math or verbal skills at the start of education, but girls start to fall behind in math as early as fifth grade (Fryer and Levitt 2011). Furthermore, Niederle (2010) finds that boys are more likely to perform in the right tail of the distribution in the math section of the SAT, Advanced Placement tests (AP) and Graduate Record Examinations (GRE) in the US. Bharadwaj et al. (2012) find similar trends in middle‐ and low‐ income countries, such as Chile, Mexico and Thailand on the Programme for International Student Assessment (PISA) ‐ around fourth grade, boys begin outperforming girls in math at both the median level and at top quantiles.

But there is considerable gender sorting that goes beyond performance. In the US and the Netherlands, boys are generally more likely to study science and math than girls even after controlling for performance, constructed from previous mathematics test scores (Buser, Niederle and Oosterbeek, 2014) or SAT scores (Turner and Bowen, 1999).<sup>1</sup> These gender specific choices which are not explained by performance may be due to the fact that girls have lower levels of self‐assessment conditional on performance and that parents are more likely to invest in mathematics education for male children, as Bharadwaj et al. (2012) find in Chile. Vietnam, however, seems to be atypical with respect to these results. Dercon and Singh (2013) in a study of the Young Lives data from Ethiopia, India, Peru and Vietnam find that girls outperform boys in Vietnam and also that parents have a pro‐girl bias in education aspirations for their children.

Another branch of literature has explored the role of psychological traits. This work suggests that women are more risk‐averse and altruistic, have a lower preference for competition and are less willing to negotiate. Some of this evidence is context‐specific. Women appear to exhibit more risk‐aversion in their investments (Jianakoplos and Bernasek ,1998; Hinz, McCarthy and Turner, 1997), a pattern that persists even controlling for lower levels of income among women. Babcock et. al. (2017) show that women are more likely than men to be asked to volunteer to tasks with a low impact on the likelihood of a promotion and are also more likely to accept. Buser, Niederle and Oosterbeek (2014) find that a lower preference for competition, controlling for academic ability, explains about 20% of the gender difference in choice of academic track among high school students in the Netherlands. Bowles, Babcock and Lai (2006) demonstrate that there are differences between genders in the propensity to initiate negotiations in the US, with Card, Cardoso and Kline (2015) finding empirical support for the role of bargaining in explaining the gender earnings gap in the Portuguese labor market.

It is important to understand when these observed differences in these psychological traits emerge. For instance, Brinig (1995) empirically tests risk preferences with a sample of elementary, high school and graduate students and finds that gender alone does not explain differences in risk preferences, but it becomes a significant predictor when interacted with age. The author finds that gender differences in risk preference peak at the age of 30. In a field experiment in Israel, Gneezy and Rustichini (2004) find that boys react to competition, by running faster in races when competing against someone rather than running alone, while girls do not. Dreber, von Essen and Ranehill (2011), on the other hand, find that boys and girls react equally to competition in a similar experiment in Sweden. There is also mixed evidence in gender differences in risk taking at younger ages. Booth and Nolen (2012) find that among

> 1 Buser, Niederle and Oosterbeek (2014) look at the track choices of Grade 9 students for their last three years of high school, whereas Turner and Bowen (1999) look at incoming university students’ choice of college major.

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