Greg Ridgeway

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Research Interests

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 put into place in police departments, including Cincinnati, Los Angeles, and New York City, in Federal Public Defender Organizations, and in drug treatment program evaluations.

Professor Ridgeway’s leadership experience in running 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 Penn, 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 $250M and 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 $75M school safety research program.

Previously Professor Ridgeway 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 on eight awarded US patents.

Selected Publications

Police use-of-force

• G. Ridgeway, B. Cave, J. Grieco, and C.E. Loeffler (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.
• G. Ridgeway (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.
• G. Ridgeway (2016). “Officer Risk Factors Associated with Police Shootings: A Matched Case-Control Study,” Statistics and Public Policy 3(1):1-6.

Benchmarking justice system performance

• V. Nguyen and G. Ridgeway (2023). "Judges on the Benchmark: Developing a Sentencing Feedback System," Justice Quarterly.
• G. Ridgeway, R. Moyer, and S. Bushway (2020). “Sentencing Scorecards: Reducing Racial Disparities in Prison Sentences at Their Source,” Criminology & Public Policy 19(4):1113-1138.
• G. Ridgeway and J.M. MacDonald (2014). “A Method for Internal Benchmarking of Criminal Justice System Performance,” Crime & Delinquency 60(1):145-162.
• G. Ridgeway and J.M. MacDonald (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.

Policy interventions

• Y. Wu and G. Ridgeway (2021). “Effect of Public Transit on Crime: Evidence from SEPTA strikes in Philadelphia,” Journal of Experimental Criminology 17:267-286.
• R. Moyer and G. Ridgeway (2020). “The Effect of Outpatient Methadone Maintenance Treatment Facilities on Place-Based Crime,” Journal of Experimental Criminology 16(2):227–245.
• R. Moyer, J.M. MacDonald, G. Ridgeway, and C. Branas (2019). “Effect of Remediating Blighted Vacant Land on Shootings: A Citywide Cluster Randomized Trial,” American Journal of Public Health 109(1):140-144.
• G. Ridgeway, J. Grogger, R.A. Moyer, and J.M. MacDonald (2019). “Effect of Gang Injunctions on Crime: A Study of Los Angeles from 1988-2014,” Journal of Quantitative Criminology 35(3):517- 541.
• S.-L. Faraji, G. Ridgeway, and Y. Wu (2018). “Effect of Emergency Winter Homeless Shelters on Property Crime,” Journal of Experimental Criminology 14(2):129-140.
• G. Ridgeway and J.M. MacDonald (2017). “Effect of Rail Transit on Crime: A Study of Los Angeles from 1988-2014,” Journal of Quantitative Criminology 33(2):277-291.
• G. Ridgeway and B. Kilmer (2016). “Bayesian inference for the distribution of grams of marijuana in a joint,” Drug and Alcohol Dependence 165:175–180.
• G. Ridgeway, A. Braga, G. Tita, and G. Pierce (2011). “Intervening in gun markets: An experiment to assess the impact of targeted gun law messaging,” Journal of Experimental Criminology 7(1):103- 109.
• P. Karaca-Mandic and G. Ridgeway (2010). “Behavioral Impact of Graduated Driver Licensing on Teenage Driving Risk and Exposure,” Journal of Health Economics 29:48-61.
• G. Tita, A. Braga, G. Ridgeway, G. Pierce (2006). “The criminal purchase of firearm ammunition in Los Angeles, California,” Injury Prevention 12:308-311.

Reviews

• G. Ridgeway (2019). “Experiments in Criminology,” Annual Review of Statistics and Its Applications 6:37-61.
• G. Ridgeway (2018). “Policing in the Era of Big Data,” Annual Review of Criminology 1:401-419.

Statistical Methods

• C.E. Loeffler, J.M. Hyatt, and G. Ridgeway (2019). “Measuring Self-Reported Wrongful Convictions Among Prisoners,” Journal of Quantitative Criminology 35(2):259-286
• G. Ridgeway, S. Kovalchik, BA Griffin, and M.U. Kabeto (2015). “Propensity score analysis with survey weighted data,” Journal of Causal Inference 3(2):237-249.
• J. Grogger and G. Ridgeway (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
• G. Ridgeway (2006). “Assessing the effect of race bias in post-traffic stop outcomes using propensity scores,” Journal of Quantitative Criminology 22(1):1-29.
• D. McCaffrey, G. Ridgeway, A. Morral (2004). “Propensity score estimation with boosted regression for evaluating adolescent substance abuse treatment,” Psychological Methods 9(4):403-425.
• G. Ridgeway and D. Madigan (2003). “A sequential Monte Carlo method for Bayesian analysis of massive datasets,” Data Mining and Knowledge Discovery 7(3):301-319.

Affiliations

• Co-director, SAS Data Driven Discovery Initiative (2021-present)
• Co-editor-in-chief, Journal of Quantitative Criminology (2021-present)
• Quattrone Center for the Fair Administration of Justice, University of Pennsylvania Law School (8/2015-present)
• Penn Injury Science Center (8/2015 present) Center for Causal Inference (8/2016-present)
• Graduate Group in Epidemiology and Biostatistics, Perelman School of Medicine (12/2017-present) Population Studies Center, School of Arts and Sciences (2/2024-present)