lower than that of a data-constructed synthetic Puerto Rico which did not raise its minimum wage. Placebo tests on other donor units, time periods, and population groups suggest that a significant portion of this gap is a result of the minimum wage. Groups with greater exposure to the minimum wage, such as teens and restaurant workers, experienced proportionally greater declines in employment. My results suggest an own-wage elasticity of employment in Puerto Rico of â0.68, higher than estimates from the mainland, which suggests that the employment response to minimum wages may be more dramatic at higher relative minimum wages. The final chapter explores the impact that removing monuments to the confederacy has had on race based hate crime. Beginning in the late 2010s, many municipalities have begun removing Confederate monuments, memorials, and/or flags in response to both public outcry and recent white supremacist acts of terrorism. While the stated goal of these removals is to move past a troubled episode in our nation’s history, what actual effect does monument removal have on acts of racially- biased violence? Using data from the FBI and the Southern Poverty Law Center and a difference-in-differences research design, I find that the number of hate crimes based on race occurring in a city increases by between 20 and 40% following the city’s removal of a confederate monument, even after controlling for a variety of covariates. Decomposition of these results shows that this increase only occurs when monuments are removed in states that were formally part of the Confederacy; although there is still no evidence that removal decreases hate crime even in non-Confederate areas.