Abstract/Summary

We use a series of historical natural experiments in association football to test whether social pressure from a home stadium crowd affected behaviour and outcomes. The standout effect of an empty stadium was that referees cautioned visiting players less often, by over a third of a yellow card per match or once for every twenty-two fouls committed. Stadium crowds caused referees to favour the home team in their decision making. Empty stadiums appear to have reduced the overall home advantage in the final outcomes of football matches, but we cannot statistically reject no effect.