Statistical Methods

We work hard to improve measurement and quantitative research in policing, especially on the difficult problem of quantifying racial bias. The field of policing research is in need of rigorous statistical analysis: traditional research methods struggle to disentangle correlation from causation and often ignore well-known issues like selection bias. Sparse data has led to scattershot analytic approaches across multiple disciplines, making it difficult to reconcile seemingly conflicting results. We work to systematize policing research using modern statistical frameworks and techniques so the field can advance.

Policy Evaluation

We evaluate policy interventions to see how they affect policing outcomes.

Public Opinion and Public Education

We engage in research on how the mass public perceives policing and crime, as well as in public-facing education so academics and the general public understand the issues involved and have the best information available. This includes setting the academic and public record straight in instances of flawed research and misinformation.


How Missing Data Makes It Harder to Measure Racial Bias in Policing

Sujata Gupta. ScienceNews. 2021.

Wharton Professor Wins NOMIS & Science Young Explorer Award

Sejin Park. The Daily Pennsylvanian. 2021.

Wharton Professor Dean Knox Recipient of 2021 NOMIS & Science Young Explorer Award

Walter Beckwith. Science Magazine. 2021.

Mummolo Receives Microsoft Funding for Police Body-Worn Camera Project

Riis L. Williams. Princeton School of Public and International Affairs. 2021.

Bocar Ba Rejoins Duke Faculty, Continues Research on Economics of Crime and Labor

Elizabeth Richardson. Duke Department of Economics. 2021.

Philly Moved Toward New Police Oversight as a Report Said the Current System Is in ‘Dire Need’ of Overhaul

Laura McCrystal and David Gambacorta. The Philadelphia Inquirer. 2021.

Collaborative Review and Reform of the PPD Police Board of Inquiry: Policy, Practice, and Custom Report

Police Advisory Commission. City of Philadelphia. 2021.

Report: Less than 1% of Civilian Complaints Filed Against Philly Police Result in Discipline

Aaron Moselle. WHYY. 2021.

Study: Police Diversity Matters

Douglas Starr. Science. 2021.

Diversity in Policing Can Improve Police-Civilian Interactions

B. Rose Huber. Princeton School of Public and International Affairs. 2021.

Law Enforcement Diversity May Improve Policing, Study Shows

Christine Fernando and Marion Renault. Associated Press. 2021.

Countering Police Bias with Data

Bianca Ortiz-Miskimen. Discovery: Research at Princeton. 2021.

Tech Firms Hire ‘Red Teams.’ Scientists Should, Too

Adam Marcus and Ivan Oransky. WIRED. 2020.

A Widely Touted Study Found No Evidence of Racism in Police Shootings. It’s Full of Errors.

Dean Knox and Jonathan Mummolo. The Washington Post. 2020.

Prominent Claims that Policing is Not Racially Biased Rest on Flawed Science

Dean Knox and Jonathan Mummolo. Medium. 2020.

Why Statistics Don’t Capture the Full Extent of the Systemic Bias in Policing

Laura Bronner. FiveThirtyEight. 2020.

Police Think They Can Get Away with Anything. That’s Because They Usually Do.

Bocar Ba and Roman Rivera. The Washington Post. 2020.

It Took Us Months to Contest a Flawed Study on Police Bias. Here’s Why That’s Dangerous.

Dean Knox and Jonathan Mummolo. The Washington Post. 2020.

Making Inferences about Racial Disparities in Police Violence

Dean Knox and Jonathan Mummolo. Proceedings of the National Academy of Sciences. 2020.

Militarization Fails to Enhance Police Safety or Reduce Crime but May Harm Police Reputation

Jonathan Mummolo. Proceedings of the National Academy of Sciences. 2018.