Why the relative age effect persists

In the context of youth sport, the relative age effect (RAE) refers to the bias towards recruiting players born towards the start of their year group in preference to their younger peers. It exists because players born towards the start of the eligibility period tend to have an advantage over those born later, purely by virtue of being older – at Under 9, for example, the age gap between the oldest and youngest can be equivalent to more than 10% of a player’s life. The consequent discrepancies in current performance understandably make it harder for scouts and coaches to judge long term potential, and so in some instances players with early birthdays take places in teams at the expense of younger players with greater long term potential.

RAE has been the subject of research and debate for many, many years. Yet it persists. The chart below shows the distribution of birth dates for over 1,600 players who have played in the Premier League U18 competition since 2016/17. With no bias in selection, we would expect to see close to 25% of players born in each quarter. Whilst the differences in this sample appear stark, initiatives across Category 1 academies since the introduction of EPPP may have already redressed the balance to an extent. A quick comparison with a sample of c. 200 players involved in the 2019/20 Coupe Gambardella (France’s equivalent of the FA Youth Cup, albeit U19) shows a staggering 65% of players with Q1 birthdays, and a mere 8% Q4.

So given the bias is widely known, well understood and unfavourable to those who develop young players and athletes, why does it continue? In part, because its existence is near-invisible at an operational level – you never see the progress of the player who wasn’t recruited. Equally, to force some kind of predetermined balance of birthdates would involve consciously deciding not to recruit some players who you consider of greater potential than others whom you do recruit – that is exceptionally difficult to do and to justify when you move from theory to reality.

Many clubs will have implemented, to varying degrees of success, initiatives to redress the balance. But, as the old adage goes, « you get what you measure », and regular reporting of consistent information will be key in delivering change. That could focus on, for example, age profiles of trialists, development centres or players flagged by individual scouts. The advent of analytics tools which can deliver simple information capture, workflow automation and data visualisation make such information quickly available to management.

The pathways of young players recently moving from U18 to first team football demonstrate the value in getting it right. From the same population of U18 players, the proportion of players who have made a first team league appearance among those born in Q3 and Q4 is 20% greater than those born in Q1 and Q2. In other words, the relatively younger players have proved more successful in making the transition to first team football.

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