Experimental 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 currently taking place over several countries in almost identical settings: professional football matches played behind closed doors. 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 refereeing decisions.

Keywords: referee bias, natural experiments, home advantage, COVID-19, Coronavirus, attendance, social pressure

JEL Classification: C90, D91, L83, Z20