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5 Jan, 2017 07:28

Gun violence spreads like a disease through social networks, study shows

Gun violence spreads like a disease through social networks, study shows

A new study finds that gun violence spreads more like a disease, and predictions can be more accurate when “social contagion” models are used.

The study from JAMA Internal Medicine was conducted with records from fatal and nonfatal gunshot injuries in urban Chicago from 2006 to 2014. Researchers led by sociologist Andrew Papachristos at Yale combed through 1,189,225 arrest records and 16,399 gunshot violence episodes recorded by the Chicago Police Department (CPD) and found that “social contagion” accounted for most of the gunshot violence.

They concluded that 63.1 percent of all shootings were related to being around an “infector,” or a person that was exposed to gun violence themselves. They also found that those “infected” by being around a person that was exposed to gun violence were shot an average of 125 days after they came in contact with the “infected” person.

One person who is infected by gun violence can infect a group of people. The researchers traced these infections from one person to another, and connected the chains of infection through the network of people, finding 4,107 separate “cascades” ranging in size from a single subject, up to 469 subjects, all infecting more and more people.


This is the first study to show that gun violence spreads directly from person to person after a shooting has occurred. This goes against the notion that gun violence is directly related to where a person grew up, or their socio-economic status in society.

The researchers conclude that gun violence should be treated more like a public health epidemic that spreads through social networks and interactions with others, rather than just through demographics and social status.

“Violence prevention efforts that account for social contagion, in addition to demographics, have the potential to prevent more shootings than efforts that focus only on demographics,” the study says.

The researchers found that they could more accurately predict the number of people shot by using a social contagion method over a demographic model, and that combining the two leads to much better results.

Last year alone, the Gun Violence Archive tallied over 57,000 gun-related incidents, with more than 14,000 deaths, and 30,000 gun-related injuries.