A study by Janet Hyde, Sara Lindberg, Amy Ellis and Carolyn Williams is getting a lot of publicity (two non-academic friends brought it up in conversation lastnight). They find that boys and girls do not differ in their performance on math tests. Unfortunately, I cannot find the actual study, so the link goes to a news story.
Hyde and colleagues sifted through math scores from 7 million students from 10 states tested in accordance with the No Child Left Behind Act, as well as the Scholastic Aptitude Test or SAT, a standardized test used for college admissions.
"Contrary to widely held stereotypes by parents and teachers that boys are better at math, our data ... showed that girls have reached parity with boys on math performance," Hyde said in a telephone interview.
What about at the very high end of the scale?
"While we did find more boys than girls above the 99th percentile at a 2-to-1 ratio, still, 33 percent of those kids who are above the 99th percentile are girls," she said.
Hyde's explanation for the fact that boys score higher on average on the math SAT's is that more girls take the SAT, so that the test includes more girls who are lower in the ability distribution.
My view would be the reason that more girls take the SAT's is that there are more girls in the middle of the ability distribution to begin with. My casual reading of the literature and observation in the classroom is that boys tend to have more variance--more at the top, and more at the bottom. That is why, as college admissions have grown, the big increase has been among girls.
The idea that more girls just randomly decide to go to college strikes me as unlikely. I would tend to think that, holding ability equal, a boy would be about as likely to want to go to college as a girl. However, I am just speculating. I am not a professor of psychology.
UPDATE: This article, which ranks disciplines according to "political correctness" would suggest that the difference between my views and those of psychology professor are predictable. Thanks to Tyler Cowen for the pointer.