Research

Working Papers

The Effectiveness and Equity of Police Stops (with Jeffrey Fagan)

Job Market Paper


Over 3.5 million pedestrians are stopped by police in the United States every year. This paper explores the effectiveness and equity of using pedestrian stops as a crime deterrence tool. Using administrative data from New York City, we test whether pedestrian stops affect neighborhood crime and high school dropout rates and explore the equity of racial disparities in stop rates. Exploiting a 2012 reform that reduced stops by 95%, we compare neighborhoods that have similar crime rates but substantially different stop rates prior to the reform. Treated neighborhoods that experienced twice the reduction in stop rates do not display differential increases in felonies and violent misdemeanors, shootings, or killings over the five years following the reform. Analysis of police surges reveals that when increases in stops are accompanied by increases in police officers, serious crime significantly declines. But alone, heightened stop rates have no measurable impact on serious crime. Comparing students across schools that are differentially exposed to changes in stop rates, we estimate that the reform reduced the probability of high school dropout by 0.36-1.66 percentage points per academic year. By instrumenting for neighborhood stop rates with the reform, we trace out the marginal return curve of stops by race and find that Black and Hispanic residents were stopped at substantially higher rates than would be optimal for crime detection.

Police Violence and Civic Engagement (with Desmond Ang)

American Political Science Review, Revise & Resubmit.

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 hyper-local 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.

Research in Progress

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 are able to 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.

The Effect of Low-level Arrests on the Early-life Trajectory of Urban Youth: Evidence from Tax and Arrest Records (with Benny Goldman)

We study the downstream effects of a teenage arrest or citation for a minor offense on adult earnings, employment, and incarceration. Prior research on the effects of criminal justice interactions on economic outcomes tends to use judge IV designs which focus on the effects of judge decisions (e.g. bail, incarceration, etc.) on defendants who, in many cases, are already tied up in the criminal justice (CJ) system. In this paper, we focus on teenagers who are plausibly interacting with the CJ system for the first time and ask whether interactions with the police for low-level offenses can trap people in the CJ system with detrimental impacts on long-run outcomes. We use the drawdown of stop and frisk policies in New York, which prior research has shown leads to no change in crime but to a large reduction in the number of citations and arrests for low-level offenses, to study the effects on long-run outcomes for exposed teenagers. Using administrative tax records linked to arrest and policing data, we will estimate impacts on earnings, incarceration, and unemployment in an exposed teenager’s mid-20s. We will complement these findings with an analysis of the dynamic effects of police surges, which simultaneously increased low-level arrests and citations but deterred future serious crime. Using maps of police surges linked to residential addresses, we will match teenagers on opposite sides of the police surge borders to identify causal effects for cohorts that directly experience the police crackdown and those that also experience crime reductions. We will examine heterogeneous impacts by race, sex, and predicted criminality, and will quantify the extent to which low-level interactions with the police mediate neighborhood rates of upward mobility by race and sex.

What Makes a Good Apple? Officer Mental Health, Risk Perceptions, and Aggressive Policing (with William Murdock)

How do officer mental health and risk perceptions influence officer performance? In collaboration with a large urban police department, we have collected three waves of survey data on officer mental health and risk perceptions and have been granted access to detailed administrative data on officer assignments and performance. This paper will first document the extent to which both levels and changes in mental health and risk perceptions predict peaceful de-escalations, uses of force, and civilian complaints. We will compare these estimates to other observable officer characteristics, such as officer tenure, military training, age, gender, and race. Next, we will correlate these factors with causal estimates of officer performance by exploiting quasi-random assignment of officers to calls for service. The long-term goal of this project is to design a randomized experiment that tests the effectiveness of low-cost interventions that provide officers with targeted information on the true risk of various encounters, as well as higher-cost interventions that seek to improve officer mental health and wellness.