Educational choice has greater effects on sex ratios of college STEM majors than has the greater male variance in general intelligence (g)

In STEM fields other than biological sciences (math-intensive STEM), there is a greater ratio of males to females (M:F ratio) than that of the general population. The Ability Distribution Hypothesis suggests that this is mainly due to greater male variance in g. Others hypothesize that this is due to sex differences in occupational interests. There has not been an empirical study to evaluate which kind of differences has greater effects on the M:F ratios in math-intensive STEM fields. To fill the gap, we examine the test scores, application for majors and final admissions in a complete dataset of college entrance. We study the M:F ratios of four math-intensive STEM majors: Economics, Engineering, Computer Science and Physical sciences and Math. In summary, we find that greater male variance exists in total test scores; greater male variance partially explains the female underrepresentation in the upper tails of total test scores; men appear to have stronger interests in Engineering and Computer Science than women, while women appear to have stronger interests in Economics and to a lesser extent Physical sciences and Math than men; compared to sex differences in test scores, sex differences in major-choosing appear to have stronger effects on the M:F ratios of math-intensive STEM majors.