More Guns Less Crime
tlambert | June 7, 2003Lott has a new posting where he responds to a letter from John Donohue to the Columbus Dispatch replying to a Lott op-ed. I earlier posted a link to the op-ed and a letter from Michael Maltz replying to it.
I'll post more on Lott's comments later, but for now I want to point to the most important thing in his posting: see also the data and updated results available at www.johnlott.org.
"Updated results?" If you go to his site you will find corrected versions of the graphs and tables that Ayres and Donohue said were incorrect because of coding errors. The most interesting of…
tlambert | May 21, 2003 Posts by d-squared and John Quiggin on data mining and Lott reminded me that Lott accused his critics of data mining in a response to Webster: The Black and Nagin paper excludes Florida after they have already excluded the 86 percent of the counties with populations fewer than 100,000. Eliminating Florida as well as counties with fewer than 100,0000 does eliminate the significance in the one particular type of specification that they report for a couple of crimes, but the vast majority of estimates were unaffected from this extreme data mining and…
tlambert | May 15, 2003ArchPundit has a thoughtful analysis of the latest from Reynolds and Lott.
Shorter dsquared: If you use some data to construct a model, then to test it properly you need new data. Lott's approach is a little different. The model that was given greatest prominence in the original Lott and Mustard paper (the results of this model where given in the abstract and whenever Lott summarized his paper) showed that there was a 3.5% decline in the violent crime rate associated with the carry laws. In the second edition of More Guns, Less Crime Lott…
tlambert | May 13, 2003Jeff Johnson of CNSNews.com writes a very pro-Lott piece on the dispute between Lott and Ayres and Donohue. Probably the most notable feature is what is not mentioned---there is nothing about the coding errors Lott made. We can be sure that Donohue mentioned the problem to Johnson, but Lott had nothing to say on the matter and Johnson chose not to mention it. [Update: I checked with Donohue and he told me that he didn't get to mentioning the coding errors. My mistake. It is still true that Lott did not use this chance to dispute the allegation of…
tlambert | May 8, 2003Three recent papers that contradict Lott's "More Guns, Less Crime" theory:
Duwe, Kovandzic and Moody, "The Impact of Right-to-Carry Concealed Firearm Laws on Mass Public Shootings" Homicide Studies Journal, 6:4 pp 271-296 (2002). Duwe et al find no statistically significant impact of carry laws on mass public shootings, contradicting Lott's claims in his new book and an earlier paper with Landes. (Lott does not even mention this paper in his book.) Even when they tried to replicate Lott's results they could not find a significant effect.
Helland and Tabarrok in Using…
tlambert | May 7, 2003Mark 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…
tlambert | May 6, 2003So what was the one word correction that prompted Lott to remove his name from his paper? In their draft, Ayres and Donohue wrote (my emphasis): On the other hand, the temporal pattern, that states adopting shall-issue laws in the late 1980s did better while those adopting in the 1990s did worse, may simply reflect the influence of a time-varying factor (the crack trade?) that caused sharp rises in crime for many states in the late 1980s, and then greater-than-average price declines in the 1990s.
Now the word "price" here makes…
tlambert | May 5, 2003Archpundit has some thoughtful comments on Mark Kleiman's post. Ryan Barrow has a short comment. Glenn Reynolds would like someone else to check to see if the Ayres and Donohue are correct about the coding errors. I think the way that Lott persistently ducks the question gives a strong indication where the truth lies.
Tom Spencer comments on Maltz's rebuke of Lott.
tlambert | May 4, 2003Brian Linse comments on Mark Kleiman's post and suggests that people should write to the University of Chicago Press and ask them to investigate Lott. Tom Spencer also comments on Kleiman's post, as do Kevin Drum and Matt Yglesias.
Lott has just published an op-ed in the Minneapolis Star Tribune entitled "Gun control advocates' credibility on line". This op-ed is largely recycled from one published a couple of weeks ago in the Columbus Dispatch. He cites research by Olson and Maltz that he alleges shows that concealed carry reduced gun carrying by criminals: Other…
tlambert | May 3, 2003In his email to Mark Kleiman, Lott accused Ayres and Donohue of lying:However, the Stanford Law Review allowed Ayres and Donohue to add an addition to their piece commenting on all this. They said that:"It is important to note that what we now refer to as the PW response has already been widely circulated as a draft, whose first author is John Lott. Moreover, Lott has repeatedly told the press and/or publish to the Internet that Ayres and Donohue have simply misread their own results. But after seeing this Reply to the original Lott, Plassmann, and Whitley paper, Lott asked the Stanford…
tlambert | May 2, 2003Mark Kleiman has written a must read post covering the recent developments and concluding:
defenders of gun rights should stop citing Lott as an authority
the University of Chicago Press should conduct a formal enquiry into the existence of the 1997 survey
the AEI should conduct an enquiry into Lott's professional ethics Mark both spoke to Lott and posted a long email. Yet again, Lott does not admit to making any coding errors. In fact he comes close to denying making such errors when he writes: Ayres and Donohue's attacks on the quality of our data are not only…
tlambert | May 1, 2003Still nothing from Lott on whether he concedes or denies the charge of coding errors.
In the mean time, let's examine his other claim: "Ayres and Donohue have simply misread their own results." This is a remarkable claim. Lott is saying that crime went down but somehow Ayres and Donohue read a decrease as an increase. If you look through the Lott/Plassman/Whitley (I'll just abbreviate this to Lott) paper to find the basis for this, you find they are referring to Ayres and Donohue's figures 3a to 3e. Figure 3b shows murder, with virtually no change…
tlambert | April 30, 2003One more quote from yesterday's Chronicle of Higher Education article: Mr. Lott also points out that because the claim of coding errors appears in a law review, it has not been subject to review by third-party scholars, as would have been the case in a peer-reviewed economics journal.
It has been weeks since Lott saw the claim of coding errors. It would have taken him a few minutes to check for the existence of the errors and not much longer to see if correcting the errors reverses his results as Ayres and Donohue claim. He must know full…
tlambert | April 29, 2003David Glenn has an article (subscription required) in The Chronicle of Higher Education on the Ayres/Donohue/Lott dispute. Here are the responses from Lott and Whitley to the allegation of coding errors: Mr. Lott replies that the alleged coding errors are irrelevant to the larger debate. "Whether one believes the regressions in the Plassmann and Whitley piece or not, just looking at Ayres and Donohue's own results -- you can't look at the graphs that Plassmann and Whitley have of Ayres and Donohue's results and not see a significant drop in violent crime."
"The basic results are not…
tlambert | April 28, 2003John Quiggin comments on the collateral damage the Lott affair has inflicted on Lott's allies and supporters. Chris Lawrence has an update to his earlier post. Tapped has a brief summary of the latest installment in the saga.
Julian Sanchez and Kevin Drum mention Lott's response, posted by Glenn Reynolds. Lott says that reason that he removed his name from the paper was because of an editorial dispute with the Stanford Law Review: When I agreed to do the paper for the Stanford Law Review that responded to Ayres and Donohue's attack on my work, I got a promise…
tlambert | April 27, 2003 skippy comments on Lott's "coding errors". Tom Spencer thinks that Lott's days are numbered. Mike Spenis has written off Lott.
Chris Lawrence agrees that there were coding errors but argues that is easy to make such errors. I agree that such errors are easy to make, but, he did it twice, and the errors seem to systematically favour his position. Another thing that strikes me when I read Ayres and Donohue's paper is that they report many regression results, some of which are favourable to the "more guns, less crime" thesis, but more of them are not. The…
tlambert | April 26, 2003 Several people have commented on the latest developments. Atrios has resolved that Lott is a liar and a fraud. Kevin Drum has his usual nice summary. Jesse Taylor isn't really interested because he believes that Lott has already been discredited. Julian Sanchez and Chris Lawrence are reluctant to draw conclusions yet.
I think we have, however, enough information to draw some conclusions. There really were coding errors in the data Lott used for his NAS panel presentation. Mustard seems to have conceded this when he withdrew a graph based on that data. And…
tlambert | April 25, 2003This is a long post, so I'll start with two summaries. One sentence summary: It looks as if Lott might have been caught cooking his "more guns, less crime" data.
One paragraph summary: Ian Ayres and John Donohue wrote a paper that found that, if anything, concealed carry laws lead to more crime. Lott, (along with Florenz Plassmann and John Whitley) wrote a reply where they argued that using data up to 2000 confirmed the "more guns, less crime" hypothesis. In Ayres and Donohue's response to that paper, they found that Lott's data contained numerous coding errors that…
tlambert | April 24, 2003David Kaun, who is Professor of Economics at University of California Santa Cruz has an article over at BuzzFlash discussing Lott's More Guns, Less Crime.