Home-field advantage, the benefit that a home team in a sporting contest enjoys over a visiting team, is one of the most well-known phenomena in sports. It's commonly thought that throngs of supporting fans at home-team venues significantly contribute to this effect. Of course, that explanation has always remained untested, until now...
As the COVID-19 pandemic emptied stadiums around the globe, researchers stepped in to analyze the effects. In a new study published to PLoS ONE, researchers primarily based out of German Sport University Cologne explored what happened to home-field advantage without any spectators in the stands. They focused specifically on ten professional soccer leagues in Europe, comparing statistics from 36,882 regular-season matches played with spectators between 2010 and 2020 to 1,006 matches played without spectators during the pandemic.
The results were somewhat unexpected.
"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.
"Driven by spectator absence, it seems that the existing differences are eliminated (if not reversed) for fouls, yellow cards and red cards," the researchers noted.
So if spectators don't entirely account for home-field advantage, what else could? Prior research suggests that the beneficial psychological effects of expecting victory, visitors' travel fatigue, familiarity with the venue, ingrained territoriality, and changes to tactical behaviors all could factor in.
Citation: Wunderlich F, Weigelt M, Rein R, Memmert D (2021) How does spectator presence affect football? Home advantage remains in European top-class football matches played without spectators during the COVID-19 pandemic. PLoS ONE 16(3): e0248590. https://doi.org/10.1371/journal.pone.0248590