A major study of recent international data on school mathematics performance casts doubt on some common assumptions about gender and math achievement -- in particular, the idea that girls and women have less ability due to a difference in biology. "We tested some recently proposed hypotheses that try to explain a supposed gender gap in math performance and found they were not supported by the data," says Janet Mertz, senior author of the study and a professor of oncology（肿瘤学） at the University of Wisconsin-Madison.

Instead, the Wisconsin researchers linked differences in math performance to social and cultural factors.

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（不足，缺乏） of outstanding women mathematicians.

That hypothesis holds that males diverge（分歧，偏离） 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.

The new study relied on data from the 2007 Trends in International Mathematics and Science Study and the 2009 Programme in International Student Assessment.

"People have looked at international data sets for many years," Mertz says. "What has changed is that many more non-Western countries are now participating in these studies, enabling much better cross-cultural analysis."

The Wisconsin study also debunked（揭穿，暴露） the idea proposed by Steven Levitt of "Freakonomics" fame that gender inequity does not hamper girls' math performance in Muslim countries, where most students attend single-sex schools. Levitt claimed to have disproved a prior conclusion of others that gender inequity limits girls' mathematics performance. He suggested, instead, that Muslim culture or single-sex classrooms benefit girls' ability to learn mathematics.