Course:KIN366/ConceptLibrary/Relative Age Effect

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Relative Age Effect
KIN 366
Instructor: Dr. Shannon Bredin
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Important Course Pages
Lecture Notes
Course Discussion

The term relative age effect (RAE) is used to describe when someone is born relative to the time period of the year, with a strong participation/success bias seen amongst those born earlier in the selection period. The selection period refers to the cut-off dates used to establish eligibility for sport or academics. Athletes/students are grouped in chronological age cohorts in order to help provide a “level playing field.” These subtle age differences do however affect the developmental outcomes of children in a given cohort. Unfortunately those born immediately following the cut-off dates show higher participation rates in high level sport and educational success; therefore, those born prior to the cut-off dates occupy a lower percentage of high level sports teams and are less likely to succeed in the early years of the educational system (Baker et al., 2010).


Cut-off dates for eligibility issues are typically determined by national governing bodies of sport or academia. The most common cut-off date used, especially in Canada, is the calendar year or December 31st. In order to be eligible for an age group in minor hockey per Hockey Canada and IIHF rules, you must be born on or before December 31st (IIHF), meaning those born in January are almost a full year older than those born in December. The school system does not have a set standard across the country as 6 provinces and all the territories use December 31st, Quebec uses September 1st and Nova Scotia September 30th, with PEI using January 31st and Alberta using March 1st. (PEI) They each have their reasoning for when the age of school entry should be, but all share the common goal of wanting children to be developmentally ready to be able to succeed in a learning environment. Because of these arbitrary yearly age categories the same athletes are constantly the older or younger in a given cohort and despite unique variability those born earlier have had more time to develop, mature and gain fundamental movement patterns and movement experiences.


Relative Age and League of Play in Canadian Hockey

Quarter of Birth (Percentage)

Category 1 2 3 4 N
Live births in Canada 24.4 25.6 26.1 23.9
NHL players 1982-1983 32.0 29.8 21.9 16.2 715
WHL players 1983-1984 41.9 29.6 19.3 9.2 698
OHL players 1983-1984 40.9 30.9 17.4 10.9 350
Edmonton 9-10 yr olds (83-84) 25.3 26.9 24.7 23.0 1839
9-10 yrs old top tier 35.3 32.5 21.0 11.2 286
11-12 yrs old top tier 38.0 26.7 19.5 15.8 329
13 yrs top tier 37.3 30.1 21.3 9.3 183
14 yrs top tier 41.6 32.1 13.9 12.4 137
15 yrs top tier 36.0 28.8 22.4 12.8 125

(Allen, 1993)

Relative Age and Plus-80th Percentile Score, Canadian Achievement Tests, Alberta School District, 1985

Season of Birth (Percentage)

Grade Winter Summer Autumn N
Grade 3 Total 34.5 34.7 30.6 480
Math > 80 56.1 31.6 12.3 57
Reading > 80 52.5 30.5 16.9 59
Grade 6 Total 32.7 34.3 32.9 434
Math > 80 41.2 34.1 24.7 86
Reading > 80 39.6 33.1 27.3 139
Grade 9 Total 31.9 33.9 34.1 504
Math > 80 36.3 32.9 30.8 88
Reading > 80 32.6 31.1 36.4 132

(Allen, 1993)

These stats, taken from Streams and Tiers (Allen, 1993), prove that relative age effects do have beneficial outcomes to those born earlier in the selection period. These stats prove the existence of RAE as there is almost an even number of hockey players and students in each age grouping, however those with early birthdays are much more prevalent among the top tier hockey players, especially in the WHL and NHL, and those with winter birthdays have a significant advantage in early years (grades 3 and 6) for math and reading achievement tests. The advantage seems to disappear after Grade 6 showing that RAE dissipate as the student ages and the reason for it remaining in later years in hockey could be due to dropout which is not allowed until the age of 16 in the Canadian school system.


In minor hockey in Canada players are tiered, with the most skilled players being selected for the top tier; however, at a young age ability can be mistaken for maturity. Because children are selected to teams that are tiered at such a young age, “those born in the first quarter are on average bigger, stronger, and better coordinated than children born in the last quarter, so, given the same innate ability, they are more likely to succeed at the top tier.” Players selected to the top tier, in turn receive superior coaching, more practice time and better competition than those selected to lower tiers. (Allen, 1993) This allows them to further develop their skill at a faster rate because of the superior movement experiences which they have been provided. Malcolm Gladwell refers to the advantages RAE provide as well as mentioning the 10,000 hour rule. The main idea of the 10,000 hour rule being that it takes 10,000 hours of practice at any skill to master it (2008). Applying it to the relative age effect and the advantages which are provided by being selected to a top tier team, the more practice time and experience you are able to get the more likely you will be to master your task, or develop superior skill acquisition. Therefore the bias which exists in favour of the more mature and developed young athlete at 6 or 8 years old, will have a lasting impact allowing them more opportunity to hone their skill, making them more likely to make the top tier teams the following season when evaluations take place again, and by making the top tier again they are given the benefit of more experience, more playing time, better coaching and the cycle continues leading to the impartiality we see amongst the different quarters.


The benefits derived from relative age effect exist to those born early on in the selection period. This is due to the extra time to develop and mature to which the younger individuals are not privy. The older athletes are therefore at an added advantage to be selected to top teams which will afford them more playing opportunities. The same can be said for students as the more mature students are more school ready and able to take part and excel in a controlled learning environment. We know that early success in school and sport is indicative of future success in the same areas so it would be beneficial to the older individuals who are most likely to reap the advantages their age creates (Allen, 1993). Unfortunately these benefits are arbitrarily decided by the age restrictions/groupings imposed by organizations and adversely affect those who are on the wrong side of the cut-off. Therefore it is important to explore all possible solutions to the relative age effect to give everyone an equal opportunity to gain valuable experience and succeed in their desired field.


Dividing players based on biological age as opposed to chronological age, could help ensure fair competition and eliminate the benefits of relative age. Delorme argues that dividing athletes into weight categories, such as those used in boxing and wrestling could help lower RAE and shows that French boxers participating in the 2010-2011 season do not demonstrate relative age effects (Delorme, 2014). This could be due to the fact that the athletes are grouped by weights and not just age, and are therefore are constantly competing against other athletes within their same development categories. If athletes are all at roughly similar maturation stages then everyone is equally likely to develop and experience success. Another possible solution is either diminishing the age discrepancy by creating 6-month cut-offs as opposed to the generally used 12 months. This only works to diminish the impact of RAE as there will still be the same athletes in the younger group every time. To eliminate the repeat cycle of the same athletes every year and what Baker et al. refer to as a “fixed bias”, a cycle of 9 and 15 months would allow different birthdays to enjoy being the more mature, older athletes over a 2 year cycle (Baker et al., 2010). This system is still unfortunately flawed as if you started in January, a September birthday would be the last in the 9 month cycle and 12th in the 15 month cycle, not affording them the opportunity to be amongst the elder athletes of a given cohort, and a 15 month cycle creates even greater discrepancy amongst the group than a 12 month age grouping category. The last solution which may well be the most efficient in diminishing the effects of skill acquisition in relation to relative age, but also the hardest to implement as the organizational structure would need to be changed. That is to abolish age groupings in their entirety especially at the youth level and rather classify and categorize athletes based on their skill level as opposed to their date of birth. This would have the impact of negating and advantages from maturity and development based on chronological age and group the athletes in a cohort with similar skill level in order to maximize the opportunity to gain critical movement experiences. If all the children in a cohort are more or less equally talented they should all be exposed to the same playing time, and game experiences increasing their ability to develop and learn and succeed in their sport of choice. Seeing as how most junior/college/professional teams don’t select players until they are at least 16, this gives athletes the opportunity to fully develop without suffering any benefits/harm based on relative age. More research would be needed to see if this is plausible and can have the desired effect.


Allen, J. (1993). Streams and Tiers: The Interaction of Ability, Maturity, and Training Systems with Age-Dependent Recursive Selection. The Journal of Human Resources. 28 (3), p.649

Baker, J., Schorer, J., Cobley, S. (2010). Relative age effects. Sportwissenschaft, 40 (1), p.26-30.

Delorme, N. (2014). Do weight categories prevent athletes from relative age effect? Journal of Sports Sciences. 32 (1), p. 16-21

Gladwell, M. (2008). Outliers: The Story of Success. New York: Little, Brown.

Government of Prince Edward Island, Education Age of Entry, Retrieved February 26, 2014, from

International Ice Hockey Federation, Rules and Regulations, Retrieved March 1, 2014, from