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Does a match without spectators affect the home team? Yes

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During this semi-lockdown period, can playing to empty seats put the home team at a disadvantage, depriving it of energy from its fans? The Rumour Detector finds the answer is more subtle: teams are likely to play on a more equal footing than usual.  
This is an old debate among sports fans: how much of an advantage do supporters give their home team? Now that the pandemic is forcing teams to play in empty stadiums or arenas, this is a good opportunity to try to settle the question. 
Home field advantage 

In the past, researchers often delved into the statistics. But they often had to account for other variables — the visiting team’s fatigue caused by their trip, or the local players’ familiarity with the venue. 

Soccer offers the most obvious home team advantage. A 2014 study in Italy analyzed the performance of soccer teams sharing the same stadium when they played each other. This eliminated the fatigue or unfamiliarity factors from the equation. The authors noted that the home team “performed” better in the presence of more fans, and scored more goals.  

Research suggests that the “home field advantage” is due more to referees who let the crowd influence them. Swedish economists analyzed soccer matches in Italy that were played behind closed doors in 2007. During public matches, the home teams normally received more favourable verdicts from the referees, fewer yellow and red cards, and fewer penalties and fouls. This advantage disappeared when the matches were played without spectators present. This means the referees were strongly (and presumably unconsciously) affected by social pressure, an American study added in 2005, and the desire to “satisfy the crowd”.  

This home team advantage has declined in the past few decades in certain sports, particularly basketball, baseball and football. The authorization of video replays to assist referees and umpires in their decisions helped “reduce the home field edge”, American information science researcher Konstantinos Pelechrinis wrote in 2019 . 

Playing during the COVID period 

What about this year? English researchers published a study in June, comparing 160 European soccer matches without an audience with several thousand pre-COVID games. The local players’ advantage crumbled. Fewer goals were scored by the home teams. When their fans were present, they had won 46% of their matches (compared to 28% ties and 26% defeats). But this proportion fell to 36% in empty stadiums. However, the sample is limited, and the authors point out that, given the quality of the teams in these rare closed-door matches, the effect of “no fans being present” is not statistically significant.  

The German Bundesliga soccer league was the first to resume operations during the pandemic. It also found that the proportion of home team victories slipped by 10 percentage points, according to a July 1 report in the New York Times. Bundesliga home team players scored less often and generally made fewer plays (passes, dribbles, etc.). Even the goalies stopped fewer shots on the home field than usual. In June, the Gracenote analytics firm analyzed 83 matches played by this same German league since it resumed play. The local team had more penalties for fouls than when the stadiums were full, and more yellow cards were handed out. On the other hand, the data collected by Impect, another data analytics firm, concluded that the overall quality of play had remained the same since the matches resumed.  

In an attempt to finish an already shortened season, the hockey and basketball leagues created “bubbles”, with the result no team is playing in its own city. This radically reduces any home team advantage that might still remain. Stay tuned.  

This article was originally published on the website of L'Agence Science-Presse (French only).


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