L'equilibrio del campionato di calcio Serie A

Abstract

One of the most important issues in the scientific literature on sports is that of the competitive balance (CB for short). In this paper we present a new index to measure the CB, named the surprise index. The surprise index has several comparative advantages vis-?-vis more conventional indices of CB. Firstly, it can easily be used to compare leagues over time, between different countries and even between different sports. Secondly, it enables us to say something about the optimal number of teams in a league. These advantages arise because of the way the CB is measured by the surprise index compared to more familiar CB-indices like the standard deviation or the concentration ratio. Whereas the latter only use the statistics of the final league table at the end of the season, the surprise index makes use of much more detailed information. The results of all matches within a competition enter into the formula. Moreover, it gives a relatively high weight to surprising outcomes within the league competition, whereas the saliency of these matches is lost when computing the standard deviation or the concentration ratio.