30 October 2026 13:00 - 14:00

This event is both online and in person.

SAL B.07, Basement, Sir Arthur Lewis Building, LSE, 32 Lincoln's Inn Fields, London WC2A 3PH

Online participants are welcome:
Please contact Lia Bergin (Communications and Events Assistant) l.bergin@lse.ac.uk to receive event updates and a link to the seminar online.

About this event

Randomized controlled trials (RCTs) are influential in shaping policy to address the massive social harm from crime. Yet crime-prevention experiments typically ignore the possibility of peer spillovers, which could misrepresent interventions' net effects in either direction. To estimate how program effects diffuse or displace across social networks, we combine four existing RCTs in Chicago (N ~12,000) with multiple administrative measures of social connections between people that capture co-arrest, co-victimization, shared classes, and shared households (N ~2 million). We quantify network spillovers and explore which social ties matter for criminal behavior. Being exposed to at least one treated peer generates 34-50 percent reductions in crime, concentrated among those who were also in the RCTs. We show that standard intent-to-treat estimates considerably understate both the impact of direct treatment in the absence of peer exposure and the interventions? total social impacts accounting for peer influence; the net violence decline is at least 80 percent greater than implied by the estimates in the original studies, and spillovers sometimes mask actual behavior change entirely. The results have important implications for how we estimate treatment effects in crime prevention, and they expand our knowledge of how people affect each other's criminal decision-making.

Participants are expected to adhere to the CEP Events Code of Conduct.

Directions

This event will take place in SAL B.07, Basement, Sir Arthur Lewis Building, LSE, 32 Lincoln's Inn Fields, London WC2A 3PH.

Online participants are welcome:
Please contact Lia Bergin (Communications and Events Assistant) l.bergin@lse.ac.uk to receive event updates and a link to the seminar online.

The building is labelled SAL on the LSE campus map. You can also find us on Google Maps. For further information, go to contact us.

European Seminars on the Economics of Crime are part of the CEP's Crime Research Group.