The examination of relative age effect in Turkey female's first football league and place in success

Abstract

Objective: to examine relative age effect and its effect on league ranking in Turkish female's first football league. Method: the data of 2684 players, who participated in the league between 2012 and 2019 was gathered from the official website of The Turkish Football Federation and their birth-dates were divided into quarters by month. To test the extent of the relative age effect in each season, a chi-square test was used to assess the observed and expected birth distribution across the sample of players. Chi-square values were followed up by calculating Odds Ratios (OR) and 95% Confidence Intervals (95%CI) for the quartile distributions in order to examine subgroup differences. Significance level was accepted as 0.05. Results: it has been found that there is the relative age effect among all season birth-quarters distributions (X-2 =90.858, p<0.05). Each season evaluate separately, it was found significant differences in five season which include 2012-2013, 2014-2015, 2016-2017, 2017-2018 and 2018-2019 seasons (respectively: X-2 ((3)) =15.309, 11.347, 24,285, 19.260, 19.168, p<0.05). It has been found that there are significant differences among teams' birth-quarter distributions according to league ranking in each season (p<0.05). Conclusion: this study was presented that there is relative age effect in Turkish woman soccer players. Even though all season league ranking assessment for the relative age effect was found statistically differences, it is difficult to say that the relative age effect is an important factor for success.