In Chapter 9

This chapter only appears in the second edition of ``More Guns, Less Crime''.

9.1 How do we know that these findings are not a result of the normal ups and downs in crime rates?

Lott starts with a false claim ``Even my most determined critics concede one point: violent-crime rates fell at the point on time that the right-to-carry laws went into effect.'' As far as I know none of Lott's critics have conceded this point, possibly because there is no good evidence that it is true (as shown earlier).

Lott goes on to argue that the reductions were not just the result of crime trends because

9.2 Does it make sense to control for nonlinear time trends in every state?

Here Lott makes a very strange argument--that including nonlinear trends for regions is reasonable but including nonlinear trends for individual states makes no sense. If it reasonable for crime rates to follow nonlinear trends in regions, then surely it is reasonable for crime rates to follow nonlinear trends in individual states. Lott argues that a crime rate that was rising before the carry law and as a result of the law started falling after the law would be fitted by a nonlinear trend, making it look like the law had no effect. Equally, you could argue that if a crime rate that following a nonlinear trend which peaked before the carry law, Lott would fit it with a model that showed an increase until the law was passed and then a decrease afterwards, making it look like the law had an effect when nothing special happened to crime rates when the law was passed.

To resolve the situation it would be necessary to fit a model with both individual nonlinear trends and a parameter that allowed the trend to change at the time of the carry law. We could then test to see if the change in the trend was statistically significant.

Unfortunately, while some of the models considered by Lott contain a parameter that measures the change in a trend at the time of the carry law, none of them contain nonlinear trends for individual states (and so would be expected to fail the Heckman-Hotz tests for misspecification). And while the model considered by Black and Nagin contains nonlinear trends for individual states it only allows the carry law to change the crime rate, and not the crime trend.

To summarize, Lott is wrong when he claims that nonlinear trends in each state make no sense, and we don't know whether his results on changes in crime trends associated with the carry laws would still be significant if nonlinear trends in each state were controlled for.

9.3 Should one expect an immediate and constant effect from right-to-carry laws with the same effect everywhere?

In the original paper written with David Mustard, the model with an immediate and constant effect was clearly the primary one--the results from it were the ones given in the abstract and the other models considered were variations on it. Black and Nagin were responding to that paper, so it was quite reasonable for them to focus on that model. They found that that model failed the Heckman-Hotz tests for misspecification.

Now that Lott has moved to a different preferred model, the appropriate way to answer their objections would be test to see if the new model satisfies the Heckman-Hotz tests. Lott has not done this.

9.4 Can changes in illegal drug use explain the results?

Lott argues that the changes in crime rates are unlikely to have been caused by changes in illegal drug use because:

9.5 Do right-to-carry laws significantly reduce the robbery rate?

This is part of Lott's response to this document. My rebuttal is here.

9.6 Is the way criminals learn about victims' ability to defend themselves inconsistent with the results?

Lott argues that the data strongly suggests that criminals respond to the actual increased risk rather than the announcement of the carry laws. However, all of the data he mentions is also consistent with a crime trend and Lott does not mention the data that shows that the increased risk was negligible.

9.7 Have prominent ``pro-gun'' researchers questioned the findings in Lott's book?

Lott actually responds again to the same Kleck quote in section 9.14, except that in that section he mistakenly attributes the quote to me. Lott writes ``Let me try to explain the meaning of Kleck's quote'', and then fails to explain the meaning of the quote.

The explanation of the quote is simple. As the quote from Kleck inside the front cover of ``More Guns, Less Crime'' indicates, Kleck has no problem with the design or methodology of Lott's study. Kleck disagrees with Lott's conclusions because Kleck's own research indicates that a significant number of people carry guns for protection even without carry laws. The number of carry permits issued represents a relatively small increase in the number of people carrying, insufficient to cause the crime decreases that Lott claims the carry laws caused.

9.8 Do concealed-handgun permit holders pose a risk to others?

It is true that permit holders are less likely to commit crimes than the average person. This is because a people with criminal records are not eligible for permits. However, Lott understates the risk they pose to others. In Texas, three permit holders have been convicted of murder, while another permit holder used his gun to kill himself after committing a murder [44].

9.9 Are the CBS and Voter News Service polls accurately reflecting how gun ownership rates vary across states?

Lott completely fails to address any of the criticisms of his use of these surveys. For details, see here.

In a later paper on safe storage laws [32] Lott and Whitley do not use these exit polls. Instead they use GSS surveys to measure how gun ownership changes as a result of a state passing a safe storage law. Using these polls they find that gun ownership declined by one percentage point per year in the states with the laws and argue that the laws caused increases in crime rates.

Lott does not explain why, after stoutly defending his use of the exit polls to measure changes in gun ownership at the state level he abandoned them for his later paper. One possible explanation is that the exit polls say the opposite thing to the GSS surveys. The exit polls show substantial increases in gun ownership in the states that passed safe storage laws. I computed a regression relating the change in gun ownership as measured by the exit polls to the number of years that a safe storage law had been in place and found that the laws were associated with a 0.06 percentage point per year increase in gun ownership rates. This increase is not statisitically significant, but it is the opposite sign to Lott's result using the GSS surveys.

Since the exit polls give the opposite result from the GSS surveys it is quite possible that if Lott has conducted his analysis in chapter 3 using the GSS surveys he would have gotten the opposite result and found that more guns were associated with more crime.

It is not good practice to choose your data source to get the result you desire.

9.10 Has Lott ignored the costs of gun violence?

Lott answers this criticism satisfactorily, since, as he points out, his models include the cost of violence.

9.11 What happens to the evidence when Florida and counties with fewer than 100,000 people are removed from the sample?

The results of excluding Florida were discussed earlier.

9.12 Are the results valid only when Maine and Florida are included?

While Lott shows that if you look at changes in the trends rather than the changes in the rates there is a still a significant change associated with the law in the states other than Maine and Florida, his results also show that issuing a permit in Maine and Florida had four times the effect on violent crime as issuing a permit in the other states. They also show that issuing a permit in Maine and Florida reduced property crime just as much as it reduced violent crime. This suggests hat the results in those states were the product of general decreases in crime relative to other states and not the carry laws.

9.13 Was it proper to assume that more permits were issued in the more populous counties after right-to-carry laws were adopted?

Since Lott has county level data on permits for some states, an appropriate response here would have been to have used this data to test to see if permits were actually issued at a greater rate in more populous counties. It is puzzling that he did not so this. The one extra piece of information that he provides in his answer seems to be evidence against his theory--he finds bigger drops associated with a change from discretionary to non-discretionary permits than from no permits to non-discretionary permits, even though you would expect a greater change in the number of permits in a change from no permits than in a change from discretionary permits.

9.14 Did the passage of right-to-carry laws result in more guns being carried in public places?

This is part of Lott's response to this document. My rebuttal is here.

9.15 Shouldn't permit holders be required to have the same type of training as police officers?

I agree that because of different circumstances citizens do not necessarily require the same training as police, but Lott contradicts himself in his comments here, stating both that ``Training requirements improve the deterrence effect for concealed-handgun laws'' and that the ``effect of increased training is clearly to reduce the deterrent effect''.

9.16 Where does the academic debate stand?

Tim Lambert