摘要：Background: The relative age effect (RAE), consists of the less presence in a particular area of those born in the last months of the year. This definition assumes that the age split is made in January, but there are studies showing that this effect also occurs when the cutting is done in other months of the year. In this case the increased presence in this area will be for those born immediately after the cutoff date. Early studies on the impact of the relative age effect in sports were published by Barnsley, Thompson and Barnsley in hockey (1985) and Barnsley, Thompson y Legault in soccer (1992). Objective: The aim of this study is to assess whether the relative age effect occurs in professional football in Spain, where the different competition categories gather players born in the same year. The analysis has included all football players competing in the Liga BBVA during the 2009-10 season. Restults: The results of our study confirm an important relative age effect on the main professional football competition in Spain, Liga BBVA, where 61% of the players are born in the first half of the year. It has also been done the study segmenting by teams, positions of the players in the field of play and nacionality, obtaining some significant results. The relative age effect seems to have important social and economic implications. A change is needed in the current systems for the talent detection and selection, because this seems to be the way for not only being more fair and consistent to younger applicants, but for the organizations to be able to optimize their performance by investing in the promotion of their own junior players rather than acquiring senior ones from outside
关键词：Relative age effect; players market; talent selection; football; liga BBVA
