"Guns in the Home and Risk of a Violent Death in the Home":

Yet another study — which I learned about because it was cited to me by a fellow academic — that shows a correlation between home gun ownership and homicide and suicide risk to occupants without controlling for some obvious confounding factors.

Consider, for instance, criminal record (both its presence and its magnitude). Criminality is highly associated with extra risk of being killed (your business associates and rivals are criminals, too) and extra risk of suicide. At least for certain types of criminality, it's also likely to be associated with an extra likelihood of gun ownership, for instance because the gun is a crime tool or because the criminal needs the gun to defend himself against his criminal associates and rivals. Does the study control for this? Nope.

There are other problems with the study as well; Gary Kleck, for instance, has pointed to evidence that in many studies, quite a few respondents (perhaps 5-10% or more) conceal their gun ownership if they can. That's especially likely to happen when there hasn't been a gun death in the house, so that concealing the gun ownership is easy; so as a result, the gun ownership among the control group (where there has been no gun death) is underestimated, and the correlation between gun ownership and gun death is overestimated.

But the failure to control for the obvious criminal history variable strikes me as especially glaring. And yet such studies are read, reported on, and believed.