Providence, RI -- "I'm too pretty to do math": This year, a T-shirtcarrying that slogan was marketed to young girls. After outragedobjections, the shirt was pulled from stores, but is still availablefor sale on the internet -- and its familiar message continues to echo:It's boys, not girls, who excel in math. Was the outrage over theshirt knee-jerk political correctness? Is it perhaps time just toaccept the fact that boys are better at math than girls?
Not unless you ignore the data. A major new study appearing in theJanuary 2012 issue of the Notices of the American Mathematical Society(http://www.ams.org/notices) marshals a plethora of evidence showingthat many of the hypotheses put forth to account for the so-called"gender gap" in mathematics performance fail to hold up. The article,"Debunking Myths about Gender and Mathematics Performance" by JonathanKane and Janet Mertz, takes a scientific, fact-based look at a subjectthat too often is obscured by prejudice and simplistic explanations.
To start with, Kane and Mertz note that, by several measures, girlsactually *do* perform as well as boys in mathematics. In manycountries, there is no gender gap in mathematics performance at eitherthe average or very high level. In other countries, notably theUnited States, the gap has greatly narrowed in recent decades. Forexample, some U.S. test score data show that girls have reached paritywith boys in mathematics, even at the high school level, where asignificant gap existed forty years ago. Another piece of evidence isfound among U.S. students who are highly gifted in mathematics,namely, those who score 700 or higher on the quantitative section ofthe SAT prior to age 13. In the 1970s, the ratio of boys to girls inthis group was 13:1; today it is 3:1. Likewise, the percentage ofU.S. Ph.D.s in the mathematical sciences awarded to women has risenfrom 5% to 30% over the past half century. If biology were destinyand boys had a "math gene" that girls lack, such large differenceswould not be found over time or between countries.
Nevertheless, other measures continue to show a significant gender gapin mathematics performance. Various hypotheses have been advanced toexplain why this gap occurs. Kane and Mertz analyzed internationaldata on mathematics performance to test these hypotheses. One is the"greater male variability hypothesis", famously reiterated in 2005 byLawrence Summers when he was president of Harvard University. Thishypothesis proposes that variability in intellectual abilities isintrinsically greater among males---hence, in mathematics, boyspredominate among those who excel, as well as among those who dopoorly.
To test this hypothesis, Kane and Mertz calculated "variance ratios"for dozens of countries from throughout the world. These ratioscompare variability in boys' math performance to variability in girls'math performance. For example, using test scores from the 2007 Trendsin International Mathematics and Science Study (TIMSS), Kane and Mertzfound that the variance ratio for Taiwanese eighth graders was 1.31,indicating that there was quite a bit more variability in math scoresamong boys than among girls. However, in Morocco, the ratio was 1.00,indicating the amount of variability observed in the two groups wasidentical. In Tunisia, this ratio was 0.91, indicating there wassomewhat more variability in math scores among girls than among boys.
If the "greater male variability hypothesis" were true, boys' mathscores should show greater variance than girls' math scores in allcountries; one should also not see such big, reproducible differencesfrom country to country. Therefore, Kane and Mertz conclude that thishypothesis does not hold up. Kane and Mertz suggest that there aresociocultural factors that differ among countries; some of thesefactors, such as different educational experiences and patterns ofschool attendance, lead to country-specific differences in boysÕvariances and girls' variances and, thus, their variance ratios.
Kane and Mertz took the same kind of data-driven approach to examinesome additional hypotheses for explaining the gender gap, such as the"single-gender classroom hypothesis" and the "Muslim culturehypothesis", both of which have been proposed in recent years byvarious people, including Steven Levitt of "Freakonomics" fame.Again, Kane and Mertz found that the data do not support thesehypotheses. Rather, they observed no consistent relationship betweenthe gender gap and either co-educational schooling or most of thecountry's inhabitants being Muslim.
They also examined the "gap due to inequity hypothesis", whichproposes that the gender gap in math performance is due to social andcultural inequities between males and females. To examine thishypothesis, they used an international gender gap index that comparesthe genders in terms of income, education, health, and politicalparticipation. Relating these indices to math scores, they concludedthat math achievement for both boys and girls tends to be higher incountries where gender equity is better. In addition, in wealthiercountries, women's participation and salary in the paid labor forcewas the main factor linked to higher math scores for students of bothgenders. "We found that boys as well as girls tend to do better inmath when raised in countries where females have better equality, andthat's both new and important," says Kane. "It makes sense that whenwomen are well educated and earn a good income, the math scores oftheir children of both genders benefit."
Mertz adds, "Many folks believe gender equity is a win-lose zero-sumgame: If females are given more, males end up with less. Our resultsindicate that, at least for math achievement, gender equity is awin-win situation."
Source: American Mathematical Society