The Riles Analytics rating system utilizes the logistic function which has proven wide applicability in many different fields. This function can be used to calculate the ‘utility’ or ‘skill’ of different players based on the results from head-to-head matches. This function is similar to the popular Elo rating system but without a specific ‘k-factor’. Updated ratings are recalculated using an updated set of data and not inherently based on the previous rating.
Currently, the Riles Analytics rating system is meant compare the relative rankings of both ATP & WTA tour level players. The baseline ratings are compiled based on ATP events from Grand Slams through ATP World Tour 250, and WTA events from Grand Slams through WTA International over the past 12 months. There is no difference in a result 11 months ago compared to one completed last week. Therefore, this rating system does not incorporate who is ‘hot’ at a given part of the season.
This methodology teases out good or bad draws in a bracket (since the ratings only matter who is the opponent and the subsequent match result instead of how far you advance in a tournament). Also, this rating system helps remove the impact of compiling more ranking points through a higher volume of tournaments played within a given year.
The output Riles Analytics efficiency ratings are expressed between 0 and 1. It is defined as the probability of a given player against a median tour level player. Ratings not only include a win efficiency (defined as the probability that a player wins a given match), but also serve and return efficiencies (the probability that a player will hold serve or break the serve). Combining the serve and return efficiencies together, a total player efficiency is calculated and used as the original basis for sorting players. The serve and return efficiencies are also used to calculate the tournament probabilities (as opposed to win efficiency) as these indicators provide a more detailed bottoms-up comparison of potential matchups.