Home Advantage Bias – Guide Notes.

There are five influential articles that have been published since 1982 on the key source of home advantage. All are agreed.

Jack Dowie’s article in New Scientist was a seminal piece. Dowie distinguishes the three Fs  – fatigue, familiarity and fans, each of which might have contributed to home advantage.

Fatigue: In a sample of 40 years of data, Dowie looked for evidence that away teams’ performances drop off relative to home teams as the game progresses, as measured by the likelihood of scoring a goal at any given point during the course of the match. Away teams did score fewer goals, on average, than home teams, but this disparity got no worse as the game developed.

Familiarity: Is familiarity with the pitch a bonus for the home team? If this is a key factor, teams who are travelling from a similar pitch to the home team should be less disadvantaged than those who are travelling to a very different sort of pitch. One obvious way to test this is ask whether teams who play on relatively big pitches have a particular statistical advantage when laying host to visitors whose own home ground boasts a small pitch, and vice versa. In fact, home advantage seemed to remain constant whatever the relative pitch sizes of hosts and visitors.

Fans: Is it the absolute number of fans, or is it the relative number of home and away fans? The data showed that the advantage conferred by playing at home was significantly greater for games played in the lower divisions than in the top division, even though the absolute number of supporters was much smaller in these games. Moreover, the advantage was much less in ‘local derbies.’ The conclusion is that the balance of support is what matters at the ground.

Nevill, Balmer and Williams looked into this further in 2002, showing 40 qualified referees video footage of 47 tackles from a Premiership match. The referees were divided into two groups, half of whom were exposed to the original soundtrack, while the other half listened to a silent version of the match. Neither group had access to the original referee’s decision. In actual matches, about 60% of bookings points (10 for a yellow, 25 for a red) are awarded to the visiting team. Those referees who watched the original soundtrack were reluctant to penalise the home team, judging 15% fewer of the tackles by home players to be fouls as compared to those referees who watched the silent footage. So in the absence of crowd noise the officials were more even-handed between the home and away sides. The original referees’ decisions, however, more accurately mirrored the behaviour of those armchair referees who had access to sound. It is as if, to get the crowd off their back, they wave play on.

In ‘Scorecasting’, Moskowitz and Wertheim (2011) compile further data to test a variety of popular theories explaining home advantage. They argue that when athletes play at home, they don’t seem to hit or pitch better in baseball … or pass better in football. The crowd doesn’t appear to be helping the home team or harming the visitors. They also checked scheduling bias against the away team, concluding that while this explains some of the home-field advantage, particularly in college sports, it’s irrelevant in many sports.

Thomas Dohmen looked at home advantage in the Bundesliga, the premier football league in Germany. Dohmen found that home advantage was smaller in stadiums that happened to have a running track surrounding the soccer pitch, and larger in stadiums without a track. Why? Apparently, when the crowd sits closer to the field, the officials are more susceptible to getting caught up in the home-crowd emotion. The social atmosphere in the stadium, he argues, leads referees into favouritism despite the fact that being impartial is optimal for them in career terms.

Here is the take of Steven Levitt and Stephen Dubner. “It’s worth noting that a soccer referee has more latitude to influence a game’s outcome than officials in other sports, which helps explain why the home-field advantage is greater in soccer, around the world, than in any other pro sport … officials don’t consciously decide to give the home team an advantage – but rather, being social creatures (and human beings) like the rest of us, they assimilate the emotion of the home crowd and, once in a while, make a call that makes a whole lot of close-by, noisy people very happy.”

References and Links

Dohmen, T.J. (2008). The Influence of Social Forces: Evidence from the Behavior of Soccer Referees. Economic Inquiry, 46, 3, 411-424. https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1465-7295.2007.00112.x

Dowie, J. Why Spain Should Win the World Cup, New Scientist, 1982, 94 (10), 693-695. https://books.google.co.uk/books?id=OFCXnqlSFKwC&pg=PA693&lpg=PA693&dq=why+spain+should+win+the+world+cup+dowie&source=bl&ots=YLnc7jJr9L&sig=ACfU3U0PEmuQAsgtRjXyo7J-1IDfmJ1VOg&hl=en&sa=X&ved=2ahUKEwjTqIjg28rhAhWBtXEKHRiXCZAQ6AEwDHoECAYQAQ#v=onepage&q=why%20spain%20should%20win%20the%20world%20cup%20dowie&f=false

Nevill, A.M., Balmer, N.J. and Williams, A.M. (2002), The influence of crowd noise and experience upon refereeing decisions in football, Psychology of Sport  and Exercise, 3 (4), 261-272. https://www.sciencedirect.com/science/article/pii/S1469029201000334

Moskowitz, T.J. and Wertheim, L.J. (2011), Scorecasting. Random House.

Levitt, S.D. and Dubner, S.J. (2015), ‘When to Rob a Bank’, Penguin Books, pp. 211-12.