No relative age effect in professional esports: a cross-national test of selection mechanisms

BackgroundThe relative age effect (RAE) is well-documented in traditional sport, but its applicability to professional esports remains largely unexplored. The two existing studies examined only the entry question, without controlling for birth seasonality, testing causal mechanisms, or analyzing post-entry career trajectories.ObjectiveThis study examined (1) whether RAE exists in professional esports after adjusting for birth seasonality; (2) whether academic cutoff dates causally influence esports career outcomes; (3) whether birth quarter affects career longevity and earnings after professional entry; and (4) whether birth quarter operates indirectly through debut age.MethodsThe sample comprised 15,065 professional esports players with confirmed birthdates from the Esports Earnings database, spanning 177 countries and 609 game titles. Methods included chi-square tests with population-adjusted expected frequencies, a cross-national quasi-experiment exploiting cutoff variation across 20 countries, Kaplan, Meier survival analysis and Cox regression, propensity score matching, and Baron-Kenny mediation analysis with the Sobel test.ResultsAfter adjusting for birth seasonality, no aggregate RAE was detected [χ2(3) = 1.38, p = 0.711]. A cohort reversal emerged: players born after 2006 exhibited a traditional RAE (OR = 1.92, p < 0.001), while those born in 1991, 2000 showed an inverse RAE (OR = 0.81, 0.85, p < 0.05). Cross-national analyses revealed no causal effect of cutoff dates on career outcomes. Post-entry, birth quarter had no direct effect on career duration (log-rank p = 0.593) or earnings (propensity-score-matched p = 0.487). Birth quarter operated indirectly through debut age: late-born players debuted 0.16 years earlier, mediating 48.5% of the total association with earnings (Sobel z = 2.57, p = 0.010).ConclusionAt the aggregate level, professional esports shows no relative age effect after adjusting for birth seasonality, and cross-national evidence is consistent with academic cutoff dates having no causal effect on career outcomes. Birth quarter is associated with career earnings only indirectly, through the timing of debut. The traditional RAE pattern emerging in the youngest cohort (born after 2006) may warrant attention as esports adopts more structured youth development systems.