Armed and Vulnerable

Philadelphia gun study

In Philadelphia, according to researchers at the University of Pennsylvania, possessing a gun is strongly associated with getting shot. Since "guns did not protect those who possessed them," epidemiologist Charles C. Branas and four co-authors conclude in the November American Journal of Public Health, "people should rethink their possession of guns." This is like noting that possessing a parachute is strongly associated with being injured while jumping from a plane, then concluding that skydivers would be better off unencumbered by safety equipment. 

Branas and his colleagues paired 677 randomly chosen gun assault cases with "population-based control participants" who were contacted by phone shortly after the attacks and matched for age group, gender, and race. They found that "people with a gun were 4.5 times more likely to be shot in an assault than those not possessing a gun."

The researchers suggest several possible explanations for this association: "A gun may falsely empower its possessor to overreact, instigating and losing otherwise tractable conflicts with similarly armed persons. Along the same lines, individuals who are in possession of a gun may increase their risk of gun assault by entering dangerous environments that they would have normally avoided. Alternatively, an individual may bring a gun to an otherwise gun-free conflict only to have that gun wrested away and turned on them."

The one explanation Branas et al. don't mention is that people who anticipate violent confrontations—such as drug dealers, frequently robbed bodega owners, and women with angry ex-boyfriends—might be especially likely to possess guns, just as people who jump out of airplanes are especially likely to possess parachutes. The closest the authors come to acknowledging that possibility is their admission, toward the end of the article, that they "did not account for the potential of reverse causation between gun possession and gun assault"—that is, the possibility that a high risk of being shot "causes" gun ownership, as opposed to the other way around.