No crowds, no home advantage in football during the COVID-19 season: are crowds able to manipulate all but the best referees’ behaviour?

This study confirmed that without crowds there was no home advantage in association football during the COVID-19 2020-21 season. Consequently, we sort to answer the obvious question, “Are crowds influencing referees’ behaviour?” The number of home and away red and yellow cards awarded in the “no crowd” COVID-19 2020-21 season (all 4 top English divisions) were compared with the home and away cards awarded during the previous 10 “crowd” seasons (2010-11 to 2019-20). Results revealed that there was no home advantage in red and yellow cards awarded by referees in all 4 English leagues/divisions during the COVID-19 2020-21 season. Referees awarded significantly more cards to away players when adjudicating with crowds (seasons 2010-11 to 2019-20). However in more recent “crowd” seasons, Premier League referees are less susceptible to such influences with a narrowing of the gap between home and away yellow cards, suggesting that their preparation, management and training provides them with an element of “crowd immunity”. It would appear that home crowds are able to influence all but the very best referees’ behaviour. These new insights provide important information for the training and management of referees.