Discussion of the Science article on gender differences in math test variance got me thinking. Since a test score is a noisy measure of some underlying ability, an unusually high score can come either from an unusual high ability, or from an unusually positive measurement error (or both). If higher male score variance is due more to a higher male ability variance than to a higher male measurement error variance, then a high female score is more likely to be due to measurement error than is the same high male score. If so,