Relative age effects (RAEs) occur when those who are relatively older for their age group are more likely to succeed. RAEs occur reliably in some educational and athletic contexts, yet the causal mechanisms remain unclear. Here we provide the first direct test of one mechanism, selection bias, which can be defined as evaluators granting fewer opportunities to relatively younger individuals than is warranted by their latent ability. Because RAEs are well-established in hockey, we analyzed National Hockey League (NHL) drafts from 1980 to 2006. Compared to those born in the first quarter (i.e., January–March), those born in the third and fourth quarters were drafted more than 40 slots later than their productivity warranted, and they were roughly twice as likely to reach career benchmarks, such as 400 games played or 200 points scored. This selection bias in drafting did not decrease over time, apparently continues to occur, and reduces the playing opportunities of relatively younger players. This bias is remarkable because it is exhibited by professional decision makers evaluating adults in a context where RAEs have been widely publicized. Thus, selection bias based on relative age may be pervasive.

Fringe benefits, Gender wage gap, Compensating wage differentials, National longitudinal study of youth,

Sex differences in some preferences and motivations are well established, but it is unclear whether they persist in selective sub-populations, such as expert financial decision makers, top scientists, or elite athletes. We addressed this issue by studying competitiveness in 1,147 varsity intercollegiate distance runners. As expected, across all runners, men reported greater competitiveness with two previously validated instruments, greater competitiveness on a new elite competitiveness scale, and greater training volume, a known correlate of competitiveness. Among faster runners, the sex difference decreased for one measure of competitiveness but did not decrease for the two other competitiveness measures or either measure of training volume. Across NCAA athletic divisions (DI, DII, DIII), the sex difference did not decrease for any competitiveness or training measure. Further analyses showed that these sex differences could not be attributed to women suffering more injuries or facing greater childcare responsibilities. However, women did report greater commitment than men to their academic studies, suggesting a sex difference in priorities. Therefore, policies aiming to provide men and women with equal opportunities to flourish should acknowledge that sex differences in some kinds of preferences and motivation may persist even in selective sub-populations.

Deaner, RO and Lowen, A. Males and females pace differently in high school cross-country races. J Strength Cond Res 30(11): 2991-2997, 2016-Previous studies have demonstrated that men are more likely than women to slow in the marathon, but it is unknown whether the sex difference in pacing occurs for other race distances. This study addressed this question by analyzing the 5-km Virginia State Championship high school cross-country race for the years 2010, 2012, 2013, and 2014, which encompassed 3,948 performances. The pacing measure was percentage change in speed from mile 1 to mile 2. Across all runners, women (9.1%) slowed significantly (p = 0.002) more than men (8.7%), although the magnitude of the difference was trivial (effect size [ES] = -0.10). However, when women and men in physiologically equated finishing time groups (e.g., <17:00 for men; <19:03 for women) were compared, men slowed significantly more (p < 0.001) in all 4 groups, and the differences were nontrivial (ESs range 0.27-0.92). Because glycogen depletion is irrelevant for 5 km performances, these results challenge the hypothesis that the sex difference in pacing is due to males' greater susceptibility to glycogen depletion. These results instead support the hypothesis that the sex difference in pacing partly reflects a sex difference in some aspect of decision making, such as overconfidence, risk perception, or willingness to tolerate discomfort. Coaches and athletes are advised to consider individual variation in these characteristics when planning training and racing.

F02, F23, L24,