gerard

Assistant Professor
Department of Sociology
Columbia University

Download my CV

Office Hours Sign Up

 

I am an Assistant Professor in Sociology at Columbia University and a member of the Data Science Institute. I use causal inference and machine learning methods to study urban inequality, violence, and racial disparities in policing. My work has been published in the American Journal of Sociology, the American Sociological Review, Demography, the Journal of Urban Economics, PLOS One, and the Proceedings of the National Academy of Sciences, among other peer-reviewed journals. My research has been funded by the Russell Sage Foundation and the Centers for Disease Control and Prevention. Findings from my research have been featured in The New York Times, The Washington Post, and Bloomberg. I received my PhD in Sociology from New York University in 2019, a Master’s in Public Policy from the Harvard Kennedy School of Government in 2014, and a BS in Engineering from the Polytechnic University of Catalonia in 2004. Before graduate school, I was a firefighter at Barcelona Fire Department from 2007 to 2011. In my free time, I enjoy running, cycling, and hiking.

News & Updates

2025

‣ The article “Severe Tornadoes and Infant Birth Weight in the United States,” co-authored with Nicholas Mark and Ethan Raker, has been accepted at Demography.
‣ The article “From the Block to the Beat: How Violence in Officers’ Neighborhoods Influences Racially Biased Policing,” co-authored with Samuel Donahue, has been accepted at the American Journal of Sociology.
‣ The article “The Fall of Violence and the Reconfiguration of Urban Neighborhoods,” co-authored with Patrick Sharkey, has been accepted at Demography.

2024

‣ The article “Police violence reduces trust in the police among Black residents,” co-authored with Jonathan Ben-Menachem, has been published in PLoS ONE.
‣ Kara Rudolph and I have been awarded a grant from the Centers for Disease Control and Prevention to study the relationship between community-level exposure to aggressive policing and adverse childhood experiences.
‣ I wrote a chapter for the book Between Us: Healing Ourselves and Changing the World Through Sociology (edited by Marika Lindholm and Elizabeth Anne Wood and published by Chicago University Press) revisiting my time as a firefighter in Barcelona through the lens of sociological concepts.
‣ The article “Exposure to Crime and Racial Birth Outcome Disparities,” co-authored with Nicholas Mark, has been published in the Journal of Urban Health.
‣ The article “Neighborhood Safety and Neighborhood Police Violence Are Associated with Psychological Distress among English‐ and Spanish‐Speaking Transgender Women of Color in New York City: Finding from the TURNNT Cohort Study,” co-authored with Dustin Duncan and others, has been published in the Journal of Urban Health.
‣ I am grateful for the opportunity to join the Russsell Sage Visiting Scholar Class of 2024–2025.

2023

‣ The study “Understanding Why EmpaTeach Did Not Reduce Teachers’ Use of Violence in Nyarugusu Refugee Camp: A Quantitative Process Evaluation of a School-Based Violence Prevention Intervention,” co-authored with researchers from the Behavioral Insights Team, the International Rescue Committee, and the London School of Hygiene and Tropical Medicine, has been published in PLoS Global Public Health.

2022

‣ The research that Sam Donahue and I are doing on the effects of diversity and peer influences in policing has been awarded a Trustee Grant from the Russell Sage Foundation.
‣ The article “Declining Violence and Improving Birth Outcomes in the US: Evidence from Birth Certificate Data,” co-authored with Nicholas Mark, has been published in Social Science and Medicine.

2021

‣ The study “The EmpaTeach Intervention for Reducing Physical Violence from Teachers to Students in Nyarugusu Refugee Camp: A Cluster-Randomised Controlled Trial,” co-authored with researchers from the Behavioral Insights Team, the International Rescue Committee, and the London School of Hygiene and Tropical Medicine, has been published in PLoS Medicine.
‣ My article “Using Machine Learning to Estimate the Effect of Racial Segregation on COVID-19 Mortality in the United States” has been published at the Proceedings of the National Academy of Sciences.

2020

‣ I started as an Assistant Professor in Sociology at Columbia University.
‣ My article “Crime and Inequality in Academic Achievement Across School Districts in the United States” has been published in Demography.

2019

‣ I started as a postdoctoral researcher at Columbia University’s Data Science Institute.

Selected Publications

Demography, 2025 (with Patrick Sharkey)

pdf appendix
Over the past few decades, U.S. cities have changed dramatically, largely because of two major trends: the fall of violence and the rise of urban inequality. Despite the attention given to each of these trends, little research has assessed how they are related to each other. This study is the first to generate causal evidence on the impact of violent crime on economic residential segregation. We document the effect of the crime drop on economic segregation in 500 US cities between 1990 and 2010, using exogenous shocks to city crime rates to identify causal effects.

PLoS ONE, 2024 (with Jonathan Ben-Menachem)

pdf appendix data
Recent high-profile incidents involving the shooting or killing of unarmed Black men have intensified the debate about how police violence affects trust in the criminal justice system, particularly among communities of color. In this article, we propose a quasi-experimental design that leverages the timing of the shooting of Jacob Blake by the Kenosha Police Department relative to when a large survey was fielded in the city of Chicago. We demonstrate that individuals interviewed 4 weeks before and 4 weeks after the shooting are comparable across a large set of observed characteristics, thus approximating an experimental setting. We find that Blake’s shooting caused substantial reductions in Black respondents’ trust in the police, concentrated among younger residents and criminalized residents. These results suggest that police violence against racial minorities may lead to lower civic …

Social Science and Medicine, 2022 (with Nicholas Mark)

pdf
The decline in crime that occurred in the last decade of the 20th century was one of the most important societal changes in recent U.S. history. In this paper, we leverage the sharp decline in violence that began in the 1990’s to estimate the relationship between county-level murder rates and individual-level birth outcomes for Black, Hispanic, and White mothers. Using the FBI’s Uniform Crime Reporting data from 1992 to 2002 and individual-level data from more than 30,000,000 US birth certificates, we employ two-way fixed effects models with a rich set of controls to compare births to similar women in the same county who experienced different crime rates during their pregnancies. Elevated murder rates are associated with substantially higher risks of low birth weight for White mothers, low birth weight and small for gestational age among Black mothers, and small for …

Proceedings of the National Academy of Sciences, 2021

pdf appendix data
This study examines the role that racial residential segregation has played in shaping the spread of the novel coronavirus disease 2019 (COVID-19) in the US as of September 30, 2020. The analysis focuses on the effects of racial residential segregation on mortality and infection rates for the overall population and on racial and ethnic mortality gaps. To account for potential confounding, I assemble a data set that includes 50 county-level factors that are potentially related to residential segregation and COVID-19 infection and mortality rates. These factors are grouped into eight categories (demographics, density and potential for public interaction, social capital, health risk factors, capacity of the health care system, air pollution, employment in essential businesses, and political views). I use double-lasso regression, a machine learning method for model selection and inference, …

Demography, 2020

pdf appendix
This study investigates the effect of violent crime on school district–level achievement in English language arts (ELA) and mathematics. The research design exploits variation in achievement and violent crime across 813 school districts in the United States and seven birth cohorts of children born between 1996 and 2002. The identification strategy leverages exogenous shocks to crime rates arising from the availability of federal funds to hire police officers in the local police departments where the school districts operate. Results show that children who entered the school system when the violent crime rate in their school districts was lower score higher in ELA by the end of eighth grade, relative to children attending schools in the same district but who entered the school system when the violent crime rate was higher. A 10% decline in the violent crime rate experienced at ages 0–6 …

Proceedings of the National Academy of Sciences, 2018 (with Laia Balcells)

pdf appendix data
This study investigates the consequences of terrorist attacks for political behavior by leveraging a natural experiment in Spain. We study eight attacks against civilians, members of the military, and police officers perpetrated between 1989 and 1997 by Euskadi Ta Askatasuna (ETA), a Basque terrorist organization that was active between 1958 and 2011. We use nationally and regionally representative surveys that were being fielded when the attacks occurred to estimate the causal effect of terrorist violence on individuals’ intent to participate in democratic elections as well as on professed support for the incumbent party. We find that both lethal and nonlethal terrorist attacks significantly increase individuals’ intent to participate in a future democratic election. The magnitude of this impact is larger when attacks are directed against civilians than when directed against members of …

American Sociological Review, 2017 (with Patrick Sharkey and Delaram Takyar)

pdf data
Largely overlooked in the theoretical and empirical literature on the crime decline is a long tradition of research in criminology and urban sociology that considers how violence is regulated through informal sources of social control arising from residents and organizations internal to communities. In this article, we incorporate the “systemic” model of community life into debates on the U.S. crime drop, and we focus on the role that local nonprofit organizations played in the national decline of violence from the 1990s to the 2010s. Using longitudinal data and a strategy to account for the endogeneity of nonprofit formation, we estimate the causal effect on violent crime of nonprofits focused on reducing violence and building stronger communities. Drawing on a panel of 264 cities spanning more than 20 years, we estimate that every 10 additional organizations focusing on crime and …

Journal of Urban Economics, 2017 (with Patrick Sharkey)

pdf
Recent evidence has found substantial geographic variation in the level of upward economic mobility across US states, metropolitan areas, commuting zones, and counties. However, minimal progress has been made in identifying the key mechanisms that help explain why some urban areas have low rates of upward mobility while others have rates of upward mobility that resemble the most mobile nations in the developed world. In this article we focus attention on one specific dimension of urban areas, the level of violent crime. Using longitudinal data and an array of empirical approaches, we find strong evidence that the level of violent crime in a county has a causal effect on the level of upward economic mobility among individuals raised in families at the 25th percentile of the income distribution. We find that a one standard deviation decline in violent crime as experienced during late …