Reponse to Webster's claims about my work on concealed handgun laws:
1) Omitted Variables and Failure to Control for Crime Cycles
"Despite claims to the contrary, the regressions do control for national and state crime trends in several different ways. At the national level, I use a separate variable for each year, a technique that allows me to account for the changes in average national crime rates from one year to another. Any national cycles in crime rates should be accounted for by this method. At the state level, some of the estimates use a separate time trend for each state, and the results with this method generally yielded even larger drops in violent-crime rates associated with nondiscretionary (shall issue) laws.
"To illustrate that the results are not merely due to the ´normal' ups and downs for crime, we can look again at the diagrams in chapter 4 showing crime patterns before and after the adoption of the nondiscretionary laws. The declines not only begin right when the concealed-handgun laws pass, but the crime rates end up well below their levels prior to the law. Even if laws to combat crime are passed when crime is rising, why would one believe that they happened to be passed right at the peak of any crime cycle?"
- John Lott, MORE GUNS, LESS CRIME, pp.
Despite Webster's claims, my work has accounted for poverty as well as several different measures of income. I also accounted for "adaptions in the criminal justice system to rising crime" by controlling for arrest rates, conviction rates, and prison sentence lengths. I have also used information on police officers and other law enforcement employees per capita.
2) Erroneous Assumptions
Webster cites Black & Nagin as claiming that my work allegedly assumes "(1) an immediate and constant effect of RTC laws; and (2) similar law effects across different states." My book replies to this also:
"One of the central arguments both in the original paper and in this book is that the size of the deterrent effect is related to the number of permits issued, and it takes many years before states reach their long-run level of permits. Again, the figures in chapter 4 illustrate this quite clearly.
"I did not expect the number of permits to change equally across either counties or states. A major reason for the larger effect on crime in the more urban countries was that in rural areas, permit requests already were being approved; hence it was in the urban areas that the number of permitted concealed handguns increased the most."
- John Lott, MORE GUNS, LESS CRIME, p. 131
3) Errors in Characterizing Right-to-Carry Laws
I relied on a paper published in the Tennessee Law Review (Spring 1995) by Clayton Cramer and David Kopel to determine when different states adopted shall issue laws. A separate Nexis data base search was also conducted to determine the exact date of adoption.
Because of different interpretations over whether a particular law constituted a shall issue law, the results were tested to see whether defining Maine and Virginia as shall issue states made a difference and it did not (in the original paper see p. 12, fn. 34 and p. 19, fn. 49 and in my book see p. 201, fn. 5).
In any case, I agree with Cramer and Kopel's classification of state laws. Virginia's 1988 law explicitly uses the term "shall-issue," and, with the exception of three counties, the state followed that rule.
4) Inclusion of Inappropriate Variables in the Analysis
The only variable that Webster mentions is the arrest rate.
"The simplest point to make, however, is that excluding the arrest rate does not alter the findings regarding concealed handguns. Reestimating the regressions in tables 4.1 and 4.3 for the same samples and control variables produces virtually identical results. Ironically, two of my strongest critics, Dan Black and Dan Nagin, also tried excluding the arrest rates, and they admitted in early drafts of their paper that their results agreed with ours: ´The inclusion of the arrest-rate variable has very little impact on the coefficient estimates of the right-to-carry laws.'"
- John Lott, MORE GUNS, LESS CRIME, p. 146
5) Interstate Variability in Estimating Right-to-Carry Effects and Sensitivity to the Inclusion of Single States
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 they ignore that doing this actually strengthens some of the results.
In my book I write:
"This particular suggestion--that we should throw out the data for Florida because the drop in violent crimes is so large that it affects the results-- is very ironic. Handgun Control, Inc. and other gun-control groups continue, as of this writing, to cite the 1995 University of Maryland study, which claimed that if evidence existed of a detrimental impact of concealed hand- guns, it was for Florida. If the Maryland study is to be believed, the inclusion of Florida must have biased my results in the opposite direction.
"While Black's & Nagin's explanations for dropping Florida from the data set are invalid, there is some justification for concern that results are being driven by a few unusual observations. Figure 7.7 shows the relationship between violent-crime rates and concealed-handgun laws when Florida is excluded. A careful comparison of this graph with that of figure 4.5, which includes Florida, reveals only a few very small differences.
"As a more systematic response to this concern, I excluded Florida and reestimated all the regressions shown in this book. Indeed, there were eight regressions out of the more than one thousand discussed in which the exclusion of Florida did cause the coefficient for the nondiscretionary variable to lose its statistical significance, although it remained negative. The rest of the regression estimates either remained unchanged or (especially for aggravated assault and robbery) became larger and more statistically significant."
- John Lott, MORE GUNS, LESS CRIME, pp.
Webster states that Florida's decline in violent crime is due to other factors besides its right-to-carry law, such as "mandatory background checks and waiting periods for handgun purchases," "other criminal justice interventions," & "maturation of Florida's crack cocaine markets." In my book I wrote:
"The claim that Florida should be removed from the data because a waiting period and a background check went into effect in 1992 is even weaker. If this were a valid reason for exclusion, why not exclude other states with these laws as well? Why only remove Florida? seventeen other states had waiting periods in 1992. A more valid response would be to try to account for the impact of these other laws--as I did in chapter 4. Indeed, accounting for these other laws slightly strengthens the evidence that concealed handguns deter crime.
"The graph for Florida in figure 7.6 produces other interesting results. The murder rate declined in each consecutive year following the implementation of the concealed-handgun law until 1992, the first year that these other, much-touted, gun-control laws went into effect. I am not claiming that these laws caused murder rates to rise, but this graph surely makes it more difficult to argue that laws restricting the ability of law-abiding citizens to obtain guns would reduce crime."
- John Lott, MORE GUNS, LESS CRIME, pp.
As to drug problems explaining crime rates, I control for illegal drug prices in my regressions.
With respect to Webster's discussion of the increase in crime in West Virginia, I write:
"Unfortunately, Black's and Nagin's evidence was not based on statewide crime rates but on the crime rates for counties with over 100,000 people. This fact is important, for instance, in West Virginia, where it means that only one single county - Kanawha - was examined. The other fifty-four counties in West Virginia, which include 89 percent of the state's population, were excluded from their estimates. They used only one county for three of the ten states, and only three counties for another state. In fact, Black and Nagin managed to eliminate 85 percent of all counties in the nation in their analysis.
"As shown in table 4.9 (see chapter 4), my estimates using all the counties certainly did not yield ´wildly' different estimates across states. Violent- crime rates fell in nine of the ten states enacting new nondiscretionary concealed handgun laws between 1977 and 1992. The differences that did exist across states can be explained by differences in the rates at which concealed- handgun permits were issued. Table 4.10 also provides evidence that the states that issued more permits experienced greater reductions in crime."
- John Lott, MORE GUNS, LESS CRIME, pp. 142-143
6) Following Black and Nagin, Webster states that my "models failed standard tests of statistical adequacy for each of the categories of crime."
If you can please point to the relevant discussion in the Black and Nagin article (Journal of Legal Studies, January 1998, Vol. 27), I would be happy to respond.
7) Lott and Mustard's findings depart from well established facts about crime
a) The impact should be greatest for robbery
"First, as anyone who has carefully read this book will know, it is simply not true that the results show "little or no effect on robbery rates." Whether the effect was greater for robbery or other violent crimes depends on whether one simply compares the mean crime rates before and after the laws (in which case the effect is relatively small for robbery) or compares the slopes before and after the law (in which case the effect for robbery is the largest). "Second, it is not clear that robbery should exhibit the largest impacts primarily because `robbery' encompasses many crimes that are not street robberies. For instance, we do not expect bank or residential robberies to decrease, and, in fact, they could even rise. Allowing law-abiding citizens to carry concealed handguns makes street robberies more difficult, and thus may make other crimes like residential robbery relatively more attractive. Yet, not only is it possible that these two different components of robbery move in opposite directions, but to rank some of these different crimes one requires information on how sensitive different types of criminals are to the increased threat.
- John Lott, MORE GUNS, LESS CRIME, pp. 133-134
b) The implausibility of rapists switching to property crimes
"No one believes that hard-core rapists who are committing their crimes only for sexual gratification will turn into auto thieves, though some thefts do involve aggravated assault, rape, or murder. Indeed, 16 percent of murders in Chicago from 1990 to 1995 occurred in the process of a robbery. What is more likely to happen, however, is that robbers will try to obtain money by other means such as auto theft or larceny. Although it is not unusual for rape victims to be robbed, the decline in rape most likely reflects the would-be rapist's fear of being shot."
- John Lott, MORE GUNS, LESS CRIME, p. 134
c) "theft is the motive for only a small fraction of the violent crimes"?
"I am also not completely clear on what Webster means when he says that ´theft is the motive for only a small fraction of violent crimes,' since robbery accounted for as much as 34 percent of all violent crimes committed during the sample between 1977 and 1992 (and this excludes robberies that were committed when other more serious crimes like murder or rape occurred in connection with the robbery)."
- John Lott, MORE GUNS, LESS CRIME, p. 134
d) "the only hint of a decrease in murder rates" was enjoyed by those under 21 years of age, too young to get concealed-carry permits, thus supposedly casting doubt upon the claim that concealed-carry laws are responsible for the decline.
"As noted in chapter 4, I tested the hypothesis that murder rates would be lower for adults than for adolescents under nondiscretionary concealed- handgun laws, and reported the results in the original paper. However, the results did not bear out this possibility. Concealed-handgun laws reduce murder rates for both adults and for adolescents. One explanation may simply be that young people also benefited from the carrying of concealed handguns by adults. Several plausible scenarios may explain this. First, criminals may well tend to leave an area where law-abiding adults carry concealed handguns, and since all age groups live in the same neighborhood, this lowers crime rates for all population groups. Second, when gun-carrying adults are physically present, they may be able to protect some youngsters in threatening situations."
- John Lott, MORE GUNS, LESS CRIME, p. 147
7) Subsequent research
a) Black and Nagin "compared crime rate trends two to three years after RTC laws were enacted with rates two to three years prior to enactment, they found no clear pattern in the result" that concealed handgun laws reduced violent crime
"A quick glance at figures 7.1 to 7.5, which plot their results, will explain their findings. Generally, the pattern is very similar to what we reported earlier. In addition, as crime is rising right up until the law is adopted and falling thereafter, it is not surprising that some values when the crime rate is going down are equal to those when it was going up. It is the slopes of the lines and not simply the levels that matter. But more generally, why choose to compare only two or three years before and after to look at changes created by the law. Why not use all the data available?
- John Lott, MORE GUNS, LESS CRIME, pp. 135-138
b) Claim that Mustard and I did not control for waiting periods as well as other gun laws.
This is simply false. I control for many different types of gun laws in many different parts of both the original paper as well as the book. Doing so actually tends to slightly strengthen the results.
I believe that the other points made by Webster about Black and Nagin's comment on my work are dealt with extremely well by David Friedman's analysis on the debate.