Selection biases based on the use of cut-of dates and on the timing of athletes’ birthdates have been termed relative age effects (RAEs) and disadvantage some athletes while advantaging others. Research has shown that young male soccer players born early within their age-group are overrepresented in elite teams (Cobley, Schorer, & Baker, 2008; Helsen, Starkes, & Van Winckel, 1998). To date, research on RAEs in soccer (and other sports) has largely focused on North-America, Europe and Australia. Purpose of this study was to investigate the existence of RAEs among players participating in the 2014 Soccer World Cup and to test whether effects vary between continental confederations. Data were collected from the official FIFA website and include players’ birthdays and nationality. In this sample, a significant overall RAE was found, χ²(3, n = 736) = 11.34, p = .01, w = 0.14. Differentiating between continental confederations, significant RAEs were found for Europe, χ²(3, n = 299) = 12.51, p = .01, w = .20, and Asia, χ²(3, n = 92) = 13.65, p < .01, w = .38. Interestingly, descriptive trends differ between South America, North-Central America and Africa. The American confederations show an expected relative age distribution whereas Africa shows an overrepresentation in quartile 4. Results indicate that RAEs still exist at the highest level of competition but vary by confederation. Further research is needed to understand the inverse RAE in Africa. Possibly this is due to inconsistent cut-of dates or different strategies with regards to talent selection.
Cobley, S., Schorer, J., & Baker, J. (2008). Relative age effects in professional German soccer: A historical analysis. J Sports Sci, 26(14), 1531-1538.
Helsen, W.F., Starkes, J.L., & Van Winckel, J. (1998). The influence of relative age on success and dropout in male soccer players. American Journal of Human Biology, 10, 791-798.