Alex Knorre

I am a Postdoctoral Research Fellow at the Department of Computer Science at Boston College. I use statistics to study crime, gun violence, homicide, drugs, and victimization. I got my PhD in Criminology at the University of Pennsylvania, where I also obtained my M.A. in Statistics. My research has been published in Criminology & Public Policy, Journal of Criminal Justice, and JAMA Network Open. I currently serve as a managing editor of Journal of Quantitative Criminology.

selected publications

A&VB

Place-based approaches to reducing violent crime hot spots: A review of the evidence on public health approaches

MacDonald, John, Knorre, Alex, Mitre-Becerril, David, and Chalfin, Aaron

Jul 2024

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Research from around the world shows that violent crime is spatially clustered in hot spots. A growing body of research shows that place-based changes to the built environment can help reduce violent crime. Increasingly, research summaries imply there are important public health approaches to reduce the hyper-concentration of violence. Past summaries of the effect of place-based changes on violence have focused primarily on their overall effect and have not paid adequate attention to the impact on violent crime within hot spots. Additionally, research summaries seldom delineate what place-based changes actually involve the work of public health departments versus that of housing agencies, redevelopment authorities, street departments, or community-based nonprofits. This review focuses on evidence from experimental and quasi-experimental studies of placed-based changes to the built environment that focus on violent crime hot spots. A narrative review discusses the context of each intervention and assesses their effect sizes on violent crime. Implications for this evidence for public health approaches to reduce violent crime hot spots are considered.
Europe-Asia Stud

The Lull Before the Storm? Criminal Justice, Crime and Incarceration in Russia (2000–2020)

Knorre, Alex, Kudryavtsev, Vladimir, Khodzhaeva, Ekaterina, Runova, Kseniia, and Titaev, Kirill

Jul 2024

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The article reviews the design of the criminal justice system and trends in crime in Russia over the last two decades (2000–2020). First, we argue that the criminal justice system is built upon the idea of meeting quotas, which ensures its accountability to the Russian state and downplays its transparency and crime-control efficiency. Second, we analyse recent crime trends and argue that Russia has experienced a long-term drop in crime. Finally, we overview the available evidence on the enforcement of drug laws and the operation of the prison system in Russia.
NBER

Did Violence Against Asian-Americans Rise in 2020? Evidence from a Novel Approach to Measuring Potentially Racially-Motivated Attacks

Knorre, Aleksei, Van Tiem, Britte, and Chalfin, Aaron

Feb 2024

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Did anti-Asian violence rise after the onset of the COVID-19 pandemic? Efforts to answer this question are compromised by the inherent difficulty of measuring racially-motivated crimes as well as concerns that reporting of racially-motivated hate crimes may have changed due to their increased salience during the pandemic. We pursue an alternative approach to studying whether anti-Asian violence rose after March 2020 that addresses each of these concerns. Using data from the FBI’s National Incident-Based Reporting System, we study inter-race violence occurring in public spaces. While public violence declined among all Americans after March 2020, the share of public violence directed at Asian-Americans by people who were previously unknown to them – or were acquaintances – rose more than it did for other Americans. While this relationship did not hold among an auxiliary sample of large US cities, the national evidence is consistent with a modest increase in racially- motivated violence directed towards Asian-Americans.
C&PP

Hydra: Lessons from the world’s largest darknet market

Goonetilleke, Priyanka, Knorre, Alex, and Kuriksha, Artem

Oct 2023

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We present a comprehensive description of Hydra, the largest darknet marketplace in the world until its shutdown in April 2022. We document the main features of Hydra such as dead-drop delivery, feedback and reputation system, escrow, and dispute resolution. Using data scraped from the platform, we quantitatively examine the scale and the structure of the marketplace. We find that it has been highly competitive, geographically covering at least 69% of the Russian population and trading a wide variety of drugs, while also allowing the wholesale trade of drugs and precursors. The dead-drop delivery system used on Hydra was expensive, as the courier costs comprised a substantial proportion of the sale price of drugs on Hydra. We contribute to the research on drug cryptomarkets by studying an unprecedentedly large non-Western marketplace that existed substantially longer than any other known darknet market. Policy Implications: The phenomenon of Hydra shows that shut-down policies applied to darknet marketplaces have a large effect and implicitly shape the whole drug market. Without these policies, a pervasive digitalization of the drug trade can occur. The major cost of allowing marketplaces to grow is the probable increase in the consumption of illegal drugs due to convenience for consumers and facilitated cooperation between suppliers. This cost must be weighed against the potential benefits, including a higher quality of drugs, a decrease in potential violence, and the incentives for a large marketplace to self-regulate. The case of Hydra also suggests the relevance of financial regulation to limit the growth of darknet marketplaces.
J of Crim Justice

Shootings and Land Use

Knorre, Alex, and MacDonald, John

May 2023

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Purpose: To test whether land use and other features of places are associated with the spatial concentration of gun violence or its growth during epidemic periods. Methods: The study uses shooting data from six major cities over a four-year period (2018–2021). Regression models with spatial lags estimate whether the land use of places is associated with differences in shooting rates and the surge in shootings that occurred in 2020–2021. Results: Mixed-land use is associated with lower rates of shootings overall, but land use has little relationship with the surge in shootings in 2020–2021. The most disadvantaged areas consistently have higher rates of shootings. The change in shooting rates is multiplicative, such that areas of concentrated disadvantage faced the highest absolute rate change in shootings in 2020–2021. Conclusions: This study underscores the importance of social disadvantage in explaining the enduring and episodic rates of gun violence.
JAMA Netw Open

Comparing Risks of Firearm-Related Death and Injury Among Young Adult Males in Selected US Cities With Wartime Service in Iraq and Afghanistan

del Pozo, Brandon, Knorre, Alex, Mello, Michael, and Chalfin, Aaron

Dec 2022

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In 2020, homicides in the United States saw a record single-year increase, with firearm injuries becoming the leading cause of death for children, adolescents, and young adults. It is critical to understand the magnitude of this crisis to formulate an effective response.To evaluate whether young adult males living in parts of 4 major US cities faced a firearm-related death and injury risk comparable with risks encountered during recent wartime service in Iraq and Afghanistan. In this cross-sectional study of young adult males aged 18 to 29 years living in the top 10\% most violent zip codes in each domestic setting (as measured by fatal shooting rates), fatal and nonfatal shooting data for 2020 and 2021 were aggregated at the zip code level for 4 of the largest US cities (Chicago, Illinois; Los Angeles, California; New York, New York; and Philadelphia, Pennsylvania). Wartime mortality and combat injury rates for the conflicts in Iraq and Afghanistan were used to assess relative risk.The relative risk of firearm-related death and nonfatal shootings in each setting as compared with combat death and injury in the comparator setting.Of 129 826 young adult males aged 18 to 29 years living in the top 10\% most violent zip codes in the 4 cities studied, 45 725 (35.2\%) were Black, 71 005 (54.7\%) were Hispanic, and 40 355 (31.1\%) were White. Among this population, there were 470 homicides and 1684 firearm-related injuries. Young adult males living in the most violent zip code of Chicago (2585 individuals aged 20-29 y) and Philadelphia (2448 individuals aged 18-29 y) faced a higher risk of firearm-related homicide than US soldiers who were deployed to Afghanistan, with risk ratios of 3.23 (95\% CI, 2.47-4.68) and 1.91 (95\% CI, 1.32-3.46), respectively. In expanding the analysis to the top 10\% of the cities’ most violent zip codes, the risks in Chicago likewise exceeded those of combat death faced by military service members, with a risk ratio of 2.10 (95\% CI, 1.82-2.46), and the risks in Philadelphia were comparable with those of deployment to war 1.15 (95\% CI, 0.98-1.39). Nonfatal shooting risks were comparable with, or exceeded, the injury risk of combat in Iraq, producing a combined annual firearm risk of 5.8\% in Chicago and 3.2\% in Philadelphia. However, these findings were not observed in the most violent zip codes of Los Angeles and New York City, where young men faced a 70\% to 91\% lower risk than soldiers in the Afghanistan war across fatal and nonfatal categories (eg, fatal shooting in most violent zip code in Los Angeles: risk ratio, 0.30; 95\% CI, 0.26-0.34; nonfatal shooting in top 10\% most violent zip codes in New York: risk ratio, 0.09; 95\% CI, 0.08-0.10). The risk of violent death and injury observed in the zip codes studied was almost entirely borne by individuals from minoritized racial and ethnic groups: Black and Hispanic males represented 96.2\% of those who were fatally shot (452 individuals) and 97.3\% of those who experienced nonfatal injury (1636 individuals) across the 4 settings studied.In this cross-sectional study, for young adult men in several of the communities studied, firearm violence carried morbidity and mortality risks that exceeded those of war. Health equity requires prioritizing effective responses.