Abstract
Despite various solutions proposed to solve the relative age effect (RAE), it is still a major problem confounding talent identification and selection processes. In the first phase, we sampled 302 under 7–21 academy soccer players from two Belgian professional soccer clubs to explore the potential of a new approach to solve the inequalities resulting from relative age- and maturity-related bias. This approach allocates players into four discrete quartile groups based on the midway point of their chronological and estimated developmental (ED) birth dates (calculated using the growth curves for stature of Belgian youth). With the use of chi square analyses, a RAE was found (p < 0.01) for the overall sample (Q1 = 41.4% vs. Q4 = 14.9%) that completely disappeared after reallocation (Q1 = 26.5%; Q2 = 21.9%; Q3 = 27.5%; Q4 = 24.2%). According to the new allocation method, the stature difference was reduced, on average, by 11.6 cm (from 24.0 ± 9.9 to 12.4 ± 3.4 cm, d = 1.57). Body mass difference between the two methods was 1.9 kg (20.1 ± 11.3–18.2 ± 13.1 kg, respectively, d = 0.15). The new method created a maximum chronological age difference of 1.9 vs. 0.8 years for the current method. With the use of this method, 47% of the players would be reallocated. Twenty-three percent would be moved up one age category, and 21% would be moved down. In the second phase, we also examined 80 UK academy soccer players to explore if reallocating players reduces the within-playing group variation of somatic and physical fitness characteristics. The percentage coefficient of variation (%CV) was reduced (0.2–10.1%) in 15 out of 20 metrics across U11–U16 age categories, with the U13 age category demonstrating the largest reductions (0.9–10.1%) in CV. The U12 and U13 age categories and associated reallocation groupings showed trivial to small (ES = 0.0–0.5) between-method differences and trivial to moderate (ES = 0.0–1.1) differences within the U14–U16 age categories. A reduction in RAE may lead to fewer dropouts and thus a larger player pool, which benefits, in turn, talent identification, selection, and development.
Highlights
The over-representation of soccer players born in the first 3 months of the selection year is typically referred to as the relative age effect (RAE) (Cobley et al, 2009)
The aggregated age groupings (i.e., U7–U8 and U9– U10) demonstrated that a RAE was present compared with the population norm distributions (p < 0.01; Q1 = 44.4 and 36.8%; Q4 = 5.6–10.5%) except for the U11–U12 group (χ2 = 5.06; p > 0.05; r = −0.55 p < 0.05; Q1 = 35.7%; Q4 = 18.6%)
The findings of the present study were four-fold: (1) the current age distribution per team and per quartile was similar to the distribution in literature and clearly showed a RAE for the entire sample of players (Barnsley et al, 1985; Verhulst, 1992; Helsen et al, 1998, 2000, 2012; Hurley et al, 2001; Musch and Grondin, 2001; Cobley et al, 2009; Nolan and Howell, 2010; Christina Steingröver et al, 2017a); (2) the RAE was calculated for aggregate age groupings (e.g., U13 and U14), and in almost all groups, a RAE was present; (3) with the use of the new allocation method, 47% (n = 141) of players would have been allocated to a different age playing category compared with the current system
Summary
The over-representation of soccer players born in the first 3 months (quartile) of the selection year is typically referred to as the relative age effect (RAE) (Cobley et al, 2009). The RAE occurs within youth sports due to arbitrary annual age grouping [i.e., under (U), U9, and U10] with fixed cutoff dates in soccer that typically align with the calendar year (January 1 to December 31), except in the UK, where it is September 1 to August 30. These groupings are used to provide age-appropriate training and game formats, it does not account for the maturity-related differences within a given age category (Helsen et al, 2005) and can contribute to premature deselection and playing position allocation of soccer players (Towlson et al, 2017). It may confound the (de)selection processes that talent development centers employ, likely thwarting the size of the talent pool clubs that nations can select from
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