The influence of age-policy changes on the relative age effect across the Australian Rules football talent pathway

OBJECTIVES: To identify the influence of age-policy changes on the relative age effect (RAE) across the Australian Football League (AFL) talent pathway. DESIGN: Retrospective cross-sectional analysis of junior AFL players attending the National Draft (National), State, and State Under 16s (U16) combines between 1999-2016. METHODS: Birth-date data was obtained for players attending the AFL State U16 (n=663, age: 15.9±0.4years), State (n=803, age: 19.1±1.7years), National (n=1111, age: 18.3±0.8years) combines. Corresponding aged-matched Australian general population birth rate data was also collected. RESULTS: A chi-squared analysis comparing birth month distributions found all combine groups differed significantly from the general population (Under 16s: χ2=62.61, State: χ2=38.83, National: χ2=129.13, p<0.001). Specifically, Under 16s had greater birth frequencies for months January to March (≥2%, p<0.05), with more State players born in January (4.9%, p<0.05). Age-policy changes at the National level reduced birth distribution bias for some months, however the RAE remained for March, June and July (3.9%, 6.1%, 4.3%, p<0.05). State U16s and National players had 2-9% lower birth frequencies for November-December births compared general population. CONCLUSIONS: Selection bias exists towards older players is present at the AFL's State U16, and is maintained at State and National level combines. Age-policy changes are only partially successful at addressing the RAE at the National level, with alternative strategies also recommended in order to address the RAE across the AFL talent pathways.