An unprecedented "natural experiment" has shown that, even with spectators completely absent from matches during the COVID-19 pandemic, professional European football teams playing at their home field have a statistical advantage over visiting teams. Fabian Wunderlich, Robert Rein, and Daniel Memmert of the German Sport University Cologne and Matthias Weigelt from the University of Paderborn present these findings in the open-access journal PLOS ONE on March 31.
For decades, researchers have analyzed the "home advantage" seen consistently across many different team sports, identifying many potential contributing factors. However, it is nearly impossible to conduct meaningful experiments during real-world sports events, so the precise influence of any given factor has remained unclear.
This has changed recently due to social-distancing measures in response to the COVID-19 pandemic, where many professional football matches have occurred without crowds, presenting an unusual opportunity to study their influence on the home advantage.
For the new study, the researchers conducted a statistical comparison of more than 1,000 professional matches played without spectators and more than 35,000 matches that occurred with spectators prior to the pandemic.
The researchers were surprised to find that, while the absence of spectators was associated with a slight decrease in home advantage--as measured by the number of goals and points scored--the difference was not statistically significant. Additional analysis of amateur games played without crowds even in non-pandemic times provided further evidence suggesting that the presence of spectators is not the main driver of home advantage.
However, in line with earlier research, the new analysis suggests that crowds may influence referee behavior. Normally, visiting teams face increased sanctioning in the form of fouls, yellow cards, and red cards; but without spectators, this so-called referee bias disappeared. Additionally, home teams experienced a decrease of their usual advantage in terms of number of shots and shots on target.
Once spectators return to stadiums, additional data will help clarify these new findings. Meanwhile, this analysis could prove informative to various stakeholders, such as referees trying to limit biased decisions or teams trying to maximize their (home) advantage over others.
The authors add: "In our analysis of more than 40.000 football matches, we could show that empty stadiums during the Covid-19 pandemic had a major impact on the referee decisions and actions on the pitch. Surprisingly, 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."
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:/
Funding: The author(s) received no specific funding for this work.
Competing Interests: The authors have declared that no competing interests exist.
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