The relative age effect in soccer: Cross-cultural evidence for a systematic discrimination against children born late in the competition year

Previous findings of skewed birth date distributions among sports professionals have been interpreted as evidence for a systematic discrimination against children born shortly before the cut-off date for each age grouping. Alternative explanations for these findings exist, however. This research therefore attempted to replicate the effect in a cross-cultural comparison. A strong relative age effect in professional soccer was found in Germany, Japan, Brazil, and Australia, showing that the effect is independent of different cut-off dates and a variety of climatic and sociocultural factors. A shifted peak in the birth date distribution of Australian soccer professionals paralleling a corresponding change in the cut-off date in Australian soccer in 1989 was also established. This pattern of results provides strong evidence for the cut-off date in youth soccer as the main cause for the relative age effect in professional soccer.