Romann Michael, Javet Marie, Cobley Stephen, Born Dennis-Peter
Department for Elite Sport, Swiss Federal Institute of Sport Magglingen, 2532 Magglingen, Switzerland.
Faculty of Health Science, University of Sydney, Lidcombe, NSW 2141, Australia.
Sports (Basel). 2021 Jul 9;9(7):99. doi: 10.3390/sports9070099.
In football, annual age-group categorization leads to relative age effects (RAEs) in talent development. Given such trends, relative age may also associate with market values. This study analyzed the relationship between RAEs and market values of youth players.
Age category, birthdate, and market values of 11,738 youth male football players were obtained from the "transfermarkt.de" database, which delivers a good proxy for real market values. RAEs were calculated using odds ratios (OR) with 95% confidence intervals (95%CI).
Significant RAEs were found across all age-groups ( < 0.05). The largest RAEs occurred in U18 players (Q1 [relatively older] v Q4 [relatively younger] OR = 3.1) ORs decreased with age category, i.e., U19 (2.7), U20 (2.6), U21 (2.4), U22 (2.2), and U23 (1.8). At U19s, Q1 players were associated with significantly higher market values than Q4 players. However, by U21, U22, and U23 RAEs were inversed, with correspondingly higher market values for Q4 players apparent. While large typical RAEs for all playing positions was observed in younger age categories (U18-U20), inversed RAEs were only evident for defenders (small-medium) and for strikers (medium-large) in U21-U23 (not goalkeepers and midfielders).
Assuming an equal distribution of football talent exists across annual cohorts, results indicate the selection and market value of young professional players is dynamic. Findings suggest a potential biased selection, and undervaluing of Q4 players in younger age groups, as their representation and market value increased over time. By contrast, the changing representations and market values of Q1 players suggest initial overvaluing in performance and monetary terms. Therefore, this inefficient talent selection and the accompanying waste of money should be improved.
在足球领域，按年龄分组的年度划分会在人才培养过程中导致相对年龄效应（RAEs）。鉴于这种趋势，相对年龄可能也与市场价值相关。本研究分析了青年球员的相对年龄效应与市场价值之间的关系。
从“transfermarkt.de”数据库获取了11738名青年男性足球运动员的年龄分组、出生日期和市场价值，该数据库能很好地代表实际市场价值。使用优势比（OR）及95%置信区间（95%CI）计算相对年龄效应。
在所有年龄组中均发现了显著的相对年龄效应（<0.05）。最大的相对年龄效应出现在U18球员中（第一季度[相对年龄较大]对第四季度[相对年龄较小]，优势比=3.1）。优势比随着年龄分组的增加而降低，即U19（2.7）、U20（2.6）、U21（2.4）、U22（2.2）和U23（1.8）。在U19组中，第一季度的球员比第四季度的球员具有显著更高的市场价值。然而，到U21、U22和U23组时，相对年龄效应发生反转，第四季度的球员相应地具有更高的市场价值。虽然在较年轻的年龄组（U18 - U20）中，所有位置都观察到了较大的典型相对年龄效应，但在U21 - U23组中，仅后卫（中小个）和前锋（中大个）出现了反转的相对年龄效应（守门员和中场球员未出现）。
假设各年度同龄人群体中足球天赋的分布是均等的，结果表明年轻职业球员的选拔和市场价值是动态变化的。研究结果表明存在潜在的偏差选拔，且在较年轻年龄组中第四季度的球员被低估，因为随着时间推移他们的代表性和市场价值有所增加。相比之下，第一季度球员不断变化的代表性和市场价值表明在表现和金钱方面最初存在高估。因此，这种低效的人才选拔以及随之而来的资金浪费情况应得到改善。
