Thursday, February 24, 2005
On this day:

"Silliest Commentary on the Larry Summers Flap"

NRO's John Derbyshire smacks down columnist Andrea Peyser's misstatement of Harvard Prez Larry Summers's remarks.

Here's Ms. Peyser (emphasis added):
WELL, he said it. Harvard University President Lawrence Summers did, in fact, declare that, in his learned opinion as head of one of the world's leading educational institutions, women, on average, are dumber than men.

And here's the Derb's excellent rebuttal:
Summers did not say anything of the kind. The only thing he said that even came close was: "There is relatively clear evidence that whatever the difference in means -- which can be debated -- there is a difference in the standard deviation, and variability of a male and a female population."

The word "means" here means "averages." There are all sorts of differences between men and women in their mean measurement of various attributes -- rates of incarceration, for instance. Whether there is a difference in means for cognitive ability is, as Summers said, debatable. (If there is one, it is small.) There is no doubt, however, that there are differences in standard deviation; and that, as Summers also said, such differences have large effects at the tails of the bell curve: "Even small differences in the standard deviation will translate into very large differences in the available pool substantially out."

To understand the difference between a mean and a standard deviation, you need to have mastered some elementary statistics, a thing that plainly Andrea Peyser never bothered with.
Derb's right...this is a lesson straight from Statistics 101.