It’s well known that sports teams enjoy an advantage when playing at home. Take a look at the Champions League semi-final from last year for example, when Barcelona played Liverpool. At home, Barcelona won 3-0 but still didn’t reach the Champions League final after losing 4-0 in the away leg, a week later. How can two such different results be possible?
More anecdotal evidence can be found when looking at World Cup winners. In total, 6 teams have won on home soil: Uruguay (1930), Italy (1934), England (1966), West Germany (1974), Argentina (1978) and France (1998). In 2002, even host nation South Korea made it to the semi-finals, something nobody predicted beforehand. Coincidence? Or did the fact that they played on home soil make the difference? Let’s have a look at the factors explaining home advantage in football.
Statistics prove it
According to statistics, there is such a thing as home advantage. The results are no anomaly. Let’s have a look at the MLS. According to MLSsoccer.com, there is a home win ratio of 49.4 percent over a 15 year period, compared to just 26.5 percent away wins. In the highly important end-of-season playoff matches, that home win percentage rises to an astonishing 59.4 percent, compared to just 19.8 percent away side victories. Clear proof of home advantage.
What about the rest of the world though? According to a study called Statistical Thinking in Sports, we can see comparable statistics in international football too. The research paper analyzed 9000 matches between 1993 and 2004 and the results showed that the sides won 50.3% of home games, losing just 25.1%.
So if we can assume that home advantage in football is well documented in a wide range of team sports, what could be the explanation? Well, there are a few reasons why home advantage exists.
One of the explanations could be that male players have a higher testosterone level when playing at home. Just like in the animal kingdom, men experience a higher level of testosterone when defending their “territory”. A study conducted by the Northumbria University of Newcastle found out that salivary testosterone levels in football players were significantly higher before a home game than an away game.
The difference in salivary testosterone levels is even higher when teams play their perceived rivals. In La Liga, Real Madrid vs Barcelona, or in the Premier League, Man United vs Man City. The study shows that perceived rivalry of the opposing team was important as testosterone levels were higher before playing an ‘extreme’ rival than a ‘moderate’ rival.
But not only ‘extreme rivalry’ pushes the testosterone levels up. Goalkeepers in particular seem to have higher levels when playing at home, compared to field players. The perceived reason for this is that goalkeepers have two “territories” to defend: the pitch and their goal area. Overall, the strikers (offensive players) tended to have higher levels of testosterone on training but lower in official games, while the goalkeepers were lowest in training and highest against an extreme rival.
Not only testosterone levels have an influence on home advantage. The sound of the spectators has an influence on the decision of the referee. This was proven by an experiment where referees were shown video recordings, both with and without sound. A research done in 2007, published in the Journal of Sports and Sciences, shows that sports with subjective officiating tend to experience greater home advantage and that referees’ decisions can be influenced by crowd noise.
What happens when the referee is assisted by the Video assistant referee (VAR)? Research has shown that when VAR was introduced in European football, less biased decisions have been documented. This suggests that the addition of VAR might help reduce this cognitive bias for our referees and lowers the influence of home advantage in football.
The climate factors
The third factor, only applicable for very specific geographic regions, is what is called the ‘climate factor’. Altitude in particular has a big impact on the performance of players. Extreme examples are Bolivia and Ecuador who play their home games high in the mountains. Ecuador plays at Quito, some 2,800 meters above sea level. Bolivia’s base is even higher, La Paz stands 3,600 meters above sea level.
In 2017, when Bolivia played Brazil, Neymar and his teammates were forced to use oxygen masks after a goalless draw on a football pitch 3,600 meters above sea-level in Bolivia. This venue, called Estadio Hernando Siles, was once banned but eventually deemed acceptable by FIFA despite the harsh conditions for players not used to this altitude.
The stadium’s architecture
A fourth explanation for home advantage can be found in the stadium’s architecture. A great example is German team Borussia Monchengladbach. Monchengladbach finished building their new stadium called Borussia-Park in 2004 and gave some specific touches to the architecture.
They chose a design where the fans are very close to the pitch which reflects the crowd’s noise back to the field with the deliberate objective to influence the referee. Since then, Monchengladbach has had the best home to away win ratio in the Bundesliga.
Another way the stadium’s architecture can influence the home advantage is the ratio between the length and width of the pitch. The most famous example is the Freiburg “square”. So called because their pitch is the shortest in the Bundesliga but also one of the widest. This was a deliberate play to allow the team to focus on wing play and use this in their advantage.
Home advantage in football is on the downturn
Home advantage in football used to be a bigger factor decades ago compared to nowadays and is on a downturn overall. In the 70s, professional clubs used to earn 75% of their points at home, this has now dropped to 60%. What are the reasons for this development? One, traveling is easier nowadays than it used to be. Private flights, luxury hotels, etc. Two, the differences in pitch conditions have narrowed over the years, due to regulation. In the next decades, this percentage is likely going lower because of the introduction of VAR. Which should be a good thing, as we want conditions to be fair and the best team to come out on top.