1 Explaining the Gender Gap in Math Test Scores: The Role of Competition Muriel Niederle and Lise Vesterlund December 16, 2009 Muriel Niederle is Associate Professor of Economics, Stanford University, Stanford, California. She is also a Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts. Lise Vesterlund is the Andrew W. Mellon Professor of Economics, University of Pittsburgh, Pittsburgh, Pennsylvania. Their e-mail addresses are <[email protected]> and <[email protected]>, respectively.2Over the past 60 years there have been substantial improvements in the college preparation of female students, and the college gender gap has changed dramatically. Goldin, Katz and Kuziemko (2006) show that female high school students now outperform male students in most subjects, and in particular on verbal test scores. The ratio of male to female college graduates has not only decreased, but reversed itself, and the majority of college graduates is now female. The gender gap in mathematics has also changed. The number of math and science courses taken by female high school students has increased and now the mean and standard deviation in performance on math test scores are only slightly larger for males than for females. Despite minor differences in mean performance, Hedges and Nowell (1995) show that many more boys than girls perform at the right tail of the distribution. This gender gap has been documented for a series of math tests including the AP calculus test, the mathematics SAT, and the quantitative portion of the GRE. Over the past 20 years the fraction of males to females who score in the top five percent in high school math has remained constant at two to one (Xie and Shauman, 2003). Examining students who scored 800 on the math SAT in 2007, Ellison and Swanson (this issue) also find a two to one male-female ratio. Furthermore, they find that the gender gap widens dramatically when examining the right tail of the performance distributions for students who participate in the American Mathematics Competitions (AMC). Substantial research has sought to understand why more boys than girls excel in math. However, given the many dimensions in which girls outperform boys, it may seem misplaced to focus on the dimension in which girls are falling short. Why not examine the gender gap in verbal test scores where females outperform males? One reason is that in contrast to, say, verbal test scores math test scores serve as a good predictor of future income. Although the magnitude of the effect of math performance on future income varies by study, the significant and positive effect is consistently documented, see e.g., Paglin and Rufolo (1990), Murnane, Willet and Levy (1995), Grogger and Eide (1995), Weinberger (1999, 2001), Murnane, Willett, Duhaldeborde and Tyler (2000) and Altonjii and Blank (1999) for a discussion. So why do girls and boys differ in the likelihood that they excel in math? One argument is that boys have and develop superior spatial skills, and this gives them an advantage in math. Such differences could have an evolutionary foundation, as male tasks such as hunting may have required greater spatial orientation than typical female tasks (for a discussion see Gaulin and Hoffman, 1988). In addition, or alternatively, it could be because boys tend to engage in play that is more movement oriented and therefore grow up in more spatially complex environments (Berenbaum et al., 2008).3The objective of this paper is not to discuss whether the mathematical skills of males and females differ, be it a result of nurture or nature. Rather we argue that the reported test scores need not reflect the magnitude of the gender differences in math skills. We will present results that suggest that the abundant and disturbing evidence of a large gender gap in mathematics performance at high percentiles in part may be explained by the differential manner in which men and women respond to competitive test taking environments. We provide evidence of a significant and substantial gender difference in the extent to which skills are reflected in a competitive performance. The effects in mixed-sex settings range from women failing to perform well in competitions (Gneezy, Niederle and Rustichini, 2003) to women shying away from environments in which they have to compete (Niederle and Vesterlund, 2007). We find that the response to competition differs for men and women, and in the examined environment gender difference in competitive performance does not reflect the difference in non-competitive performance. We use the insights from these studies to argue that the competitive pressures associated with test taking may result in performances that do not reflect those of less competitive settings. Of particular concern is that the distortion is likely to vary by gender and that it may cause gender differences in performance to be particularly large in mathematics and for the right tail of the performance distribution. Thus the gender gap in math test scores may exaggerate the math advantage of males over females. Due to the way tests are administered and rewards are allocated in academic competition, there is reason to suspect that females are failing to realize their full potential or to have that potential recognized by society. Gender Differences in Competitive Performance and Selection Performance in Competitive Environments Clear evidence that incentive schemes may generate gender differences in performance has been shown by Gneezy, Niederle and Rustichini (2003). In an experiment conducted at the Technion in Israel, individuals are presented with an incentive scheme and asked to solve mazes on the Internet for 15 minutes. Four different incentive schemes were examined. Thirty women and thirty men perform under each incentive scheme, with no one performing under more than one incentive scheme. Though gender was not explicitly mentioned, participants could see one another and determine the gender composition of the group. In a non-competitive environment, three men and three women receive an individual piece-rate payment of $0.50 for every maze he or she solves. In this environment, the gender gap4in performance is small, with men solving an average of 11.2 mazes and women solving 9.7 mazes. The emphasis is not on determining whether this gender gap in performance reflects differences in ability, experience or performance costs, but rather on determining