Thursday, June 26, 2008

Megan McArdle on Gun Statistics

In the wake of the Heller case (which I think was decided correctly), I expect there will be a spate of op-eds and blog posts about gun control. Indeed, Megan McArdle has already plunged into the debate with this post on gun statistics. One of the main problems with gun control debates—which contributes to their food-fight-like nature—is that "gun control" is a hopelessly ambiguous phrase that means different things to different people. As a result, the two sides often end up talking past each other. McArdle's post mostly addresses the effects of allowing "normally law-abiding citizens" to carry handguns, but she wanders out of that sphere a few times (e.g., discussing "would-be homicides"), which muddles her argument. So I'm not entirely sure what she means by this:

It turns out that suicides and would-be homicides weren't paying much attention to the legality of their actions. It also turns out that having a gun in your hands does not seem to turn a previously law-abiding citizen into a spur-of-the-moment killer.
Lest this be construed as a broad claim that guns are benign, the following should be pointed out (over and over again): it also turns out that having a gun in your hands tends to turn previously non-lethal crimes (e.g., assaults, robberies) into spur-of-the-moment homicides. As for the arguments about gun ownership serving as a deterrent, I agree that we don't have sufficient data to definitively answer the question. But based on the limited data we do have, one side of the debate is clearly winning:
In the gun policy debate, a related claim about the benefit of widespread gun ownership is that it serves to deter burglars, and especially “hot” burglaries of occupied homes (Kleck, 1997; Kopel, 2001). This claim is based on little evidenc of any kind. The only systematic analysis of this point of which we are aware (Cook & Ludwig, 2003b) demonstrates by use of the geocoded National Crime Victimization Survey data that the individual likelihood of residential burglary or hot burglary is not reduced by living in a county with high gun prevalence. One reason may be that a high gun prevalence increases the profitability of burglary, because stolen guns are readily fenced and easier to carry than televisions and many other types of loot.
Broadly, I agree with McArdle that the available statistics on guns are pretty weak, although I'm probably more willing to draw conclusions based on the available evidence than she is. There has been statistical malpractice on both sides of the debate, to be sure (Michael Bellesiles comes to mind); but I can recognize statistical malpractice when I see it, so I'm not too worried about getting bamboozled. Speaking of statistical malpractice, what's John Lott up to these days?


Anonymous said...

"the individual likelihood of residential burglary or hot burglary is not reduced by living in a county with high gun prevalence"

That might be true nationwide, but I suspect "gun prevalance" is not the sole issue when it comes to reducing burglaries, particularly "hot" burglaries. I've lived and worked in two areas where hot/nighttime residential burglaries were almost unheard of. Both had high rates of gun ownership, but I suspect more importantly, both were in "castle doctrine" states that gave homeowners essentially carte blanche to kill a burglar in their home on sight without legal consequence, with no requirement to retreat. Texas actually permits you to shoot a burglar in the back as he flees if he's fleeing with stolen property. Many parts of the US have high rates of gun ownership but do require a homeowner or other crime victim to retreat if possible. Widespread gun ownership isn't going to deter crime much if you're likely to go to jail if you use your gun to protect yourself. Do you know of any studies comparing "castle doctrine" jurisdictions with non-CD areas that have similar rates of gun ownership?