Deltoid

Joe B. Simpson said:

The New England Journal of Medicine. 1991 Dec 5. 325 (23). pp 1615-1620. Special Article: Effects Of Restrictive Licensing Of Handguns On Homicide And Suicide In The District Of Columbia. Loftin-Colin. McDowall-David. Wiersema-Brian. Cottey-Talbert-J.

Note that the study showed an immediate decline in homicide and suicide rates after enacting the ban.

Which is a LIE, because the suicide RATE in DC was the same after the ban as it was before the ban, though the rate in surrounding areas not affected by the ban fell 10%. The GUN suicide rate in DC fell more than the GUN suicide rate in the other areas, but the fact that the overall suicide rate in DC remained constant illustrates perfectly the substitution principal.

So that we can see who is lying, here are the changes in the rates (data from Appendix B of Loftin et al’s article):

DC (age adjusted rate per 100k population)
                 before after
Suicide          11.4   10.5
Gun suicide       4.1    3.5
Non-gun suicide   7.3    7.0

Maryland-Virginia (rate per 100k pop)
                 before after
Suicide          10.6   10.0
Gun suicide       5.2    5.0
Non-gun suicide   5.4    5.0

This certainly does NOT support the substitution hypothesis, which predicts an increase in DC non-gun suicides to compensate for the decrease in gun suicides. The decrease in overall rates was also larger in DC than in the surrounding areas, falsifying your other claim.

pim writes:

Are you arguing that the increase in D.C.’s suicide and homicide rates is related to a law passed 12 years earlier ?

Thomas Grant Edwards said:

I don’t see why this is difficult to imagine. It might have taken 12 years for most of the legal grandfathered guns in the hands of average citizens to filter into the hands of criminals, seeing as how it is impossible for a D.C. resident to legally sell his gun.

1. Is it? Why can’t they sell it outside DC?

2. Are you saying that it takes 12 years to illegally sell a gun?? If you are saying that this supposed transfer happened gradually over 12 years then surely your theory predicts a gradual increase over 12 years, rather than a decrease for ten years and then a sharp increase (which is what actually occured).

3. The sharp increase also occured in the suburbs of Washington outside DC. Did the DC law cause this too?

I will add that I think the Drug War is the main cause of high crime in D.C. But the gun ban removed an important crime deterrent.

Perhaps it did, but there is no evidence to support this claim.

James B. Clark writes:

Here’s your table. You didn’t include the data from 1967-1972, so I have no idea what it looks like. If you pick 1975, 1976, 1977, or 1978 I would bet that a decline in the homicide rates would be detected by the methods in the Loftin study.

Probably. All this means however, is that because the data is noisy, statistics cannot tell us exactly when the drop occured.

Charles Scripter writes:

Curious. If the data is so noisy that one cannot determine exactly when the “drop” occurred, then Pim certainly cannot claim that the “drop” corresponds to the gun ban.

He cannot claim that the drop occured exactly at the time of the ban. He can claim that the drop occured at about the time of the ban.

Even if we believe that all of Kleck’s respondents were truthful, his estimate of the number of DGU’s is plus or minus 600,000 (95% confidence interval). I don’t see you complaining that people cannot claim that the number is 2,549,862 because of this uncertainty.

James B. Clark writes:

If they had used used 1976 as the cutoff instead of 1977, they’d have gotten even more statistically significant results. The problem is, you can’t look at data, notice a trend, then test for the trend.

Which they didn’t do. (Else they would have used 1976 as the cutoff as you note.)

Charles Scripter writes:

If the “statistical significance” test would have indicated 1976, then how did they choose 1977? Ah, I understand… The authors wished to find a correlation with the 1977 gun ban, and massaged the data to match…

You’re confused. I’ll say it again — The problem is, you can’t look at data, notice a trend, then test for the trend. This is real trap in the analysis of quasi-experimental data. With an experiment you can spot a trend and then collect more data to test the significance. This is not possible in a quasi-experiment. You have to start with the hypothesis to be tested before you go looking at the data.

Lott (along with Eli Lehrer) has an editorial in the Washington Times which claims that the 1976 gun ban caused crime to increase.

D.C. residents need more protection: Crime has risen significantly since the gun ban went into effect. In the five years before Washington’s ban in 1976, the murder rate fell from 37 to 27 per 100,000. In the five years after it went into effect, the murder rate rose back up to 35. In fact, the murder rate after 1976 has never fallen back to what it was in 1976. Robberies and overall violent crime changed just as dramatically. Robberies fell from 1,514 to 1,003 per 100,000 and then rose by over 63 percent, up to 1,635.

If you look at the graph you will see the trick that Lehrer and Lott have played. I’ve graphed the homicide and robbery rates for the ten years on either side of the law so you can see the trick Lott has used. (Data is from here.) Notice how the crime rates fluctuate from year to year. If you choose one year at random to represent the situation after the law was passed their is a good chance that it will be unrepresentative. Of course, they didn’t just choose one year at random. They chose 1981, which just happens to be the year that had the highest homicide and robbery rates of the ten following years. (And contrary to their claim, the murder rate in 1985 was below the 1976 rate.)

Also by presenting rates for just 1971 and 1976, they make it look as if the rates were decreasing before the law, instead of going up and down. The law was also in effect for only part of 1976, so that year is not a good choice to represent the situation before the law.

If you look at the graphs you will see that homicides tended to be lower after the law and robberies were about the same. Of course, just looking at the graphs only gives a rough idea of the possible effects of the law. This has been studied by several researchers. Loftin at al (NEJM 325:1615-1620) found significant decreases in firearms homicides and no significant change in non-firearms homicides. Kleck et al (Law & Society Review 30(2):361-380) disputed their findings, arguing that the law had no effect. Whoever is correct, there is no published support for Lehrer and Lott’s claim that the law caused crime increases.

Lott has an article in the National Review Online where he claims that the Washingtonian DC handgun ban caused crime increases:

Crime rose significantly after the gun ban went into effect. In the five years before Washington’s ban in 1976, the murder rate fell from 37 to 27 per 100,000. In the five years after it went into effect, the murder rate rose back up to 35. During this same time, robberies fell from 1,514 to 1,003 per 100,000 and then rose by over 63 percent, up to 1,635.

I’ve graphed the homicide and robbery rates for the ten years on either side of the law so you can see how Lott cherry picked his numbers as usual. (Data is from here.) Notice how the crime rates fluctuate from year to year. If you choose one year at random to represent the situation after the law was passed their is a good chance that it will be unrepresentative. Of course, Lott didn’t just choose one year at random. He chose 1981, which just happens to be the year that had the highest homicide and robbery rates of the ten following years.

The law was also in effect for only part of 1976, so that year is not a good choice to represent the situation before the law.

If you look at the graphs you will see that homicides tended to be lower after the law and robberies were about the same. Of course, just looking at the graphs only gives a rough idea of the possible effects of the law. This has been studied by several researchers. Loftin at al (NEJM 325:1615-1620) found significant decreases in firearms homicides and no significant change in non-firearms homicides. Kleck et al (Law & Society Review 30(2):361-380) disputed their findings, arguing that the law had no effect. Whoever is correct, there is no published support for Lott’s claim that the law caused crime increases.

Over on his blog, Lott presents a graph showing crime rates. And it looks good for his case—it’s V shaped, with the bottom of the V right when the law was passed. Except that he graphed the overall crime rate. The majority of crimes are non-violent ones like larceny, where handguns are not a factor, even offensively or defensively. His graph isn’t even remotely relevant but if he graphed something relevant like homicide it wouldn’t support his case.