Further discussion of Ian Ayres & John Donohue

8/20/03 Exchange over letter in St. Louis Post-Dispatch

This is a summary of long previous post that was listed (previous original posts are here and here). Sometimes academic exchanges get out of control and they use language that is pretty inflamatory. Ian Ayres and John Donohue provide an example of such an exchange. The bottom line of that discussion is that the 1977 to 2000 county level data set has been up on my web site since February. To make the entire process easily accessible for others, the regression files are also available. Anyone who wants to critically examine the data set is thus completely free to do so and can compare it to the corrected output. It can be downloaded from the site. The data set was corrected, and the results labeled "corrected" figures, and tables have been up since April and were clearly labeled. I have also had a statement on the web site next to where the downloads were provided. While the exact wording in that statement has been edited over time, the content has remained essentially unchanged. Instead of writing to a newspaper and than posting their comment on blog sites, if there had been any confusion, a more direct approach would have been for either Ayres or Donohue to contact me and ask for clarifications.

The estimates do change somewhat, but the basic point is still clear. Whether one uses the types of statistical tests that Ayres and Donohue use for all their regressions or whether one uses the type of methodology that Plassmann argues very strongly for in the Stanford Law Review piece with John Whitley, you still get a drop in crime. Plassmann's emphasis on the type of empirical estimation that he wants to use arises because of the truncation issues and the nature of the data being count data. A statement that was available to those who wanted to download the data set used in the Plassmann and Whitley paper is available here.

There is a pretty obvious reason why these guys have choosen to publish their work in nonrefereed publications. Despite their continuing claims to the press, Ayres and Donohue's own papers do NOT provide any statistically significant evidence that violent crimes increase (for a brief discussion see point 2 here). Even most of their own results show that violent crime rates decline after right-to-carry laws are passed.

. On a different topic, a new piece is now available on "why most of what you see in the media about guns is wrong "

Update: If there had been any confusion as of August, there was surely no concern by September 20th at the American Law and Economics Association meetings. Yet, Ian Ayres continued to claim that there was a big mystery over why the tables had the "t-statistics" reported in the Tables.