In Philadelphia, researchers at the University of Pennsylvania find, possessing a gun is strongly associated with getting shot. Since “guns did not protect those who possessed them,” they conclude, “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 designed to slow their descent. “Can this study possibly be as stupid as it sounds?” asks Stewart Baker at Skating on Stilts. Having shelled out $30 for the privilege of reading the entire article, which appears in the November American Journal of Public Health, I can confirm that the answer is yes.
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While the reseachers took into account a few confounding variables related to this tendency (including having an arrest record, living in a rough neighborhood, and having a high-risk occupation), they cannot possibly have considered all the factors that might make people more prone to violent attack and therefore more likely to have a gun as a defense against that hazard. To take just one example, not every criminal has an arrest record. Yet it seems fair to assume that criminals in Philadelphia are a) more likely than noncriminals to be armed and b) more likely than noncriminals to be shot. That does not mean having a gun increases their chance of being shot. Certainly they believe (as police officers do) that having a gun makes them safer than they otherwise would be. Nothing in this study contradicts that belief.
Of course, most people will only see the headline, so the underlying purpose of publishing the “study” has been achieved.