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Login: | Explaining level changesDivision 3B: Colston Imperials A v Weston (Wed 16 Mar 2011)Match played between Alan Elvins (home) and Chris Farrant (away).Match won by Chris Farrant. Result: 8-10,9-6,2-9,4-9. Starting level for Alan Elvins: 646, level confidence: 68%. Starting level for Chris Farrant: 600, level confidence: 74%. Set manually. Alan Elvins to win as he is currently playing 8% better than Chris Farrant. Chris Farrant won 75% of the games and 60% of the points. This games result would be expected if he was better by around 25%. This points result would be expected if he was better by around 24% (english scoring). These are weighted and combined to calculate that Chris Farrant played 25% better than Alan Elvins in this match. Assuming that any level changes are shared between both players, for this result it looks like Chris Farrant actually played at a level of 695 and Alan Elvins at a level of 558. Without any damping, both players would need to be adjusted by 16% to match this result. Factoring in the relative levels of confidence which allows players with low confidence in their levels to change more quickly, the adjustment for Chris Farrant changes to +14% and Alan Elvins changes to -15%. After applying standard match damping, the adjustment for Chris Farrant becomes +8.3% and for Alan Elvins becomes -9%. Apply match/event weighting of 75% for 'Mixed Spring 2011' so the adjustment for Chris Farrant is +6.2% and for Alan Elvins is -6.6%. 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 Alan Elvins 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. Chris Farrant: 86%, Alan Elvins: 82%. Reduce level confidence based on how unexpected the result is. Chris Farrant: 74%, Alan Elvins: 71%. A final adjustment of -0.1% 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 Alan Elvins: 614, level confidence: 71%. Final level for Chris Farrant: 637, level confidence: 74%. Notes
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