Errors in More Guns, Less Crime

Unless otherwise specified, the page numbers below are the same in first and second editions of Lott's book. Unfortunately, Lott has corrected only one of these errors in the second edition, and that ``correction'' turns an error into what is probably a lie.
Page 3
Lott writes ``If national surveys are correct, 98 percent of the time that people use guns defensively, they merely have to brandish a weapon to break off an attack.'' In fact, Kleck's survey [22] indicates that 24% fired the weapon and the NCVS indicates that 38% fired the weapon [40]. Five other surveys give numbers between 34% and 67% [21].

In the second edition Lott changes ``national surveys'' to ``a national survey that I conducted''. This is a fabrication. There is no evidence that Lott ever conducted such a survey. Lott provides some details about what he claims to have done in a letter to The Criminologist [28] and a phone conversation with James Lindgren [23].

Unfortunately for Lott, he first made the claim about 98% brandishing on Feb 6, 1997 [24] before the survey he alleges it came from was completed. Even if he did conduct a survey (unlikely, given the lack of evidence that he did), he has not told the truth about the origin of the 98% figure.

Page 4
Lott claims that Lawrence Southwick [43]
found that the probability of serious injury from an attack is 2.5 times greater for women offering no resistance than for women resisting with a gun. In contrast, the probability of women being seriously injured was almost 4 times greater when resisting without a gun than with resisting with a gun. ...

Men also fare better with guns, but the differences are significantly smaller. Behaving passively is 1.4 times more likely to result is serious injury than resisting with a gun. Male victims, like females also run the greatest risk when they resist without a gun, yet the difference is again much smaller: resistance without a gun is only 1.5 times as likely to result in serious injury than resistance with a gun. The much smaller difference for men reflects the fact that a gun produces a smaller change in a man's ability to defend himself than it does for a woman.

Southwick's description of his findings is very different from Lott's (page 362 of [43])

Table 6 also reports the number of serious injuries received by those who choose each set of actions. The only significant difference here is in the likelihood of receiving an injury if one takes no action.

What Southwick noted and Lott failed to report to his readers is that none of the numbers Lott reported are statistically significant.

Here are 95% confidence intervals (calculated from the data in table 6 of [43]) for the injury rate ratios mentioned by Lott:

Ratio value lower upper
    limit limit
female: no resist/gun 2.5 0.35 17.4
female: resist/gun 4.0 0.57 28.1
male: no resist/gun 1.4 0.85 2.3
male: resist/gun 1.5 0.91 2.4
All of the confidence intervals include the number 1. This means that resisting with a gun is not associated with a statistically significant lower injury rate for women or men. Nor are the differences between the ratios for men and women statistically significant.

Even if the ratios were statistically significant they would not prove that resisting a criminal attack with gun is a safer choice than not offering resistance. Correlation is not the same as causation. The correlation in the NCVS data could equally well come about if serious injury made with-gun resistance less likely or if there were other differences between with-gun resistors and others. The BJS warns against drawing the conclusions that Lott does [40].

Page 5
The ``hot burglary'' rate in Canada is 9% [41] which is less than than that for the US. The ``hot burglary'' rate in England is indeed higher than that for the US, but if that is enough to conclude that guns cause this difference, we should also conclude that guns cause the US homicide rate to be far higher than that of England. Lott also claims that American burglars spend more time than their foreign counterparts ``casing'' a house. This is pure speculation--he has no evidence at all for this claim.

Cook and Ludwig conducted a multi-variate analysis of gun prevalence and burglary in the US [7] and found that where there were more guns the burglary rate was actually higher (that is, more guns, more burglary). Moreover, the ``hot burglary'' rate was not lower where there were more guns.

Page 10
Lott states that child-resistant bottle caps actually have resulted in ``3,500 additional poisonings of children under age 5 annually from [aspirin-related drugs] ...[as] consumers have been lulled into a less-safety-conscious mode of behavior by the existence of safety caps.'' I reviewed the literature on this topic and found that the only study to conclude that child-resistant packaging caused harm is the one cited by Lott. All the other studies (none of them mentioned by Lott) found substantial reductions in poisonings [42]. The most recent and sophisticated study [42] found a 45% reduction in deaths. Furthermore, no evidence for the claimed ``lulling'' effect exists--studies have found that people do not store medicines with child-resistant caps differently from medicines without them.
Page 11
Lott claims that the National Crime Victimization Survey does not weight regions by population and relies too heavily on urban data. Lott offers no evidence for this claim and apparently would have us believe that the NCVS has been conducted incompetently for over 25 years and no-one has noticed and made the trivial fix to the problem. He also falsely claims that a law-enforcement agency asks the NCVS questions. In fact, the NCVS is conducted by the Census Bureau, which is not a law-enforcement agency.
page 11
Lott claims that ``fifteen national polls...imply that there are 760,000 defensive handgun uses to 3.6 million defensive uses of ant type of gun per year''. However, the reference he cites [22] gives a table containing data from thirteen polls. However, three of the polls are not national polls, but are confined to a single state and two of the polls do not yield an estimate at all. Two later surveys [22,6] could be added to this yielding a total of ten ``national polls''.

In a reply [28] to an article by Otis Dudley Duncan [13] that pointed out this error, Lott compounds his error. Rather than admit to making a mistake, he falsely claims that the table contains fifteen polls. It doesn't--there are thirteen polls listed in that table [22].

Page 24
Lott grossly misrepresents Kellermann's study. He states that ``they fail to report that in only 8 of these 444 homicide cases could it be established that the gun involved had been kept in the home.'' Kellermann et al do indeed fail to report that, but that is because it is not true. They do note that in 8 out of a subset of 14 cases the police report stated that the gun involved had been kept in the home. Needless to say, 14 is not equal to 444. Lott goes on to claim that ``all or virtually all the homicide victims were killed by weapons brought into their homes by intruders''. This claim is also false. Table 1 of Kellermann's paper [19] shows that only 14% of the homicide victims were killed by intruders. My analysis of Kellermann's data shows only 8% of the homicide victims were killed with guns by intruders.

This is not the only way that Lott has misrepresented Kellermann's study. He claims that the case-control method, as used by Kellermann, was not designed to study these sort of issues because other factors could cause a correlation between gun ownership and homicide. This claim is also false. Lott fails to tell his readers that Kellermann did a multivariate analysis, controlling for dozens of other factors. Earlier (page 4), a simple correlation without controlling for other factors was enough for Lott to conclude causation when it suited his purposes.

Page 52-53
In table 4.1 he claims that carry laws cause a 7.7% decrease in murder. However, in table 3 of the Lott-Mustard paper the result of the same regression is shown as a decrease of -0.0765 in the natural log of the murder rate, which is a decrease of $1-e^{-0.0765} = 7.4\%$. Lott has obtained his percent changes by multiplying the change in the natural log of the crime rates by 100. This is only an approximation to the correct value, and for large changes, not a good one. Every single percent change given in this table and the other tables giving percent changes (tables 4.3, 4.4, 4.5, 4.6, 4.8, 4.9, 4.10, 4.11, 4.13, 4.14, 5.1, 5.4, 5.5, 5.6, 5.7, 9.1, 9.3, 9.4, 9.6 and A5.1) is calculated incorrectly.

Page 54
Lott claims that there were only 200 accidental handgun deaths in the US in 1988. While it may be true that there were 200 gun deaths were a handgun was identified as the gun type involved, in most accidental deaths the gun type was not identified, and it is incorrect to assume, as Lott does, that in none of these a handgun was involved. If we assume that the handgun percentage for these was the same as for the ones where the gun type was identified then there were 632 accidental handgun deaths [21].
Page 68
Lott claims that blacks benefit more than other groups from concealed-handgun laws. However, his own table 5.2 shows that blacks did not benefit more.
Page 113
Lott's claim that there is no worldwide relationship between gun ownership and crime rates is false. Using gun ownership data from the International Crime Victimization Survey Killias found significant correlations between gun ownership and homicide rates [20].
Page 160 (161 in 2nd edition)
Lott falsely claims that women and blacks benefit the most from concealed-handgun laws in terms of reduced rates of murder. His own table 5.2 shows that the change in murder rates was the same for blacks and whites and for women and men.
Page 160 (161 in 2nd edition)
Lott claims that the ``halo'' effect from shall issue laws also protects juveniles who are not eligible for concealed weapon permits. As discussed earlier the fact that juvenile homicides declined as much as adult homicides is evidence that the crime decreases were not caused by the shall issue laws, not evidence for extra benefits from such laws. It seems as if Lott can interpret any outcome at all as evidence for benefits from shall issue laws.

Page 32 of [27]
Lott claims that ``Guns are used for defensive purposes about five times as often as they are used for crimes.'' In fact, the National Crime Victimization Survey indicates that the number of gun crimes (about 850,000 in 1996 [38]) is about twelve times as much as the number of defensive gun uses (about 72,000 in 1996 [38]). This is surely not surprising--criminals are more likely to be involved in a situation where a gun might be useful, and so have more incentive to carry a gun. They can also only choose to commit crimes on the occasions when they are carrying a gun.

Lott arrives at his claim by taking the lowest available estimate for gun crimes (430,000 from the FBI's UCR) and a high estimate for defensive gun uses (An average of the estimates computed by Kleck [21], omitting the NCVS estimate). While that produces a ratio favourable to Lott's position, it is impossible for both estimates to be correct. According to the respondents in Kleck's survey (which is the basis for all the estimates computed in [21]) one fifth of his estimated 2.5 million defensive gun uses were against gun crimes, implying that every single time a criminal committed a gun crime, they encountered an armed victim. This is clearly impossible.

Tim Lambert