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November 03, 2017

Penn study concludes that gun violence is not contagious

According to the findings of a recent study from the University of Pennsylvania and the University of Oxford, the effects of gun violence are felt most within specific neighborhoods, rather than a spreading phenomenon.

In other words: Gun violence is not contagious, according to the study.

“It’s been known for some time that gun violence, like many other forms of crime and other social problems, can be clustered within certain neighborhoods,” Charles Loeffler, an assistant professor of criminology at the University of Pennsylvania, said in a statement.

“So when we observe that a particular part of the city has an elevated risk, how do we understand what the phenomenon actually is?”

Loeffler worked with Oxford statistician Seth Flaxman, using data from firearm-related 911 calls in Washington, D.C., and an acoustical gunshot locator system, to test two hypotheses.

First, the researchers asked whether gun violence could be an epidemic, spreading to surrounding environments. Alternatively, researchers considered the conclusion that gun violence is clustered in certain neighborhoods at certain times, “but it may not actually be spreading in any real sense,” Loeffler said. The latter is termed an endemic pattern.

In concluding the latter hypothesis is what occurs, researchers see the opportunity for more effective ways to curb gun violence.

“We found that a substantial fraction of the gun violence was better characterized as this endemic, non-random clustering rather than as an epidemic, contagious, diffusing process,” Loeffler said.

With this in mind, researchers argue place-based gun violence interventions targeting specific neighborhoods instead of individuals or groups could be more effective.

Though this conclusion seemed to ring true for the areas studied in D.C., Loeffler admitted that the trends of gun violence could be vastly different in other cities.

"The reality of D.C. may be different than the nature of gun-violence problems in Chicago or Los Angeles or Philadelphia,” he said.

Ironically, the report was released just before the Las Vegas massacre that killed almost 60 people on Oct. 1. With this mass shooting and the hundreds that have occurred in the last five years, since the shooting at Sandy Hook Elementary School, other studies and scholars yield conflicting conclusions to Penn's findings.

Though the acts of gun violence may be more clustered in specific communities, Yale University researchers earlier this year questioned the role of social networks in public exposure to gun violence. Studying Chicago arrests for eight years, the Yale study found more than 60 percent of gun violence occurred in “connected chains” of social networks.

Take a look at the full Penn study, published in the Journal of Quantitative Criminology, here.