Greg Ridgeway, Ph.D.

Rebecca W. Bushnell Professor of Criminology, Department and Undergraduate Chair of Criminology, Professor of Statistics and Data Science at the University of Pennsylvania

NPI Affiliated Scholars Program


Greg Ridgeway is a Rebecca W. Bushnell Professor of Criminology, the department and undergraduate chair of Criminology, and a professor of Statistics and Data Science at the University of Pennsylvania.

Professor Ridgeway’s research involves the development of statistical, computational, and analytical methods to improve our understanding of crime and the functioning of the justice system. At the same time, he has great interest in putting those methods into practice. His methods have been implemented in police departments, including Cincinnati, Los Angeles, and New York City, as well as in federal public defender organizations and in drug treatment program evaluations.

Professor Ridgeway’s leadership experience overseeing research organizations in the public and private sectors is well-suited for teaching and mentoring students with career aspirations in public service, research organizations, or academia.

Prior to coming to the University of Pennsylvania, Professor Ridgeway was the Acting Director of the National Institute of Justice and, as such, a member of the Senior Executive Service—the highest leadership position in the federal government’s civil service. NIJ is the Justice Department’s science agency with 80 employees and a budget of $250 million. NIJ is charged with strengthening the social, physical, and forensic sciences in order to improve our understanding of crime and advance justice. While leading NIJ, Professor Ridgeway implemented many reforms to clarify the scientific focus of the institute and implemented initiatives including a $75 million school safety research program.

Previously, he was director of the RAND Safety and Justice Program and the RAND Center on Quality Policing where he worked with numerous criminal justice organizations around the world. Professor Ridgeway is a Fellow of the American Statistical Association, a distinction he received for being one of the world’s foremost statisticians engaged in crime research. He is the inventor of eight awarded US patents.


Police Use of Force

Ridgeway, G., Cave, B., Grieco, J., & Loeffler, C.E. (2021). A conditional likelihood model of the relationship between officer features and rounds discharged in police shootings. Journal of Quantitative Criminology, 37(1), 303–326. https://doi.org/10.1007/s10940-020-09468-4

Ridgeway, G. (2020). The role of individual officer characteristics in police shootings. The ANNALS of the American Academy of Political and Social Science, 687(1), 58–66. https://doi.org/10.1177/0002716219896553

Ridgeway, G. (2016). Officer risk factors associated with police shootings: A matched case-control study. Statistics and Public Policy, 3(1), 1–6. https://doi.org/10.1080/2330443X.2015.1129918

Benchmarking Justice System Performance

Nguyen, V., & Ridgeway, G. (2023). Judges on the benchmark: Developing a sentencing feedback system. Justice Quarterly, 41(1), 1–37. https://doi.org/10.1080/07418825.2023.2244738

Ridgeway, G., Moyer, R. A., & Bushway, S. D. (2020). Sentencing scorecards: Reducing racial disparities in prison sentences at their source. Criminology & Public Policy, 19(4), 1113–1138. https://doi.org/10.1111/1745-9133.12529

Ridgeway, G., & MacDonald, J. M. (2014). A method for internal benchmarking of criminal justice system performance. Crime & Delinquency, 60(1), 145–162. https://doi.org/10.1177/0011128713514802

Ridgeway, G., & MacDonald, J.M. (2009). Doubly robust internal benchmarking and false discovery rates for detecting racial bias in police stops. Journal of the American Statistical Association, 104(486), 661–668. https://doi.org/10.1198/jasa.2009.0034

Policy Interventions

Wu, Y., & Ridgeway, G. (2021). Effect of public transit on crime: Evidence from SEPTA strikes in Philadelphia. Journal of Experimental Criminology, 17, 267–286. https://doi.org/10.1007/s11292-020-09416-z

Moyer, R., & Ridgeway, G. (2020). The effect of outpatient methadone maintenance treatment facilities on place-based crime. Journal of Experimental Criminology, 16, 227–245. http://doi.org/10.1007/s11292-018-9347-1

Moyer, R., MacDonald, J.M., Ridgeway, G., & Branas, C. C. (2019). Effect of remediating blighted vacant land on shootings: A citywide cluster randomized trial. American Journal of Public Health, 109(1), 140–144. https://doi.org/10.2105/AJPH.2018.304752

Ridgeway, G., Grogger, J., Moyer, R.A., & MacDonald, J.M. (2019). Effect of gang injunctions on crime: A study of Los Angeles from 1988-2014. Journal of Quantitative Criminology, 35(3), 517–541. https://doi.org/10.1007/s10940-018-9396-7

Faraji, S.L., Ridgeway, G., & Wu, Y. (2018). Effect of emergency winter homeless shelters on property crime. Journal of Experimental Criminology, 14, 129–140. https://doi.org/10.1007/s11292-017-9320-4

Ridgeway, G., & MacDonald, J.M. (2017). Effect of rail transit on crime: A study of Los Angeles from 1988-2014. Journal of Quantitative Criminology, 33(2), 277–291. https://doi.org/10.1007/s10940-016-9296-7

Ridgeway, G., & Kilmer, B. (2016). Bayesian inference for the distribution of grams of marijuana in a joint. Drug and Alcohol Dependence, 165, 175–180. https://doi.org/10.1016/j.drugalcdep.2016.06.004

Ridgeway, G., Braga, A. A., Tita, G., & Pierce, G. (2011). Intervening in gun markets: An experiment to assess the impact of targeted gun law messaging. Journal of Experimental Criminology, 7(1), 103–109. https://doi.org/10.1007/s11292-010-9113-5

Karaca-Mandic, P., & Ridgeway, G. (2010). Behavioral impact of graduated driver licensing on teenage driving risk and exposure. Journal of Health Economics, 29(1), 48–61. https://doi.org/10.1016/j.jhealeco.2009.10.002

Tita, G., Braga, A.A., Ridgeway, G., & Pierce, G.L. (2006). The criminal purchase of firearm ammunition in Los Angeles, California. Injury Prevention, 12, 308–311. https://doi.org/10.7249/RP1243


Ridgeway, G. (2019). Experiments in criminology: Improving our understanding of crime and the criminal justice system. Annual Review of Statistics and Its Applications, 6, 37–61. https://doi.org/10.1146/annurev-statistics-030718-105057

Ridgeway, G. (2018). Policing in the era of big data. Annual Review of Criminology, 1, 401–419. https://doi.org/10.1146/annurev-criminol-062217-114209

Statistical Methods

Loeffler, C.E., Hyatt, J.M., & Ridgeway, G. (2019). Measuring self-reported wrongful convictions among prisoners. Journal of Quantitative Criminology, 35(2), 259–286. https://doi.org/10.1007/s10940-018-9381-1

Ridgeway, G., Kovalchik, S. A., Griffin, B.A., & Kabeto, M.U. (2015). Propensity score analysis with survey weighted data. Journal of Causal Inference, 3(2), 237–249. https://doi.org/10.1515/jci-2014-0039

Grogger, J., & Ridgeway, G. (2006). Testing for racial profiling in traffic stops from behind a veil of darkness. Journal of the American Statistical Association, 101(475), 878–887. ASA 2007 Outstanding Statistical Application Award. https://doi.org/10.1198/016214506000000168

Ridgeway, G. (2006). Assessing the effect of race bias in post-traffic stop outcomes using propensity scores. Journal of Quantitative Criminology, 22(1), 1–29. https://doi.org/10.7249/RP1252

McCaffrey, D., Ridgeway, G., Morral, A. (2004). Propensity score estimation with boosted regression for evaluating adolescent substance abuse treatment. Psychological Methods, 9(4), 403–425. https://doi.org/10.7249/RP1164

Ridgeway, G., & Madigan, D. (2003). A sequential Monte Carlo method for Bayesian analysis of massive datasets. Data Mining and Knowledge Discovery, 7(3), 301–319. https://doi.org/10.1023/A:1024084221803

Areas of Focus

  • The development of statistical, computational, and analytical methods to improve our understanding of crime and the functioning of the justice system.