The relative age effect

What is the ‘Relative Age Effect’?

A multitude of factors affect how well one can develop as a footballer; innate physical traits such as height or bone density, social factors affecting motivation as a developing player and IQ are just some examples of these. One factor that probably isn’t as widely considered is the month in which one is born, but evidence points towards this having a statistically significant effect on the likelihood of one succeeding as a football player. For example, in 2009 at professional English youth academies, 57% of youngsters were born in the three month period from September to December, with only 14% born in the three month period from June to August.

The observation of success as an athlete being linked to the cut-off date for age group competition is known as the Relative Age Effect. As has already been stated, it is a phenomenon that repeats itself over a plethora of sports, but it is far more noticeable in sports that rely more heavily on physicality, such as American Football and Ice Hockey. Children born right after the cut off date for age grade competition have a distinct advantage over those born right before; in football this cut off date is 1st September. Children born in September therefore are advantaged due to greater physical development (due to an extra year of growth and development) than those born in August of the same year. This can be illustrated using a traffic light process with green players (born 1st September-31st December) having a psychological and physical advantage over yellow (1st January-30th April) and Red (1st May-31st August). There are exceptions to this, as genetics and nurture will play an important role.

This physical advantage is then compounded by a psychological advantage. The greater attention paid to those born directly after the cut off date has obvious physical repercussions; higher standard of coaching and greater attention paid to development will reap a fitter and technically proficient young prospect. However, possibly even more significant are the effects that such attention has on confidence and the player’s psyche. A child with self confidence and belief in their abilities, is far more likely to persist with a sport than one who lacks these qualities, and the greater attention paid to children born just after the cut off date provides these psychological benefits.

How is it affecting the development of young players?

Another question can be posed, that of whether players born immediately after the cut off date retain an advantage as they progress through their careers? This question can be definitively answered; they do not. A 2018 study by John R. Doyle concerning the relative age effect found that players born at the start of the cycle do not, on average, appear to be better footballers than their peers born at the end of the cycle. Players born at the start of the cycle in general do not have higher transfer values than those born at the end of the cycle, nor are they given more game time.

Another study (released in December 2015 in the CIES Football Observatory Monthly Report written by Drs. Raffaelle Poli, Loic Ravenel and Roger Besson) finds that as age increases the average date of birth of players approaches those of the average citizen, showing that as ages increase the relative age effect holds less significance. The paper states 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 diminishes with age, but it is important to note that it does not disappear.

There is clear and significant evidence of the existence of a relative age effect in football. There is evidence that these players born in September and the months closely proceeding the cut off date for age grade competition do not actually become better players than their younger counterparts. The relative age effect is obviously bad for players (as younger players who are technically proficient and actually more talented are overlooked); it is also bad for the sport, as potentially exceptional players do not realise their potential. Therefore, a question must be posed; what, if anything, are clubs and associations doing to counteract the phenomenon?

What is being done to counter it?

Unfortunately, there is very little being done. Suggestions have been made that simply raising awareness could mitigate the effect. Coaches being made aware that, to an extent, physical development at a young age fails to indicate future success of a player could lead to a fairer selection process. The issue with this is that it still requires a bold coach to select for future development (that they would not necessarily be credited for), over present results, which will be an indicator of their performance. There have also been discussions over the prospect of staggering cut off dates for different sports and prolonging selection period for players, but neither has resulted in concrete change.

There are hundreds of factors that affect the development of a young player, with date of birth, surprisingly being one of the most significant. While there has been little done to mitigate the relative age effect, it is important to note that there is no inherent advantage further on in development caused by date of birth.

What do you think should can be done to counter the bias linked with the relative age affect? Have you ever encountered it , and where?