Are the Official World Golf Rankings Biased?∗

Golf is a global sport with professional golfers playing on many organized tours throughout the world. The largest and most important tours for male professionals include the PGA Tour, European Tour, Japanese Tour and Asian Tour. The Official World Golf Ranking, or OWGR, is a system for ranking male professional golfers on a single scale. We say a ranking system is unbiased if otherwise identical golfers who happen to play on different tours have the same (or very similar) ranks. In this paper, we investigate whether the OWGR system is biased for or against any of the tours, and if so, by how much. To investigate any potential bias, we compare the OWGR system with two unbiased methods for estimating golfer skill and performance. The first is a score-based skill estimation (SBSE) method, which uses scoring data to estimate golfer skill, taking into account the relative difficulty of the course in each tournament round. The second is the Sagarin method, which uses win-lose-tie and scoring differential results for golfers playing in the same tournaments, to rank golfers. Neither the score-based skill method nor the Sagarin method use tour information in calculating player ranks, and therefore neither method is biased for or against any tour. Using data from 2002 to 2010 and comparing the results ranks from the OWGR and score-based methods, we find that PGA Tour golfers are penalized by an average of 26 to 37 OWGR ranking positions compared to non-PGA Tour golfers. Qualitatively similar results are found when comparing OWGR and Sagarin ranks. In all cases, the bias is large and statistically significant. We find a persistent bias through time and also find that the bias tends to be the largest for golfers with SBSE ranks between 40 and 120.