Menu | Explaining level changesTom Archer v Jim O’brien (Mon 20 Nov 2023)Match won by Tom Archer. Result: 15-5,15-8,14-16,15-6.Starting level for Tom Archer: 2,068, level confidence: 65%. Starting level for Jim O’brien: 986, level confidence: 69%. Tom Archer to win as he is currently playing 110% better than Jim O’brien. Tom Archer won 75% of the games and 63% 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 69% (PAR scoring). These are weighted and combined to calculate that Tom Archer played 39% better than Jim O’brien in this match. Due to the difference between the players' levels, allow for the likelihood that Tom Archer was taking it easy by anything up to 14%. This gives him an allowed level range for this match between 1,433 and 2,068 without affecting his level. As Tom Archer has played below his allowed range at 1,403, his level reduction is 2.1% before damping. On the assumption that Tom Archer would normally have been playing at level 1,786 (based on typical behaviour), Jim O’brien played better than expected and therefore gains a pre-damping level increase of 14%. Allowing for the difference in level between the players, including some additional protection for the better player, the adjustments have been reduced to 1.2% and 9.5% respectively. Factoring in the relative levels of confidence which allows players with low confidence in their levels to change more quickly, the adjustment for Tom Archer changes to -1.2% and Jim O’brien changes to +8.8%. After applying standard match damping, the adjustment for Tom Archer becomes -0.9% and for Jim O’brien becomes +5.9%. Given Tom Archer's level and the type of match played, an additional damping of 1.4% has been applied to his level change. Apply match/event weighting of 50% for 'Ickleford Boxes' so the adjustment for Tom Archer is -0.4% and for Jim O’brien is +2.9%. As Jim O’brien has a provisional level, this match has been used to calibrate his level so Tom Archer's level has been left unchanged. Increase level confidence due to one more match played. Tom Archer: 80%, Jim O’brien: 83%. Reduce level confidence based on how unexpected the result is. Tom Archer: 65%, Jim O’brien: 68%. 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 Tom Archer: 2,065, level confidence: 65%. Final level for Jim O’brien: 1,013, level confidence: 68%. Notes
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