Consistencies in sex differences on the Cognitive Abilities Test across countries, grades, test forms, and cohorts

Strand, Deary, and Smith (2006) reported an analysis of sex differences on the Cognitive Abilities Test (CAT) for over 320,000 UK students 11-12 years old. Although mean differences were small, males were overrepresented at the upper and lower extremes of the score distributions on the quantitative and non-verbal batteries and at the lower extreme of the verbal battery.

We investigate whether these results were unique to the UK or whether they would be seen in other countries, at other grades, cohorts, or forms of the test.

The sample consisted of three nationally representative cohorts of US students in grades 3 through 11 (total N=318,599) for the 1984, 1992, and 2000 standardizations of the US version of the CAT.

We replicated and extended the Strand et al. (2006) results by comparing the proportions of males and females at each score level across countries (UK vs. US), grades (3-11), and cohorts/test forms (Forms 4, 5, and 6 standardized in 1984, 1992, and 2000, respectively).

The results showed an astonishing consistency in sex differences across countries, grades, cohorts, and test forms.

Implications for the current debate about sex differences in quantitative reasoning abilities are discussed.