Forum Archive : Ratings

Rating versus error rate

From:   Douglas Zare
Address:   Douglas.Zare@gmail.com
Date:   3 July 2006
Subject:   FIBS rating vs. error rate
Forum:   GammOnLine

What error rate corresponds to each rating on FIBS? There are fewer than
100 players with ratings over 1900, and some of those are bots or rating
manipulators. I collected some data, and the results surprised me.

When I started playing on FIBS in late 1999, I remember watching many
matches between players rated over 1800. I aspired to achieve that
rating, and felt that when I first did, it was a fluke of the dice. Only
when I finally started to recognize mistake after mistake between
players rated over 1800 did I feel my 1800+ rating was justified. I
don't think I ever broke 2000, and my rating was somewhere over 1900
when I took a long enough break from FIBS (mainly to play for money
elsewhere) for my account to expire.

For the May NEBC final, I played a 15 point match with Walter Trice on
FIBS. I decided to warm up by playing a few matches on FIBS, and then
decided to keep playing until my rating improved from the initial 1500
to 1900, which took about 800 experience points (220 matches).

Here are the average Snowie-style error rates of my human opponents in
matches of 3 points or more, grouped by rating:

1400-1500: 15.25
1500-1600: 13.86
1600-1700: 11.17
1700-1800: 9.55
1800+: 8.13

I have to say that I'm pretty surprised by those results. An 1850 rating
corresponds to an error rate of 8? That's a lot more errors than I
expected. Each 100 rating points corresponds to an improvement of about
1.5 millipoints per move. Extrapolating, someone with an error rate of
3.5 millipoints per move should have a rating of about 2150.

Has the level of play on FIBS dropped recently, or has it been like this
for years, but I didn't notice? Has anyone else conducted similar
studies recently?

Douglas Zare
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Constructing a ratings system  (Matti Rinta-Nikkola, Dec 1998) 
Converting to points-per-game  (David Montgomery, Aug 1998)  [Recommended reading]
Cube error rates  (Joe Russell+, July 2009)  [Long message]
Different length matches  (Jim Williams+, Oct 1998) 
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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) 
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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)  [GammOnLine forum]
Ratings and rankings  (Chuck Bower, Dec 1997)  [Long message]
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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