Yesterday the Annals of Internal Medicine published a meta-analysis of 15 studies that aimed to measure the relationship between gun ownership and the risk of suicide or homicide. Over all, University of California at San Francisco epidemiologist Andrew Anglemyer and his two co-authors found, people with access to guns were about three times as likely to kill themselves and about twice as likely to be killed as people without such access. The Daily Beast's Brandy Zadrozny says Anglemyer et al.'s study "has seemingly put an end to the debate" over whether owning a gun makes people more or less safe, "at least in terms of suicide and homicide." Not quite.
Like the underlying studies, almost all of which started with suicide or homicide cases and matched them to "controls," the meta-analysis cannot tell us whether the observed relationships are causal and, if so, in which direction the causation runs. "Whether the presence of a firearm among case patients is the result of environmental characteristics or living conditions is unclear," the authors observe. "For example, some persons may purchase a firearm for protection because of neighborhood crime." If so, that same high crime rate would increase their chances of being killed, whether or not they owned guns. Similarly, a woman might buy a gun to protect herself against an abusive boyfriend or husband. If he ends up killing her, that does not necessarily mean buying the gun made her less safe. Rather, it was her vulnerability to violence that motivated her to buy the gun.
That scenario seems especially relevant given that Anglemyer and his colleagues found the risk of homicide victimization associated with owning a gun was much higher for women than for men. Among men, the additional risk was just 29 percent, while for women it was 184 percent. Suicide risk, by contrast, was somewhat higher for men than for women, for whom the additional risk associated with access to a gun was not statistically significant.
Assuming that suicide is an impulsive act, it seems plausible that, other things being equal, access to a gun would make it easier to complete. But it is also possible that people prone to suicide are more likely to buy guns, either because they already have thought about killing themselves or because the same personality traits or circumstances that increase their risk of suicide also make gun ownership more attractive. The studies considered by Anglemyer et al. did not distinguish between these alternative explanations.
It is hard to know what is going on here without more details about the circumstances of each death. For example, in how many cases, if any, did an abusive husband disarm his wife and use the gun she bought for self-defense against her? Were the people who committed suicide determined enough that if a gun had not been available they would have killed themselves anyway? The studies not only do not answer such questions; they typically do not even distinguish between deaths by firearm and deaths by other means, a puzzling omission if the aim is to measure the risks posed by gun ownership.
More on the relationship between gun ownership and suicide here.