Alex Knorre

I am a Postdoctoral Research Fellow at the Department of Computer Science in 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.

selected publications

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.
J of Drug Issues

Do Russian Police Fabricate Drug Offenses? Evidence From Seized Heroin’s Weight Distribution

Knorre, Alex

Oct 2020

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Current Russian drug policy is punitive toward people who use drugs. Moreover, criminal justice in Russia is driven by strong organizational incentives to increase performance indicators of police such as clearance rate. Taken together, these might lead to the use of extrajudicial and illegal police practices, as documented by several qualitative studies. In this article, we explore quantitative evidence of such practices, namely, weight anomalies of the seized heroin that result from minimum threshold amounts established by the law. We find significant discontinuities in the weight distribution of seized heroin near minimum threshold amounts. Placebo tests rule out alternative explanations of the discontinuity and show that the most likely source of the revealed discontinuities is police manipulations with seized heroin.
SSRN

Hydra: Lessons from the World’s Largest Darknet Market

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

Jun 2022

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We present a comprehensive description of Hydra, the largest darknet marketplace in the world until its shutdown in April 2022. This paper documents the main features of this online platform (such as user feedback, escrow, dispute resolution, and certification of drug quality) and quantitatively examines the scale and the structure of the marketplace. Using data scraped from the platform, we find that the marketplace appears to have been highly competitive, geographically covering 69% of the Russian population, and trading a wide variety of drugs. Hydra was also used for deals between producers and sellers, who traded wholesale quantities of drugs and precursors. The dead-drop delivery system utilized on Hydra was expensive, as the courier costs comprised a substantial proportion of the sale price of drugs on Hydra. Finally, by examining product feedback we find that despite evidence that reputation was of critical importance to the operation of the platform, user ratings were skewed towards the highest possible rating value.