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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:69.95%69.42%69.12%
NameUseridGCRPercent wonGCR1GCR2
Hexa Sakkbosa601855136.5/151 = 90.40%18281883
Francis Fahystamandua1850247.0/298 = 82.89%18251874
Play Testerplaytester1835119.5/138 = 86.59%17811889
dax00dax001822161.0/167 = 96.41%18221821
Kevin Paceypanther1775520.0/691 = 75.25%17771773
Carlos Cetinasissa1742652.5/1012 = 64.48%17211762
Homo Simiaalienum173133.0/40 = 82.50%17331729
Cameron Milesshatteredglass171515.0/17 = 88.24%17081722
Jochen Muellerleopold_stotch169755.0/92 = 59.78%16851709
H Spetyura169013.0/13 = 100.00%16771704
Gary Giffordpenswift167960.5/85 = 71.18%15821776
Fergus Dunihofergus167063.5/101 = 62.87%16651675
Jose Carrilloj_carrillo_vii166287.5/155 = 56.45%16641659
Tim O'Lenatim_olena164117.5/27 = 64.81%16421641
Vitya Makovmakov3331636385.0/814 = 47.30%15911681
David Paulowichdavid_64162611.0/13 = 84.62%16311622
Stephen Williamsneph161811.0/12 = 91.67%15751660
shift2shiftshift2shift161711.0/19 = 57.89%16101624
P. A. Stonemann CSS Dixielandcssdixieland161316.0/23 = 69.57%15991627
Daniel Zachariasarx1613162.0/270 = 60.00%16111614
Vitya Makovmakov16127.5/8 = 93.75%16101614
Charles Danielfrozen_methane161035.0/64 = 54.69%15801640
Andreas Kaufmannandreas16077.0/7 = 100.00%16101605
Pericles Tesone de Souzaperitezz15888.0/8 = 100.00%15881588
Erik Lerougeerik1582140.5/260 = 54.04%16581507
ctzctz157912.0/17 = 70.59%15531604
kokoszkokosz15767.0/8 = 87.50%15571595
attack hippoattackhippo15765.5/7 = 78.57%15721580
Abdul-Rahman Sibahisibahi157516.0/23 = 69.57%15671582
Plamen Draganovdraganov15724.0/4 = 100.00%15721573
TH6notath615727.0/12 = 58.33%15711573
Alexander Trotterqilin15714.0/4 = 100.00%15721570
Jenard Cabilaomgawalangmagawa157011.0/23 = 47.83%15841556
Stephen Stockmanstevestockman156910.0/16 = 62.50%15741565
Christine Bagley-Joneszcherryz15683.5/5 = 70.00%15671569
je jujejujeju156536.5/61 = 59.84%15491582
John Gallantbigjohn156116.0/28 = 57.14%15481574
Raymond Dlewel156013.0/22 = 59.09%15771544
Isaac Felpsattacker14415585.0/6 = 83.33%15591557
Thor Slavenskyslavensky15545.0/7 = 71.43%15361573
Nicola Caridiniccar15543.0/3 = 100.00%15571550
Nicholas Wolffnwolff15539.0/15 = 60.00%15751532
Roberto Lavierirlavieri200315503.0/3 = 100.00%15451555
pallab basupallab154731.0/60 = 51.67%15271566
Greg Strongmageofmaple1544106.0/219 = 48.40%15951494
S Ssim15436.0/9 = 66.67%15311554
michirmichir15412.0/2 = 100.00%15411541
carlos carloscarlos154116.0/27 = 59.26%15201562
Sandra#Paul BRANDLYARDsandravers13067515373.0/4 = 75.00%15351538
Neil Spargospargo15363.0/4 = 75.00%15291542
Tom e4ktome4k15362.0/2 = 100.00%15351536
Nicholas Wolffmaeko153465.5/142 = 46.13%15601508
Todd Witterstoddw15342.0/2 = 100.00%15331535
Eric Greenwoodcavalier15344.0/6 = 66.67%15441524
Julien Coll Moratfacteurix15322.0/3 = 66.67%15301534
Máté Csarmaszcsarmi15313.0/6 = 50.00%15501513
Jake Palladinocerebralassassin15312.0/2 = 100.00%15271535
Matthew Montchalinmatthew_montchal15313.0/4 = 75.00%15291533
Fred Koktangram15282.0/3 = 66.67%15291527
joe rosenbloombootzilla15282.0/3 = 66.67%15271529
Uwe Kreuzercaissus15272.0/2 = 100.00%15241530
Chuck Leegyw6t152717.5/39 = 44.87%15141539
Joseph DiMurotrojh15261.0/1 = 100.00%15331519
Yeinzon Rodríguez Garcíayeinzon15241.0/1 = 100.00%15281520
Adrian Alvarez de la Campaadrian15243.5/6 = 58.33%15241524
Tom Westtwrecks15211.0/1 = 100.00%15231519
dicepawndicepawn15201.0/1 = 100.00%15221518
von raidervonraider15201.0/1 = 100.00%15191520
Larry Wheelerbrainburner15191.0/1 = 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
Samuel Hoskinscouriergame15161.0/2 = 50.00%15251507
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
Georg Spengleravunjahei15149.0/28 = 32.14%15031525
xxmanxxman15131.0/2 = 50.00%15191508
Joe Joycejoejoyce151321.5/62 = 34.68%14711554
Max Kovalmaxkoval15131.0/1 = 100.00%15071519
Leon Careyleoncarey15121.0/1 = 100.00%15071518
spiptorben15121.0/2 = 50.00%15121513
pheko Motaungcouriermabovini151235.5/70 = 50.71%15631461
Nathanlokor15111.0/2 = 50.00%15121510
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%15151500
As Bardhiasbardhi15071.0/2 = 50.00%15131501
Zachary Wadeazost1215063.0/5 = 60.00%15001513
Graeme Neathamgrayhawke15031.0/2 = 50.00%15011505
Albert Vámosiblackrider_4815031.0/4 = 25.00%15161490
Colin Adamslionhawk15021.0/2 = 50.00%15051500
Hans Henrikssonhasurami15022.0/4 = 50.00%14911512
Gee Beegdimension15021.0/2 = 50.00%15011502
Tom Trenchtomdench9515010.5/1 = 50.00%15011502
Kent Weschlerperplexedibex15001.0/3 = 33.33%15021498
Colin Weaveruselessgit15001.0/4 = 25.00%14991500
Eni Lienili149911.5/46 = 25.00%15191479
noy noynoy14993.0/7 = 42.86%14871511
Thom Dimentunwiseowl14982.0/5 = 40.00%15001497
Juan Pablo Schweitzer Kirsingerdefender14971.0/2 = 50.00%14951499
John Smithultimatecoolster14953.0/9 = 33.33%14951495
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
wyatt wyattquimssarcasm14900.0/1 = 0.00%14971483
ugo judeugojude14900.0/1 = 0.00%14951484
Ricardo Florentinoricmf14900.0/1 = 0.00%14931487
jesus babyboypokechamp14900.0/1 = 0.00%14971482
John Badgerjbadger14900.0/1 = 0.00%14951484
potato imaginatorpotato14900.0/1 = 0.00%14931486
Urvish Desaiurvishdesai14890.0/1 = 0.00%14931486
Milton Haddockmiltonhaddock14890.0/1 = 0.00%14961483
Hsa Saidh14890.0/1 = 0.00%14971481
makomako14890.0/1 = 0.00%14961482
xerisianxxerisianx14890.0/1 = 0.00%14931485
Esperllynmogik14890.0/1 = 0.00%14961482
loveokenloveoken14890.0/1 = 0.00%14931484
Hafsteinn Kjartanssonhnr0114890.0/1 = 0.00%14961481
Anders Gustafsonancog14890.0/1 = 0.00%14961481
Matias I.tsatziq14890.0/1 = 0.00%14961481
Steve Polleychessfan5914890.0/1 = 0.00%14931484
Jason Stehlyjasonstehly14880.0/1 = 0.00%14931483
Éric Manálangedubble1914880.0/1 = 0.00%14941482
Erlang Shenerlangshen14880.0/1 = 0.00%14941481
Ben Reinigerbenr14880.0/1 = 0.00%14941481
Ivan Velascoswordandsilver14870.0/1 = 0.00%14911483
Rob Brownsteelhead14870.0/1 = 0.00%14911483
Four PlayerChessfourplayerchess14870.0/1 = 0.00%14911482
DJ Linickdjlinick14870.0/1 = 0.00%14911482
Lamai grouplamai14860.0/1 = 0.00%14921481
Dead Accountqqzlbpdilchr14860.0/1 = 0.00%14911481
Bradlee Kingstonbrad1914860.0/1 = 0.00%14891482
Boyko Ahtarovzdra4148510.0/23 = 43.48%14891482
Mike Smolowitzmjs170114850.0/1 = 0.00%14891481
Brock Sampsonthe_iron_kenyan14850.0/1 = 0.00%14871483
Andy Thomasandy_thomas14850.0/1 = 0.00%14871483
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
Julianredpanda148517.0/35 = 48.57%14641506
Alexandr Kremenakremen14850.0/1 = 0.00%14881481
Siwakorn Songragskyhistory14840.0/1 = 0.00%14851483
Derek Mooseelevatorfarter14841.0/3 = 33.33%14841484
James Sprattwhittlin14840.0/1 = 0.00%14871481
Ronald Brierleybenwb14840.0/1 = 0.00%14841484
Jacob Eugenioe45w14840.0/1 = 0.00%14861482
dghanddghand14840.0/1 = 0.00%14851483
Doge Masterdogemaster14840.0/1 = 0.00%14861481
László Gadosdani198314841.0/4 = 25.00%14821485
higuyzzz91028 Charles Kimdallastexas14840.0/1 = 0.00%14861481
Lwebato14840.0/1 = 0.00%14851482
Jeremy Goodyamorezu14840.0/1 = 0.00%14851482
andy lewickiherlocksholmes14840.0/1 = 0.00%14861481
yi fang liuliuyifang14840.0/1 = 0.00%14861481
sixtysixty14830.0/3 = 0.00%14871480
anon anonchessvar114830.0/1 = 0.00%14851481
Turk Osterburgtalen3141593141514830.0/1 = 0.00%14851481
Paolo Porsiapillau14830.0/1 = 0.00%14861480
Solomon Salamasol71014830.0/1 = 0.00%14831483
Dan Kellydankelly14830.0/1 = 0.00%14841481
Antony Vailevichjabberw0cky114830.0/1 = 0.00%14831482
Andreas Bunkahlebunkahle14830.0/1 = 0.00%14831482
MichaÅ‚ Jarskihookz14830.0/1 = 0.00%14821483
Roberto Cassanotamerlano14830.0/1 = 0.00%14841481
Jose Canceljoche14820.0/1 = 0.00%14831482
Tony Quintanillatony_quintanilla14820.0/1 = 0.00%14821483
btstwbtstw14820.0/1 = 0.00%14841481
manolo manolomanolo14820.0/1 = 0.00%14841481
cdpowercdpower14820.0/1 = 0.00%14841480
scythian blunderq1234514820.0/2 = 0.00%14851479
wabbawabba14820.0/1 = 0.00%14831481
Uri Bruckbruck14820.0/2 = 0.00%14921473
Nicholas Archerchess_hunter14820.0/2 = 0.00%14881477
Hung Daobyteboy14820.0/1 = 0.00%14831481
legendlegend14820.0/2 = 0.00%14911473
Giuseppe Acciarocoopwie14822.0/5 = 40.00%14771488
Jun Ocampojunpogi14820.0/2 = 0.00%14861478
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
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
blundermanblunderman14810.0/1 = 0.00%14811481
Abe Anonapostateabe14810.0/1 = 0.00%14801482
Mark Thompsonmarkthompson14810.0/2 = 0.00%14931469
arcasorarcasor14800.0/1 = 0.00%14791481
rederikrederik14800.0/1 = 0.00%14781481
championchampion14800.0/2 = 0.00%14841475
Diego M.diego14790.0/3 = 0.00%14841475
Bn Emnelk11414790.0/2 = 0.00%14831474
voicantvoicant14790.0/1 = 0.00%14761481
trtztrtz gfghtrtztrtz14790.0/2 = 0.00%14831474
N Wolffpoint01iv14781.0/3 = 33.33%14731483
Francesco Casalinofrancesco14780.0/2 = 0.00%14841472
Ivan Kosintsevbombino14780.0/1 = 0.00%14751481
ologyology14780.0/1 = 0.00%14741481
andres fuentesxabyer14780.0/2 = 0.00%14801475
qidb602qidb60214770.0/2 = 0.00%14841470
Frank Istvánistvan6014760.0/2 = 0.00%14851467
Ivan Ivankillbill22514760.0/1 = 0.00%14701481
Alexander Krutikovlonewolf14761.0/4 = 25.00%14721479
Francisco Magalhãeslowcarbknight14760.0/1 = 0.00%14701481
Aurelian Floreacatugo1476251.5/725 = 34.69%15551396
wdtrwdtr14750.0/3 = 0.00%14791471
tedy efwttei27fmrw7de14750.0/1 = 0.00%14691481
Nathan Holdenlinsolv14750.0/1 = 0.00%14681482
John Twycrossjt14750.0/2 = 0.00%14751474
Szling Ozecszling_ozec14740.0/3 = 0.00%14771471
Todor Tchervenkovtchervenkov14741.0/4 = 25.00%14731474
Charles Gilmancharles_gilman14740.0/2 = 0.00%14731474
Lennon Figueiredogiwseppe14731.0/4 = 25.00%14711476
Pablo Denegrideep_thinker14730.0/2 = 0.00%14761471
Armin Liebhartlunaris147320.0/51 = 39.22%14561489
Steve Hsteve_201014720.0/2 = 0.00%14691474
Travis Comptonblackrood14710.0/2 = 0.00%14711471
danielmacduffdanielmacduff14700.0/3 = 0.00%14691472
Kacper Rutkowskikacperrutkowski14700.0/2 = 0.00%14731467
cherokee malansailorhertzog14700.0/2 = 0.00%14771464
Zoli M Zoltánbaltazarprof14700.0/5 = 0.00%14831457
dfe6631dfe663114700.0/2 = 0.00%14651474
andrewthepawnandrewthepawn14690.0/2 = 0.00%14671472
Pat Quexionezsuperpatzermaste14690.0/4 = 0.00%14691469
Sergey Biryukovsbiryukov14690.0/4 = 0.00%14691468
Adam DeWittchessshogi14680.0/3 = 0.00%14751462
iuchi45iuchi4514680.0/2 = 0.00%14681468
jeremy diniericharles_bukowski14680.0/2 = 0.00%14671470
A tomiatomi14684.5/16 = 28.12%14611476
Memedes Lulagiwseppe314670.0/2 = 0.00%14691466
Zac Sparxkrinid14660.0/2 = 0.00%14671465
Donut Donutdonutdonut14650.0/2 = 0.00%14651465
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
Michael Huntkronsteen3314580.0/3 = 0.00%14491467
Nick Wolffwolff145826.0/72 = 36.11%14221493
Andy Lewickiondraszek14560.0/3 = 0.00%14501462
Graemegraemecn14560.0/3 = 0.00%14551457
louisvlouisv14550.0/3 = 0.00%14581453
Николай Сокольскийalexich14540.0/4 = 0.00%14611448
John Langleyjonners14520.5/4 = 12.50%14521451
Dayrom Gilallahukbar14510.0/3 = 0.00%14511452
Michael Schmahlmschmahl14515.0/15 = 33.33%14601441
Scott McGrealagentofchaos14507.0/19 = 36.84%14511448
Linn Russellfreakat14490.0/3 = 0.00%14491449
Joshua Tsamraku14495.0/12 = 41.67%14261472
Aaron Maynardvopi14491.0/6 = 16.67%14451452
Adalbertus Kchewoj14481.0/5 = 20.00%14411454
vitaliy ravitztalsterch14462.0/15 = 13.33%14321459
Dmitry Strelyabba8314450.0/5 = 0.00%14611430
Jeremy Goodjudgmentality144343.5/127 = 34.25%14401446
heche60heche6014432.0/12 = 16.67%14441442
Jean-Louis Cazauxtimurthelenk14421.0/7 = 14.29%14331451
dmitarzvonimirdmitarzvonimir14420.0/5 = 0.00%14391444
Sagi Gabaysagig7214410.5/16 = 3.12%14251458
Paul Rapoportnumerist14360.0/5 = 0.00%14401431
Evan Jorgensonsabataegalo14350.0/7 = 0.00%14221448
Evert Jan Karmanevertvb14342.5/11 = 22.73%14181450
Phoenix TKartkr10101014332.0/9 = 22.22%14361430
Jon Dannjon_dann14300.0/4 = 0.00%14271433
juan rodriguezrodriguez142911.5/38 = 30.26%14471411
Matthew La Valleesherman10114266.0/23 = 26.09%14121441
Alan Galetornadic14233.0/20 = 15.00%14211425
Daniil Frolovflowermann14223.0/16 = 18.75%14071436
Jack Zavierubersketch14210.0/6 = 0.00%14161426
boukineboukine14204.0/13 = 30.77%13891452
Вадря Покштяpokshtya14185.0/19 = 26.32%14041433
Arthur Yvrardtorendil14160.0/7 = 0.00%14111421
Jeremy Hook10011014162.0/30 = 6.67%14121420
John Davischappy14123.0/17 = 17.65%14001424
yellowturtleyellowturtle14110.0/10 = 0.00%14131408
Samuel de Souzasamsou14110.0/8 = 0.00%14111411
Evan Jorgensonejorgens14100.0/7 = 0.00%14011419
George Dukegwduke140942.5/117 = 36.32%13531465
Митя Стрелецкийsocrat8314010.0/10 = 0.00%13911412
darren paullramalam139313.5/100 = 13.50%13651420
mrxx2016mrxx201613920.0/12 = 0.00%14031382
Bogot Bogotolbog138812.0/44 = 27.27%13751401
Jarid Carlsonsacredchao137213.0/68 = 19.12%13411402
Nakanaka13550.0/11 = 0.00%13271383
Сергей Маэстроfantomas13521.0/31 = 3.23%13481356
Diogen Abramelindanko13320.0/35 = 0.00%13141350
Oisín D.sxg131042.0/189 = 22.22%12951325
Сергей Бугаевскийbugaevsky12933.0/56 = 5.36%12871300
wdtr2wdtr2129221.5/151 = 14.24%12751310
per hommerbergper3112792.0/60 = 3.33%12461313
Alisher Bolsaniraja8512730.0/46 = 0.00%12561290
Richard milnersesquipedalian12637.0/129 = 5.43%12871238

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