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Matthew Lu

USATT#: 85535

Introduction
This page explains how Matthew Lu (USATT# 85535)'s rating went from 2400 to 2382 at the Youth National Ranking Tournament held on 28 Mar 2019 - 30 Mar 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 Matthew Lu for this tournament.

Initial Rating Pass 1 Pass 2 Pass 3 Final Rating (Pass 4)
2400 2355 2400 2400 2382


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 104 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 Xi3, 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 Youth National Ranking Tournament held on 28 Mar 2019 - 30 Mar 2019 for Matthew Lu, and its source tournament are as follows:
Initial Rating From Tournament Start Day End Day
2400 JOOLA North American Teams 23 Nov 2018 25 Nov 2018

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 Matthew Lu's match results and applying the point exchange table, gives us the following result:

Matthew Lu's Wins
Winner Loser
Point Spread Outcome Gain Player USATT # Rating Player USATT # Rating
215 EXPECTED 1 Matthew Lu 85535 2400 Daniel Zhou 97477 2185
194 EXPECTED 1 Matthew Lu 85535 2400 Aneesh Raghavan 93049 2206
161 EXPECTED 2 Matthew Lu 85535 2400 Avery Ang-Yau Chan 91928 2239
127 EXPECTED 3 Matthew Lu 85535 2400 Daniel Ng 88317 2273
412 EXPECTED 0 Matthew Lu 85535 2400 Rolan Guang 215498 1988
161 EXPECTED 2 Matthew Lu 85535 2400 Avery Ang-Yau Chan 91928 2239
3 EXPECTED 8 Matthew Lu 85535 2400 Alexander M Wu 92296 2397
221 EXPECTED 1 Matthew Lu 85535 2400 Ethan Liu 91756 2179
189 EXPECTED 1 Matthew Lu 85535 2400 Jensen Feng 95314 2211
27 UPSET 10 Matthew Lu 85535 2400 Ted Chensheng Li 89340 2427
205 EXPECTED 1 Matthew Lu 85535 2400 Evan Lai 86894 2195

Matthew Lu's Losses
Winner Loser
Point Spread Outcome Loss Player USATT # Rating Player USATT # Rating
211 EXPECTED -1 Michael Minh Tran 80507 2611 Matthew Lu 85535 2400
169 UPSET -35 Mudit Mahajan 91747 2231 Matthew Lu 85535 2400
15 EXPECTED -7 William Bai 81300 2415 Matthew Lu 85535 2400
104 UPSET -20 Aziz Zarehbin 91906 2296 Matthew Lu 85535 2400
55 EXPECTED -6 Sid Naresh 84903 2455 Matthew Lu 85535 2400
55 EXPECTED -6 Sid Naresh 84903 2455 Matthew Lu 85535 2400

You can click here to view a table of outcomes and points gained/lost from all the matches with all the players in this tournament.

The "Outcome" column above, shows whether the match had an expected (player with the higher rating wins the match) or an upset (player with the higher rating loses the match) outcome. Based on this outcome, and using both the player's initial rating, we apply the point exchange table from above and show the ratings points earned and lost by Matthew Lu in the "Gain" column. Matches are separated out into two tables for wins and losses where points are gained and lost respectively. We get the following math to calculate the Pass 1 Rating for Matthew Lu:

Initial Rating Gains/Losses Pass 1 Rating
2400 + 1 - 1 + 1 + 2 - 35 + 3 - 7 + 0 + 2 - 20 + 8 - 6 + 1 - 6 + 1 + 10 + 1 =2355

You can click here to view a table of pass1 calculations for all the rated players in this tournament.

Pass 2 Rating
The purpose of this pass is solely to determine ratings for unrated players. To do this, we first look at the ratings for rated players that came out of Pass 1 to determine an “Pass 2 Adjustment”. The logic for this is as follows:

  1. We calculate the points gained in Pass 1. Points gained is simply the difference between the Pass 1 Rating and the Initial Rating of a player:

    ρi2 = Pi1 - Pi0
    where,

    Symbol Universe Description
    Pi0 Pi0+ the initial rating for the i-th player. We use the symbol P and the superscript 0 to represent the idea that we sometimes refer to the process of identifying the initial rating of the given player as Pass 0 of the ratings processor.
    Pi1 Pi1+ the Pass 1 rating for the i-th player.
    ρi2 ρi2 the points gained by the i-th player in this tournament. Note here that we use the superscript 2 to denote that this value is calculated and used in Pass 2 of the ratings processor. Further, ρi2 only exists for players who have a well defined Pass 1 Rating. For Players with an undefined Pass 1 Rating (unrated players), will have an undefined ρi2.
    i i[1,104] the index of the player under consideration. i can be as small as 1 or as large as 104 for this tournament and the i-th player must be a rated player.

  2. For rated players, Pass 1 points gained, ρi2, is used to calculate the Pass 2 Adjustment in the following way:
    1. If a player gained less than 50 points (exclusive) in pass 1, then we set that player's Pass 2 Adjustment to his/her Initial Rating.
    2. If a player gained between 50 and 74 (inclusive) points in pass 1, then we set the player's Pass 2 Adjustment to his/her Final Pass1 Rating.
    3. If a player gains 75 or more points (inclusive) in pass 1, then the following formula applies:
      • If the player has won at least one match, and lost at least 1 match in the tournament, then the player's Pass 2 Adjustment is the average of his/her Final Pass 1 Rating and the average of his/her opponents rating from the best win and the worst loss, represented using the formula below:

        αi2 = Pi1 + Bi + Wi 2 2

        where αi2 is the Pass 2 Adjustment for the current player, Pi1 is the Pass 1 Rating, Bi is the rating of the highest rated opponent against which the current player won a match, and Wi is the rating of the lowest rated opponent against which the current player lost a match.
      • If a player has not lost any of his/her matches in the current tournament, the mathematical median (rounded down to the nearest integer) of all of the player's opponents initial rating is used as his/her Pass 2 Adjustment:

        αi2 = {Pk0}

        where Pk0 is the initial rating of the player who was the i-th player's opponent from the k-th match.
        Symbol Universe Description
        i i[1,104] the index of the player under consideration. i can be as small as 1 or as large as 104 for this tournament and the i-th player must be a rated player.
        q q[1,772] the index of the match result under consideration. q can be as small as 1 or as large as 772 for this tournament and the q-th match must be have both rated players as opponents.
        g g[1,5] the g-th game of the current match result under consideration. q can be as small as 1 or as large as 5 for this tournament assuming players play up to 5 games in a match.
        Pk0 Pk0+ initial rating of the i-th player's opponent from the k-th match.


      • Therefore, the Pass 2 Adjustment for Matthew Lu is calculated as follows:
        • Given the initial rating of 2400,
        • and the Pass 1 rating of 2355,
        • the Pass 1 gain is 2355 - 2400 = -45.
        • Since the Pass 1 gain of -45 is less than 50, the Pass 2 Rating (also referred to as Pass 2 Adjustment) is reset back to the initial rating.
        • Therefore the Pass 2 Adjustment for Matthew Lu is 2400.

        You can click here to view a table of Pass 2 Adjustments for all the rated players in this tournament.

  3. After calculating the Pass 2 Adjustment for all the rated players as described above, we can now calculate the Pass 2 Rating for all the unrated players in this tournament (which is the main purpose of Pass 2). Pass 2 Rating is calculated using the following formula:
    1. If all of the matches of an unrated player are against other unrated players, then the Pass 2 Rating for that player is simply set to 1200. You can click here to view these players who received a 1200 Pass 2 Rating. Not all of Matthew Lu's matches were against unrated players. So this rule does not apply to him.
    2. For unrated players with wins and losses, where at least 1 of the opponents has an initial rating, the Pass 2 Rating is the average of the best win and the worst loss (using the Pass 2 Adjustment of all rated players) as defined by this formula here:

      Pi2 = Bi2 + Wi2 2

      where Pi2 is the Pass 2 Rating for the i-th player, Bi2 is the largest Pass 2 Adjustment (best win) of the opponenet against whom the i-th player won a match, and Wi2 is the smallest Pass 2 Adjustment (worst loss) of the opponent against whom the i-th player lost a match.
    3. For unrated players with all wins and no losses, where at least 1 of the opponents has an initial rating, the Pass 2 Rating is calculated using the following formula:
      Pi2 = Bi2 + k=0Mi-1 I(Bi2-αk2)
      where the function I(x) is defined as, \begin{equation} I(x)=\left\{ \begin{array}{ll} 10, & \text{if}\ x >= 1, x <= 50 \\ 5, & \text{if}\ x >= 51, x <=100 \\ 1, & \text{if}\ x >= 101, x <= 150 \\ 0, & \text{otherwise} \end{array}\right. \end{equation}
      where,
      Symbol Universe Description
      Pi2 Pi2+ the pass 2 rating, of the i-th player in this tournament only applicable to unrated players, where Pi0 is not defined
      Bi2 Bi2+ the largest of the Pass 2 Adjustments of opponents of the i-th player against whom he/she won a match.
      αk2 αk2+ the Pass 2 Adjustment of the player who was the opponent of the i-th player in the k-th match
      I(x) I:+ a function that maps all integers to one of the values from -- 0, 1, 5, 10.
      Mi Mi+ total number of matches played by the i-th player in this tournament
      k k[0,Mi-1]+ The index of the match of the i-th player ranging from 0 to Mi-1
    4. For unrated players with all losses and no wins, where at least 1 of the opponents has an initial rating, the Pass 2 Rating is calculated using the following formula:
      Pi2 = Wi2 + k=0Mi-1 I(Wi2-αk2)
      where I(x) is defined above and,

      Symbol Universe Description
      Pi2 Pi2+ the pass 2 rating, of the i-th player in this tournament only applicable to unrated players, where Pi0 is not defined
      Wi2 Wi2+ the smallest of the Pass 2 Adjustments of opponents of the i-th player against whom he/she lost a match.
      αk2 αk2+ the Pass 2 Adjustment of the player who was the opponent of the i-th player in the k-th match
      I(x) I:+ a function that maps all integers to one of the values from -- 0, 1, 5, 10.
      Mi Mi+ total number of matches played by the i-th player in this tournament
      k k[0,Mi-1]+ The index of the match of the i-th player ranging from 0 to Mi-1
    5. For the rated players, all the work done in Pass 1 and Pass 2 to undone and they have their ratings reset back to their initial ratings while the unrated players keep their Pass 2 Adjustment as their final Pass 2 Rating. Since Matthew Lu is a rated player, his Pass 2 Adjustment of 2400 will be ignored, along with him Pass 1 Rating of 2355 and his Pass 2 Rating will be set to his initial rating of 2400 with which he came into this tournament.


Click here to see detailed information about the Pass 2 Ratings of all the other players in this tournament.

Pass 3 Rating
Any of the unrated players who have all wins or all losses are skipped in Pass 3. Since Matthew Lu has an initial rating of 2400, he is not an unrated player, and therefore this rule does not apply to him. You can click here to view list of all the players that are skipped in this Pass 3.

Pass 3 Rating is calculated using 2 steps described below:
  1. In the first part of Pass 3, we apply the point exchange table described in Pass 1 above except this time by using all the players' Pass 2 Ratings. Looking at Matthew Lu's wins and losses and applying the point exchange table, gives us the following result:
    Matthew Lu's Wins
    Winner Loser
    Point Spread Outcome Gain Player USATT # Rating Player USATT # Rating
    215 EXPECTED 1 Matthew Lu 85535 2400 Daniel Zhou 97477 2185
    194 EXPECTED 1 Matthew Lu 85535 2400 Aneesh Raghavan 93049 2206
    161 EXPECTED 2 Matthew Lu 85535 2400 Avery Ang-Yau Chan 91928 2239
    127 EXPECTED 3 Matthew Lu 85535 2400 Daniel Ng 88317 2273
    412 EXPECTED 0 Matthew Lu 85535 2400 Rolan Guang 215498 1988
    161 EXPECTED 2 Matthew Lu 85535 2400 Avery Ang-Yau Chan 91928 2239
    3 EXPECTED 8 Matthew Lu 85535 2400 Alexander M Wu 92296 2397
    221 EXPECTED 1 Matthew Lu 85535 2400 Ethan Liu 91756 2179
    189 EXPECTED 1 Matthew Lu 85535 2400 Jensen Feng 95314 2211
    27 UPSET 10 Matthew Lu 85535 2400 Ted Chensheng Li 89340 2427
    205 EXPECTED 1 Matthew Lu 85535 2400 Evan Lai 86894 2195

    Matthew Lu's Losses
    Winner Loser
    Point Spread Outcome Loss Player USATT # Rating Player USATT # Rating
    211 EXPECTED -1 Michael Minh Tran 80507 2611 Matthew Lu 85535 2400
    169 UPSET -35 Mudit Mahajan 91747 2231 Matthew Lu 85535 2400
    15 EXPECTED -7 William Bai 81300 2415 Matthew Lu 85535 2400
    104 UPSET -20 Aziz Zarehbin 91906 2296 Matthew Lu 85535 2400
    55 EXPECTED -6 Sid Naresh 84903 2455 Matthew Lu 85535 2400
    55 EXPECTED -6 Sid Naresh 84903 2455 Matthew Lu 85535 2400

    You can click here to view a table of outcomes and points gained/lost from all the matches with all the players in this tournament for Pass 3 Part 1.

    The "Outcome" column above, shows whether the match had an expected (player with the higher rating wins the match) or an upset (player with the higher rating loses the match) outcome. Based on this outcome, and using both the player's Pass 2 Rating, we apply the point exchange table from above and show the rating points earned and lost by Matthew Lu in the "Gain" column. Matches are divided up into two tables for wins and losses where points are "Gain"ed for the wins and "loss"ed for losses. Putting all the gains and losses together, we get the following math to calculate the rating for Matthew Lu in this first part of Pass 3:

    Pass 2 Rating Gains/Losses Pass 3 Part 1 Rating
    2400 + 1 - 1 + 1 + 2 - 35 + 3 - 7 + 0 + 2 - 20 + 8 - 6 + 1 - 6 + 1 + 10 + 1 =2355


    You can click here to view a table of these calculations for all the players in this tournament.

  2. Given the Pass 3 Part 1 rating calculated above, the second part of Pass 3 looks very similar to the part of Pass 2 that deals with rated players where we calculate their Pass 2 Adjustment.
    1. First, we calculate the points gained in Pass 3 Part 1. Points gained is simply the difference between the Pass 3 Part 1 Rating and the Pass 2 Rating of a player:

      ρi3 = pi3 - Pi2
      where,

      Symbol Universe Description
      Pi2 Pi2+ the Pass 2 Rating for the i-th player.
      pi3 pi3+ the Pass 3 Part 1 rating for the i-th player. (Note that since this is an intermediate result, we are using a lower case p instead of the upper case P that we use to indicate final result from each pass of the ratings processor.
      ρi3 ρi3 the points gained by the i-th player in this tournament in Pass 3.
      i i[1,104] the index of the player under consideration. i can be as small as 1 or as large as 104 for this tournament.

  3. Pass 3 points gained, ρi3, is then used to calculate the Pass 3 Part 2 Rating in the following way:
    1. If a player gained less than 50 points (exclusive) in Pass 3 Part 1, then we set that player's Pass 3 Part 2 Rating to his/her Pass 2 Rating.
    2. If a player gained between 50 and 74 (inclusive) points in Pass 3 Part 1, then we set the player's Pass 3 Part 2 Rating to his/her Pass 3 Part 1 Rating.
    3. If a player gains 75 or more points (inclusive) in Pass 3 Part 1, then the following formula applies:
      • If the player has won at least one match, and lost at least 1 match in the tournament, then the player's Pass 3 Part 2 Rating is the average of his/her Pass 3 Part 1 Rating and the average of his/her opponents rating from the best win and the worst loss, represented using the formula below:

        αi3 = pi3 + Bi3 + Wi3 2 2

        where αi3 is the Pass 3 Part 2 Rating for the current player, pi3 is the Pass 3 Part 1 Rating, Bi3 is the rating of the highest rated opponent against which the current player won a match, and Wi is the rating of the lowest rated opponent against which the current player lost a match.
      • If a player has not lost any of his/her matches in the current tournament, the mathematical median (rounded down to the nearest integer) of all of the player's opponents rating is used as his/her Pass 3 Part 2 Rating:
        αi3 = {pk3}

        where pk3 is the Pass 3 Part 1 Rating of the i-th player's opponent from the k-th match.

      • Therefore, the Pass 3 Part 2 Rating for Matthew Lu is calculated as follows:
        • Given the Pass 2 Rating of 2400,
        • and the Pass 3 Part 1 rating of 2355,
        • the Pass 3 Part 1 gain is 2355 - 2400 = -45.
        • Since the Pass 3 Gain of -45 is less than 50, the Pass 3 Part 2 Rating is reset back to the Pass 2 Rating.
        • Therefore the Pass 3 Part 2 Rating for Matthew Lu is 2400.

      The Pass 3 Part 2 rating ends up becoming the final Pass 3 rating (also referred to as the Pass 3 Adjustment) except as follows:
      • In the cases where the Pass 3 Part 2 rating is less than the players' initial rating Pi0, the Pass 3 rating is reset back to that players initial rating. Matthew Lu's Pass 3 Part 2 Rating came out to 2400. Since this value is greater than Matthew Lu's initial rating of 2400, his Pass 3 Adjustment is set to his Pass 3 Part 2 Rating of 2400.

      • It is possible for the admin of this tournament to override the Pass 3 Adjustment calculated above with a value they deem appropriate. Matthew Lu does not have a manually overridden value for his Pass 3 Adjustment, therefore the value remains at 2400.
      You can click here to view a table of Pass 3 Part 2 Ratings for all the players in this tournament along with any manually overridden values.

Pass 4 Rating
Pass 4 is the final pass of the ratings processor. In this pass, we take the adjusted ratings (Pass 3 Adjustment) of all the rated players, and the assigned rating of unrated players (Pass 2 Rating), and apply the point exchange table to the match results based on these ratings to arrive at a final rating. Looking at Matthew Lu's match results and applying the point exchange table, gives us the following result:

Matthew Lu's Wins
Winner Loser
Point Spread Outcome Gain Player USATT # Rating Player USATT # Rating
215 EXPECTED 1 Matthew Lu 85535 2400 Daniel Zhou 97477 2185
194 EXPECTED 1 Matthew Lu 85535 2400 Aneesh Raghavan 93049 2206
161 EXPECTED 2 Matthew Lu 85535 2400 Avery Ang-Yau Chan 91928 2239
62 EXPECTED 6 Matthew Lu 85535 2400 Daniel Ng 88317 2338
412 EXPECTED 0 Matthew Lu 85535 2400 Rolan Guang 215498 1988
161 EXPECTED 2 Matthew Lu 85535 2400 Avery Ang-Yau Chan 91928 2239
3 EXPECTED 8 Matthew Lu 85535 2400 Alexander M Wu 92296 2397
221 EXPECTED 1 Matthew Lu 85535 2400 Ethan Liu 91756 2179
18 EXPECTED 7 Matthew Lu 85535 2400 Jensen Feng 95314 2382
27 UPSET 10 Matthew Lu 85535 2400 Ted Chensheng Li 89340 2427
205 EXPECTED 1 Matthew Lu 85535 2400 Evan Lai 86894 2195

Matthew Lu's Losses
Winner Loser
Point Spread Outcome Loss Player USATT # Rating Player USATT # Rating
211 EXPECTED -1 Michael Minh Tran 80507 2611 Matthew Lu 85535 2400
102 UPSET -20 Mudit Mahajan 91747 2298 Matthew Lu 85535 2400
89 EXPECTED -4 William Bai 81300 2489 Matthew Lu 85535 2400
104 UPSET -20 Aziz Zarehbin 91906 2296 Matthew Lu 85535 2400
55 EXPECTED -6 Sid Naresh 84903 2455 Matthew Lu 85535 2400
55 EXPECTED -6 Sid Naresh 84903 2455 Matthew Lu 85535 2400

You can click here to view a table of outcomes and points gained/lost from all the matches with all the players in this tournament.

The "Outcome" column above, shows whether the match had an expected (player with the higher rating wins the match) or an upset (player with the higher rating loses the match) outcome. Based on this outcome, and using both the players' Pass 3 Adjustment, we apply the point exchange table from above and show the ratings points earned and lost by Matthew Lu in the "Gain" and "Loss" columns. Matches are separated out into two tables for wins and losses where points are gained and lost respectively. We get the following math to calculate the Pass 4 Rating for Matthew Lu:

Pass 3 Rating Gains/Losses Pass 4 Rating
2400 + 1 - 1 + 1 + 2 - 20 + 6 - 4 + 0 + 2 - 20 + 8 - 6 + 1 - 6 + 7 + 10 + 1 =2382

You can click here to view a table of Pass 4 calculations for all the players in this tournament.