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Login: | Explaining level changesDivision 2: Weston v University of Bath Ladies A (Thu 11 Feb 2016)Match played between Rosie Bellinger (home) and Alice Richards (away).Match won by Alice Richards. Result: 7-9,9-4,9-5,5-9,3-9:9-4,10-8,9-6:4-9,9-6,9-4,9-1:2-9,9-4,9-7,3-9,10-8:9-6,9-4,9-2. Starting level for Rosie Bellinger: 927, level confidence: 53%. Starting level for Alice Richards: 677, level confidence: 73%. Set manually. Rosie Bellinger to win as she is currently playing 37% better than Alice Richards. Alice Richards won 60% of the games and 52% of the points. This games result would be expected if she was better by around 10%. This points result would be expected if she was better by around 4% (english scoring). These are weighted and combined to calculate that Alice Richards played 9% better than Rosie Bellinger in this match. Assuming that any level changes are shared between both players, for this result it looks like Alice Richards actually played at a level of 825 and Rosie Bellinger at a level of 761. Without any damping, both players would need to be adjusted by 22% to match this result. Allowing for the difference in level between the players, the adjustments have been reduced to 18% and 18% respectively. Factoring in the relative levels of confidence which allows players with low confidence in their levels to change more quickly, the adjustment for Alice Richards changes to +13% and Rosie Bellinger changes to -18%. After applying standard match damping, the adjustment for Alice Richards becomes +8.1% and for Rosie Bellinger becomes -10.5%. Apply match/event weighting of 75% for 'Womens Ladies Spring 2016' so the adjustment for Alice Richards is +6.1% and for Rosie Bellinger is -7.7%. Apply limits to the amount of change for a single match which are based on player level, level confidence and time since last match so that Rosie Bellinger is limited to -5% level change. In general a player's level won't go up by more than 10% or drop more than 5% if they've played in the last 7 days but those limits are relaxed if their previous match was further back. Increase level confidence due to one more match played. Alice Richards: 86%, Rosie Bellinger: 73%. Reduce level confidence based on how unexpected the result is. Alice Richards: 70%, Rosie Bellinger: 60%. A final adjustment of -0.5% has been made to both players as part of the automatic calibration that is performed after each match. All players in this pool will have been adjusted equally in order to remain equivalent to other player pools. Final level for Rosie Bellinger: 882, level confidence: 60%. Final level for Alice Richards: 712, level confidence: 70%. Notes
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