This study of Sweden’s 24 football districts analyses whether contextual factors

(number of players, number of elite teams, and number of elite players on each

district team) influence the district teams’ relative age effect (RAE) and the way

in which contextual factors and RAE correlate with the U15 teams’ competitive

success. The analysis is based on register data on district players (4,516 girls

and 4,501 boys, all 15 years old) who attended an annual elite football camp:

birthdate, the total number of players aged 15, club membership, senior elite

clubs, proportion of elite players on the district teams, and match outcomes.

Based on the birthdates of the players born between 2001 and 2012, a relative

age index was constructed for each district. The results showed a relative age

effect (RAE) for the selected district players (boys and girls) compared to the

general 15-year-old football population; however, birthdate only affected the

competitive success of the boys’ district teams. The analysis points out that

contextual factors such as the number of football players and the presence of elite

clubs are important to consider in order to understand how RAE is produced

and its relationship to the success of winning matches for boys’ district teams.