Sex differences in achievement: Distributions matter

Sex differences in general and specific aspects of reading, math, and writing were investigated using the standardization sample from the Wechsler Individual Achievement Test-Third Edition (Pearson, 2009a). We examined mean and variance differences, differences at points along score distributions, and the percentage of males and females in the normative descriptive ranges used for the measures (e.g., average, high average). Statistically significant and small differences were found for Oral Reading Fluency, Math Problem Solving, and a Mathematics composite. Male advantages in Math Problem Solving were more substantial among high math achievers, and the male advantage on Mathematics was largely due to advantages on Math Problem Solving. Small to moderate sex differences were found for writing. Females scored consistently higher across those distributions, with the largest differences being in essay writing and sentence composition. Percentages of the sexes whose scores were in normative descriptive categories varied across measures. Although it has been concluded generally that male and female achievement is similar due to small effect sizes, those conclusions are limited as differences are often a function of achievement level. These differences have important real-world implications, for example, related to identifying those with learning problems and talents.