More Guns Less Crime

A few years ago, the National Research Council reviewed the evidence on firearms and crime and concluded: There is no credible evidence that "right-to-carry" laws, which allow qualified adults to carry concealed handguns, either decrease or increase violent crime. Paul Cassell says that he finds plausible a new paper by Moody and Marvell that reanalyzes the data and finds carry laws associated with less crime. I do not find Marvel and Moody's conclusions plausible and they are not supported by the results of their regressions. The results are all over the place. Some crimes are up, some…

You may recall how Alex Robson demonstrated his ignorance of basic statistics and of climate research. Now he has written an op-ed in Sydney's Daily Telegraph where he claims that there is no research at all that contradicts John Lott: Laws for the concealed carrying of guns are present in some form or another in 48 US states, and serious research (most notably by Professor John Lott of the State University of New York) consistently demonstrates their deterrent effect. Robson seems to be unaware that the National Academy of Sciences reviewed the research and conducted its own analysis and…

Richard Lempert comments on why he found Lott's results implausible when they first came out: To give another example, long before other research called their results into question, it was common sense that made me suspicious of John Lott and David Mustard's claim in the Journal of Legal Studies that right to carry laws diminish violent crime. What made me skeptical was their finding that while right to carry laws diminish violent crimes like murder, rape, and aggravated assault they led to increases in non-violent property crimes. The authors had an explanation for this; namely, that the…

I've discovered another one of John Lott's attempts to rewrite history. Read on. Lott has written a response to Kevin Drum's summary of Lott's model changing antics. Here's Drum: 1. Lott and two coauthors produced a statistical model ("Model 1") that showed significant crime decreases when states passed concealed carry gun laws. 2. Back in April, two critics discovered that there were errors in the data Lott used. When the correct data was plugged into Lott's model, his results went away. 3. After a long silence, Lott admitted the data errors and posted a table with new…

Lott and Dabney have an op-ed in the Washington Times on concealed handguns in the workplace. As usual, Lott misrepresents the state of current research on firearms. Lott and Dabney write: Indeed, international data as well as data from across the United States indicate that criminals are much less likely to attack residents in their homes when they suspect that the residents own guns. Not so. In The Effects of Gun Prevalence on Burglary: Deterrence vs Inducement Philip Cook and Jens Ludwig found that areas in the US with higher gun ownership tended to have more burglaries, and more…

On his blog Lott has a sequence of postings telling a story of how the University of Chicago Federalist Society tried to organize a debate between himself and John Donohue, but Donohue kept backing out. What really happened bears little relation to the story Lott tells. In fact, Lott's account is so misleading that the Federalist Society cancelled a talk by Lott because he refused to correct his postings. His first posting was on 30 Nov 2004: Disappointingly, John Donohue has at the last minute withdrawn from our scheduled debate on Thursday (see note for 11/29 below). I will still give a…

In 1996 we were discussing Lott's "More Guns, Less Crime" paper on the firearmsreg mailing list. I've posted my comments on my blog as entries for August 1996.

The NAS has responded to Lott's attack on their panel on firearms research. I'm posting their whole letter: A Lott of misinformation The recent column by John Lott about the National Research Council's project and report on improving scientific information and data on firearms ["Mountain of evidence shows gun control doesn't work," commentary, Jan. 8] contained significant errors. The NRC is the operating arm of the National Academy of Sciences and the National Academy of Engineering. In composing the committee, the NRC ensured that all areas of relevant scientific expertise for the…

One of the disagreements between Lott and the NAS panel is on the question of whether the models fit the data. Joel Horowitz explains the problem in Appendix D of the report. For people who don't like equations, I'll try to explain the issue with some pictures. The graphs below show straight lines (these are the models in our example) fitted to two different data sets. While the line is roughly the same distance from the data points in both cases, the one on the left is bad fit, while the one on the right is a good fit. The points on the left lie on a curve and not a straight line…

Lott has some more comments on the NAS panel report on firearms research. (Also posted at the Volokh Conspiracy.) Lott adds to his earlier claims that the panel was biased with this:In fact, the panel apparently originated with the desire from some to respond to the debate on that issue and to respond specifically to my research that concludes that allowing law abiding citizens to carry concealed weapons reduces crime. I originally overheard Phil Cook and Dan Nagin discussing the need for a panel to "deal with" me in the same way that an earlier panel…

Lott has published an op-ed in the New York Post on the NAS panel. Lott once again claims that the panel was stacked:The panel was set up during the Clinton administration, and all but one of its members (whose views on guns were publicly known before their appointments) favored gun control. In his op-ed he doesn't tell us who the members are who were publicly known to be "entirely pro-gun control", but in his book The Bias Against Guns he gives three names: Richard Rosenfeld, who wrote an editorial in JAMA saying "current knowledge does not warrant relaxing or abandoning any of the Brady…

Jim Lindgren thinks the panel was too generous to Lott: From the portions that I have read, I found the report sober, impressive, and fair, though there are substantial parts of this literature that I am unfamiliar with. As to Lott's work, I actually thought that the Council's report was too generous to his research in spots. In particular, I thought that it failed to point out just how much Lott's results are driven by poorly executed demographic controls, a point that Ayres and Donohue make effectively in their Stanford exchange. While the Council's report raises a lot of questions about…

As I predicted, Lott claims that the panel was stacked: My piece in the LA Times is still accurate today. While I will write up a more substantive discussion, James Q. Wilson's very unusual dissent in the first appendix says a lot. Wilson concluded that all the research provided "confirmation of the findings that shall-issue laws drive down the murder rate . . . ." The NAS won't tell me how many panels have had dissents previously, though they admit that they are very rare. It is disappointing that the panel refused to let me ask questions during…

Stuart Benjamin writes: [John Lott's] core thesis, though, was called into doubt by a number of researchers, most prominently in a study (and reply, both complete with data sets) written by Ian Ayres and John Donohue, two top empirical economists. They concluded that the data did not support Lott's assertions regarding right-to-carry laws and crime. Lott helped to write and then withdrew his name from a response to Ayres and Donohue. He responded in other venues to them, but did not respond to some of their key assertions. Perhaps he was waiting/hoping for vindication from the closest…

The National Academy of Sciences panel on firearms and violence has reported its findings. The press release says: There is no credible evidence that "right-to-carry" laws, which allow qualified adults to carry concealed handguns, either decrease or increase violent crime. To date, 34 states have enacted these laws. There is almost no evidence that violence-prevention programs intended to steer children away from guns have had any effects on their behavior, knowledge, or attitudes regarding firearms. More than 80 such programs exist. Research has found associations between gun…

Lott has a new post on blog where he writes: 6/15/04 Two-thirds of Police Chiefs think Right-to-carry Laws Reduce Crime A new survey by the National Association of Chiefs of Police asks members: "Do you agree that a national concealed handgun permit would reduce rates of violent crime as recent studies in some states have already reflected?" 65.7 percent of members say "Yes". There are other interesting questions in the survey. Two-thirds oppose one-gun-a-month rules. Over half think that the rules allowing pilots to carry concealed handguns are too restrictive. It may be that two-…

Summary: Lott now claims that an incriminating file where he had been caught cooking his results was not meant to have been on his website and was only there because his webmaster screwed up. Unfortunately, his latest story is full of holes. Way back in September last year I detailed how, after Ayres and Donohue showed that correcting Lott's coding errors made his results go away, Lott changed his model to bring his results back. Then when I asked him questions about the changed model, he tried to cover up the change by replacing the file at johnlott.org…

Helland and Tabarrok's paper 'Using Placebo Laws to Test "More Guns, Less Crime"' has been published in Advances in Economic Analysis & Policy. Their objective was to correct for serial correlations in the crime data. I explained earlier how, if crimes rates in adjacent counties tend to behave in the same way, results could wrongly appear to be statistically significant. There is a similar problem with crime rates in the same county in two successive years tending to be the same. Helland and Tabarrok use a technique (placebo laws) that deals with serial…

On August 18, in his interview with Chris Mooney, when he was asked if there were coding errors, Lott replied:There are a couple minor errors, the data is on, the data is available for anybody to look at, anybody can go and download the data, I've made it so that people can go and easily replicate the results, if you went to the website... Two days later Lott admitted that there were "a few hundred data entries that contained mistakes". Now when Lott talked to Mooney, he must have known how many errors there were, since he had corrected them…

Lott has posted some criticism of Chris Mooney's article. Let's see how many errors he has successfully identified: 1) Paraphrasing claim from the Chronicle of Higher Education stating that the "coding errors had not been reviewed by a third party." I was never asked by the Mother Jones reporter about this reference. In fact, after the Chronicle piece was published I immediately e-mailed David Glenn at the Chronicle to point out that two different points had been merged together in his piece. It's hard to see what Lott's beef is here. The…