Are football referees really biased and inconsistent? Evidence from the English Premier League

Abstract

This paper presents a statistical analysis of patterns in the incidence of disciplinary sanction (yellow and red cards) taken against players in the English Premier League over the period 1996-2003, using bivariate negative binomial and bivariate Poisson regressions. Several questions concerning sources of inconsistency and bias in refereeing standards are examined. Evidence is found to support a time consistency hypothesis, that the average incidence of disciplinary sanction is predominantly stable over time. However, a refereeing consistency hypothesis, that the incidence of disciplinary sanction does not vary between referees, is rejected. The tendency for away teams to incur more disciplinary points than home teams cannot be attributed to the home advantage effect on match results, and appears to be due to a refereeing bias favouring the home team.