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Login: | Explaining level changesDivision 2: Lansdown Avon County Girls v Weston A (Thu 22 Oct 2015)Match played between Megan Williams (home) and Ann Heath (away).Match won by Ann Heath. Result: 1-9,0-9,6-9. Starting level for Megan Williams: 162, level confidence: 26%. Starting level for Ann Heath: 213, level confidence: 67%. Ann Heath to win as she is currently playing 31% better than Megan Williams. Ann Heath won all of the games and 79% of the points. This games result would be expected if she was better by around 55% or more. This points result would be expected if she was better by around 97% (english scoring). These are weighted and combined to calculate that Ann Heath played 97% better than Megan Williams in this match. Assuming that any level changes are shared between both players, for this result it looks like Ann Heath actually played at a level of 261 and Megan Williams at a level of 132. 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 19% and 19% respectively. Factoring in the relative levels of confidence which allows players with low confidence in their levels to change more quickly, the adjustment for Ann Heath changes to +7.6% and Megan Williams changes to -19%. After applying standard match damping, the adjustment for Ann Heath becomes +5.3% and for Megan Williams becomes -10.9%. Apply match/event weighting of 75% for 'Womens Ladies Winter 2015' so the adjustment for Ann Heath is +3.9% and for Megan Williams is -8%. 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 Megan Williams 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. Ann Heath: 82%, Megan Williams: 51%. Reduce level confidence based on how unexpected the result is. Ann Heath: 67%, Megan Williams: 42%. A final adjustment of -0.2% 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 Megan Williams: 154, level confidence: 42%. Final level for Ann Heath: 220, level confidence: 67%. Notes
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