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Relative Age Effect

Steve Lawrence is a consultant to Cruyff Football and Ajax in the Netherlands. With a Masters in International Sports Management, Steve founded the Football Analytics Lab and is at the forefront of research into the topic of Relative Age Effects. In this article, Steve explains how the Relative Age Effect works and discusses the impact of this phenomenon.


Relative Age Effects have become a well known, if slightly puzzling, phenomenon in youth football where players with birthdates at the beginning of the season have a huge advantage over their teammates born later in the season.

Relative age effects are not confined to football but can be seen across sport, education and childhood development generally. Hundreds of academic papers have been published on relative age, birthdate effects and school entry age effects since the 1930s, but the paper which pinpointed the issue in respect of competitive youth sport was written in 1985 by Barnsley, Thompson & Barnsley and was titled ‘Hockey success and birth-date: The relative age effect.’

A slightly later paper by Barnsley & Thompson in 1988, also about ice-hockey,...

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