Our behaviours are highly influenced by social pressure. This column takes as a natural experiment the 2020 season of the Japanese professional football league, which held matches without spectators due to the COVID-19 pandemic, to examine whether the presence of spectators puts pressure on referees’ decisions. The authors find that the home team advantage is real: the number of fouls decided against the home team decreased significantly in matches with spectators. The absolute number of home-team supporters mattered.
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