Relative Age Effect

RELATIVE AGE EFFECT

For young boys starting out in ice hockey a few months of age and development can make a big difference. Players that are older by only a few months are often smarter, bigger, faster, and more athletic than other players. A five year old born in January is 20% older than a five year old born in December of the same year. A 20% difference is like comparing a 10 year old to an eight year old or a 20 year old to a 16 year old. Players born in earlier months are therefore more likely to make travel teams and receive higher quality coaching and increased time in training. This phenomenon is called relative age effect.

Really looking at the numbers can be very eye opening. Some research by Adonna and Yates has looked at birth months of all Canadian players that have been in the NHL. There have been 883 players in the NHL born in January and February, 691 born in June and July, and 660 born in November and December. They have also found that birth rates in Canada are at the lowest in January and February and higher in the summer months. Therefore, January and February have the lowest birth rates and still produce the highest number of players. It seems that relative age effect is very prominent even at the highest levels of ice hockey.

Relative age effect occurs because there is a sorting of players based on performance starting at a very early age. The better (older) children get noticed by coaches and parents. This relative age effect phenomenon and player sorting seems to have started in Canadian youth hockey beginning with players born in 1951.
Players born in 1951 would have started playing hockey in 1956 or 1957. This is when Canada really began scrutinizing its young players in order to field national level teams. This was spurred by the Soviet Union entering the World Hockey Championships and winning gold in 1954. Also, the Soviet Union entered the Olympics for the first time in 1956 and also won gold. This appears to be the turning point of modern ice hockey and the beginning of relative age effect.

The actions that have caused relative age effect were done with the intention of bringing out the best hockey talent in Canada (and now the USA as well). However, this is clearly not the most efficient use of the talent pool. Many good players are ignored or overlooked at a very early age simply because they are relatively younger than other players are their level. "It implies that the minor hockey development system is considerably sub-optimal with respect to bringing the nation's hockey talent to the fore, and this has significance for Olympic and National Teams" Daniel and Jansen (1987).

References

Addona, Vittorio and Yates, Phillip A. (2010) "A Closer Look at the Relative Age Effect in the National Hockey League," Journal of Quantitative Analysis in Sports: Vol. 6: Iss. 4, Article 9.
Daniel, T. and C. Jensen (1987): "More on the Relative Age Effect," Canadian Association for Health, Physical Education and Recreation, 53, 21-24.