The phenomenon by which children born early in their year of birth perform more highly than children born later in the same cohort, is called the Relative Age Effect. Just out of curiosity, Philip Hans Franses, Professor of Applied Econometrics at Erasmus School of Economics, conducted a small study to evaluate whether an RAE would also hold for the players in the UEFA Champions League.
In sports it is well known that there is a Relative Age Effect (RAE). This implies that children born earlier in the year can be better in school and in particular in sports. Evidence of the RAE is reported for NHL (1) hockey and Football (2).
824 players involved
The 68th season of Europe's elite club competition (2022-2023) has been on its way for a while. 8 pools with each 4 teams of top-division European clubs compete for the cup with the big ears. Each team has about 21 to 26 players, and in total 824 players are involved.
Based on the birth days data (3&4), Philip Hans Franses has drawn the following graph (where 1 is January, and 12 is December). 103 players are born in January, 76 in February, whereas in November and December only 66 and 60 celebrate their birthdays, respectively.
RAE prominently holds
The downward trend as the year proceeds is clearly visible in the graph. Also, in a competition involving players from all kinds of countries, age levels, and positions in the field, the RAE prominently holds.