title: Relative Age Effect in UEFA Championship Soccer Players.
abstract: Relative Age Effect (RAE) is the breakdown by both age grouping and dates of birth of athletes. In the past 20 years the existence of this effect has been shown with higher or smaller impact in multiple sports, including soccer. The purpose of this study was to identify the existence of RAE in European soccer players. The sample included 841 elite soccer players who were participants in the UEFA European Soccer Championship in different categories. The professional category (n = 368), U-19 (n = 144) and U-17 (n = 145) were in 2012, and U-21 was in 2011 (n = 184). The Kolmogorov-Smirnov test and the Levene test recommended the use of nonparametric statistics. The results obtained by the square test ( the Kruskal-Wallis test and Cohen's effect sizes revealed the existence of RAE (χ(2) = 17.829, p < 0.001; d = 0.30), with the size of their different effects depending on their category or qualifying round achieved by the national team and the existence of significance in the observed differences by category. Therefore, we could continue examining RAE which is present in elite soccer, and could be considered a factor that influences performance of the national teams tested. RAE was not evident in the professional teams analysed, however it was present in the three lower categories analysed (youth categories), with its influence being greater on younger age categories (U-17).
authors.affiliation: Faculty of Teaching Education (Cuenca), University of Castilla-la Mancha, Spain. EDAF research group.
authors.forename: Sixto
authors.initials: S
authors.lastname: González-Víllora
authors.affiliation: Faculty of Teaching Education (Toledo), University of Castilla-la Mancha, Spain. EDAF research group.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Pastor-Vicedo
authors.affiliation: University of Castilla-la Mancha, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Cordente
keywords: amateur vs. professional players; international soccer; relative age effect; talent identification