The ‘Marsh Ratings’ are a historical tennis rating system providing numerical evaluations with an emphasis on quality of performance unlike the official rankings which have a greater emphasise on quantity of recent results. Consequently inactivity results in slower decay of rating than can be seen in the official rankings and can be considered more representative of actual playing standard. For this reason players may still be rated quite highly even after months of inactivity. Achievement points are awarded to players for results in the majors based on the following criteria. Winner – 81points. Runner Up – 54 points. Semi Finalist eliminated by winner – 36points. Semi Finalist eliminated by runner up – 27 points. Quarter Finalist eliminated by winner 18 points. Quarter Finalist Eliminated by Runner up 9 pts. A spread adjuster is then calculated which and applied to the Achievement points depending on the time scale the achievement points were spread over. The maximum spread adjuster would is 9 and this is applied where all the achievement points are achiever with a single rolling year. If however the best that can be said is that half are contained within a single year and the other half within the adjoining year the spread adjuster would be 7.5. etc. This represents dominance within the game. It is harder to score eight major wins in 2 years than it is in 16 years. The dominance rating is then subjected to an opposition adjuster. This is calculated by a players main 6 competitors domination weighting as defined within the domination calculations. The dominance rating multiplied by the opposition adjuster gives the overall rating of the player. The overall rating therefore takes into account, total achievement, dominance or lack of it and the standard the dominance was achieved over. E.g. Hana Mandlikova had a career in which she won 4 majors, finished runner up in 4 majors and lost in 6 major semi finals. Her overall achievement points for her entire career were 92 points which puts her 14th on the list of women singles players of the open era. Her spread factor stands at 3.50 because while her total achievement was not massively concentrated, neither was it excessively spread out. 92 x 3.50 = 322 domination points. This makes her the 15th most dominant woman singles player of the open era. However, Hana Mandlikova had to complete against both Martina Navratilova and Chris Evert when she was in her prime. This gives her quite a high opposition adjuster of 4.19. 322 x 4.19 = 1349 overall rating. The fact that she achieved her level of dominance against Martina and Chris sees her actual rating boosted to a level that puts her 9th in the list of women singles players of the open era.