Jim Lindgren believes that a post by Carl Bogus on the DC handgun ban is uninformed. Bogus wrote:
A careful study that compared the nine year period before the ban was enacted with the nine years following enactment, and then compared what happened in D.C. with the immediately surrounding areas in Maryland and Virginia, found that the handgun ban reduced gun-related homicides by 25% and gun-related suicides by 23 percent. Colin Loftin, Ph.D., et al., “Effects of Restrictive Licensing of Handguns of Homicide and Suicide in the District of Columbia,” 325 New Eng. J. Med. 1615 (Dec. 5, 1991). The law did not turn Washington into the Garden of Eden, and crime rates fluctuated, particularly during the last few years of the study when the use of “crack” cocaine was increasing and homicides increased dramatically. Nevertheless, the effect of the law was both immediate and sustained, and things would have been worse without it.
Now this can certainly be criticised — the study did not conclude that the reductions were caused by the ban since it is possible that some other factor was the cause. But Lindgren’s comments are not correct:
From what I’ve seen, the Loftin study that Bogus points to should not be taken seriously. A simple Google search would have revealed why. According to Dean Payne’s re-analysis, if you use Loftin’s homicide and suicide data, adjust for population changes (as you must), and use per capita rates (as you must), the DC ban is associated with more deaths after the ban, not fewer. …
That the New England Journal of Medicine would publish a time-series article that did not account for population changes over roughly a two-decade period is embarrassing, but then peer review seems to suffer when gun control articles are involved.
While the numbers given in Loftin’s paper were for numbers of homicides and suicides rather than rates, Loftin et al state that they get similar results if age adjusted per-capita rates are used. (This corrects for change in the age structure of the population as well as its size.) The results for age adjusted per-capita rates were given in supplementary material. Here they are:
Type of fatality Before change and location law after law rate rate SE % t statistic per 100k Homicide District of Columbia Gun-related 20.9 -4.1 1.18 -20 -3.47 Non-gun-related 10.87 1.15 0.66 11 1.74 Maryland and Virginia Gun-related 3.12 -0.4 0.29 -13 -1.54 Non-gun-related 1.66 0.19 0.14 11 1.29 Suicide District of Columbia Gun-related 4.13 -0.63 0.37 -15 1.72 Non-gun-related 7.29 -0.28 0.62 -4 -0.45 Maryland and Virginia Gun-related 5.18 -0.14 0.37 -3 -0.37 Non-gun-related 5.38 -0.43 0.4 -8 -0.41