Outperforming the Soccernomics model: Slovenia and Ghana

Yes, the Slovenian goal was that big of a deal.

In a recent post I commented on how the Soccernomics model for predicting international competition goal differential applied to the England/USA match. In this post I will use that same model to show how big the wins by Ghana and Slovenia were in this weekend’s World Cup competition.

Ghana and Slovenia represent two ends of the Soccernomics model spectrum – some might say the wrong ends to be on if you want to succeed in international soccer. Slovenia is perhaps the newest team on the block, having played the fewest international matches of all the participants in this year’s competition. This is due to the fact that they only became a nation in 1991 as a consequence of the breakup of Yugoslavia (I have chosen to assign the Yugoslavian matches to its biggest successor – the nation of Serbia). Interestingly enough, Slovenia does possess a moderate amount of wealth and thus has a reasonable GDP when compared to other nations. Ghana, while having over fifty years of international soccer competition under its belt (nearly ten times the matches of Slovenia), is the most impoverished nation in this year’s World Cup. While Slovenia pays a far bigger price for its lack of experience in the Soccernomics model, both nations are often the underdog when using the model to predict match outcome. Let’s see how big of a disadvantage each team faced in their first matches.

Sources of Data

Before going much further, a comment must be made about the data sources used in this analysis.

• GDP: Throughout this post, I have used IMF data found in this Wikipedia article.
• Population: Throughout this post, I have used the data found within this Wikipedia article. As one can see, there is no real authoritative source for population data – the list is compiled from several reliable sources. The Slovenian government and UN estimates were used as sources for the populations of Ghana, Slovenia, Serbia, and Algeria.
• International Experience: This is perhaps the weakest data set in my study. I have used Russell Gerrard's AIFR data set, which was also used by the authors of Soccernomics. The main liability of this data is that it is only current through 2001, thus the last nine years of experience are not included in my analysis. This means that a few of the ratios, especially for a country like Slovenia where over half their experience is missing from its total international match count, are a bit off. This risk is somewhat mitigated through the use of natural logs in the model. As an example, doubling Slovenia’s experience and assuming Algeria played no matches between 2001 and 2010 reduces Algeria’s goal differential advantage by 1/3. That means that any observation we observe from the model is still likely real and significant. The risk continues to decline as more established teams (i.e. Ghana and Serbia) face each other. If anyone has any ideas where I might find data for international matches between 2001 and 2010, I am all ears.

Ghana vs. Serbia

This match represented the second chance for an African nation to claim a full three points at the first African World Cup. Before ever starting the match, the Ghanian team were underdogs, but just how big?

Population

• Ghana: 23,837,000
• Serbia: 9,850,000

GDP per capita

• Ghana: $671
• Serbia: $5,809

International experience

• Ghana: 389 matches
• Serbia: 578 matches

Serbia has nearly a nine-fold advantage in per capita GDP, a nearly fifty per cent advantage in international experience, and a nearly a two-and-a-half-fold disadvantage in population. This equates to 0.5 goal differential advantage for Serbia – certainly an advantage, but not a huge one. Thus, the victory by Ghana, representing a 1.5 goal residual from the Soccernomics prediction, may be more symbolic in its overperformance.

Slovenia vs. Algeria

Slovenia has played the role of world beaters over the last decade, making shocking runs in Euro 2000, qualifying for World Cup 2002, and defeating the Russians in the European playoff for qualification at World Cup 2010. Just how big of an underdog were they in the opening match?

Population

• Slovenia: 2,059,470
• Algeria: 34,895,000

GDP per capita

• Slovenia: $24,417
• Algeria: $4,027

International experience

• Slovenia: 73 matches
• Algeria: 250 matches

Slovenia’s population is clearly better off economically than their former Serbian brethren as well as their Algerian opponents. However, they suffer greatly in the Soccernomics model with less than one tenth the population and one third the international experience of Algeria. This translated to a 1.0 goal differential advantage for Algeria. Slovenia’s victory, which translates to a 2.5 goal residual for the team, is huge. If Slovenia can tie or win against the US (1.7 goal advantage) and England (2.3 goal advantage), it will have likely completed one of the best performances against the Soccernomics model of all the teams in this year’s World Cup.