How your Thursday USATT League

USA Table Tennis player ratings are processed by North American Table Tennis (NATT) as a contracted service. NATT uses proprietary software called ‘Matchpoint’ to process the ratings in a manner consistent with the rules established by USA Table Tennis. Matchpoint is integrated with the USATT membership system.. Tournaments are processed in chronological order. Late reporting tournaments, when processed, cause all subsequent tournaments to reprocess in chronological order. Rating points are gained/lost by winning and losing matches. If a player defeats many opponents with a higher rating, their rating may be adjusted upwards and the tournament reprocessed with this higher rating. This is done to protect the ratings of players who have lost matches to a player who began the competition severely underrated and who demonstrates a consistent playing level far above the rating with which that player entered the competition.

According to USATT, the League processing & Tournament processing algorithms are identical

Your league & tournament ratings are not processed by anyone at CTTC. Data is fed into USATT

Each new member is assigned a rating based on results from their first tournament. The more matches that are reported, the more accurate the initial rating will be. The Initial Rating calculation is described in Step 2, below. Rating calculations: Points are gained and lost according to the rating difference between their two players by the following chart.

Rating Chart
Point Spread Between Players	Expected Result (Higher Rated Player Wins: -Number of points exchanged)	Upset Result (Lower Rated Player Wins: Number of -- points exchanged)
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

Four passes of the data through the system are used to calculate the final tournament ratings results, in this sequence:

Step 1: Find players that should be adjusted. :- Based on results against other rated players in the tournament, a determination is made as to whether that player should have their rating adjusted upwards. This is based on a mathematical calculation. There are two main ways that a player can get adjusted: a few wins against significantly higher rated players or many wins over slightly higher rated players. The more matches a player plays during a tournament, the greater chance they have of being adjusted. A player who plays only 2 or 3 matches in a reported tournament, including a large upset, is unlikely to be adjusted.

Step 2: Find unrated player initial ratings. :- Based on results against rated players in the tournament (including the adjusted ratings calculated in step 1), initial ratings are calculated for all unrated players. The standard calculation is based on the average of the best win vs. worst loss. However, if the difference between these two numbers is too large or the player does not have either a win or a loss, then a mathematical calculation based on individual game scores is used to determine or refine the initial rating calculation. In addition, matches against other unrated players may be used to help determine this initial rating. There will be an opportunity after the tournament is processed to go back and manually set this rating for a player.

Step 3: Find final adjusted ratings. - Similar to step 1 except that player adjustments are based both on results against previously rated players as well as unrated players (using the ratings set in step 2). The adjusted ratings found in this step will be used for the final calculation of points won/lost for the tournament.

Step 4: Final ratings. :- Total points won/lost will be calculated for each player based on the ratings chart. Players with adjusted ratings from step 3 will start step 4 with this rating and will gain/lose points based on this new rating.

Matchpoint allows tournaments to be processed “out-of-order”. When a late reporting tournament is processed, all the subsequent tournament results are rebatched and recalculated as well, so that a player’s ratings history is always correct to that point.

A complete record of all tournament results is stored within the database. This allows for match corrections to be made. Sometimes players incorrectly indicate the winner/loser of a match in their paperwork to the Tournament Director. Sometimes a Tournament Director will incorrectly report a result to USA Table Tennis. Sometimes NATT will make a data entry error and show an incorrect result.

If an error is verified, the results are corrected and reprocessed for rating. No changes will be made to tournaments that are more than six months old.