“In terms of the home advantage itself, surprisingly, only a non-significant decrease is found,” the researchers wrote. “Home teams still perform clearly better than away teams in matches without spectators, which means that the home advantage is not predominantly caused by spectator presence,” they added in a statement.
The researchers defined home advantage as the average goal and point difference enjoyed by home teams. (In soccer, three points are awarded for a win, one for a draw, and zero for a loss.) According to the data, this advantage did fall between roughly 17% and 32% without spectators, but the change was not statistically signifcant, indicating an unacceptable probability that the result could have occurred by chance alone.
Home teams did, however, take statistically fewer shots without spectators in attendance, perhaps because they didn’t feel as much fan pressure to create scoring opportunities in situations unlikely to lead to a goal. Referees bias in favor of home teams, likely fueled by crowd pressure, also seemed to vanish entirely.