Results showed that men prefer working with things and women prefer working with people, producing a large effect size

From Men and Things, Women and People: A Meta-Analysis of Sex Differences in Interests by Rong Su, James Rounds, and Patrick Ian Armstrong.

The present study makes several important contributions to the literature. First, it is the first comprehensive meta-analysis on sex differences in vocational interests. We synthesized evidence from interest inventories over four decades and found large sex differences in vocational interests, with men preferring working with things and women preferring working with people. These sex differences are remarkably consistent across age and over time, providing an exception to the generalization that only small sex differences exist. Second, this study provides a systematic review of the sex differences in the STEM interests that has not previously appeared in the literature. The pattern of sex differences in the STEM interests revealed by the present study closely resembles the composition of men and women in corresponding occupations and contributes to the understanding of the gender disparity in the STEM fields. The results suggest that the relatively low numbers of women in some fields of science and engineering may result from women’s preference for people-oriented careers over thingsoriented careers.

Buried in the text of the paper there is also this interesting nugget.

The present study provided evidence that intragroup differences were substantially larger than intergroup differences.