Donohue and Kleiman comment

Mark Kleiman has posted some comments from John Donohue about the Stanford Law Review controversy. Donohue isn't even sure what the changed word was that caused Lott to withdraw his name. (Details are here if you are interested.) And like the rest of us, Donohue is puzzled as to why Lott has no direct response to the serious allegation of coding errors.

I also have some comments from Donohue responding to claims in Lott's The Bias Against Guns. Donohue writes:

The figures on pages 237-239 of Lott's new book are the same as Figures 4a-4f in the LPW reply ("Weighted least squares estimates using county-level data from 1977-2000" for various crime categories). These are Figures that the Stanford piece shows to be wrong because of his mis-coding, but since they are now out in book form, I guess Lott doesn't want to address the fact that they are all wrong.

Just before the figures above, Lott implicitly accuses me of being somewhat deceptive: "Donohue doesn't use simple dummies for each year. Instead they [I guess now he's talking about both me and Ian, even though he's referring to the Brookings paper and we didn't do this in the Stanford piece] aggregate years into two-year groupings...This is an unusual approach, but they do it to obscure in their results the large drop that occurs between the year of passage and the first full year that the law is in effect for their sample period." But the Stanford piece does contain the year-by year dummies, which don't support Lott in any event.

Lott then goes on to say "Despite all the work that has been done on the topic of concealed handguns, it is remarkable that no academic study has found a bad effect from these laws." Not true if you take the aggregated state-specific effects on crime (which are modestly positive -- ie. pernicious).

Kleiman also has another, interesting post on the mechanisms by which concealed-carry laws could cause crime increases or decreases. He can see mechanisms by which it might cause violent crime increases or decreases, but not property crime increases, suggesting that the property crime increases that Ayres and Donohue found were caused by something other factor. This other factor could well have caused the violent crime increases.

Well, there is a mechanism by which the laws could have caused property crime increases. In fact, Lott and Mustard proposed it in their initial paper---criminals are deterred from robberies into property crimes. Of course, Ayres and Donohue found that robberies went up as well, but that could be explained by some criminals being deterred and switching to property crimes, while others decide to carry guns, leading to an increase in impulsive robberies that more than makes up for the decrease caused by some robber switching to property crime. [Update: Kleiman points out that the increase in the number of property crimes is too large to be explained by any plausible decrease in robberies, so this mechanism doesn't work.]

Now, while this mechanism is possible, I don't think that the carry laws caused the crime increase. My reason is the same as the reason why, before Lott's results were refuted, I didn't think that carry laws caused a crime decrease. The carry laws did not cause any significant increase in gun ownership. Nor were there significantly more guns carried in public places. And nor were there more guns used to defend against crime. There may be a very small number of crimes committed by permit holders, and a very small number of criminals might take up gun carrying after encountering a permit holder, but the crime increases this would cause would be smaller than those observed by Ayres and Donohue. So it is possible that the carry laws increased crime, but I would expect the increase to be very small.

However, some people have ignored or dismissed these issues and citing Lott's work, advocated passing such laws to reduce crime. To be consistent, such people should now advocate repealing the carry laws to reduce crime. To my knowledge, not one carry law advocate has done this.

Glenn Reynolds comments on Kleiman's post, stating than in his area the carry law made little difference in gun carrying.

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