A new long-term study of 1.5 million teenagers in 75 countries has revealed some pretty fascinating things about the differences between male and female achievement in reading and math.

The study, published in *PLoS One*, used an enormous data set to look at sex differences in math and reading achievement. The researchers wanted to see if any of these differences correlated with issues like income inequality and national education policies. What they found was pretty surprising.

It's worth quoting from this executive summary of the study at length:

The researchers used data collected by the Programme for International Student Assessment (PISA), which included math and reading achievement data for nearly 1.5 million 15-year-olds in 75 countries.

The study’s findings include:

- Sex differences in math are inversely correlated with sex differences in reading, meaning that countries with smaller sex differences in math have larger sex differences in reading, and vice versa.
- The sex difference in math was negligible among the students at the bottom of the math achievement continuum, but the difference increased as performance levels rose. This difference ranged from 1.9 points favoring girls to 2.4 points favoring boys among boys and girls at the bottom 5% of achievers. At the high end of performance scores, the performance difference ranged from 19.3 points to 21.7 points, both favoring boys. The authors note that this large difference between boys’ and girls’ achievement in math has implications for the under-representation of women in STEM fields.
- Conversely, sex difference in reading is smaller at the high end of the performance continuum. The average sex difference in reading was three times larger than the sex difference in math. The average difference increased from 32 points in 2000 to 38.8 points in 2009. In 2009, the bottom 5% of boys scored 50 points lower than the bottom 5% of girls.
- Countries with higher living standards showed larger differences in math.
- Among all countries, as math and reading scores for both boys and girls go up, living standards and gender equality measures are more likely to be higher.
In considering possible approaches to closing the gender gap in STEM employment, the authors argue that increasing national prosperity is not enough. “The implication is that if policy makers decide that changes in these sex differences are desired, different approaches will be needed to achieve this for reading and mathematics,” they state. “Interventions that focus on high-achieving girls in mathematics and on low-achieving boys in reading are likely to yield the strongest educational benefits.”

The researchers believe that the dramatic difference between male and female math performance at the high end of the spectrum is correlated to the difference between numbers of men and women enrolled in math-related college courses. If we had equal numbers of men and women pursuing math in higher education, we'd probably see a shift in these scores.

*You can read the full study at PLoS One*