PageRank Reveals Top Soccer Teams
In this course and in general, the PageRank algorithm is typically associated for ranking websites. This algorithm was developed by Google and is used to rank importance of a website based on how many other sites have a link to this site. Sometimes there are other applications as well, including ranking scientific papers or candidates in an election. Though, not many people would realize that PageRank can also be used to rank teams of an internationally played sport in a global tournament. That’s right, researchers from Methodius University in Macedonia have found such application of PageRank. More specifically, this algorithm can be used to holistically rank the top national soccer teams in the World Cup.
First, the results would be taken from over 7000 games in the World Cup among all the nations in the world since 1930. Then a network graph is created so that an edge exists between two nodes if and only if the nodes, representing the nation’s soccer teams, have played against each other before. The weight and other attributes of this edge also vary depending on the various criteria used from the game’s results. Once the graph is fully formed, then the PageRank algorithm will run with numerous iterations to determine the soccer teams’ rankings.
The results generated from the PageRank algorithm are surprisingly relevant. Its top ranked team is Brazil, which makes sense since Brazil has historically a great record in soccer and even won the World Cup 5 times, the most of any nation. Then the next few nations ranked by PageRank are Italy, Germany, Netherlands, and Argentina, in that order. These results also seem sensible for an avid soccer follower since these teams frequently make the semifinals in past World Cups. Also, not only do the results seem reasonable, researchers have also compared PageRank’s rankings against the rankings of the official soccer’s governing body, FIFA. The official rankings have Brazil, Germany, Italy, Argentina, and Spain in that order. This is remarkably close to the PageRank’s rankings since they have 4 out of 5 nations in common and are almost in the correct order.
Though, it is also important to note that there are critical differences as well. For example, Netherlands showed up 4th on the PageRank’s rankings while it is 8th on FIFA’s rankings. In addition, Denmark is 17th on PageRank’s rankings but is 25th on FIFA’s rankings. Even then, the rankings do not seem to differ drastically (< 10%) considering there are over 200 national soccer teams who had ever played in the World Cup.
Certainly, PageRank’s algorithm has shown itself tremendously useful for estimating a team’s relative performance in a World Cup. This algorithm is also not confined to soccer and can be applied in many other sports as well. When one has the time to build a program, scrape previous results from the web, and analyze the data with PageRank, one can provide exciting output for sports enthusiasts to see how their favorite teams rank. Even for those who are new to a particularly sport, PageRank can also serve as a useful reference since it gives newcomers a starting point for them to decide which teams to follow.
Source:
http://www.technologyreview.com/view/535861/pagerank-algorithm-reveals-worlds-all-time-top-soccer-team/