Survey of the major world sports rating systems
Using a common framework, this paper presents a survey of the major world sports rating systems (WSRSs) in skiing (sponsored by the International Skiing Federation (FIS)), men's tennis (Association of Tennis Professionals (ATP)), women's tennis (Women's Tennis Association (WTA)), soccer (Federation of International Football Associations (FIFA)) and golf (Royal and Ancient Golf Club of St Andrews). These systems are not otherwise available in the literature. Each of the WSRSs has three phases: first, the observed results are weighted to provide points for each competition; second, these points are combined to provide a seasonal value; third, the seasonal values are combined to provide a rating. The final result or placement (and not the score or time) is the most important factor in determining points for a given competition. In skiing, men's tennis and women's tennis, the rating is calculated from results over one season, while three seasons are used in golf and six seasons are used in soccer. In cross-country skiing and men's tennis, the seasonal value is calculated from the sum of the best values from that season's competitions. In alpine skiing and women's tennis, the sum of all values from that season's competitions is used. In golf and soccer, an averaging process is used. Besides potentially encouraging more entries, a 'best' system and one using all values also generates simple integer ratings rather than decimal ratings as are obtained with an averaging system. The simplest system is that of FIS in skiing, where one table of points is used for all alpine and cross-country disciplines. In contrast, considering that soccer (as a sport) prides itself on the simplicity of the game, it is surprising that FIFA's system is so complex, It is also surprising in soccer that a 'friendly' (often a pick-up exhibition used for player development) counts two-thirds as much as does a World Cup final played before a worldwide TV audience. It is hoped that this survey will serve as a valuable resource for those studying sports rating systems.