A Discourse on the Relative Age Effect in Football

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This study examined the influence of performance level on the prevalence of the relative age effect in youth football within England.  The research presented highlights that this criterion influences the distribution of football players within England. The current study consists of corresponding findings to preceding research into English football. (Simmons & Paull, 2001; Glamser & Vincent, 2004; Musch & Grondin, 2001).

Relative age effect was most prevalent within the highest level of youth football within England, i.e., the academy level. The number of players that participate for academy teams decreases as the months of the selection period progresses through the year. Players born earliest in the selection period were compromised of 47.8% of the total number of players. This number decreased to 28.4% for players born between December and February, 15.9% between March and May and 7.9% between June and August. (Figure 1). Simmons & Paull (2001) comply with the studies current results in relation to youth football players at the highest level. Similarities arise through the comparison of the two studies with Simmons & Paull (2001) who accumulated results showing 61% of centre of excellence players were represented by the oldest players in the teams, with the younger players being underrepresented occupying 11% of the total number of players. The two studies highlight a large bias towards the oldest players by 39.9% and 50% respectively.

Furthermore in relation to the birth bias towards players born early within the selection period participating at the highest level Musch & Grondin, (2001) found that in the United Kingdom, Sweden, and Belgium 70% of elite youth players were born within the first half of the year. The current study presents comparable results supporting the research in which statistical analysis found 76.2% of the academy players were born within the first half of the year.

The study aimed to view if the level of football being played impacted the relative age effect. The current study found that the birth bias towards the oldest players although present at each level did not always increase. The players participating at the lowest level (community) consisted of 24.2% of the total amount of players in which emerge from the youngest age group. This was only 4.1% less than the total amount for the oldest players, highlighting the lowest bias between players within the study along with the grass root players. In relation to the impact of the performance level of a participant on the relative age effect, the study’s results provide evidence that the significance of raising the performance level does not affect the selection of younger players when moving from the community scheme to a grass root team. The results contest previous research conducted by Mujika et al (2007). The Difference in the youngest and oldest players within the two subgroups of community and grass root does not alter with the adjustment in standard of play; Mujika et al (2007) found within their study that as the performance level increased so did the relative age effect. In numerous age groups, the impact of the relative age effect can be seen to decrease as the performance level increases (Table 2 & 3). Although the study opposes this area of research by Mujika et al, (2007) the study corresponds when viewing academy players. In relation to corresponding with Mujika et al, (2007) the current study found similar results in the impact of the birth bias when reaching the academy level. Mujika et al, (2007) found that the difference between players who participate within the highest level of youth football and the ones who participate within the lowest level was of significance, finding that this difference was 23.7% in favour for the older players with the current study presenting a difference of 23.6%.

The impact on performance levels of players participating within each of the subgroups differed throughout different age groups.  Table 4 presents evidence highlighting that during the participation within the under 10’s age group at every standard of play the bias towards the older players is at the lowest level, evidently in the community and grass root subgroup the bias can be seen  to be in favour of the younger players. There is a higher representation of younger players over older players in the under 10’s age group by 7.5% and 2.2% respectively contesting research by Helsen et al (2000) who found the relative age effect to impact each age group including players as young as 8 year old. Table 4 progresses to highlight the most affected age group in total throughout the different standards of play is within the under 9’s age group. The difference between the oldest and youngest players are 12.1% in the community group, 6.5% in the grass root subgroup with the highest difference being 51.1% in favour of the older players. The most significant finding found that there was no relative age effect within the community scheme at under 15’s, this age group was also the lowest within grass root players with a difference of 1.8%. The findings into the age in which the relative age effect is present resonates with research from Helsen et al (2000). In which both studies found that the relative age effect is present within the youngest age groups, with the older players being labelled as talented.

Overall the statistical research found that in relation to performance level, the relative age effect is most predominant when reaching the academy standard with low performance levels providing little evidence of a significant bias. The age of a player in relation to the impact of the relative age effect at academy level provides evidence suggesting that the impact of the relative age effect is prominent throughout all ages with the older age groups presenting higher numbers of older players.

The study’s secondary aim was to view if football coaches where the relative age effect has most impact are currently arranging strategies to limit the bias. The research found that out of the four coaches interviewed on the matter every coach had been made aware of the relative age effect. Highlighting this result along with the impact the relative age effect has at this performance level contests preceding research by Cobley et al (2009). Cobley et al (2009) stated that raising awareness in coaches would be effective in reducing the effect. The current results highlight that coaches have been made aware and results from Figure 1 and Table 2 present results against research that states raising awareness is an effective strategy to reduce the relative age effect as it is still predominant. Whilst coaches in the study conveyed that they had been made aware, results from the interviews highlight uncertainty in the definition and understanding of the issue. Responses consisted of phrases presenting this uncertainty, for example ‘if I’m Right; I think’. This finding should be considered when analysing research by Cobley et al (2009) because although the coaches have been made aware, the issue has not been fully understood limiting knowledge and in turn limiting the impact this could have on them.

The coaches interviewed in the study stated that they were made aware of the relative age effect through ‘development days and coaching courses’. The relative age effect has most impact in relation to the standard of play that the coaches questioned work at. Baker et al (2010) suggested that increasing awareness and under­standing of the relative age effect as part of coach training and education programs, may help centre coaches attention to the potential selection bi­as. Results in the study deviate from Baker et al (2010) research as the coaching courses have not centred coaches to the selection bias, coaches felt that the relative age effect did not affect them as they mainly view ‘technical ability’ and argued that ‘You don’t know how old that player is when you select him’. This provides evidence suggesting the coaching courses are raising awareness but the issue of the relative age effect is not being made specific to the coaches to allow understanding.

The preceding research into limiting the relative age effect in football referred to raising awareness and the implementation of new selection periods. (Baker et al 2010; Cobley et al 2009; Vaeyens et al, 2005; Simmons and Paull, 2001) The initial strategy has been contested throughout this study in which found new ways the coaches are aiming to reduce the bias. The coaches at academy level suggested the strategy of ‘playing players up or down one year’ can help develop players. The results present new findings in the research to limiting the relative age effect within football. However  whilst the academy coaches can be seen to be implementing this, Figure one and Table one highlight results questioning the effectiveness of this strategy as the relative age effect is predominant at that performance level. Relating to prolonging the playing career of players that the relative age effect detriments coach D provided strategies to facilitate this. Coach D when viewing coaching strategies suggests ‘social’ development is imperative. Actions such as allowing players ‘to set up sessions, do demonstrations and be captains’, all with the aim of improving confidence and allowing the younger players to progress. The strategy aims to prolong and develop players when already within the academy team; however this would not change the birth bias in the most important area which is the selection process. If the younger players are not progressing through to the team then the strategy would become redundant.

Interviews including the academy coach’s emphasised that when selecting players the main attribute the coach’s look for is technical ability, with impact the player has in the game being the secondary attribute. Malina et al,(2004) stated there were ‘advantages in body size, fat free, mass and several components of physical fitness, including aerobic power, muscular strength, power, endurance, and speed’. The physical attributes portrayed by Malina et al (2004) can contribute to players utilising them in different positions to produce this ‘impact’ within games. (Bloomfield et al 2007). The preponderance of evidence implied the impact of the player during a game was one of the attributes coaches viewed as necessary in performing at the academy standard. However, in interviewing coaches, acceptance of selecting the older players came to the fore in one instance. Coach B conveyed that they would look to the players the birth bias effects; ‘if i needed a centre half i do look at the taller age ranges’. The preceding research along with the current studies qualitative results suggests the selection process used by coaches, seek to identify the attributes that the players oldest in the selection period are perceived to possess. This implicit acknowledgement provides evidence of why the relative age effect is so predominant at this performance level.


The primary aim of the study was to investigate the performance level at which birth date may affect selection for performance pathways in English football. The current study’s findings present divergent results in comparison to preceding research that highlighted as the performance level of a player increased, so did the relative age effect. (Till et al 2010; Mujika et al 2007) The current study’s results presents that the performance level of a player only illustrates an impact on the birth date of a performer once the highest level of youth football is achieved. The results establish that the football pathway towards elite football demonstrates a bias towards the oldest players within the selection period, this bias dissimilar to any other standard in English football. The results compiled within the study provides evidence that once players reached the highest level of youth football the players who were born earliest within selection periods possessed the necessary attributes to continue. Whereas the evidence implies that players born latest within the selection period have not at this stage of selection acquired those attributes. The study’s results differentiate from previous in which throughout each standard of play the impact of the relative age effect progressively increases. The data is of important value to members of the academy structure, highlighting an area in which improvement is acquired.

The secondary aim of the study was to explore the football coaches understanding of the relative age effect in addition to establishing whether strategies are currently in place to minimize the effect. The present findings highlight that the coaches within the academy structure are aware of the relative age effect, however unlike previous research suggested this awareness is not substantial enough to minimize the relative age effect at this level. (Cobley et al 2009; Baker et al 2010).  The coaches informed that the awareness was arisen through coaching courses and development days. Preceding research by Barker et al (2010) suggested that awareness through these sources would ignite a response in minimizing the bias. The current study provides sufficient evidence contesting this research as although the coaches are aware of the level of impact the relative age effect has; it is still predominant at this level.

In relation to strategies currently in place the study presented new findings into actively reducing the relative age effect. These strategies were to play players up or down one year dependant on a players development stage and to increase confidence of younger players within the teams, both of which were proven to be ineffective through statistical data gathered throughout the study. The area of weakness within the strategies in attempting to reduce the impact that birth date has on selection, is that they are currently aimed to limit the bias once players have been selected. The study was unsuccessful in presenting an effective strategy in reducing the relative age effect within English football, comparable to preceding research. The study provides guidance into the application of future research in which should concentrate on strategies in placement prior to selection, rather than once players have been selected.

The study’s results presents informative data with great value for academy coaches and scouts. The study highlights that the academy’s approach to minimizing the effect currently is ineffective, providing evidence that action is needed in order to reduce the relative age effect at this standard.

The current study was limited to the Yorkshire region when compiling results for the study due to time and convenience, future research should explore a wider circumference to analyse the overall impact on English football. In relation to the sample size of the study, the number of players viewed was imperative to acquiring informative results; however, it is recommended that future research contributes increased time in the collection of a larger broad sample size in order to comprehensively view the impact of the relative age effect in English football.

To conclude, the study found that the performance level of a player only has an impact on the birth date in relation to selection once the highest level of youth football is viewed. The coaches are currently aware of the relative age effect but as yet there are no successful strategies in order to reduce this effect in the English game.