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Jillian Carr

Shot Stopper

Monday, September 26, 2016

 Gun Control

As gun violence continues to escalate nationwide, research coauthored by Krannert economics professor Jillian Carr takes aim at widely enforced juvenile curfew laws that are intended to reduce crime but may actually increase it.

Armed with empirical evidence from ShotSpotter — an audio surveillance company that tracks and records gunfire incidents for police departments across the country — Carr and Jennifer Doleac, a professor at the University of Virginia, are gaining the ear of policymakers and the legal community with a paper titled “Keep the Kids Inside? Juvenile Curfews and Urban Gun Violence.” 

Their research, forthcoming in the Review of Economics and Statistics, specifically tests the net effect of juvenile curfews on the number of gunfire incidents in Washington, DC, where the weekday curfew time changes from midnight to 11 pm on September 1st each year. The rationale behind the policy is that when the curfew time shifts, crime between 11 pm and midnight should go down.

Acknowledging novelist Roal Dahl’s concept of a witching hour, Carr and Doleac refer to the treated hour — 11:00 to 11:59 pm on weekdays — as the “switching hour.”

Although traditional crime-reporting measurements such as 911 calls suggest that juvenile curfews are effective deterrents against gun violence, the more accurate data from ShotSpotter indicates that gunfire incidents actually increase as a result of juvenile curfews.

“Our findings show that the curfew increased gun violence in Washington, DC, by 0.045 incidents per hour,” Carr says. “That aggregates to seven additional city-wide gunfire incidents per week during the switching hour alone.”

Sadly, Carr and Doleac’s research becomes timelier with each day's headlines. And an important conclusion is that additional research and better data is needed to address one of society’s most significant problems.

“The goal of juvenile curfews is to reduce crime by keeping potential offenders and victims off the streets during the hours when gun violence is most prevalent,” Carr explains. “That same policy also removes bystanders and potential witnesses, however, so their net effect on public safety is unclear.

“Whether surveillance data is something you like or not, it’s very helpful to researchers and policymakers because it’s empirical and doesn’t rely on human reporting. As the technology improves, using such data will help us better understand crime patterns, more accurately estimate the effects of policy and ultimately save lives.”

An abstract and downloadable PDF of “Keep the Kids Inside? Juvenile Curfews and Urban Gun Violence” is available at

Contributors: Jillian Carr, assistant professor of economics, Purdue University Krannert School of Management; Jennifer Doleac, assistant professor of public policy and economics, University of Virginia Frank Batten School of Leadership and Public Policy.