Competitive Balance and Outcome Uncertainty Estimation: Applications to the National Basketball Association and Wales Football League

This paper analyzes the effects of schedule changes on outcome uncertainty (OU) in the National Basketball Association (NBA) and the Wales Football League (WFL). It discusses the unbiased estimators of OU and competitive balance (CB) as well as the within- and between-division CBs comprehensively. Comparing the WFL with the NBA, the degree of schedule imbalance was greater in the WFL, and the variation in division strength of the WFL was larger than that of the NBA. Our analysis on schedule imbalance and variations in division strength implies that both leagues benefitted from an unbalanced schedule in terms of OU and the positive effect was greater for the WFL than the NBA. The magnitude of OU enhancement was 4.5–7.7% and 8.6–10.9% relative to the CB in NBA and WFL, respectively.