THE WEIGHT OF EVIDENCE….The indefatigable Tim Lambert has yet more today on famous gun researcher John Lott. The question at hand is this: of the people who have used a gun defensively, how many of them merely brandished the gun as opposed to firing it?

Last we heard, Lott claimed that he had done a survey that showed the number was 98%, and a whole bunch of us were scratching our heads trying to figure out how he got that figure. The raw survey data has mysteriously disappeared, of course, but the best guess is that in a survey of 2,424 people, about 25 would have reported a defensive gun use. 98% of 25 is 24.5, which means that one half of a person actually fired a gun.

Lott has tried to explain this half a person as a sample weighting issue, but here’s what Tim found when he tried to use Lott’s weighting procedure with his more recent survey data:

….the weighting procedure is systematically biased against minorities and people from small states.

[much arithmetic snipped….]

I didn’t notice this problem until I took his data set from the 2002 survey and tried to follow his procedure. With 6 out 7 people brandishing (86%), after weighting using his procedure, the weighted brandishing percentage is 99.8%. It turns out that the person who fired was a minority woman from a small state, and ends up with a weight about 100 times as small as that for the other defensive gun users. Obviously this is incorrect.

Presto! 86% is transformed into 99.8%! The thing is, this really is obviously incorrect. In fact, it’s so obviously incorrect that Lott didn’t even try to get away with using this procedure in his more recent survey.

So why did he use it the first time around? Tim, of course, has a guess.