How relevant is home advantage in football?
Factball #9
In one of the Premier League analysis programs at the beginning of the last decade, Andy Gray, a former Scottish striker turned commentator, coined one of the phrases that circulate the most on social networks about the difficulty of playing in certain football stadiums as an opponent.
The year 2010 was ending, and at that time, both Cristiano Ronaldo and Lionel Messi were at the peak of their faculties (physical and psychological) and dominated European football, playing for Real Madrid and Barcelona, respectively. After praising the attributes of the two stars and their ability to score goals, Andy left the infamous question in the air:
But can they do it on a cold, rainy night in Stoke? -Andy Gray, 2010
Stoke City is not even in its best phase as a club nowadays, but the phrase remains on the tip of the fans' tongues, who have no reservations in reproducing it whenever they want to accuse an athlete of having their life made easy in any other championship.
Discounting the slight English haughtiness when it comes to the quality of their football, the truth is that there is a widespread belief that playing in a stadium other than your own is always more complicated.
So that there is no doubt, let's roll up our sleeves and investigate this issue, resorting to facts!
The home advantage
In my search for the truth, one researcher stood out for having carried out a considerable amount of studies on this topic. Richard Pollard, now in the Department of Statistics at California Polytechnic State University, was one of the pioneers in football match data analysis. Some even say that he created the famous metric of expected goals (xG).
Richard was inspired by the work of Charles Reep, seen by many as the “Godfather” of modern football analysis. However, it was Richard who introduced Reep to the already revolutionary Graham Taylor, who, with innovative tactics based on data analysis, led Watford (chaired by Elton John, yes, that one, the singer! ) to 3 promotions in 5 years culminating in an epic second place in the top echelon of English football, in the 1982-83 season.
However, today I'm writing to you about Mr. Pollard for his studies of home advantage. The first dissertation dates back to 1986 but was later updated, in 2005. Before going into details, I'll start by telling you, so that there are no doubts and ending the suspense, that football teams around the world actually have an advantage for playing in their stadium, in front of their supporters.
Pollard’s method, which was used across 48 European leagues from 1996 to 2002, calculated the percentage of points won in home games of the total points obtained in a given championship. A value of 50% means that there is no home advantage, as the points earned at home and away are precisely the same. Therefore, the higher the percentage, the stronger the home advantage. This method, even though it is simple, has sufficient explanatory power. The main conclusions to be retained were:
There are significant differences between leagues - the Albanian league has a preponderance of the home advantage of 79%, while the Latvian one has 52.5%;
The Top 5 leagues have similar values - the percentages are between 60% and 65% for the first divisions;
The home advantage loses strength as you go down the pyramid of competitions - in the English leagues, it was 60.7% for the first division and 55.1% for the 9th;
There is a decrease in the strength of the home advantage over the years - in the case of the first division of English football, the percentage between 1888 and 1900 was 67.9%, and between 1992 and 2002, it was 60.6%;
In another study by the same author, it was also possible to draw some conclusions about women's football. In an analysis of 47,042 matches from 26 European competitions between 2004 and 2010, home advantage was also verified in the ladies' game. However, the effects were smaller, with the average being 54.2% while that of men was 60.0%. An even more interesting fact in this study was the fact that the Gender Gap Index, which quantifies the status of women in each country, has the ability to predict the differences between women's and men's games - the more similar the status of women and men in a given country, the smaller the difference between the home advantage in the respective leagues.
Causes
One of the major limitations of these studies, more because of the difficulty than the lack of trying, is to discover the causes for these differences that occur when playing at home.
Apart from the cold and rain of Stoke-on-Trent, many other reasons could explain the home advantage. Now let’s look at the potential causes:
Crowd
Starting with the crowd’s support, which is perhaps the aspect we all want to believe will make a difference, the results are intriguing.
On the one hand, we have already found in Pollard's study that the higher the division in which you play, the stronger the home advantage is, and this presupposes a greater audience in the stadium. However, in the lower divisions, the edge continues to be verified.
In addition, the Covid-19 pandemic has given researchers a unique opportunity to assess and corroborate this issue. In a study of 4844 games on the European continent in the 2019/20 season, which was played with and without fans in the stands, the results are clear. Home teams playing behind closed doors amassed fewer points and scored fewer goals than when they had supporters cheering them on.
On the other hand, it is almost impossible to know precisely how this fan support translates into practical results. Is it because of the intensity of the chants, the density in the stands, or the coercion of the referees? And do the fans bolster the home team, or do they intimidate the opposition? Hard to know…
Travel
The results of various studies regarding fatigue caused by travel are inconclusive.
However, one fact is clear: in derbies, that is, games between teams from the same city where there is no need to travel, the preponderance of the home advantage is more diminutive.
Familiarity
In terms of familiarity with stadium conditions, there is much to retain.
Fields with unusual dimensions, a different turf, or with a specific ball type are all factors that have been proven to impact the home advantage.
Furthermore, a study on the Brazilian championship concluded that teams from the north and south of Brazil generally have a more considerable advantage when playing at home than those from the center region. The weather and the tiredness of the trip are two of the factors found as possible explanations for the result.
Still, within the scope of the specificities of the stadiums, altitude is an aspect that will already be known to the South American athletes who play in the continental competitions and have to play in La Paz, in Bolivia, at more than 3600 meters of altitude.
But even in Europe, a study concludes that teams whose stadium is at higher altitudes benefit significantly from increased home advantage. More specifically, for every 100 meters of altitude difference between the stadiums of the home and away teams, the probability of the home team winning the game is 1.1 percentage points higher. So now, don't you all start building stadiums on mountains, please!
Referee bias
Pollard also tells us there are solid indications that referees are influenceable. Whether handing out penalties, free kicks, or yellow and red cards, it seems clear that referees tend to favor the home team. However, it is impossible to conclude that this comes from the crowd’s pressure, even if it is the most likely scenario.
Territoriality
This is perhaps the explanation that most surprised me and which I believe to be quite conceivable. Since human beings are “instinctive animals”, it is natural that they are always ready to protect their territory. Now, in a football game, not only is this plausible but it is proven in two ways. The first is that home players experience an increase in hormonal activity before games, and the other is that there are teams that benefit from an increase in the home advantage because they are located in an isolated or historically conflicted geographical location.
Special tactics
Playing at home and playing away is always different in the minds of players and coaches. Therefore, premeditated or not, there is an adjustment in how teams present themselves in the opponent's stadium. Thus, it will be natural that a visiting team that appears more defensive is, in fact, maximizing the opportunities for the home team to be more offensive, hence getting closer to conquering the three points.
Psychological factors
Whether the home advantage is explained by the support of the fans, the referee, or the fragility of the opponent, the truth is that the players know such advantage exists, and that could very well be one of the main reasons for it to exist if you understand me correctly—a self-fulfilling prophecy, therefore.
Interaction of causes
The chart below is also proposed by Pollard and represents the most likely scenario, in my opinion - the home advantage is explained by the interaction of all these causes and not one or two in particular.
Conclusion
There is still a long way to go in analyzing this issue, and there are indications that lead us to believe that there may be explanatory factors that have not yet been contemplated in any study.
However, it is more likely that they will all have an impact on each other and that their combination is the driving force behind the intrinsic advantage of playing at home.
In practical terms, there will be many measures to be taken from this information for the teams that play at home, and for the sake of football, I hope I am not teaching anything new to any coach or sports director:
Try to implement unique characteristics in your stadium that can surprise your opponents - grass height, pitch width or length, specific floodlights, or even eliminate the distance from the stands to the pitch;
Create player motivation strategies that demonstrate they already have an advantage, even before the home game starts;
Promote interaction between athletes and the public in order to galvanize both;
Implement more offensive tactics and take more risks during the home games;
Seek to relate the history of the club with the basic instinct of survival and protection of the territory;
Apply pressure on the referee (this can be debatable, depending on each one's view of ethical limits);
Spare a fatigued key athlete at a home game rather than away;
Choose home games to try new tactics and systems that are not yet fully developed;
Debut youth academy athletes at home games, where they will feel less pressure and more support from the crowd.
I cannot promise clubs will win matches by following these recommendations, but data tells us they will certainly be closer.
That's all for this week, and I can only finish this edition of Factball by stating that with everything that has been explained here, it is perhaps fair to say that Messi and Cristiano could not score as many goals in Stoke as they did in the mild temperatures of Spain.
Best regards and a trivela from Ricardo Quaresma,
João Francisco
Extra Time
Fact 🔍
For some years, the Brunei national team competed in Malaysian club competitions, even winning the Malaysian Cup in 1999.
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🖋 Katie Whyatt in The Athletic
