Relation between sex difference in mathematics and overall mathematics score for OECD and non-OECD countries.

<p>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 (<i>M</i> = 10.5,<i>SD</i> = 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, <i>M = </i>5.4, <i>SD</i> = 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.