The only clues Lott gives me is references to two papers, one by Bartley and Cohen, and one by Plassmann and Tideman. I don't include any quotations from these papers, so perhaps Lott is trying to say that I didn't accurately report their conclusions.

Bartley and Cohen [4] summarize their conclusions in their abstract:

We find that the deterrence results are robust enough to find them difficult to dismiss as unfounded, particularly those findings about the change in violent crime trends. The substitution effects are not robust with respect to different model specifications.

I wrote:

if we restrict things to just models that include a trend component, homicide and robbery show consistent reductions. For this reason, Bartley and Cohen argued that Lott's results should not be dismissed as unfounded.

Lott also claims:

Bartley has another piece in Economic Letters where he describes how his paper with Cohen provides ``strong support'' for the deterrence hypothesis. [3]What Bartley actually says is:

Bartley and Cohen (1998) find that some evidence does exist from extreme-bounds analysis that violent crimes, such as rape and murder, may be reduced by the passage of these laws.The words ``strong support'' do not appear anywhere in Bartley's article.

Plassmann and Tideman [39] summarize their conclusions in their abstract:

John Lott and David Mustard have argued that their county-level weighted least-squares analysis shows that the right to carry concealed handguns has a statistically significant deterrent effect on crime. However, the number of crimes committed in a county in a year is a non-negative integer that is zero or one in most cases for some important crimes, which makes the estimates of an analysis that assumes a normal distribution unreliable. In a weighted least-squares analysis the conclusions of Lott and Mustard with respect to murders vanish when some plausible changes are made in the specification that is estimated. However, when the data are analyzed as the product of a generalized Poisson process, the average effect of shall-issue laws on the number of murders is even stronger than Lott and Mustard estimated, and the effect is estimated with much greater precision.I wrote:

Plassman and Tideman [39] point out that Lott's analysis technique assumes that crime rates are normally distributed and that this is not even close to being true for low crime counties. When they made some plausible changes to the specification, the effects on murder vanished. However, when they did their own analysis assuming that the murder rate was Poisson distributed, they found an even stronger effect (a 12% decrease).

Readers can judge for themselves whether my summaries are accurate.

Tim Lambert