According to previous studies, competitive balance has significantly declined in the UEFA Champions League group stage over the recent decades. Our paper introduces six alternative indices for measuring ex ante and ex post competitive balance in order to explore the robustness of these results. The ex ante measures are based on Elo ratings, while the ex post measures compare the group ranking to reasonable benchmarks. We find no evidence of any trend in the competitive balance of the UEFA Champions League group stage between the 2003/04 and 2023/24 seasons.

翻译：先前研究表明，近几十年来欧洲冠军联赛小组赛的竞争平衡性显著下降。本文引入六种替代指标来度量事前与事后竞争平衡性，以探究这些结论的稳健性。事前度量基于Elo评分体系，而事后度量则将小组赛排名与合理基准进行比较。通过对2003/04至2023/24赛季数据的分析，我们未发现欧洲冠军联赛小组赛竞争平衡性存在任何趋势性变化的证据。