Forum Archive : Ratings

Table of ratings changes From:   Patti Beadles Address:   pattib@netcom.com Date:   22 August 1994 Subject:   Re: FIBS ratings formula Forum:   rec.games.backgammon Google:   pattibCuwttn.F8v@netcom.com Ratings changes are based on several things-- the length of the match, the experience level of each player, the current rating of both players, and whether the higher-rated or lower-rated player wins. Experience figures into this in an interesting way. For players with 400 or more experience points, there's no influence. For players with less than 400, the experience turns into a simple multiplier. Your experience affects your rating change only, not that of your opponent. Here are a couple of tables showing the ratings change for various match lengths and ratings differences. Note that you need to use a different table depending upon whether the higher-rated or lower-rated player wins. Ratings change when higher-rated player wins, assuming 400+ experience.* diff 1 3 5 7 9 11 ---- -------- -------- -------- -------- -------- -------- 100 1.884998 3.119854 3.899648 4.491772 4.974016 5.381994 200 1.770753 2.782339 3.345620 3.727760 4.006327 4.216725 300 1.658005 2.457773 2.826207 3.029076 3.142692 3.201313 400 1.547453 2.151421 2.353534 2.415209 2.409120 2.366478 Ratings change when lower-rated player wins, assuming 400+ experience.* diff 1 3 5 7 9 11 ---- -------- -------- -------- -------- -------- -------- 100 2.115002 3.808349 5.044624 6.091233 7.025984 7.884505 200 2.229247 4.145864 5.598652 6.855246 7.993673 9.049774 300 2.341995 4.470430 6.118065 7.553929 8.857308 10.065186 400 2.452547 4.776783 6.590738 8.167797 9.590880 10.900022 * For a player with lesser experience, multiply the number in the table by -experience/100+5, e.g. for 200 experience, 3. So if a 1500 player beats a 1700 player in a 3-point match, I would look in the table and find that for a 3-point match, lower player wins, 200 difference, the change is 4.15 (rounded.) If the 1700 player won, the change for both players is 2.78. -Patti   Did you find the information in this article useful?           Do you have any comments you'd like to add?

 

Ratings

Constructing a ratings system  (Matti Rinta-Nikkola, Dec 1998) 

Converting to points-per-game  (David Montgomery, Aug 1998) 

Cube error rates  (Joe Russell+, July 2009) 

Different length matches  (Jim Williams+, Oct 1998) 

Different length matches  (Tom Keith, May 1998) 

ELO system  (seeker, Nov 1995) 

Effect of droppers on ratings  (Gary Wong+, Feb 1998) 

Emperical analysis  (Gary Wong, Oct 1998) 

Error rates  (David Levy, July 2009) 

Experience required for accurate rating  (Jon Brown+, Nov 2002) 

FIBS rating distribution  (Gary Wong, Nov 2000) 

FIBS rating formula  (Patti Beadles, Dec 2003) 

FIBS vs. GamesGrid ratings  (Raccoon+, Mar 2006) 

Fastest way to improve your rating  (Backgammon Man+, May 2004) 

Field size and ratings spread  (Daniel Murphy+, June 2000) 

Improving the rating system  (Matti Rinta-Nikkola, Nov 2000) 

KG rating list  (Daniel Murphy, Feb 2006) 

KG rating list  (Tapio Palmroth, Oct 2002) 

MSN Zone ratings flaw  (Hank Youngerman, May 2004) 

No limit to ratings  (David desJardins+, Dec 1998) 

On different sites  (Bob Newell+, Apr 2004) 

Opponent's strength  (William Hill+, Apr 1998) 

Possible adjustments  (Christopher Yep+, Oct 1998) 

Rating versus error rate  (Douglas Zare, July 2006) 

Ratings and rankings  (Chuck Bower, Dec 1997) 

Ratings and rankings  (Jim Wallace, Nov 1997) 

Ratings on Gamesgrid  (Gregg Cattanach, Dec 2001) 

Ratings variation  (Kevin Bastian+, Feb 1999) 

Ratings variation  (FLMaster39+, Aug 1997) 

Ratings variation  (Ed Rybak+, Sept 1994) 

Strange behavior with large rating difference  (Ron Karr, May 1996) 

Table of ratings changes  (Patti Beadles, Aug 1994) 

Table of win rates  (William C. Bitting, Aug 1995) 

Unbounded rating theorem  (David desJardins+, Dec 1998) 

What are rating points?  (Lou Poppler, Apr 1995) 

Why high ratings for one-point matches?  (David Montgomery, Sept 1995) 

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