Wednesday, June 9, 2010

Larry Summers was Correct

Turns out Larry Summers was correct about the variance of math scores across gender. See this article in the NYTimes by John Tierny. Recall that Summers conjectured that one reason whey there are fewer women in science at Harvard was that the greater variation in math scores among men meant more in the extreme upper tail, and that Harvard physicists came from the extreme upper tail. This has nothing to do with average scores across gender, the point is about variance.

Now some researchers have looked at this by studying students who took College Admissions tests while in the seventh grade -- obviously high achievers.

The Duke researchers — Jonathan Wai, Megan Cacchio, Martha Putallaz and Matthew C. Makel — focused on the extreme right tail of the distribution curve: people ranking in the top 0.01 percent of the general population, which for a seventh grader means scoring above 700 on the SAT math test. In the early 1980s, there were 13 boys for every girl in that group, but by 1991 the gender gap had narrowed to four to one, presumably because of sociocultural factors like encouragement and instruction in math offered to girls.

Since then, however, the math gender gap hasn’t narrowed, despite the continuing programs to encourage girls. The Duke researchers report that there are still four boys for every girl at the extreme right tail of the scores for the SAT math test. The boy-girl ratio has also remained fairly constant, at about three to one, at the right tail of the ACT tests of both math and science reasoning. Among the 19 students who got a perfect score on the ACT science test in the past two decades, 18 were boys.

Meanwhile, the seventh-grade girls outnumbered the boys at the right tail of tests measuring verbal reasoning and writing ability. The Duke researchers report in Intelligence, “Our data clearly show that there are sex differences in cognitive abilities in the extreme right tail, with some favoring males and some favoring females.”

So it is possible for men and women to achieve the same mean scores on math tests yet persistent differences to appear when one looks at the variance. But Harvard presumably only hires scientists from the upper tail, not the lower one.

Wonder if any of Summers' critics will apologize?

No comments: