Abstract. Sex differences in mathematical ability were examined in a nation-wide sample of 32,346 Jordanian 4th graders (age 9–10 year) on a 40-item mathematics test. Overall, boys were found to perform slightly worse ( d = −0.12) but had slightly more variation in scores ( SD = 1.02 and SD = 0.98 for boys and girls, respectively). However, when results were disaggregated by school type, single-sex versus coed (i.e., coeducational), boys were found to perform better than girls in coed schools ( d = 0.27) but worse across single-sex schools ( d = −0.37). Two-parameter item response theory analysis showed that item difficulty was similar across sexes in the full sample. Item loadings exhibited substantial departure from measurement invariance with respect to boys and girls at single-sex schools, though. For boys and girls at coed schools, both the item difficulty and item loading correlations were highly similar, evincing that measurement invariance largely held in this case. Partially consistent with findings from other countries, a correlation between item difficulty and male advantage was observed, r = .57, such that the relative male advantage increased with increased item difficulty. Complicating interpretation, this association did not replicate within coed schools. Item content, Bloom’s cognitive taxonomy category, and item position showed no relation to sex differences.
