Sex Differences in Variability in Intellectual Abilities: A New Look at an Old Controversy

Contemporary research on sex differences in intellectual abilities has focused on male-female differences in average performance, implicitly assuming homogeneity of variance. To examine the validity of that assumption, this article examined sex differences in variability on the national norms of several standardized test batteries. Males were consistently more variable than females in quantitative reasoning, spatial visualization, spelling, and general knowledge. Because these sex differences in variability were coupled with corresponding sex differences in means, it was demonstrated that sex differences in variability and sex differences in central tendency have to be considered together to form correct conclusions about the magnitude of cognitive gender differences.