Research

Publications

Police Violence and Civic Engagement (with Desmond Ang)

American Political Science Review, 2023.

Roughly a thousand people are killed by American law enforcement officers each year, accounting for more than 5% of all homicides. We estimate the causal impact of these events on civic engagement. Exploiting hyperlocal variation in how close residents live to a killing, we find that exposure to police violence leads to significant increases in registrations and votes. These effects are driven entirely by Black and Hispanic citizens and are largest for killings of unarmed individuals. We find corresponding increases in support for criminal justice reforms, suggesting that police violence may cause voters to politically mobilize against perceived injustice.

Working Papers

Stopped by the Police: The End of “Stop-and-Frisk” on Crime and High School Engagement (with Jeffrey Fagan)  [Slides, Updated Draft Coming Soon]

Over 3.5 million pedestrians are stopped by police in the United States every year. This paper explores whether the concentration of pedestrian stops deters crime and affects the educational investments of high school students. We study a federal lawsuit that abruptly reduced stop rates in New York City by over 95%, without fundamentally altering patrol officer presence. In a differences-in-differences framework, we compare neighborhoods that had similar crime rates but different stop rates prior to the reform. Despite experiencing twice the reduction in stop rates, treatment neighborhoods do not display differential increases in felonies and violent misdemeanors, major felonies, shootings, killings, or a cost-weighted crime measure over the five years following the reform. Our estimates can rule out a 1.5% increase in felonies and violent misdemeanors. Coinciding with the reform, we document a sharp 44% reduction in the likelihood of dropping out of high school due to criminal justice involvement. Effect sizes are six (two) times larger for Black (Hispanic) male students relative to their peers, and almost three times larger for students from high-stop neighborhoods. We also observe sharp reductions in suspensions and chronic absenteeism. In aggregate, point estimates indicate that the reform prevented 949 students from dropping out of high school each year.

Research in Progress

Racial Bias in Police Stopping Decisions (with Jeffrey Fagan)

This paper explores whether racial disparities in pedestrian stops reflect true racial differences in criminal behavior or result from unfair targeting by patrol officers. We exploit a court-ordered reform that sharply reduced stop rates across New York City to estimate outcomes of marginal stops – stops that would have occurred absent the reform. As a test for racial bias, we compare estimates of marginal stop outcomes across races. Our analysis is motivated by a model of officer stopping decisions where statistically rational officers face diminishing marginal returns to stops and seek to maximize the detection of criminal behavior less race-specific costs to conducting stops. Using a LATE framework, we instrument for neighborhood stop rates with the timing of the reform, circumventing common pitfalls of outcomes tests, such as omitted variables bias and infra-marginality bias. Pairwise comparisons of marginal stop outcomes in the first year of the reform find that Black and Hispanic pedestrians were over-stopped; marginal Black (Hispanic) stops detect criminal behavior 24% (34%) less frequently than marginal white stops. Shifting stops from minority pedestrians to white pedestrians would have improved efficiency. Estimating marginal stop outcomes over the three years after the reform, we trace out a marginal return curve for each racial group. To equate marginal returns across races, we estimate that the police had to reduce stops of Black and Hispanic pedestrians by an additional 298,000 stops per year. Since our approach allows officers to statistically discriminate or “rationally” racial profile, we interpret these results as conservative estimates of racial discrimination.

Supporting Pathways out of Poverty: Randomized Evaluation of Mobility Mentoring (with Larry Katz and Liz Engle)

Current public support services tend to address a particular symptom of poverty rather than central causes. This paper explores whether holistic, individualized mentoring combined with monetary incentives can help low-income public housing residents achieve economic self-sufficiency. The intervention called Mobility Mentoring includes an individualized coaching plan, weekly meetings to set and assess goals, and temporary financial assistance to incentivize goals or help participants overcome financial obstacles. We evaluate the intervention through a randomized experiment. With the assistance of the Boston Housing Authority (BHA), we recruited public housing and voucher recipients who are able to work and randomly assign half to treatment. Treatment group participants can receive three years of Mobility Mentoring Services, while the control group receives the services usually available to them in the community. Drawing on administrative tax data, our primary outcomes explore the impact of the program on employment, earnings, and household income. We will also examine impacts on financial health, housing stability, public benefit receipt, and survey measures of health and well-being. We plan to follow study participants for ten years from random assignment in administrative data sources, allowing us to assess whether the intervention generates economic self-sufficiency in the long-run.

Debt after Death: Randomized Evidence on Emergency Financial Assistance for the Urban Poor  (with Mary Kate Batistich)

Widespread financial fragility in the United States, in which 40% of households report being unable to cover an emergency $400 expense, could leave middle and low-income households vulnerable to poverty traps brought on by unplanned shocks that lead to a cycle of debt and poor financial standing. However, there is little causal evidence on the implications of unanticipated financial shocks for low-income individuals, and even less evidence on emergency financial assistance provided at the time of the shock. In this paper, we partner with a non-profit that provides financial assistance for burial and funeral (BaF) services to individuals with household incomes below 40% AMI in a large U.S. city. Using a randomized controlled trail, half of study participants will randomly receive $1000 towards BaF expenses, while the other half will receive up to $8000 towards their BaF bill. Historically, BaF bills typically cost about $5500, meaning that we expect the average difference in support between treatment and control groups to be about $4500. Using administrative records, we will passively track impacts on credit outcomes, income, employment, public assistance, and housing stability. We anticipate that funding will support a sample size of 590 participants, enabling us to detect a 0.22 standard deviation change in a standardized credit index. We will also explore the potential of a matched sample that does not experience a death in the family, allowing us to estimate the impact of the shock itself.

Academics and Athletics: A Randomized Trial of Multi-Faceted Mentorship (with Noam Angrist) 

This study evaluates a novel mentorship program combining athletics and academics to close achievement gaps among urban public high school students in the U.S., a setting where racial achievement gaps have persisted for over 20 years. We estimate the causal effect on GPAs – a consequential outcome capturing both academic and non-academic performance in school – by leveraging randomized lotteries run to determine program admission. Results from a pilot show large effects on standardized GPAs of 0.50 standard deviation (p-value= 0.016). This translates to students moving from a “C+” to “B” average. The majority of students are Black and Hispanic, and a single semester of attending the program closes 45-70% of the racial achievement gap. The program ranks among the most cost-effective education interventions in the literature, since it reduces cost by leveraging college volunteer mentors and boosts impact by coupling both cognitive and non-cognitive skill acquisition. We plan to collect additional administrative records to expand this analysis to a larger sample and broader array of outcomes, including high school attendance and disciplinary actions, on-time grade progression and graduation, and college going and completion.