Factors influencing home-ground advantage
This is a somewhat simplified summary of what we know, but generally, there are four factors influencing home ground advantage:
1. Travel fatigue for visiting teams 2. Familiarity with the city, the facilities, the playing arena 3. Crowd factors, which can be further broken down into: 1. How the crowd influence the players 2. How the crowd influence the referee/officials
As mentioned, I'll tackle travel tomorrow, when I talk about Super Rugby, so let's look at the others, in reverse order.
The crowd influence on officials - a subconscious bias
Starting with the referees (a favorite of sports fans everywhere!), there is a real perception, true or not, that visiting teams are often ‘robbed’ by referee decisions. It turns out this is not a perception without some merit. Studies have found, for example, that visiting teams in ice-hockey and basketball concede more penalties and have more players sent off for foul play than the home team.
It's also been found that the discrepancy in penalties awarded to visiting and home teams increases as the crowd increases in size. And that when two London teams play football against each other, thus reducing the "unevenness" of crowd support, the discrepancy is reduced, suggesting that this may be the influence of the crowd on the referee. Even the most neutral and professional referee, with no intention of cheating can be swayed by the cheers or boos of a crowd.
For example, one study had football referees make judgments based on video footage of obvious foul play, but some refs watched without sound, while others watched with full sound, including crowd reactions to fouls. It turns out that with the sound, the referee is more likely to be swayed towards what the crowd is calling for - fewer free-kicks to away teams, more to home teams, no foul when the home team is guilty. This is summarized in the figure below. And this is just on a TV screen, away from the cauldron of pressure of real-time action, where the crowd may have even more influence.
Further supporting this idea is that in the Olympic Games, the host country often wins significantly more medals, but most of them come in the subjectively scored events (ice-skating, gymnastics etc). Given the football referee study, it's not difficult to see how a rapturous cheering crowd might be worth half a point here and there to a judge, despite their best efforts to block out crowd factors!
I must point out that there is other possible reasons why visiting teams are penalized more. One is that the "hostile environment" of the away arena produces a “victim” or “us against the world” attitude that sees visiting teams play more aggressively than they would otherwise. This has in fact been documented for visiting teams, and, on occasion, for home teams, depending on the context of the match and the crowd behavior.
Also, the home team is often more aggressive and dominates play (defending their territory, perhaps), forcing the opposition to concede penalties as a result of applied pressure. One analysis of decisions in the NHL found no difference in mistakes between home and away teams, suggesting that the penalty discrepancy may be justified (I am not quite sure how to reconcile that with the football study above, where the refs were making different judgments of fouls simply because of sound...)
Crowd influence on players - motivation, desire and anxiety
Harder to measure, but possibly as significant, is the effect of crowd support on player motivation and effort. Certainly, sport is filled with testimonies of players who find "something extra", who raise their level because they're at home. I guess one needs to be careful about taking a collection of testimonies and saying they are evidence (the plural of anecdote is not evidence!), especially because linking these factors to performance is very difficult.
But there's no question that "psychology" (an incredibly broad term) plays a role in sports performance. But the sword may cut both ways when it comes to home-ground advantage. A visiting team, with the odds against them, may well perform better than at home because of the desire to silence the crowd, and because of the added prestige of beating a team in their own country - I've experienced this with the SA Sevens side.
On the other hand, the effect of the crowd and the momentum they may give to players (who, for all the talk of "zoning the crowd out" must surely be aware of it) may be decisive - I have also experienced this with the Sevens team. If you were to define a set of psychological requirements for success, you'd almost certainly put "confidence", "self-belief" and "high level of motivation" on the list, and in theory, that's what being at home brings.
To throw a curveball at that oversimplification of the theory, there was a fascinating opportunistic study a few years ago when a college basketball team had to play 11 of their matches behind closed doors because of a measles outbreak that forced the school to be quarantined. It turned out that the team played better WITHOUT fans! Their stats were up - more points, more free-throws and better shooting percentages. Of course, 11 matches is a small sample when you consider how many factors might influence each performance outcome, but it does suggest that perhaps, fans influence players negatively, through increased anxiety. Maybe the other team is just more anxious, and plays relatively worse!
