An Analysis Of Parity Levels In Soccer

By Andrew Puopolo

A new season of European soccer is upon us. The Premier League kicked off this past weekend with some exciting matches and a major upset as Burnley defeated defending champions Chelsea at Stamford Bridge. Over the next couple of weeks, the other major European leagues will kick off their new season and fans will be excited to watch their teams battle it out for a title.

Or will they? Many fans of soccer are becoming increasingly worried that the game is becoming more and more unequal. The superpower teams have access to a clear majority of the resources, especially the ever-increasing television revenues and it seems as though those teams will dominate their respective leagues for many years to come. Last season, the top seven teams in England also had the seven highest budgets, with 8th place Southampton closer to the relegation zone than 7th place Everton. In Italy and Germany, it was business as usual as Juventus and Bayern Munich won their leagues for the 6th and 5th consecutive time respectively. In Spain, the top 3 was the same for the fourth season running.

Two years ago, current HSAC president Brendan Kent took a look at comparing the parity in MLS to the parity in the Big 5 European leagues using Gini coefficients, and came to the conclusion that MLS had much more parity than its European counterparts.

Inspired by Brendan’s work, I decided to expand upon it to test the following:

1.) To confirm Brendan’s work from 2 years ago across a longer time horizon (15 years).
2.) To show that the English League Championship, dubbed “the hardest league in the world” has levels of parity higher than its top division counterpart.
3.) To try to determine which European league has exhibited the highest levels of parity over the last 15 years.
4.) To see if levels of parity have shifted changed in certain leagues over time.

To do this, I calculated the Gini coefficient of every season dating back to 2003 in the following six leagues:

1.) English Premier League
2.) Spanish La Liga
3.) Italian Serie A
4.) German Bundesliga
5.) Major League Soccer
6.) English Football League Championship

The first four of these leagues were chosen because they are widely regarded to be the four best leagues in the world, as they have provided every single Champions League finalist since 2004. Major League Soccer was chosen as a control to test my methodology. MLS has a salary cap and therefore all teams have theoretically have equal resources. The English Football League Championship was chosen to compare directly to the English Premier League as having the same league structure and sporting culture but more income equality across the entire division.

For those uninitiated with economic theory, the Gini Coefficient is a measure of income inequality within a country. A country with a Gini coefficient of 100 has one person having all the economic resources while a country with a Gini Coefficient means everyone is equal. In this example, we use the number of points achieved by each team as our unit of income. The higher the Gini Coefficient, the more inequality there is across the league.

Before running any statistical tests, I will first graph the parities of each of the six leagues on the same set of axes, followed by the identical graph of the four major European Leagues.

Note: When calculating the league points for each team in the league, the number of points earned through results was used instead of the number of points on the final league table (in cases of teams being deducted points).

There are a few important things to note here before we dive deeper with more advanced statistical tests.

1.) For the most part (12 of the 15 seasons), the MLS had the lowest Gini coefficient.
2.) The English League Championship had a lower Gini coefficient than the Premier League in every season recorded, seemingly confirming our hypothesis.
3.) The league with the highest Gini coefficient has changed over time. Italy had the highest coefficient around the time of the infamous Italian match fixing scandal. In the last part of the first decade of this century, the Premier League took over, with the same four teams finishing in the first four places for 6 consecutive years. In recent years, the growing income inequality between the 2 Madrid clubs, Barcelona and the rest of La Liga has led to growing levels of inequality.
4.) La Liga’s Gini coefficient has steadily trended upward over the last 15 years while most of the other leagues remained constant.

We also look at the average Gini coefficient of each league.

This would imply that the Premier League has had the lowest levels of parity over the past 15 seasons (and contradicting the argument put forward by many proponents of the English game), but we ought to dig deeper into that claim given that the average Gini coefficient over the last 15 years by the Big 4 European Leagues are pretty close.

We will now test each of our hypotheses outlined above using statistical methods.

Question 1: Does the MLS exhibit more parity than the other 5 leagues?

The first question we are trying to answer is an extension of Brendan’s work applied to larger time sample. We will first run an analysis of variance test on the six leagues tests

This tells us that there is large statistical significance to imply that the average Gini coefficient of all 6 leagues are not the same. We now test the MLS against our second lowest coefficient using a t test.

From this, we can conclude at the 90% significance level that MLS has demonstrated the highest levels of parity over the last 15 years out of any of the six leagues that we have tested.

Question 2: Does the Championship exhibit more parity than the Premier League?

Our second question was does the English League Championship would exhibit much greater levels of parity than the English Premier League as a result of more comparable budgets across the league, despite having otherwise identical structures (culture, travel, stadiums etc.). We also test this using a t-test.

From this, we can confirm our second hypothesis that the Championship has much higher levels of parity than the Premier League.

Question 3: Is there a difference in parity between the four biggest leagues?

Our third question, trying to measure parity between the Big Four Leagues, we test using an analysis of variance test between the top 4 European Leagues.

Here, we find that there is no statistical significance implying that the Gini coefficients between any of the four leagues is different.

Question 4: Has the parity in leagues changed over the years?

To test this, I regressed each of the leagues against the entire time period to see if there was a statistically significant slope to imply that the levels of parity have changed in the last 15 years. After conducting this analysis for all 6 leagues, I found that only Spain’s La Liga exhibited a statistically significant difference in parity levels. I found that on average La Liga increased its Gini coefficient by about .5 per year. This makes sense, given the increased dominance of Real Madrid and Barcelona (and now Atletico Madrid) over the last 15 years.

To summarize, we came to the following conclusions:
1.) MLS has higher levels of parity than the major 4 European Leagues
2.) The English League Championship has significantly higher levels of parity than the English Premier League
3.) There is no real difference in parity levels across the four major leagues
4.) Spain’s La Liga has exhibited diminishing levels of parity over the last fifteen seasons.

Sorry Premier League fans, but your league unfortunately does not have any more parity than the “two team leagues” that you so often deride.

Editors Note: If you have any questions about this article, please feel free to reach out to Andrew at andrewpuopolo@college.harvard.edu.

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2 Comments

  • Good article – you dont need to know the financial makeup of the league to make that conclusion however. My own http://www.possessionwithpurpose.com Total Soccer Index – that excludes monetary investment as well as points earned in the league table clearly shows which leagues had greater parity in 2014 between MLS, EPL, LaLiga, Bundesliga, UEFA CL and the WC 2014… the simple analysis comes straight from looking at how well the TSI compares (r) to the league table… the greater the r to points earned in the league table the less parity within the league… feel free to contact me to discuss. This year I have added an improvement to TSI to bring the (r) even closer to the league table, again, without measuring points earned – it’s simply derived from the primary bell curve of activities that occur on the pitch… both in terms of quality and quantity… The original TSI was published in London, England 2016, International Science and Soccer II; Taylor, Francis, and Routledge.

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