TOUGH TO GET AMERICANS TO LOVE AN UNJUST GAME:

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.

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