Outliers: The Story of Success · chapter 1 · id outliers-c1-05-the-relative-age-effect-extend

“The relative age effect extends well beyond Canadian hockey -- studies of European soccer youth academies show the same pattern, with Q1-born players overrepresented across UEFA nations in U17, U19, and U21 squads.”

holdsconfidence: high⚠ extracted by pipeline, re-audit pending

Receipts

Relative Age Effect in European Soccer (2023), PLoS ONEsource alive

The relative age effect is widespread among European adult professional soccer players. Players born in Q1 were overrepresented, with the highest percentage in defensive and midfield positions (34.0% and 34.2%).

Helsen, Van Winckel & Stamboel, relative age effect in youth soccer across Europepaywalled — manual check queued

Birth distribution data from over 4,000 players involved in qualifying squads for U17, U19 and U21 tournaments organized by UEFA showed a declining distribution from the beginning of the year.

This claim is a stable, citable object. If you can falsify a verdict, tell us — corrections are loud here.