Soccer: is scoring goals a predictable Poissonian process?

TL;DR

This paper models soccer match outcomes using a fitness-based approach, demonstrating that goal scoring approximates a Poisson process with predictable outcomes influenced by team fitness and minor correlations.

Contribution

It introduces a fitness-based model for soccer outcomes, showing goal scoring is nearly Poissonian and quantifying the limits of match predictability.

Findings

Goals follow a Poisson process with predictable expectations.

Minor correlations increase the likelihood of draws.

Fitness distribution explains non-Poissonian goal distributions.

Abstract

The non-scientific event of a soccer match is analysed on a strictly scientific level. The analysis is based on the recently introduced concept of a team fitness (Eur. Phys. J. B 67, 445, 2009) and requires the use of finite-size scaling. A uniquely defined function is derived which quantitatively predicts the expected average outcome of a soccer match in terms of the fitness of both teams. It is checked whether temporary fitness fluctuations of a team hamper the predictability of a soccer match. To a very good approximation scoring goals during a match can be characterized as independent Poissonian processes with pre-determined expectation values. Minor correlations give rise to an increase of the number of draws. The non-Poissonian overall goal distribution is just a consequence of the fitness distribution among different teams. The limits of predictability of soccer matches are quantified. Our model-free classification of the underlying ingredients determining the outcome of soccer matches can be generalized to different types of sports events.