persons (Hyde, Fennema, and Lamon, 1990). Averaged over all samples of the general population, d = –0.05, a negligible difference favoring females.

An independent meta-analysis confirmed the results of the first meta-analysis (Hedges and Nowell, 1995). It found effect sizes for gender differences in mathematics performance ranging between 0.03 and 0.26 across large samples of adolescents—all differences in the negligible to small range. Results from the International Assessment of Educational Progress also confirm that gender differences in mathematics performance are small across numerous countries including Hungary, Ireland, Israel, and Spain (Beller and Gafni, 1996).

For issues of the underrepresentation of women in the physical sciences, however, this broad assessment of the magnitude of gender differences is probably less useful than an analysis by both age and cognitive level tapped by the mathematics test. These results from one meta-analysis are shown in Table 2-1. Ages were grouped roughly into elementary school (ages 5-10 years), middle school (11-14), high school (15-18), and college age (19-25). Insufficient studies were available for older ages to compute mean effect sizes. Cognitive level of the test was coded as assessing either simple computation (requires the use of only memorized math facts, such as 7 × 8 = 56), conceptual (involves analysis or comprehension of mathematical ideas), problem solving (involves extending knowledge or applying it to new situations), or mixed. The results indicated that girls outperform boys by a small margin in computation in elementary school and middle school and there is no gender difference in high school. For understanding of mathematical concepts, there is no gender difference at any age level. For problem solving there is no gender difference in elementary or middle school, but a small gender difference favoring males emerges in high school and the college years. There are no gender differences, then, or girls perform better, in all areas except problem solving beginning in the high school years.

This gender difference in problem solving favoring males deserves attention because problem solving is essential to success in occupations in engineering and the physical sciences. Perhaps the best explanation for this gender difference, in

TABLE 2-1 The Magnitude of Gender Differences in Mathematics Performance as a Function of Age and Cognitive Level of the Test

Age group

Cognitive Level



Problem solving

















SOURCE: Hyde et al. (1990).

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