It may be just a stereotype that girls aren't as good at math as boys. Wisconsin researchers instead found cultural and social factors contribute to math ability more than gender.
FROM SCIENCE DAILY:
The new study, by Mertz and Jonathan Kane, a professor of mathematical and computer sciences at the University of Wisconsin-Whitewater, was published on Dec. 12, 2011 in Notices of the American Mathematical Society. The study looked at data from 86 countries, which the authors used to test the "greater male variability hypothesis" famously expounded in 2005 by Lawrence Summers, then president of Harvard, as the primary reason for the scarcity of outstanding women mathematicians.
That hypothesis holds that males diverge more from the mean at both ends of the spectrum and, hence, are more represented in the highest-performing sector. But, using the international data, the Wisconsin authors observed that greater male variation in math achievement is not present in some countries, and is mostly due to boys with low scores in some other countries, indicating that it relates much more to culture than to biology.
-NewsAnchorMom Jen