IN 2010 700m people huddled together in front of their television sets to watch the World Cup final between the Netherlands and Spain. Even more are expected to tune in to this year's contest, which kicks off on June 12th with a match between Brazil and Croatia in São Paulo. Brazil are the runaway favourites to win the tournament, with bookmakers offering odds of less than three to one on the home team lifting the trophy. The Economist's own faintly dubious analysis gives Brazil by far the best chance of winning. Many pundits agree that the country will benefit from a strong home advantage, as local crowds roar on the Seleção. How much does playing on home turf really affect a team's performance?
Armchair analysts and sports scientists have come up with all sorts of theories to explain why playing at home helps. In 2007 a study investigated the influence of crowd noise on referees in the English football Premier League. It showed that some were more likely to flash yellow cards and award penalties against touring players than the hosts, because they relied on the split-second rise in the home crowd's roar as a cue to determine if a tackle deserved punishment. In the most recent season of the Spanish football Liga, two-thirds of all penalty kicks were awarded to the home team. Biased referees are not the only worry for visiting teams. Hectic travel schedules can tire them out and unfamiliar conditions can spook them. Foreign teams sometimes struggle against Bolivia at its Hernando Siles stadium, which lies at a headache-inducing altitude of 3,636 metres (11,932 feet). A bit of gamesmanship also comes in handy. One successful London football club reputedly offers a cramped away-team dressing room with low kit-lockers and high shirt-hangers.
Do these factors really make a difference? The numbers suggest that they do. In the latest English football season, the top 20 clubs enjoyed a home success rate of 50%, while their victory rate on the road was 32%. In 12 of the past 19 World Cups the host nation has made it to the semi-finals and six times it has gone on to win. The effect can be seen in other sports too. Before the start of the London Olympics in 2012, UK Sport, a government agency, pored over the results of more than 100 big tournaments across 14 Olympic sports and predicted that the London home advantage would boost Britain's medal haul by as much as 25%. As it turned out, Britain bettered its 2008 performance by winning 18 more medals (10 of them gold), an improvement of 38%. At the Beijing games, China won 59% more medals than it had done at the 2004 Athens games. Russia topped the medal table in Sochi; in the previous winter Olympics it had come sixth.
Given these numbers, it is not surprising that teams have poured money into maximising their home advantage. The Beaver stadium at Pennsylvania State University, for example, was acoustically tweaked to amplify noise levels during the college American-football matches that take place there. (A study from 2009 found that American-football crowds maintain a quiet hum of 75-80 decibels during "home plays", but blare at 110-115 decibels when a visiting team has the ball, impairing the quarterback’s range of communication.) Brazil has spent a fortune on a lavish, if somewhat leisurely, programme of stadium construction and renovation. In all its home advantage is worth the equivalent of a 0.6-goal headstart in every match, according to Goldman Sachs, an investment bank. Like most others, Goldman predicts that Brazil will triumph this year. Other countries' fans will have to hope for a miracle—and perhaps bid to stage the Cup on their own home turf next time.
