The Effect of Seeding on Tournament Outcomes: Evidence From a Regression-Discontinuity Design

Seeding in tournaments is a process of creating a schedule based on performance in the recent past. It is used in many athletic disciplines to ensure that particularly attractive match ups do not occur until the later stages of the tournament. We exploit the discontinuous nature of the seeding system in the UEFA Champions League and the UEFA Europa League as a natural experiment to estimate the causal effect of being seeded. We find no evidence that seeding itself contributes positively to the team's success in the tournament. This finding is surprising given the substantial drop in average strength of the opponents for seeded teams and in striking opposition to the findings of previous studies.