Refereeing controversies are to World Cups what gaffes are to political campaigns: overly discussed and inevitable. This year’s tournament kicked off yesterday, and already it has its first. In the opening game between Croatia and Brazil—this year’s host and the most soccer-crazed nation on earth—the heavily favored Brazilians played unevenly. They went ahead only on a questionable penalty kick: The Brazilian forward Fred (just Fred, as Pelé was just Pelé) went down after a Croatian defender placed his hand on Fred’s upper arm with all the aggression of an usher at a memorial service.
The Croatians were, and remain, livid, accusing the match’s Japanese referee of being in the tank for the host nation. One penalty in one game is hardly a large dataset, but there is evidence that, in fact, they’re right. That evidence comes from economists.
The home-field advantage, it turns out, is a sizable advantage. In a recent research report on the World Cup, Goldman Sachs (GS) calculated that the home-field advantage is worth 0.4 goals a game, which, in a sport heavy on 1-0 and 2-1 scores, is a huge factor. “The home team has won 30 percent of all World Cups since 1930,” the report reads, “and over 50 percent of all World Cups held in a traditional football powerhouse (Brazil, Italy, Germany, Argentina, Uruguay, Spain, France and England).”
But what causes home-field advantage? Every sports arena is festooned with banners thanking the fans for their support. The implication is that their noise and emotion is what makes the difference, raising the spirits of the home team and cowing the visitors.
The crowd does have an effect, but not necessarily on the team. A few social scientists have tried to look at the issue of home-field advantage empirically, and they’ve found that the crowd’s role in the phenomenon is that they sway the referees. Much of this research is laid out in the book Scorecasting, by Tobias Moskowitz and Jon Wertheim. In soccer, a sport in which an single officiating decision is more likely to determine the outcome than in others, this particular home-field effect seems to be particularly strong,
In a 2005 paper, economists Luis Garicano, Ignacio Palacios-Huerta, and Canice Prendergast looked at the length of so-called injury time at the end of Spanish professional soccer matches. The clock in a soccer match does not stop, even when there is a stoppage of play—for an injury, for example, or a penalty kick, or a substitution—so a referee keeps a tally of how much extra time needs to be added at the end of each 45-minute half. No one but the referee knows exactly how long it is. What the Spanish study showed is that referees tended to extend injury time when the home team was behind in a close game, giving them more time to try to tie the score. They cut it short when the home team was ahead. “[I]f the home team is behind by 1 goal, injury time is 35 percent above average, whereas if it is ahead by 1 goal, the injury time is 29 percent below average,” the authors wrote. Also, the bigger the crowd at the game, the bigger the effect.
A 2003 study of German professional soccer matches found a similar, albeit less dramatic, injury-time effect. The author of that paper, Thomas Dohmen, looked at a number of factors, including whether a team’s home stadium had a running track surrounding the field, as many do, setting the stands back from the field. He wondered whether that physical buffer between the referee and the fans would mitigate the effect. It did: In stadiums with a track, the home-field effects disappeared.
Injury time isn’t the only thing that could be affected by crowd pressure on the referees; it just happens to be an easy one to quantify. Referees make all sorts of calls that shape games: fouls, offsides, the awarding of yellow and red cards. And in a finding that would vindicate Croatia’s fans, Dohmen looked at the awarding of penalty kicks and found a home-field effect there, too.
Referees are trained to ignore the crowd, and there’s no evidence thus far of corruption at the tournament. But the human susceptibility to peer pressure is strong. In a famous study by the psychologist Solomon Asch, subjects placed in a room in which everyone else gave a clearly incorrect answer to a visual perception test would themselves give the wrong answer, and many of them would begin to doubt their own perception. Tens of thousands of screaming people are even harder to disagree with.