October 12, 2020

Sports Betting As An Investment

How often do favourites win in football?

Football match odds

 

In this article, we will look into how often the favourites win in football (for you Americans out there: We will look at how often favorites win in soccer games 🙂).

We do so by looking at some selected European top leagues to see if there are any differences between the leagues and the analysis will include all the full seasons from 2011/12 – 2018/19 plus the 2019/20 season until when the corona virus stopped all tournaments.

 

It is our aim to specifically address the following questions:

  • How often do the favourites win in football?
  • How often do home team favourites win?
  • How much does home advantage matter in football?
  • Is it profitable backing favourites?

 

The analysis includes the following leagues:

  • Belgium: Jupiler League (BJL)
  • Germany: 1. Bundesliga (GEB)
  • Denmark: Superliga (DKS)
  • England: Premier League (EPL)
  • France: Ligue 1 (FR1)
  • Italy: Seria A (ITA)
  • Holland: Eredivisie (HLE)
  • Spain: Primera Divisíon (SPP)

 

In total, we have a database covering 25,029 matches so it is fair to say that we should be able to make some serious analysis and conclusions on the subject.

 

What defines a favourite?

 

First of all, to discuss if the favourites win more often than not, we obviously need to be clear on what we mean by ”a favourite”. We will define the favourite as the team which has the lowest odds for winning a football match. In the rare case the Draw has the lowest odds, the ”Draw” will be claimed the favourite. So, essentially, the favourite is defined as the most likely outcome based on the odds set by the bookmakers at just before the game starts.

 

A favourite does NOT need to be below odds 2.0 (i.e., ”odds on”) to constitute a favourite by this definition – we will later look at performance related to various odds ranges but at this general level, any odds are accepted.

 

Overall results

 

In total, 53.5% of the favourites won (including when Draws were the ”favourites”).

 

If we split this into Home, Draw & Away, the figures look like this:

  • The home team was the favourite in 17,524 matches (70% of all matches)
    • Of these, the home team won 55%
  • The Draw was the favourite outcome in 26 matches (0.1% of all matches)
    • Of these, the Draw was the outcome in 12 matches (i.e., 46%)
  • The away team was the favourite in 7,479 matches (30% of all matches)
    • Of these, the away team won 49.8%

 

We can look at it in a slightly different way to additional information.

The table below shows the outcome combined with favourite (home vs away):

Home Win Draw Away Win
Home Fav. 55% 25% 20%
Draw Fav. 23% 46% 31%
Away Fav. 25% 25% 50%
All 46% 25% 29%

 

So we find that the home team wins 46% of the matches, while the away team wins 29% of the matches. We can use these figures to calculate how much the home advantage actually is: If it did not matter at all playing home, away or on neutral ground, you would expect the home and away wins to be exactly the same, but since they are not, playing in front of a home crowd cheering you on clearly has a positive impact.

If we want to quantify the value of the home advantage, we will remove the draw from the equation. The draw accounts for 25% of all results, which leaves us with 75% to share between home and away, i.e. 37.5% for each. The home wins stand at 46%, so the home advantage can be quantified to 22.7%, and likewise, if we look at the away ”disadvantage”, you get -22.7% (29% wins vs 33%).

 

The home team win percentage is clearly much lower than the number of times the home team is actually the favourite (55% wins vs 70% favourites), but so are the away team figures. The reason is that the Draw happens more than ”Odds Favourite” in itself would suggest. It is important, however, to note that this does not mean the odds are wrong as a whole – it simply means than on the single games, the odds can be ”wrong” (bear in mind that just because a team is a major favourite, say at odds 1.10, it still means that it will be expected NOT to win in 1/10 matches like this) but as a total, they may be right.

This may sound confusing, but if we look at the odds vs the aggregated number of wins, it may be clearer what we mean.

 

For every match, the odds suggest a likelihood of the 3 outcomes – the home win, the draw, and the away win.

Let’s say that we, for instance, have a match with the following odds:

  • Home win: 1.60
  • Draw: 4.20
  • Away win: 5.25

 

From these odds, we can calculate the ”implied” probability of the three potential outcomes – but we have to take any bookmaker overround into account (which is basically the bookmaker’s ”edge”, i.e. how they primarily make their money).

 

If we start by using the odds as they are, the implied probabilities are:

  • Home win: 1/1.60 = 62.50%
  • Draw: 1/4.20 = 23.81%
  • Away win: 1/5.25 = 19.05%

 

The total adds up to 105.36, so the bookmakers overround on this particular match is 5.36%.

 

Since the total probability can only be 100% – no more, no less – we need to divide all the probabilities by 1.0536, so the actual estimated probability by the bookmaker for this match is:

  • Home win: 59.3%
  • Draw: 22.6%
  • Away win: 18.1%

 

We can now do this for all the matches and thus calculate a total expected number of home wins, draws and away wins, and compare these figures to the actual figures.

The result is amazingly accurate… as shown in the diagram below:

So, the difference between the bookmaker’s estimate and the actual outcome is pretty much just a small decimal number. If anything, it certainly shows that the bookmakers know what they are doing..!

Going back to the actual outcomes, we saw that the home team wins 46% of the matches. This can, of course, be ”translated” into odds – a win rate of 46% equals an average odds of 1/0,46 = 2.17. If we disregard the overround for a second, what this means is that a match where the home team has odds at 2.17 or close to it, will be a match where they two teams are actually considered totally even in quality. The only thing that makes the home team become the favourite is simply the fact, that they are the home team, i.e. they have the home team advantage. In fact, we can calculate the exact ”true” average odds for a match with two perfectly even teams:

 

Bear in mind that these odds are averages and do not take into account the fact that some teams are much better at home than away or vice versa, compared to the norm.

 

League differences

 

Now that we have seen, that overall the home advantage is ”worth” 22.67% on a general level across all the leagues included, let’s have a look if there are any significant differences between the leagues.

This is shown in the diagram below.

[For league descriptions, we refer to the top of the article]

 

We can clearly see that there are differences between the leagues and one league stands out in particular, the Danish Superliga, where the home advantage is less significant. The English Premier League is spot on the average while the league with the highest home advantage appears to be the Spanish Primera Divisíon.

The Danish Superliga is the league with the lowest attendance figures, so maybe that is the reason for the lower home advantage?

Below is shown the attendances for the years 2011-19 by league:

[For league descriptions, we refer to the top of the article]

 

The average for the period is as follows:

Attendances by league, average 2011-19

[For league descriptions, we refer to the top of the article]

 

The German 1. Bundesliga is the league with the highest average attendances but it is not the league with the most significant home advantage, so the average attendances are not the sole explanation as to why there is a home advantage (case in point: Belgium, with the 2nd lowest average attendances, has the 2nd highest home advantage. It also is not a matter of travel distance as Belgium is the smallest country in this group of countries).

We saw previously that the bookmakers are very good at estimating wins, draws, and losses on an aggregate scale but how good are they if we break it down by league?

Book estimated home wins vs actual by league

 

We find that the bookmakers tend to underestimate the home team generally, albeit not by much.

If we narrow it down to odds favourites only, we get the following:

 

Book est home wins vs actuals for favourites

 

We get pretty much the same picture – a small tendency by the bookmakers to underestimate the home advantage, but only to a small degree.

 

Is it profitable to back favourites?

 

Given that we have seen that the bookmakers are very good at estimating the winners on an aggregate level, it would be very likely that just backing the favourites blindly would not be profitable, and this is very much the case as shown in the table below.

League Fav W% ROI
BJL 52,5% -6%
GEB 51,2% -7%
DKS 49,9% -5%
EPL 54,4% -4%
FR1 51,2% -3%
ITA 55,2% -1%
HLE 55,9% -6%
SPP 55,4% -4%
Total 53,5% -4%

 

For every $100 spent, you would lose $4. The smallest loss is found in the Italian Seria A at just 1%, but generally blindly backing the favourites is clearly not a good idea. Narrowing it down to home favourites only does not improve things either:

 

League Home Fav W% ROI
BJL 55,7% -5%
GEB 52,9% -6%
DKS 51,4% -5%
EPL 55,4% -4%
FR1 52,3% -3%
ITA 55,9% -3%
HLE 58,7% -4%
SPP 57,1% -2%
Total 55,0% -4%

 

 

Summary

 

It was our aim with this article to gain some insight into how favourites perform and if there is a profit just backing them blindly.

 

We found the following:

  • Favourites win 53.5% of the time
  • Home team favourites win more often than away team favourites
  • Home teams are the favourites in 70% of the matches
  • Playing at home improves results by 22.7% on average but the home advantage varies by league
  • Bookmakers tend to underestimate the home advantage to a small degree
  • It is not profitable to back the favourites blindly

 

The following sites were used for this research:

https://en.wikipedia.org/wiki/Main_Page
(general research)

http://www.european-football-statistics.co.uk/index1.htm
(attendances)

https://www.football-bet-data.com/default.asp
(results and odds)

https://www.flashscore.com/ (results and odds)