By Mark Baber
December 9 – The latest monthly report produced by the CIES looks at the issue of birth date bias finding that “players born in the first months of the year are strongly over-represented” in 30 top divisions in Europe – the exception being England where the bias is towards the period September- December as the age classes are based on September 1 rather than January 1.
According to the authors of the report “In football, players with the disadvantages of being born in the last months of the year and of later physical development currently have little chance of pursuing a career at a high level. The relative age effect has negative consequences not only for the players themselves, but also for football as a whole insofar as it leads to considerable bias in selections.”
A sample of 28,685 footballers having played in 31 top division European leagues since the 2009/10 season has been used for the study which finds that almost twice as many players are born in January than in December and the footballers born during the first three months of the year represent 30.5% of the total, as opposed to 19.3% for players born between October and December.
In the case of England, the CIES analysis shows 39.9% of players are born between September and December as compared to 24.4% born between May and August (24.4%).
The study finds the “relative age effect is particularly strong during the early years of a professional career. As age increases, the average day of birth of players tends to rejoin that of the average citizen. For example, a player of 21 years of age at most is, on average, born on the 9th June, while the average date of birth of a player over 31 is 23rd June.” This suggests, as the authors argue, that “”From 23 years of age upwards, a double mechanism is at work: precocious players who have not been able to confirm the hopes placed in them are progressively ousted in favour of those with a greater potential who had previously been cast aside. The relative age effect thus tends to lessen without, however, completely disappearing.”
Even more disappointing is the study’s finding that the “relative age effect is particularly strong among the principal training clubs. This suggests that when a team has first pick in terms of selecting youths, it tends to favour players with a precocious development even more.”
The authors conclude that “It is thus high time that the organisations in charge of the development of youth players and the game such as FIFA, the Confederations, the national associations, the leagues and clubs take the question of the relative age effect seriously.”
The shocking results of this study are even worse when you consider that they are worse than those found in a 10-year old study by this writer on “Birth Date Bias in the Premiership,” which used an Association of Football Statisticians data set of 1779 English players attached to Premiership squads from the 1992-93 to the 2004-05 season. That study found 34.68% of English players in the Premier League were born from September – December indicating there has been a considerable deterioration in the situation since then.
In May 2005, the Football Association claimed education on this topic was included in all courses relating to children at the front end of selection to the professional game and said that raising awareness of this topic would be extended to the grassroots game. The FA also said that it had been examining solutions to the problem including the possibility of basing training classes on a rolling birthday intake, so that each child would have experience as both the oldest and youngest in the class and splitting the season into six-month cohorts by having two birth-registration dates.
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