for
Bob Chen

USATT#: 93379 | Coach Level: National

##### Introduction
This page explains how Bob Chen (USATT# 93379)'s rating went from 2683 to 2685 at the 2019 JOOLA North American Teams held on 29 Nov 2019 - 1 Dec 2019. These ratings are calculated by the ratings processor which goes through 4 passes over the match results data for a tournament. The following values are produced at the end of each of the 4 passes of the ratings processor for Bob Chen for this tournament.

Initial Rating Pass 1 Pass 2 Pass 3 Final Rating (Pass 4)
2683 2684 2683 2683 2685

You can click here to view a table of all the resultant values from each of the 4 passes (and the initial rating) of the ratings processor for all of the 1031 players in this tournament. Sections below for further details on the initial rating and the 4 passes of the ratings processor.

Note: We use mathematical notation to express the exact operations carried out in each pass of the ratings processor below. Whenever you see a variable/symbol such as for example ${X}_{i}^{3}$, we are following the convention that the superscript part of the variable (in this case "3") indicates an index (such as in a series), and it should not be misconstrued to be an exponent (which is how it is used by default).

##### Initial Rating
The initial rating of a player for a tournament is the rating the player received at the end of the most recent tournament prior to the current tournament. If this is the first tournament the player has ever participated in (based on our records), then the player has no initial rating.

The initial rating for 2019 JOOLA North American Teams held on 29 Nov 2019 - 1 Dec 2019 for Bob Chen, and its source tournament are as follows:
Initial Rating From Tournament Start Day End Day
2683 2019 Joola LA Open 31 Aug 2019 1 Sep 2019

Click here to view the details of the initial ratings for all the players in this tournament.

##### Pass 1 Rating
In Pass 1, we only consider all the players that come into this tournament with an initial rating while ignoring all the unrated players. If a rated player has a match against an unrated player, then that match result is ignored from the pass 1 calculations as well. We apply the point exchange table shown below to all the matches participated in by the rated players:

Point Spread Expected Result Upset Result
0 - 12 8 8
13 - 37 7 10
38 - 62 6 13
63 - 87 5 16
88 - 112 4 20
113 - 137 3 25
138 - 162 2 30
163 - 187 2 35
188 - 212 1 40
213 - 237 1 45
238 and up 0 50

Suppose player A has an initial rating of 2000 and player B has an initial rating of 2064, and they played a match against each other. When computing the impact of this match on their rating, the "Point Spread" (as it is referred to in the table above) between these two players is the absolute value of the difference their initial ratings. When the player with the higher rating wins, presumably the better player won, which is the expected outcome of a match, and therefore the "Expected Result" column applies. If the player with the lower rating wins the match, then presumably this is not expected, and therfore it is deemed as an "Upset Result" and the value from that column in the table above is used. So, in our example of player A vs player B, if player B wins the watch, then the expected outcome happens, and 5 points are added to player B's rating and 5 points are deducted from player A's rating. Looking at Bob Chen's match results and applying the point exchange table, gives us the following result:

##### Bob Chen's Wins
Winner Loser
Point Spread Outcome Gain Player USATT # Rating Player USATT # Rating
151 EXPECTED 2 Bob Chen 93379 2683 Lidney Castro 216598 2532
421 EXPECTED 0 Bob Chen 93379 2683 Charlie JT Wang 94523 2262
403 EXPECTED 0 Bob Chen 93379 2683 Igor Shulkin 18534 2280
300 EXPECTED 0 Bob Chen 93379 2683 Tommy Xu 201568 2383
122 EXPECTED 3 Bob Chen 93379 2683 Ye Tian 95248 2561

##### Bob Chen's Losses
Winner Loser
Point Spread Outcome Loss Player USATT # Rating Player USATT # Rating
93 EXPECTED -4 Weixing Chen 27378 2776 Bob Chen 93379 2683