Abstract
The relative age effect (RAE; when one’s birthdate leads to participation or performance advantages over their peers) has been widely examined across traditional sports, but remains underexplored in action sports. Additionally, limited research has evaluated how methodological decisions—particularly the choice of expected birthdate distribution—influence RAE detection, particularly amongst international samples. The purpose of this study was to investigate RAEs in X-Games athletes and to examine how different methods of determining expected birthdate distributions influence RAE findings. The sample included 310 X-Games athletes across five sports: skateboarding, BMX, motocross, skiing, and snowboarding. Chi-square goodness-of-fit tests were used to compare observed birth quartile distributions to four different expected distribution methods: (1) assumed equal distributions, (2) weighted average birthrate distributions based on athlete country of origin, (3) expected birthrate distributions based on a country’s general population, and (4) the birthrate of a single country representing a broader region (e.g., France representing Europe). Results showed that RAE detection varied depending on the method used. Using equal distributions, RAE was identified in summer athletes and male skateboarders. Using weighted averages, additional RAE findings emerged in the overall sample and male summer athletes. A RAE was also observed for USA athletes when using equal distributions; however, this effect disappeared when recorded national birthrate distributions were used. No significant effects were found when using single-country birth distributions to represent a continent. These findings suggest that the choice of expected distribution method meaningfully influences RAE detection and may contribute to inconsistencies across the broader RAE literature.
