Rating system overview - Revision history

Judycole: 2021-08-02 - Clarified term of service of Jim Hughes

2021-08-02T16:20:10Z

2021-08-02 - Clarified term of service of Jim Hughes

Judycole: 2020-07-30 - Added the word difference

2020-07-30T16:53:35Z

2020-07-30 - Added the word difference

CM000003: Added logistic formula

2018-04-24T17:32:08Z

Added logistic formula

Ccree at 15:26, 23 March 2010

2010-03-23T15:26:05Z

Poslfit: link

2010-03-14T18:29:02Z

link

Knleeds: edited wording about Expected Wins again

2010-03-14T15:18:44Z

edited wording about Expected Wins again

Knleeds: Added a note that the expected wins is just an estimate.

2010-03-01T05:04:47Z

Added a note that the expected wins is just an estimate.

Jhughes at 17:55, 26 March 2009

2009-03-26T17:55:56Z

Tapani: ratings/rating

2009-03-18T06:28:29Z

ratings/rating

Tapani: formatted, added intro paragraph, added links, moved email link to Jim's contact page

2009-03-18T01:30:36Z

formatted, added intro paragraph, added links, moved email link to Jim's contact page

← Older revision		Revision as of 16:20, 2 August 2021
Line 38:		Line 38:
	[[Jim Hughes]]		[[Jim Hughes]]

−	Chair, [[Ratings and Recognition Committee]]	+	Chair, [[Ratings and Recognition Committee]], 2009-2011

@@ Line 18: / Line 18: @@
 How exactly are Expected Wins calculated?
 They are calculated fractionally for each opponent, then added up.
-If the between your rating and your opponent&rsquo;s rating is ''d'',
+If the difference between your rating and your opponent&rsquo;s rating is ''d'',
 you are expected to win 1&divide;(1+''e''<sup>0.0031879&middot;''d''</sup>) games against them.
 </div>

← Older revision		Revision as of 17:32, 24 April 2018
Line 14:		Line 14:

	3. Your win-loss record (ties count as a half a win.)		3. Your win-loss record (ties count as a half a win.)
		+
		+	<div style="float:right; width:20em; border: 1px dotted black; padding: 0.25em; margin:0.25em;font-size:80%">
		+	How exactly are Expected Wins calculated?
		+	They are calculated fractionally for each opponent, then added up.
		+	If the between your rating and your opponent’s rating is ''d'',
		+	you are expected to win 1÷(1+''e''<sup>0.0031879·''d''</sup>) games against them.
		+	</div>

	The rating program first calculates a number to estimate how many games you will probably win. This is known as your “Expected Wins.” The rating program uses your intial rating and the ratings of all your opponents to perform this calculation. It then subtracts your Expected Wins from your actual number of wins to get the difference. It then multiplies the difference by your K value (see below) to calculate your rating change. If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points. If you won more games than expected, then you will gain rating points.		The rating program first calculates a number to estimate how many games you will probably win. This is known as your “Expected Wins.” The rating program uses your intial rating and the ratings of all your opponents to perform this calculation. It then subtracts your Expected Wins from your actual number of wins to get the difference. It then multiplies the difference by your K value (see below) to calculate your rating change. If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points. If you won more games than expected, then you will gain rating points.

← Older revision		Revision as of 15:26, 23 March 2010
Line 31:		Line 31:
	[[Jim Hughes]]		[[Jim Hughes]]

−	~~Managing Director~~, [[Ratings and Recognition Committee]]	+	Chair, [[Ratings and Recognition Committee]]

@@ Line 9: / Line 9: @@
 You have just completed a tournament so we know several things:
-. Your rating going into the tournament (determining your initial rating is complex, so I will leave that to a different page),
+. Your rating going into the tournament (determining your initial rating is complex, so I will leave that to a [[initial rating|different page]]),
 . The ratings of your opponents, and

@@ Line 15: / Line 15: @@
 . Your win-loss record (ties count as a half a win.)
-The rating program first figures out how many games you should have won.  (This is just an estimate.) This is known as your &ldquo;Expected Wins.&rdquo;  The rating program uses your intial rating and the ratings of all your opponents to perform this calculation.  It then subtracts your Expected Wins from your actual number of wins to get the difference.  It then multiplies the difference by your K value (see below) to calculate your rating change.  If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points.  If you won more games than expected, then you will gain rating points.
+The rating program first calculates a number to estimate how many games you will probably win.  This is known as your &ldquo;Expected Wins.&rdquo;  The rating program uses your intial rating and the ratings of all your opponents to perform this calculation.  It then subtracts your Expected Wins from your actual number of wins to get the difference.  It then multiplies the difference by your K value (see below) to calculate your rating change.  If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points.  If you won more games than expected, then you will gain rating points.
 The K value, or sometimes called the Multiplier, is usually 20.  However players with less than 50 tournament games will have a higher K value, the idea being this helps accelerate them to their &ldquo;proper&rdquo; rating. Also, once a player's rating goes above 1800 or 2000, their K value drops to 16 or 10, respectively.

@@ Line 25: / Line 25: @@
 In a pure mathematical sense, your rating is essentially your overall winning percentage weighted by your opponents&rsquo; weighted winning percentages. It does not directly measure your word knowledge, board vision, time and rack management skills or other attributes required to be a good Scrabble player.
-On the other hand, the object is to win the game.  The better players will tend to wim more games, and the ratings reflect that.  Remember that Scrabble has a certain amount of inherent randomness, so in any given game, the lower rated player has a chance.  And upsets do happen.
+On the other hand, the object is to win the game.  The better players will tend to win more games, and the ratings reflect that.  Remember that Scrabble has a certain amount of inherent randomness, so in any given game, the lower rated player has a chance.  And upsets do happen.
 I hope this article gave you some insight into how the rating system works.  I plan on publishing additional, more technical articles in the future.  If there is something specific you would like to see documented, or have questions / comments, please feel free to drop me a note.

@@ Line 15: / Line 15: @@
 . Your win-loss record (ties count as a half a win.)
-The ratings program first figures out how many games you should have won.  This is known as your &ldquo;Expected Wins.&rdquo;  The ratings program uses your intial rating and the ratings of all your opponents to perform this calculation.  It then subtracts your Expected Wins from your actual number of wins to get the difference.  It then multiplies the difference by your K value (see below) to calculate your rating change.  If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points.  If you won more games than expected, then you will gain ratings points.
+The rating program first figures out how many games you should have won.  This is known as your &ldquo;Expected Wins.&rdquo;  The rating program uses your intial rating and the ratings of all your opponents to perform this calculation.  It then subtracts your Expected Wins from your actual number of wins to get the difference.  It then multiplies the difference by your K value (see below) to calculate your rating change.  If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points.  If you won more games than expected, then you will gain rating points.
 The K value, or sometimes called the Multiplier, is usually 20.  However players with less than 50 tournament games will have a higher K value, the idea being this helps accelerate them to their &ldquo;proper&rdquo; rating. Also, once a player's rating goes above 1800 or 2000, their K value drops to 16 or 10, respectively.
-The ratings system also implements Acceleration and Feedback points.  If someone does exceedingly well - that is gains a lot of ratings points - they are awarded Acceleration points and their opponents are awarded Feedback points. The underlying assumption in this case is that the player was &ldquo;underrated&rdquo; going into the tournament and they should have been rated higher.  Hence the Acceleration points.  Furthermore, because they were underrated, their opponents probably lost more (or didn't gain as many) points than they would have, hence the Feedback points.
+The rating system also implements Acceleration and Feedback points.  If someone does exceedingly well - that is gains a lot of rating points - they are awarded Acceleration points and their opponents are awarded Feedback points. The underlying assumption in this case is that the player was &ldquo;underrated&rdquo; going into the tournament and they should have been rated higher.  Hence the Acceleration points.  Furthermore, because they were underrated, their opponents probably lost more (or didn't gain as many) points than they would have, hence the Feedback points.
 This leads to the common question &ldquo;Is my rating an indication of how good a Scrabble player I am?&rdquo;
@@ Line 25: / Line 25: @@
 In a pure mathematical sense, your rating is essentially your overall winning percentage weighted by your opponents&rsquo; weighted winning percentages. It does not directly measure your word knowledge, board vision, time and rack management skills or other attributes required to be a good Scrabble player.
-On the other hand, the object is to win the game.  The better players will tend to wim more games, and the ratings reflect that.  remember that Scrabble has a certain amount of inherent randomness, so in any given game, the lower rated player has a chance.  And upsets do happen.
+On the other hand, the object is to win the game.  The better players will tend to wim more games, and the ratings reflect that.  Remember that Scrabble has a certain amount of inherent randomness, so in any given game, the lower rated player has a chance.  And upsets do happen.
-I hope this article gave you some insight into how the ratings system works.  I plan on publishing additional, more technical articles in the future.  If there is something specific you would like to see documented, or have questions / comments, please feel free to drop me a note.
+I hope this article gave you some insight into how the rating system works.  I plan on publishing additional, more technical articles in the future.  If there is something specific you would like to see documented, or have questions / comments, please feel free to drop me a note.
 [[Jim Hughes]]
 Managing Director, [[Ratings and Recognition Committee]]

@@ Line 1: / Line 1: @@
-Each tournament player has a numerical rating.  This rating is most commonly used to assign players to their appropriate divisions in a tournament.  The rating is also used, in part, to determine which players qualify for certain tournaments, for example the World Scrabble Championships.
+This '''[[rating system overview]]''' describes how the [[rating]] system works at a very high (and not too technical) level.
-The obvious question is "How is the rating calculated? (Don't forget, this is supposed to be a non-technical article, so don't throw in any of that fancy math stuff!)"
+Each [[tournament]] player has a numerical rating.  This rating is most commonly used to assign players to their appropriate divisions in a tournament.  The rating is also used, in part, to determine which players qualify for certain tournaments, for example the [[World SCRABBLE Championship]].
 Ok, here goes:
@@ Line 13: / Line 15: @@
 . Your win-loss record (ties count as a half a win.)
-The ratings program first figures out how many games you should have won.  This is known as your "Expected Wins."  The ratings program uses your intial rating and the ratings of all your opponents to perform this calculation.  It then subtracts your Expected Wins from your actual number of wins to get the difference.  It then multiplies the difference by your K value (see below) to calculate your rating change.  If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points.  If you won more games than expected, then you will gain ratings points.
+The ratings program first figures out how many games you should have won.  This is known as your &ldquo;Expected Wins.&rdquo;  The ratings program uses your intial rating and the ratings of all your opponents to perform this calculation.  It then subtracts your Expected Wins from your actual number of wins to get the difference.  It then multiplies the difference by your K value (see below) to calculate your rating change.  If you won fewer games than what was expected, then the difference will be negative meaning you lose rating points.  If you won more games than expected, then you will gain ratings points.
-The K value, or sometimes called the Multiplier, is usually 20.  However players with less than 50 tournament games will have a higher K value, the idea being this helps accelerate them to their "proper" rating. Also, once a player's rating goes above 1800 or 2000, their K value drops to 16 or 10, respectively.
+The K value, or sometimes called the Multiplier, is usually 20.  However players with less than 50 tournament games will have a higher K value, the idea being this helps accelerate them to their &ldquo;proper&rdquo; rating. Also, once a player's rating goes above 1800 or 2000, their K value drops to 16 or 10, respectively.
-The ratings system also implements Acceleration and Feedback points.  If someone does exceedingly well - that is gains a lot of ratings points - they are awarded Acceleration points and their opponents are awarded Feedback points. The underlying assumption in this case is that the player was "underrated" going into the tournament and they should have been rated higher.  Hence the Acceleration points.  Furthermore, because they were underrated, their opponents probably lost more (or didn't gain as many) points than they would have, hence the Feedback points.
+The ratings system also implements Acceleration and Feedback points.  If someone does exceedingly well - that is gains a lot of ratings points - they are awarded Acceleration points and their opponents are awarded Feedback points. The underlying assumption in this case is that the player was &ldquo;underrated&rdquo; going into the tournament and they should have been rated higher.  Hence the Acceleration points.  Furthermore, because they were underrated, their opponents probably lost more (or didn't gain as many) points than they would have, hence the Feedback points.
-This leads to the common question "Is my rating an indication of how good a Scrabble player I am?"
+This leads to the common question &ldquo;Is my rating an indication of how good a Scrabble player I am?&rdquo;
-In a pure mathematical sense, your rating is essentially your overall winning percentage weighted by your opponents' weighted winning percentages. It does not directly measure your word knowledge, board vision, time and rack management skills or other attributes required to be a good Scrabble player.
+In a pure mathematical sense, your rating is essentially your overall winning percentage weighted by your opponents&rsquo; weighted winning percentages. It does not directly measure your word knowledge, board vision, time and rack management skills or other attributes required to be a good Scrabble player.
 On the other hand, the object is to win the game.  The better players will tend to wim more games, and the ratings reflect that.  remember that Scrabble has a certain amount of inherent randomness, so in any given game, the lower rated player has a chance.  And upsets do happen.
@@ Line 27: / Line 29: @@
 I hope this article gave you some insight into how the ratings system works.  I plan on publishing additional, more technical articles in the future.  If there is something specific you would like to see documented, or have questions / comments, please feel free to drop me a note.
-Jim Hughes
+[[Jim Hughes]]
-jamespintx@yahoo.com
+Managing Director, [[Ratings and Recognition Committee]]