Nate Silver, head of ESPN‘s data journalism website FiveThirtyEight, is most famous for being significantly more accurate in his predictions for the 2008 presidential race and nailing 49 of the 50 states while, in the process, turning into someone who’s educated guesses have merit. So when Nate Silver’s crew decides to dedicate their craft toward nailing down who has the best odds of advancing in the World Cup, people pay attention. The fact that his team of writers are using a power rankings system that he created back in 2010 is just icing on the cake.
This methodology, called the Soccer Power Index (ESPN loves Power Indexes), is well thought out, and explicitly explained in this blog posting right here from all the way back in 2009. For those of us lacking the time to read all about the ins and outs of mathematics we might not have the inclination to parse, here’s the quick and dirty breakdown nestled in the midst of the introduction:
The SPI proceeds in four major steps: Calculate competitiveness coefficients for all games in database; Derive match-based ratings for all international and club teams; Derive player-based ratings for all games in which detailed data is available; Combine team and player data into a composite rating based on current rosters; use to predict future results.
Sound good? Of course it does. To simplify it even further, the competitiveness coefficient is a measure of how seriously players take a given match (and the tangible differences in effort); match based ratings are essentially offense and defense rankings for the team; while the player based ratings are offensive and defensive rankings for, you guessed it, the players; and then you take those numbers and project them against the same numbers for the rest of the field.