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The Chess Variant Pages



Game Courier Ratings for %

This file reads data on finished games and calculates Game Courier Ratings (GCR's) for each player. These will be most meaningful for single Chess variants, though they may be calculated across variants. This page is presently in development, and the method used is experimental. I may change the method in due time. How the method works is described below.

There may be a delay while it reads the database and calculates results.

Game Filter: Log Filter: Group Filter:
Tournament Filter: Age Filter: Status Filter:
SELECT * FROM FinishedGames WHERE Rated='on'

You are viewing ratings based on a wildcard that includes all Chess variants played on Game Courier. This is not as meaningful as ratings based on a single variant, which you may find in the Related menu for each preset.

Game Courier Ratings for %
Accuracy:69.61%68.88%68.54%
NameUseridGCRPercent wonGCR1GCR2
Hexa Sakkbosa601864136.5/151 = 90.40%18281901
Francis Fahystamandua1845247.0/298 = 82.89%18251865
Play Testerplaytester1845100.5/114 = 88.16%18231867
dax00dax001826161.0/167 = 96.41%18181834
Kevin Paceypanther1783514.0/658 = 78.12%17911776
Carlos Cetinasissa1737639.5/997 = 64.14%17221751
Cameron Milesshatteredglass171415.0/17 = 88.24%17071721
Homo Simiaalienum170227.0/33 = 81.82%17001705
Jochen Muellerleopold_stotch169855.0/92 = 59.78%16881708
H Spetyura168913.0/13 = 100.00%16761701
Gary Giffordpenswift168060.5/85 = 71.18%15841776
Fergus Dunihofergus167263.5/101 = 62.87%16621681
Jose Carrilloj_carrillo_vii166387.5/155 = 56.45%16651662
Tim O'Lenatim_olena164517.5/27 = 64.81%16461643
Vitya Makovmakov3331626375.0/800 = 46.88%15761676
David Paulowichdavid_64162511.0/13 = 84.62%16311619
P. A. Stonemann CSS Dixielandcssdixieland162514.0/18 = 77.78%16271623
Stephen Williamsneph161811.0/12 = 91.67%15751661
shift2shiftshift2shift161811.0/19 = 57.89%16121623
Charles Danielfrozen_methane161235.0/64 = 54.69%15821642
Vitya Makovmakov16127.5/8 = 93.75%16101614
Daniel Zachariasarx1610154.0/256 = 60.16%16101609
Andreas Kaufmannandreas16077.0/7 = 100.00%16091605
Pericles Tesone de Souzaperitezz15888.0/8 = 100.00%15881588
Erik Lerougeerik1580140.5/260 = 54.04%16591502
ctzctz157912.0/17 = 70.59%15541604
kokoszkokosz15767.0/8 = 87.50%15581595
Abdul-Rahman Sibahisibahi157616.0/23 = 69.57%15661585
attack hippoattackhippo15765.5/7 = 78.57%15711580
je jujejujeju157436.5/60 = 60.83%15661583
TH6notath615747.0/12 = 58.33%15721576
Alexander Trotterqilin15714.0/4 = 100.00%15711570
Jenard Cabilaomgawalangmagawa157011.0/23 = 47.83%15841556
Christine Bagley-Joneszcherryz15693.5/5 = 70.00%15671572
Stephen Stockmanstevestockman156910.0/16 = 62.50%15741565
John Gallantbigjohn156316.0/28 = 57.14%15461580
Raymond Dlewel156013.0/22 = 59.09%15771544
Isaac Felpsattacker14415585.0/6 = 83.33%15591557
Thor Slavenskyslavensky15555.0/7 = 71.43%15371574
Nicholas Wolffnwolff15549.0/15 = 60.00%15741534
Nicola Caridiniccar15543.0/3 = 100.00%15571550
Roberto Lavierirlavieri200315503.0/3 = 100.00%15451555
pallab basupallab154731.0/60 = 51.67%15271568
carlos carloscarlos154416.0/27 = 59.26%15221567
Greg Strongmageofmaple1544105.0/218 = 48.17%16001488
S Ssim15436.0/9 = 66.67%15311554
michirmichir15412.0/2 = 100.00%15411541
Nicholas Wolffmaeko154065.5/142 = 46.13%15611519
Sandra#Paul BRANDLYARDsandravers13067515373.0/4 = 75.00%15341539
Tom e4ktome4k15362.0/2 = 100.00%15351536
Neil Spargospargo15353.0/4 = 75.00%15281542
Eric Greenwoodcavalier15344.0/6 = 66.67%15441524
Todd Witterstoddw15342.0/2 = 100.00%15321535
Plamen Draganovdraganov15342.0/2 = 100.00%15331534
Julien Coll Moratfacteurix15312.0/3 = 66.67%15291534
Jake Palladinocerebralassassin15312.0/2 = 100.00%15271535
Matthew Montchalinmatthew_montchal15313.0/4 = 75.00%15291533
Chuck Leegyw6t153017.5/39 = 44.87%15171544
Fred Koktangram15282.0/3 = 66.67%15291527
joe rosenbloombootzilla15282.0/3 = 66.67%15271529
Uwe Kreuzercaissus15272.0/2 = 100.00%15241530
Joseph DiMurotrojh15261.0/1 = 100.00%15331519
Yeinzon Rodríguez Garcíayeinzon15241.0/1 = 100.00%15281520
Adrian Alvarez de la Campaadrian15243.5/6 = 58.33%15241523
Tom Westtwrecks15211.0/1 = 100.00%15231519
von raidervonraider15201.0/1 = 100.00%15191520
dicepawndicepawn15201.0/1 = 100.00%15221518
Larry Wheelerbrainburner15201.0/1 = 100.00%15211518
Natalia Dolindowhitetiger15191.0/1 = 100.00%15201519
Dougbughouse15191.0/1 = 100.00%15201518
Richard Titlertitle15181.0/1 = 100.00%15191518
strings 808017424strings80801742415181.0/1 = 100.00%15181518
Trevor Savagesavage15181.0/1 = 100.00%15181518
yas kumkumagai15181.0/1 = 100.00%15181518
David Levinsmidrael15181.0/1 = 100.00%15181518
whitenerdy53whitenerdy5315181.0/1 = 100.00%15181518
jj15181.0/1 = 100.00%15181518
Antonio Bruzzitotonno_janggi15181.0/1 = 100.00%15181518
eunchong leeeunchong15181.0/1 = 100.00%15181518
Angel47 Usmanangel4715181.0/1 = 100.00%15181518
calebblazecalebblaze15181.0/1 = 100.00%15181518
Garrett Smithgmsmith15171.0/2 = 50.00%15241511
Jan Żmudajanzmuda15171.0/1 = 100.00%15181517
Titus Ledbettertbl215171.0/1 = 100.00%15181517
M Wintherkalroten15171.0/1 = 100.00%15181516
Hesham Husseinegy_sniper15171.0/1 = 100.00%15171517
bosa6bosa615171.0/1 = 100.00%15151519
Aaron Smithzirtoc15162.5/5 = 50.00%15131520
Georges-Clounet Jesuispartoutgeorgesclounet15161.0/1 = 100.00%15131519
Antonio Barratotonno15161.0/1 = 100.00%15141518
pink sockpickett_aaron15152.0/3 = 66.67%15151515
Simon Langley-Evansslangers15151.5/2 = 75.00%15131516
Joe Joycejoejoyce151521.5/62 = 34.68%14711558
Georg Spengleravunjahei15149.0/28 = 32.14%15041525
xxmanxxman15131.0/2 = 50.00%15191508
Max Kovalmaxkoval15121.0/1 = 100.00%15061519
Leon Careyleoncarey15121.0/1 = 100.00%15071518
spiptorben15121.0/2 = 50.00%15121512
pheko Motaungcouriermabovini151235.5/70 = 50.71%15641460
Nathanlokor15101.0/2 = 50.00%15111509
Antoine Fourrièreantoinefourriere15091.5/2 = 75.00%15081511
mystery playercentipede15092.0/5 = 40.00%15131505
Anthony Viensstarkiller15082.0/4 = 50.00%15001515
xeongreyxeongrey15078.0/17 = 47.06%15141501
As Bardhiasbardhi15071.0/2 = 50.00%15131501
Zachary Wadeazost1215063.0/5 = 60.00%15001513
Albert Vámosiblackrider_4815031.0/4 = 25.00%15161490
Gee Beegdimension15031.0/2 = 50.00%15031502
Graeme Neathamgrayhawke15031.0/2 = 50.00%15011504
Colin Adamslionhawk15021.0/2 = 50.00%15051500
Hans Henrikssonhasurami15022.0/4 = 50.00%14921512
Tom Trenchtomdench9515010.5/1 = 50.00%15011502
Colin Weaveruselessgit15001.0/4 = 25.00%14991500
Kent Weschlerperplexedibex15001.0/3 = 33.33%15021498
noy noynoy15003.0/7 = 42.86%14871512
Thom Dimentunwiseowl14992.0/5 = 40.00%15001497
Eni Lienili149911.5/46 = 25.00%15191478
Juan Pablo Schweitzer Kirsingerdefender14971.0/2 = 50.00%14951499
John Smithultimatecoolster14953.0/9 = 33.33%14961495
Max Fengwowimbob111214941.0/3 = 33.33%14971492
DFA Productions70nyd014920.0/1 = 0.00%14961489
don anezdonanez14920.0/1 = 0.00%14961488
Michael Christensenjustsojazz14920.0/1 = 0.00%14961487
hubergerdhubergerd14920.0/1 = 0.00%14961487
vikvik14910.0/1 = 0.00%14961486
kunkunkunkun14910.0/1 = 0.00%14971486
Hugo Mendes-Nuneshugo199514910.0/1 = 0.00%14971485
Fabner Cruz Gracilianofabner14910.0/1 = 0.00%14971484
Bob Brownbobhihih14900.0/1 = 0.00%14971484
Ricardo Florentinoricmf14900.0/1 = 0.00%14931487
ugo judeugojude14900.0/1 = 0.00%14951485
potato imaginatorpotato14900.0/1 = 0.00%14931486
wyatt wyattquimssarcasm14900.0/1 = 0.00%14971483
John Badgerjbadger14900.0/1 = 0.00%14951484
Urvish Desaiurvishdesai14900.0/1 = 0.00%14941486
jesus babyboypokechamp14900.0/1 = 0.00%14971482
Samuel Hoskinscouriergame14890.0/1 = 0.00%14951484
xerisianxxerisianx14890.0/1 = 0.00%14941485
Hsa Saidh14890.0/1 = 0.00%14971481
loveokenloveoken14890.0/1 = 0.00%14941484
Milton Haddockmiltonhaddock14890.0/1 = 0.00%14951483
makomako14890.0/1 = 0.00%14961482
Steve Polleychessfan5914890.0/1 = 0.00%14941484
Esperllynmogik14890.0/1 = 0.00%14951482
Hafsteinn Kjartanssonhnr0114890.0/1 = 0.00%14961481
Máté Csarmaszcsarmi14891.0/4 = 25.00%15011476
Anders Gustafsonancog14890.0/1 = 0.00%14961481
Erlang Shenerlangshen14890.0/1 = 0.00%14961481
Jason Stehlyjasonstehly14890.0/1 = 0.00%14941483
Matias I.tsatziq14880.0/1 = 0.00%14961481
Éric Manálangedubble1914880.0/1 = 0.00%14941482
Ben Reinigerbenr14880.0/1 = 0.00%14941481
Ivan Velascoswordandsilver14870.0/1 = 0.00%14911483
Rob Brownsteelhead14870.0/1 = 0.00%14911483
DJ Linickdjlinick14870.0/1 = 0.00%14911482
Dead Accountqqzlbpdilchr14860.0/1 = 0.00%14911481
Four PlayerChessfourplayerchess14860.0/1 = 0.00%14901481
Bradlee Kingstonbrad1914860.0/1 = 0.00%14891482
Mike Smolowitzmjs170114850.0/1 = 0.00%14891481
Brock Sampsonthe_iron_kenyan14850.0/1 = 0.00%14881483
Andy Thomasandy_thomas14850.0/1 = 0.00%14871483
Todor Tchervenkovtchervenkov14851.0/3 = 33.33%14861484
Luis Menendezpleyades2114850.0/1 = 0.00%14881482
Nasmichael Farrismichaeljay14850.0/1 = 0.00%14881482
Travis Comptonironlance14850.0/1 = 0.00%14881481
Gus Dunihoduniho14850.0/1 = 0.00%14881481
Alexandr Kremenakremen14850.0/1 = 0.00%14881481
Julianredpanda148417.0/35 = 48.57%14641504
Derek Mooseelevatorfarter14841.0/3 = 33.33%14841484
Siwakorn Songragskyhistory14840.0/1 = 0.00%14851483
James Sprattwhittlin14840.0/1 = 0.00%14871481
Jacob Eugenioe45w14840.0/1 = 0.00%14861482
Doge Masterdogemaster14840.0/1 = 0.00%14861481
higuyzzz91028 Charles Kimdallastexas14840.0/1 = 0.00%14861481
Jeremy Goodyamorezu14840.0/1 = 0.00%14851482
andy lewickiherlocksholmes14840.0/1 = 0.00%14861481
yi fang liuliuyifang14830.0/1 = 0.00%14861481
Ronald Brierleybenwb14830.0/1 = 0.00%14841483
sixtysixty14830.0/3 = 0.00%14871480
Turk Osterburgtalen3141593141514830.0/1 = 0.00%14851481
dghanddghand14830.0/1 = 0.00%14841482
scythian blunderq1234514830.0/2 = 0.00%14871479
anon anonchessvar114830.0/1 = 0.00%14851481
Boyko Ahtarovzdra4148310.0/23 = 43.48%14891477
Solomon Salamasol71014830.0/1 = 0.00%14831483
Paolo Porsiapillau14830.0/1 = 0.00%14851480
Dan Kellydankelly14830.0/1 = 0.00%14841481
Antony Vailevichjabberw0cky114830.0/1 = 0.00%14831482
MichaÅ‚ Jarskihookz14830.0/1 = 0.00%14821483
Jun Ocampojunpogi14830.0/2 = 0.00%14881478
Andreas Bunkahlebunkahle14830.0/1 = 0.00%14831482
Jose Canceljoche14830.0/1 = 0.00%14831482
Tony Quintanillatony_quintanilla14830.0/1 = 0.00%14821483
Hung Daobyteboy14820.0/1 = 0.00%14841481
László Gadosdani198314821.0/4 = 25.00%14791486
Roberto Cassanotamerlano14820.0/1 = 0.00%14841481
btstwbtstw14820.0/1 = 0.00%14841481
cdpowercdpower14820.0/1 = 0.00%14841480
manolo manolomanolo14820.0/1 = 0.00%14841481
wabbawabba14820.0/1 = 0.00%14831481
Uri Bruckbruck14820.0/2 = 0.00%14921473
legendlegend14820.0/2 = 0.00%14901474
Nicholas Archerchess_hunter14820.0/2 = 0.00%14881477
anna colladoapatura_iris14820.0/1 = 0.00%14811482
Minh Dangminhdang14820.0/1 = 0.00%14811482
Joseph Grangercdafan14820.0/1 = 0.00%14811482
luigi mattagigino4214820.0/1 = 0.00%14801483
Thomas Meehanorangeaurochs14820.0/1 = 0.00%14821481
Robin Sneijderrobinwooter214820.0/1 = 0.00%14811482
Виктор Байгужаковbajvik14820.0/1 = 0.00%14821481
Giuseppe Acciarocoopwie14812.0/5 = 40.00%14761486
Wottonwotton14810.0/1 = 0.00%14811481
Harry Gaoharrygao14810.0/1 = 0.00%14811481
y kumyasuhiro14810.0/1 = 0.00%14811481
Ryan Schwartzshunoshi14810.0/1 = 0.00%14811481
ben chewben558214810.0/1 = 0.00%14811481
14810.0/1 = 0.00%14811481
Babo Jeffbabojeff14810.0/1 = 0.00%14811481
wonsang leewonsang14810.0/1 = 0.00%14811481
Vitali Maslanskivitali_1014810.0/1 = 0.00%14811481
paulblazepaulblaze14810.0/1 = 0.00%14811481
Abe Anonapostateabe14810.0/1 = 0.00%14801482
blundermanblunderman14810.0/1 = 0.00%14811481
Mark Thompsonmarkthompson14810.0/2 = 0.00%14931469
arcasorarcasor14800.0/1 = 0.00%14791481
rederikrederik14800.0/1 = 0.00%14781481
Diego M.diego14800.0/3 = 0.00%14841475
championchampion14800.0/2 = 0.00%14841475
Bn Emnelk11414790.0/2 = 0.00%14841474
voicantvoicant14790.0/1 = 0.00%14761481
N Wolffpoint01iv14781.0/3 = 33.33%14731483
Francesco Casalinofrancesco14780.0/2 = 0.00%14841472
Ivan Kosintsevbombino14780.0/1 = 0.00%14751481
trtztrtz gfghtrtztrtz14780.0/2 = 0.00%14831473
ologyology14780.0/1 = 0.00%14741481
Aurelian Floreacatugo1478251.5/723 = 34.79%15551400
qidb602qidb60214770.0/2 = 0.00%14841470
andres fuentesxabyer14770.0/2 = 0.00%14801474
Frank Istvánistvan6014760.0/2 = 0.00%14851467
Ivan Ivankillbill22514760.0/1 = 0.00%14711481
Alexander Krutikovlonewolf14761.0/4 = 25.00%14721479
wdtrwdtr14760.0/3 = 0.00%14801471
Francisco Magalhãeslowcarbknight14750.0/1 = 0.00%14701481
tedy efwttei27fmrw7de14750.0/1 = 0.00%14691481
Nathan Holdenlinsolv14750.0/1 = 0.00%14681482
John Twycrossjt14740.0/2 = 0.00%14751474
Szling Ozecszling_ozec14740.0/3 = 0.00%14771471
Charles Gilmancharles_gilman14740.0/2 = 0.00%14731474
Lennon Figueiredogiwseppe14731.0/4 = 25.00%14711476
Pablo Denegrideep_thinker14730.0/2 = 0.00%14761471
Armin Liebhartlunaris147120.0/51 = 39.22%14581485
cherokee malansailorhertzog14710.0/2 = 0.00%14791464
Sergey Biryukovsbiryukov14710.0/4 = 0.00%14701472
Steve Hsteve_201014710.0/2 = 0.00%14681473
Travis Comptonblackrood14710.0/2 = 0.00%14701471
Kacper Rutkowskikacperrutkowski14700.0/2 = 0.00%14731467
Pat Quexionezsuperpatzermaste14700.0/4 = 0.00%14711469
danielmacduffdanielmacduff14700.0/3 = 0.00%14681472
Zoli M Zoltánbaltazarprof14700.0/5 = 0.00%14831457
dfe6631dfe663114700.0/2 = 0.00%14651474
andrewthepawnandrewthepawn14690.0/2 = 0.00%14671472
Jean-Louis Cazauxtimurthelenk14691.0/5 = 20.00%14671470
iuchi45iuchi4514680.0/2 = 0.00%14681468
Adam DeWittchessshogi14680.0/3 = 0.00%14751462
A tomiatomi14684.5/16 = 28.12%14611476
jeremy diniericharles_bukowski14680.0/2 = 0.00%14661469
Memedes Lulagiwseppe314670.0/2 = 0.00%14691466
Zac Sparxkrinid14660.0/2 = 0.00%14681465
Donut Donutdonutdonut14650.0/2 = 0.00%14661465
Scott Crawfordmathemagician14650.0/7 = 0.00%14741455
playshogiplayshogi14650.0/2 = 0.00%14661463
michael collinsverderben14641.0/5 = 20.00%14701457
Michael Nelsonmikenels14630.0/2 = 0.00%14611466
Namik Zadenamik14630.0/2 = 0.00%14611465
andy lewickietaoni14630.0/2 = 0.00%14611464
Dmitry Strelyabba8314590.0/4 = 0.00%14751443
Michael Huntkronsteen3314580.0/3 = 0.00%14491467
Nick Wolffwolff145626.0/72 = 36.11%14231490
louisvlouisv14550.0/3 = 0.00%14581453
Graemegraemecn14550.0/3 = 0.00%14541457
Andy Lewickiondraszek14550.0/3 = 0.00%14491461
Николай Сокольскийalexich14540.0/4 = 0.00%14611448
John Langleyjonners14520.5/4 = 12.50%14521451
Dayrom Gilallahukbar14510.0/3 = 0.00%14511452
Michael Schmahlmschmahl14505.0/15 = 33.33%14581442
Linn Russellfreakat14490.0/3 = 0.00%14491449
Scott McGrealagentofchaos14487.0/19 = 36.84%14541443
Joshua Tsamraku14485.0/12 = 41.67%14251471
Aaron Maynardvopi14481.0/6 = 16.67%14441452
Adalbertus Kchewoj14481.0/5 = 20.00%14411454
vitaliy ravitztalsterch14462.0/15 = 13.33%14321460
heche60heche6014432.0/12 = 16.67%14451442
dmitarzvonimirdmitarzvonimir14420.0/5 = 0.00%14391444
Sagi Gabaysagig7214410.5/16 = 3.12%14251458
Jeremy Goodjudgmentality143943.5/127 = 34.25%14301448
Paul Rapoportnumerist14360.0/5 = 0.00%14351437
Evan Jorgensonsabataegalo14360.0/7 = 0.00%14221449
Evert Jan Karmanevertvb14352.5/11 = 22.73%14191451
Phoenix TKartkr10101014332.0/9 = 22.22%14371430
juan rodriguezrodriguez143011.5/38 = 30.26%14431417
Jon Dannjon_dann14300.0/4 = 0.00%14261433
Matthew La Valleesherman10114276.0/23 = 26.09%14111444
Alan Galetornadic14233.0/20 = 15.00%14211424
boukineboukine14214.0/13 = 30.77%13901453
Daniil Frolovflowermann14213.0/16 = 18.75%14061436
Jack Zavierubersketch14210.0/6 = 0.00%14171425
Вадря Покштяpokshtya14175.0/19 = 26.32%14041429
Jeremy Hook10011014162.0/30 = 6.67%14121420
Arthur Yvrardtorendil14160.0/7 = 0.00%14111421
John Davischappy14133.0/17 = 17.65%14001425
yellowturtleyellowturtle14110.0/10 = 0.00%14141408
Samuel de Souzasamsou14110.0/8 = 0.00%14111411
Evan Jorgensonejorgens14100.0/7 = 0.00%14011418
George Dukegwduke140542.5/117 = 36.32%13531457
Митя Стрелецкийsocrat8314020.0/10 = 0.00%13911413
mrxx2016mrxx201613940.0/12 = 0.00%13911396
darren paullramalam139313.5/100 = 13.50%13681419
Bogot Bogotolbog138812.0/44 = 27.27%13761401
Jarid Carlsonsacredchao137413.0/68 = 19.12%13411407
Nakanaka13550.0/11 = 0.00%13261384
Сергей Маэстроfantomas13541.0/31 = 3.23%13521356
Diogen Abramelindanko13310.0/35 = 0.00%13171344
Oisín D.sxg131242.0/189 = 22.22%12901335
Сергей Бугаевскийbugaevsky12963.0/56 = 5.36%12911301
wdtr2wdtr2129121.5/149 = 14.43%12691313
per hommerbergper3112832.0/58 = 3.45%12491316
Alisher Bolsaniraja8512760.0/46 = 0.00%12571296
Richard milnersesquipedalian12657.0/120 = 5.83%12881243

Meaning

The ratings are estimates of relative playing strength. Given the ratings of two players, the difference between their ratings is used to estimate the percentage of games each may win against the other. A difference of zero estimates that each player should win half the games. A difference of 400 or more estimates that the higher rated player should win every game. Between these, the higher rated player is expected to win a percentage of games calculated by the formula (difference/8)+50. A rating means nothing on its own. It is meaningful only in comparison to another player whose rating is derived from the same set of data through the same set of calculations. So your rating here cannot be compared to someone's Elo rating.

Accuracy

Ratings are calculated through a self-correcting trial-and-error process that compares actual outcomes with expected outcomes, gradually changing the ratings to better reflect actual outcomes. With enough data, this process can approach accuracy to a high degree, but error remains an essential element of any trial-and-error process, and without enough data, its results will remain error-ridden. Unfortunately, Chess variants are not played enough to give it a large data set to work with. The data sets here are usually small, and that means the ratings will not be fully accurate.

One measure taken to eke out the most data from the small data sets that are available is to calculate ratings in a holistic manner that incorporates all results into the evaluation of each result. The first step of this is to go through pairs of players in a manner that doesn't concentrate all the games of one player in one stage of the process. This involves ordering the players in a zig-zagging manner that evenly distributes each player throughout the process of evaluating ratings. The second step is to reverse the order that pairs of players are evaluated in, recalculate all the ratings, and average the two sets of ratings. This allows the outcome of every game to affect the rating calculations for every pair of players. One consequence of this is that your rating is not a static figure. Games played by other people may influence your rating even if you have stopped playing. The upside to this is that ratings of inactive players should get more accurate as more games are played by other people.

Fairness

High ratings have to be earned by playing many games. They are not available through shortcuts. In a previous version of the rating system, I focused on accuracy more than fairness, which resulted in some players getting high ratings after playing only a few games. This new rating system curbs rating growth more, so that you have to win many games to get a high rating. One way it curbs rating growth is to base the amount it changes a rating on the number of games played between two players. The more games they play together, the more it approaches the maximum amount a rating may be changed after comparing two players. This maximum amount is equal to the percentage of difference between expectations and actual results times 400. So the amount ratings may change in one go is limited to a range of 0 to 400. The amount of change is further limited by the number of games each player has already played. The more past games a player has played, the more his rating is considered stable, making it less subject to change.

Algorithm

  1. Each finished public game matching the wildcard or list of games is read, with wins and draws being recorded into a table of pairwise wins. A win counts as 1 for the winner, and a draw counts as .5 for each player.
  2. All players get an initial rating of 1500.
  3. All players are sorted in order of decreasing number of games. Ties are broken first by number of games won, then by number of opponents. This determines the order in which pairs of players will have their ratings recalculated.
  4. Initialize the count of all player's past games to zero.
  5. Based on the ordering of players, go through all pairs of players in a zig-zagging order that spreads out the pairing of each player with each of his opponents. For each pair that have played games together, recalculate their ratings as described below:
    1. Add up the number of games played. If none, skip to the next pair of players.
    2. Identify the players as p1 and p2, and subtract p2's rating from p1's.
    3. Based on this score, calculate the percent of games p1 is expected to win.
    4. Subtract this percentage from the percentage of games p1 actually won. // This is the difference between actual outcome and predicted outcome. It may range from -100 to +100.
    5. Multiply this difference by 400 to get the maximum amount of change allowed.
    6. Where n is the number of games played together, multiply the maximum amount of change by (n)/(n+10).
    7. For each player, where p is the number of his past games, multiply this product by (1-(p/(p+800))).
    8. Add this amount to the rating for p1, and subtract it from the rating for p2. // If it is negative, p1 will lose points, and p2 will gain points.
    9. Update the count of each player's past games by adding the games they played together.
  6. Reinitialize all player's past games to zero.
  7. Repeat the same procedure in the reverse zig-zagging order, creating a new set of ratings.
  8. Average both sets of ratings into one set.


Written by Fergus Duniho
WWW Page Created: 6 January 2006