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Login: | Explaining level changesDavid Drake v Ruth Drysdale (Thu 09 Jun 2022)Match won by David Drake. Result: 15-6,15-3,15-8.Starting level for David Drake: 890, level confidence: 82%. Set manually. Starting level for Ruth Drysdale: 693, level confidence: 69%. David Drake to win as he is currently playing 28% better than Ruth Drysdale. David Drake won all of the games and 73% of the points. This games result would be expected if he was better by around 55% or more. This points result would be expected if he was better by around 165% (PAR scoring). These are weighted and combined to calculate that David Drake played 165% better than Ruth Drysdale in this match. Assuming that any level changes are shared between both players, for this result it looks like David Drake actually played at a level of 1,278 and Ruth Drysdale at a level of 483. Without any damping, both players would need to be adjusted by 44% to match this result. Allowing for the difference in level between the players, the adjustments have been reduced to 38% and 38% respectively. Factoring in the relative levels of confidence which allows players with low confidence in their levels to change more quickly, the adjustment for David Drake changes to +32% and Ruth Drysdale changes to -38%. After applying standard match damping, the adjustment for David Drake becomes +16.4% and for Ruth Drysdale becomes -19%. Apply match/event weighting of 50% for 'Redland Green Boxes' so the adjustment for David Drake is +8.2% and for Ruth Drysdale is -8.7%. 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 Ruth Drysdale 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. David Drake: 91%, Ruth Drysdale: 83%. Reduce level confidence based on how unexpected the result is. David Drake: 63%, Ruth Drysdale: 58%. A final adjustment of +0.3% 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 David Drake: 962, level confidence: 63%. Final level for Ruth Drysdale: 664, level confidence: 58%. Notes
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