Note the difference between males and females in the right tail of the distribution.
Intelligence (Article in Press)
Males have greater g: Sex differences in general mental ability from 100,000 17- to 18-year-olds on the Scholastic Assessment Test
Douglas N. Jackson and J. Philippe Rushton
In this study we found that 17- to 18-year old males averaged 3.63 IQ points higher than did their female counterparts on the 1991 Scholastic Assessment Test (SAT). We analysed 145 item responses from 46,509 males and 56,007 females (total N = 102,516) using a principal components procedure. We found (1) the g factor underlies both the SAT Verbal (SAT-V) and the SAT Mathematics (SAT-M) scales with the congruence between these components greater than 0.90; (2) the g components predict undergraduate grades better than do the traditionally used SAT-V and SAT-M scales; (3) the male and the female g factors are congruent in excess of .99; (4) male–female differences in g have a point-biserial effect size of 0.12 favoring males (equivalent to 3.63 IQ points); (5) male–female differences in g are present throughout the entire distribution of scores; (6) male–female differences in g are found at every socioeconomic level; and (7) male–female differences in g are found across several ethnic groups. We conclude that while the magnitude of the male–female difference in g is not large, it is real and non-trivial. Finally, we discuss some remaining sex-difference/brain-size/IQ anomalies.