Everyone knows that sports teams enjoy a big advantage whenever they play at home. But does anyone know why? Most of us probably think we do - after all, it seems obvious. Home teams have the crowd behind them, roaring them on, filling them with confidence; their opponents have to deal with the crowd's open hostility or, perhaps worse, its silent contempt, which both drain confidence away. Home players get to sleep in their own beds, make their own way to the ground, change at their own pegs; the away team has to deal with sleepless nights in strange hotels, plus all the misery of travelling long distances to unfamiliar places - the mindless coach journeys, the wrong turnings, the traffic hold-ups, and the prospect of having to get changed too quickly in an alien dressing room. The home team know the playing conditions inside out; the away team never know when they are going to get ambushed by their lack of local knowledge. The home team feel at home; the away team feel lost.
For most of the history of professional sport, these explanations for home advantage were quite enough - sport is a tribal business, and local tribes liked to think that anyone who strayed on to their patch was in for a hard time. What else was there to say? But professional sport is changing faster than at any time in its history and much of what we used to take for granted is now open to question. Two forces in particular have conspired to ensure that the traditional wisdom can no longer be relied on when it comes to home advantage: science and money.
Sports scientists want to know what makes players perform to their full potential, and home advantage has become one of the battlegrounds for their competing theories. Meanwhile, the money men want to know why home advantage should still matter at all. In an increasingly globalised world, it is not clear to many of them what 'home' means any more. If you scour the planet for the best players, and if you pay them enough, surely they should feel at home anywhere ? Then there are the fans, many of whom are now to be found thousands of miles away from the ground of the team they support. Why should these fans be denied the chance to cheer on their team, and empty their pockets in the process? If the NFL are prepared to move a regular season game from Miami to Wembley, it can't be long before Uefa try to stage a Champions League match in Malaysia.
Would it matter if clubs started playing some of their home games far away? It would to the traditional fans, who believe that their team need them, with all their passion and their loyal commitment to the cause. They do not want anything to get in the way of that relationship. Many believe that they can have a direct impact on the outcome of matches and that the home support can effectively act as an extra man in tricky situations. Fans also want to believe that they can punish their team by withholding their approval. This is an idea that appeals to the players and the media as well. When Joey Barton tells Newcastle fans that their vicious abuse is holding the club back and destroying the confidence of the players, it suits Barton and his team-mates, as an excuse for their own poor performances; it suits the fans, giving them a sense of their own importance; and it suits the media, as it gives them a story.
Even Newcastle fans seem subdued compared to some crowds in the US, particularly for college sports, and above all at indoor arenas, where their ability to generate noise and heat increases a sense of ownership over the team and the venue, and the sense, too, of having a direct influence on matches. Studies of college basketball (which often attracts huge, hysterically partisan crowds) have revealed a widespread conviction among fans that they can have a considerable impact on the team's performance. When their team play poorly, it is the fans' fault for not getting behind them and not intimidating the opposition; when their team play well, it is the fans who can take the credit for defending 'their turf '. Fans talk about home advantage as though it were something in their gift to bestow or withhold: they scream, they holler, they pout, they sulk, and the players on both sides respond accordingly.
Except, in reality, they don't. The fans, the players and the media have merely bought into a myth of their own relative power or powerlessness, one that fits what they want to believe. There is no evidence that home advantage is much affected, if at all, by the size, intensity or commitment of the fans. Instead, home advantage is remarkably consistent within individual sports across different locations and different crowds. Where it varies, the factors that count are the ones that usually count in sport: skill, luck and changes of circumstance. So, for example, home advantage in English football has been relatively steady across the four main leagues for the best part of a generation, unaffected by crowd size or levels of fan interest: though it varies a bit season by season, overall the home teams win roughly 60 per cent of all the points on offer.
Within that figure, there are, inevitably, giant differences between clubs. The most impressive current home record in British football, perhaps in all sport, belongs to Chelsea, who are unbeaten in league matches at Stamford Bridge since March 2004, over a total of more than 70 games (at the time of writing the record stands at 77). But you don't have to look far to find the explanation. Shortly before the run started, Roman Abramovich bought the club. Shortly after it started, he installed José Mourinho as manager. Between them, the pair spent several hundred million pounds on players. The stadium, meanwhile, remained more or less unchanged, as did the fans (if anything they have become more subdued over recent years, sated by success). All the supporters have been called on to do is sit back and watch.
Individual teams do sometimes find that home advantage deserts them. When Arsenal moved from Highbury to the Emirates, their home form suffered. Though they did not lose many games, they drew a large number of matches against teams (Aston Villa, Middlesbrough, Everton, Newcastle, Portsmouth) they would normally have expected to beat. This corresponds with a trend frequently observed in the United States, which shows that teams tend to sacrifice home advantage for about six to nine months when they move to a new stadium, as the players take time to adjust to their new surroundings. This holds even when the move is from one anonymous modern sports arena to another, and even when, as in Arsenal's case, crowd capacity increases. What it suggests is that familiarity with one's surroundings is more important than fan support.
It could be argued that, since the move to a new stadium is usually as traumatic for supporters as it is for players, if not more so, the Arsenal fans were the ones who took their time to adjust to the Emirates, and it was only when they found their old voice that the team started to respond. But there is no evidence to back this up: Highbury was a notoriously quiet place at the best of times. It is all too easy for fans to jumble up cause and effect, and to assume that their team only started playing well once they started cheering, rather than that they started cheering only once their team started playing well.
It is the easiest mistake to make when watching any sport: to imagine that a sequence of events is best explained by the order in which we remember it rather than the order in which it happened. When a team go forward, the home support gets to its feet and starts to generate more noise; every now and then, one of these forward moves results in a goal, and the crowd sound explodes. What fans tend to remember is that when they began to make more noise, a goal was scored. What they forget are the countless times when the noise fizzled out because the move fizzled out. It is nice for screaming fans to believe that they can help suck the ball into the net when things get desperate. But the fact remains that the movement of the ball does much more to determine the noise of the crowd than the noise of the crowd does to determine the movement of the ball.
There is one conventional fan's-eye view that does seem to be confirmed by the scientific evidence. As well as trying to roar on the players, home fans direct much of their vocal effort at the referee. And they do it because they think it sometimes works - referees believed to be 'homers' are the ones who don't seem to be able to resist the pressure of 50,000 voices telling them what to do. Recent research suggests that there is some truth in this.
In what has become a famous experiment in sports-science circles, a sample of 40 referees were exposed to a recording of Liverpool 's match with Leicester at Anfield during the 1998-99 season, with half watching the match with all crowd effects included and half watching a silent version. The researchers found that the referees who heard the sound of the crowd were less likely to call fouls against the home team than the ones who saw the game in silence (though, interestingly, the baying of the crowd did not make them more likely to penalise the away team). This preference for the home team coincided with the actual decisions of the match official on the day. The researchers concluded that referees tend to avoid making calls against the home team as a way of shielding themselves from the extra stress levels that come with antagonising the crowd. It's not that the officials do what the crowd wants ('Send him off, ref!'); they just try not to do whatever would direct the crowd's fury straight at them. The psychologists call this 'avoidance'.
I asked Jeff Winter, the recently retired Premier League referee whose autobiography is called Who's the B******d in the Black, whether he thought the crowd could influence an official as much as most people (and now some psychologists) seem to think. 'I can only speak for myself, but I never, ever felt I was influenced by the crowd,' he replies, before pausing to add, 'but subconsciously, who knows.' What Winter is adamant about is that the size of the crowd, the sheer volume of noise, is not the main factor. 'If you're refereeing at Old Trafford,' Winter says, 'in front of 80,000-odd people, it's like working with the radio on in the background. It's literally background noise.'
People think the facts speak for themselves, but as Winter rightly insists, 'it's all about how you read them'. For example, he says, 'the facts add credence to the view that referees are swayed by the crowd at Old Trafford and some people will say Man United never have penalties given against them at home '. But the true story is that United spend large parts of every game at Old Trafford camped in the opposition's half, which means they are bound to get more penalties from even the most impartial officials. If anything, Winter thinks, an aggressive crowd is more likely to push an experienced official the other way. 'If as a referee you walk out to a hostile crowd, especially if you've got history with the club, by human nature you're not exactly going to bend over backwards to help them. Poor little Bolton Wanderers will get the 50-50s because the nasty Man United fans are singing songs about me.'
But how can he be sure? Along with being a shrewd judge of other people's prejudices, Winter shares in the occupational hazard of any successful referee, which is an excessive regard for his own opinion. Now he has retired and is watching more games on TV, Winter has noticed that even the best referees are not immune to outside influence, though he thinks it comes from the big clubs rather than the crowd. There is what he calls a 'fear factor' among the professional officials, because they are frightened of losing out financially if they get on the wrong side of the most powerful figures in the game, including managers and marketing men as well as players. I ask him how long he thinks this has been going on : five years maybe, longer than that? He replies, without a hint of irony: 'It's got worse since I retired.' (He finished refereeing in 2004.) He doesn't think any of his former colleagues are favouring the big teams deliberately, but, as he puts it, 'subconsciously, if your job is on the line, it's better to be safe than sorry'.
The truth is that in sport no one ever really knows how they are being shaped by forces beyond their control, not even the ones who think they do, such as Jeff Winter. That's why, to get the clearest possible picture of what is really going on, it is usually best to take the longest possible view. Some of the most interesting recent studies of home advantage have tried to tease out the longterm historical trends, in order to see if they tell their own story. They reveal that home advantage has declined in all major sports over time, but not by as much nor as steadily as one might expect. For instance, in the earliest years of the Football League in England, the home team tended to win about 70 per cent of the points on offer, compared to closer to 60 per cent today. One explanation for this may well be to do with the referees: the officials were by definition less experienced and therefore potentially more susceptible to crowd pressures in the 1890s than they are now. Another likely change concerns travel: getting to and from grounds in the early years of the sport was a laborious business and physical discomfort was par for the course; these days, the top players are ferried around in unimaginable luxury and, if the hotel room isn't good enough, someone finds them a better one. Local conditions were more likely to vary wildly in the early years of the sport; now, most teams know exactly what to expect, and the top grounds increasingly resemble one another, in their luxurious fittings and soulless efficiency.
And yet, plausible as all these explanations are, none of them really fits the data. These changes - bringing in professional referees, cosseted stars and identikit stadiums - all happened relatively recently, in the past decade or two, as money has started to slosh through the sport. Yet the big change in home advantage occurred 60 years ago, in the aftermath of the Second World War. When the Football League resumed with the 1946-47 season, home teams suddenly found it much harder to dominate in the ways they had before the war. It was between 1939 and 1946, when there was no football, that home advantage dropped from close to 70 per cent of all points won to nearer 60 per cent. This suggests that something deeper and more mysterious is going on here than simply shifts in the material conditions of the game. Men who went away to war came back to find that their old grounds no longer felt so much like home; meanwhile, the away grounds, even in remote parts of the country, probably did n ot feel so foreign, either. Most of the players had seen something of the world beyond football and, though home advantage didn't disappear and even tended to reassert itself during the more parochial Fifties, Sixties and Seventies, it never reacquired its old significance.
The enduring mystery is why home advantage should vary depending on the sport you play. Basketball is the game where playing at home still counts for most, closely followed by football. In American football and ice hockey, however, away teams are at less of a disadvantage. The NHL in particular has seen a sharp decline in the dominance enjoyed by the home sides. During the early years of the league, home sides took well over 70 per cent of the points on offer; it is nearer to 55 per cent today. But baseball remains the sport where home advantage counts for least. Indeed, baseball is the only major sport that has occasionally seen seasons during which away teams actually won more games than the home teams (for example, in 1972 the home winning percentage for all teams in the National League across nearly 1,000 games was a mere 49.4 per cent). No season in the history of English League football has even come close - the lowest recorded level of home advantage was 55.8 per cent in what was then the Third Division in 1993-94, and that looks like a statistical freak.
Why should baseball be so different? One possible explanation is that home advantage is primarily a team phenomenon and baseball is less of a team sport than the others - it is more about individual confrontations between batter and pitcher. (Cricket is similar, but the home side prepare the pitch, which gives their players a huge advantage in terms of local knowledge.) Studies of how well home players do at the major tournaments in individual sports (British players at Wimbledon, British golfers at The Open) provide no evidence of any advantage. If anything, the reverse seems to be true - just look at the lamentable record of various French players at Roland Garros, who often seem overwhelmed by the weight of expectation. Tim Henman did not reach four Wimbledon semifinals because he was playing at home; he did it because he was playing on grass, which was his favourite surface. If the grass courts could have been transplanted far away, to New York or Melbourne, he might actually have won the thing.
Team sports, however, are about having confidence in your team-mates and being able to co-ordinate what you do together. In a sport such as basketball, success depends on how the players relate to each other and the level of confidence that they have in their ability to find each other on the court. It is this confidence that seems to be boosted by the familiarity of playing at home, regardless of any quirks in the playing conditions (and most basketball courts are pretty much the same everywhere; it's just the backdrop that changes). If you feel comfortable with your location, you have a better chance of knowing where your team-mates are.
How then to explain the relative lack of home advantage enjoyed by teams in American football and ice hockey? American football is one of the few sports where the crowd can actually influence what takes place on the field, by generating enough noise to make it almost impossible for the opposing quarterback to be heard above the din, when he is telling team-mates what play they are running. Yet during regular-season NFL games, being at home is not a major factor. It is no coincidence that in their attempts to market themselves overseas, the NBA have sanctioned only pre-season warm-ups in London while the NFL found a team willing to forgo home advantage in a regular-season game. It was less of a sacrifice.
I asked Alistair Kirkwood, who is in charge of strategic planning and development for the NFL in Europe and had been instrumental in bringing the game to Wembley, whether it had been hard to persuade Miami to give up a home game. 'Not really - there were half a dozen other teams interested as well,' he says. In the event, both teams - the Dolphins' 'visitors' were the New York Giants - looked a little lost in the unfamiliar surroundings of a muddy Wembley, and it was a scrappy game that the Dolphins eventually lost 13-10. You can't read much into a single game - Miami won only one match all season - but in the end, no one seemed to feel much at home.
The more interesting question, as Kirkwood admits, is why home advantage should count for less in the NFL than, say, in English football, to the extent that it did not really matter where the game was played. He has two possible answers. 'The draft system and salary cap mean that NFL teams are generally much more evenly matched than sides in the English Premiership,' he says, 'so home advantage doesn't have the same impact.' This sounds counter-intuitive, since if teams are evenly matched in other respects, home advantage should count for more, given that it is the one thing you cannot put a cap on. But Kirkwood has a point - if home advantage is about confidence, then there is a possibility that it feeds on the disparities between teams. Strong sides are practically invincible against weak teams when they play at home (Chelsea are highly unlikely to lose to Derby at Stamford Bridge), so the weaker teams save all their energy for the home games, when they feel they might have a chance.
Kirkwood also thinks it may have something to do with the fan culture, and the different time horizons of the two sports. NFL fans are as passionate as those in the Premier League, just not in the same way. 'Head coaches don't get fired midseason in the NFL,' Kirkwood says, 'and because the complexities of learning a new system are too great, the quick-fix is just not an option.' Instead, when things are going wrong, everyone starts waiting for next year and the chance for the draft system to even things out again. At this point, the fans may do what Kirkwood calls 'a complete 180' and even start to think about the benefits of finishing last so that they have the chance of a number-one draft pick.
'The badge of honour of the English soccer fan is to remain loyal no matter what,' he suggests. 'Ironically, the parity between NFL teams means the opportunity to succeed is never too far away, which gives the fans a reason to distance themselves from the current team.' NFL fans have a season-by-season mindset, which can make them more detached on a game-by-game basis. British football fans are invariably hopeful that a quick-fix could make the difference in the short term (Sack the manager! Get us a decent striker! Take him off!). Deep down, though, they know that their club will find their own level, and that they are stuck with them. It is this combination of short-term optimism and long-term pessimism that creates the particular fervour of the home support at an English league game.
It's an elegant theory, but Kirkwood, like most people, is probably overestimating the importance of the crowd. There is a further possibility, one that connects to the darker side of American sport. Another significant piece of recent research has suggested that one of the crucial determinants of home advantage may be the higher levels of testosterone that are to be found among the players of the home side. Researchers tested the saliva of under-19 football players before a series of training sessions, home games and away games. They found that the players' testosterone levels were at the male average before the training sessions and away matches, but before home matches levels were 40 per cent higher than average and this figure could rise to 67 per cent if the game was against a particularly bitter rival.
Testosterone raises aggression levels, but it also helps to channel that aggression and gives players much quicker recovery times from intense physical exertion. If home teams have more of it than away teams, that would help to explain where some of the home advantage comes from.
American football is a sport awash with testosterone. If playing at home were the only way to generate more of it, that would imply that home advantage should be a more significant factor in inherently violent contact sports than in somewhat gentler pursuits ( such as basketball and, perhaps, soccer). But of course there are other ways of raising testosterone levels, including by taking steroids. You don't have to be unduly cynical to suppose that a sport that has traditionally had a lax attitude to steroid abuse might see the testosterone advantage of home teams wiped out by artificial means.
Read part two of this article