Sex Differences in Mathematics and Reading Achievement Are Inversely Related: Within- and Across-Nation Assessment of 10 Years of PISA Data
The mathematics scores have been averaged for the four assessments, which means that some countries’ scores are based on four assessments (e.g., Germany and 32 other countries/regions which participated in all four assessments), and some countries’ scores on only one assessment (e.g., Malta and 15 other countries). Sex difference in mathematics equals boys’ mean score - girls’ mean score. The OECD countries not only have higher overall scores, their mathematics gap, favoring boys, is more tightly clustered between −5.5 and 17.5 points (M = 10.5,SD = 5.1). The two outliers are Iceland (HDI rank = 2, GGGI rank = 1) and Georgia (HDI rank = 61, GGGI rank = 40). In contrast, there is considerable variability in the non-OECD countries (between −15.0 and 30.0 points, M = 5.4, SD = 10.5), with boys’ having higher mathematics achievement in some of them (e.g., Costa Rica) and girls having higher mathematics achievement in others (e.g., Albania). The same analyses applied to the 4 individual PISA assessments show the same pattern.