In addition a nonparametric Kruskal-Wallis analysis of variance was performed to determine whether instructor gender influenced female response rates. For each of these three domains, we have five plausible values and 80 replicate weights. We observed individual class sessions to determine participation rates. Only instructors who had a total of five or more students participate in any one of these three types of student—instructor interactions across the three observed class sessions were included in the analysis. This occurred only for two instructors in which either the camera was too far away to see any of the students who spoke or students spoke so briefly it was impossible to identify them. Although there are other ways for students to interact in class e. On the basis of a meta- analysis of some constructs, she concludes that there are only few psychological variables on which men and women differ, such as some motor and sexual behaviors Hyde, Although not shown, this model includes two random-effect terms: What do these findings mean for policy makers or educators who wish to reduce the sex differences in mathematics performance, in particular the underrepresentation of women in fields such as mathematics? Our finding that the sex differences in mathematics and reading are inversely related, not only between but also within countries, is inconsistent with this hypothesis. The aim of PISA is to measure reading, mathematical, and scientific skills in 15 year olds the exact age for inclusion is 15 years and 3 months to 16 years and 2 months. The hypothesis relies on an assumption that is not directly testable with the data, namely that increased resources are associated with increased performance. To fully assess this hypothesis requires a separate investigation, but our preliminary analysis for details, see Figure S1 of the enrollment in mathematics degree programs in two relatively egalitarian countries United Kingdom and The Netherlands for which we have the relevant data suggests that such a link indeed exists; not only has the proportion of male and female undergraduate students in mathematics remained stable since at least a decade, the ratio of men to women is similar to that observed in the high end of the mathematics performance in the PISA data. Enrollment in mathematics at Dutch and British universities. In any case, the inverse relation between the sex differences in reading and mathematics, especially at the extreme ends of the achievement distributions, poses unique challenges for those who wish to resolve these sex differences. Shanghai, Hong Kong, and Macao.