Causal Effects of an Absent Crowd on Performances and Refereeing Decisions During COVID-19

Abstract

The COVID-19 pandemic has induced worldwide natural experiments on the effects of crowds. We exploit one of these experiments that took place over several countries in almost identical settings: professional football matches played behind closed doors within the 2019/20 league seasons. We find large and statistically significant effects on the number of yellow cards issued by referees. Without a crowd, fewer cards were awarded to the away teams, reducing home advantage. These results have implications for the influence of social pressure and crowds on the neutrality of decisions.

Keywords: Attendance, Coronavirus, COVID-19, Home Advantage, Natural Experiments, Referee Bias, Social Pressure

JEL Classification: C90, D91, L83, Z20