Talk:Elo rating system

Elo in Snooker??
In the introduction it is claimed that the elo rating system is used as a rating system in snooker (amongst others). I have removed that until someone can provide a source for that. For me it's just plain wrong. The Snooker World Rankings are based on the prize money won within the last 2 years, i.e. where your rating is based on how far you've come in tournaments, and not on the outcome of individual games and the rating of the opponent.

Roger Cook
No mention of Roger Cook? Eroica (talk) 16:14, 30 May 2022 (UTC)
 * Here is something I found that explains his significance. It would be better to cite something that looks more like a reliable source.  Since this quotes the introduction to Elo's report to FIDE, it would be preferable to cite that report, if one can dig it up; or do you have another source in mind?  Bruce leverett (talk) 20:57, 30 May 2022 (UTC)
 * The obvious place to look is in The Rating of Chess Players Past & Present (Elo 1978). I didn't remember it, but checking the index I see the book does mention Roger Cook on page 14.
 * "It was with this thought in mind that the writer in 1959 undertook to examine the logic and rationale of the rating systems then in use and to develop a system based on statistical and probability theory. Quite independently and almost at the same time, György Karoly and Roger Cook developed a system based on the same principles for the New South Wales Chess Association (Cook and Hooper 1969)."
 * This doesn't agree precisely with chess-poster, although they don't necessarily conflict directly. The Elo bibliography indicates that Cook and Hooper 1969 is Cook, R. and Hooper, F., N.S.W.C.A. Grading System, privately printed pamphlet, 1969.  I didn't have any luck finding any mention of it online, but this isn't surprising.  Also there is this: https://www.reddit.com/r/chess/comments/v1dn9k/roger_cook_passed_away_actual_inventor_of_the_elo/.  Quale (talk) 04:29, 1 June 2022 (UTC)
 * Thanks for fixing this. There was a problem with the reference name "AEE1986" appearing twice with different contents, so I removed the name from the new citation.


 * I notice that all the other citations of Elo in this article specify the 1986 edition. I have found a .pdf of that online at .  I see that the credit to Karolyi and Cook is now on page 4.  I think I will convert the citation to use 1986 instead of 1978, and 4 instead of 16, if you don't mind.  Bruce leverett (talk) 05:26, 1 June 2022 (UTC)
 * At first I was going to suggest that I could change the citations to the original 1978 edition, but looking at Elo's preface to the second edition I think your idea is better. Thanks.  Quale (talk) 05:52, 1 June 2022 (UTC)

Who invented the K-factor?
The development of the Elo system can be followed here: Digitaal archief Chess Life.

Chess Life, March 5 & April 5, 1960 Chess Life, June 1961. pp. 160-1 A. E. Elo; Analytical Reports, 1961, 1963 & 1965, (Privately Printed) A. E. Elo; Historical Rating List, Chess Life April 1964 Chess Life, July & August 1967

It would be interesting to uncover the reports from 1961, 1963 and 1965. KP (talk) 12:51, 26 July 2022 (UTC)

Figure 2
shouldn't the solid and the dotted black lines be the other way around in figure 2? CwelTHC (talk) 17:11, 1 May 2023 (UTC)


 * or rather the rating change values be flipped around to account for greater changes in unexpected outcomes CwelTHC (talk) 17:14, 1 May 2023 (UTC)
 * by "figure 2" i guess you mean the one with caption beginning "Graphs of probabilities and Elo rating changes…"? —Tamfang (talk) 20:58, 21 May 2023 (UTC)

The development of the Percentage Expectancy Table
D       P    |    D       P    |    D        P Rtg.Dif   H   L  | Rtg Dif  H   L  | Rtg Dif   H   L     0-3    .50 .50 | 122-129 .67 .33 | 279-290  .84 .16 4-10  .51 .49 | 130-137 .68 .32 | 291-302  .85 .15   11-17   .52 .48 | 138-145 .69 .31 | 303-315  .86 .14   18-25   .53 .47 | 146-153 .70 .30 | 316-328  .87 .13   26-32   .54 .46 | 154-162 .71 .29 | 329-344  .88 .12     33-39   .55 .45 | 163-170 .72 .28 | 345-357  .89 .11    40-46   .56 .44 | 171-179 .73 .27 | 358-374  .90 .10    47-53   .57 .43 | 180-188 .74 .26 | 375-391  .91 .09 54-61   .58 .42 | 189-197 .75 .25 | 392-411  .92 .08    62-68   .59 .41 | 198-206 .76 .24 | 412-432  .93 .07     69-76   .60 .40 | 207-215 .77 .23 | 433-456  .94 .06     77-83   .61 .39 | 216-225 .78 .22 | 457-484  .95 .05  84-91   .62 .38 | 226-235 .79 .21 | 485-517  .96 .04     92-98   .63 .37 | 236-245 .80 .20 | 518-559  .97 .03  99-106  .64 .36 | 246-256 .81 .19 | 560-619  .98 .02 107-113 .65 .35 | 257-267 .82 .18 | 620-735  .99 .01 114-121 .66 .34 | 268-278 .83 .17 | over735 1.00 .00

It is easy to verify the table is actually built with standard deviation 2000/7 as an approximation for 200√2.

A citation to a detailed description of the construction of the table by Elo is desirable.

The construction by pencil and paper is not trivial and prone to errors.

Since the normal curve flattens, one would expect that the number of rating differences within one percentage row does not decrease. However, there is a discontinuity at D = 345-357, P = 89%. This suggests that the table may contain irregularities Rtg Dif Range 279 290 11 291 302 11 303 315 12 316 328 12 329 344 15 345 357 12 <--- 358 374 16 375 391 16  392 411 19

KP (talk) 08:11, 4 August 2023 (UTC)

Use Outside of Chess - Other board and card games - Elo in Poker
While not a universal metric for poker, GGPoker has incorporated an Elo rating system into one of its Sit & Go online poker formats, ‘Spin & Gold ELO’,  where player ratings are determined by win rate. Players are then awarded a letter score based on that rating, with E at the low end of 1200, A at 4000+, Master at 5000+ and Grand Master if they rank within the top 100 players. While the Elo ratings of each player affect how many points are gained or lost, they do not affect match-making.

https://www.pokerlistings.com/rise-up-the-spin-gold-elo-ranking-system-at-ggpoker

https://donkhunter.com/en/news/ggpoker-introduces-spin-gold-elo-ranking-syste,1033.html

https://www.ggpoker.com/poker-games/spin-gold-elo/ Chris H (GGPoker) (talk) 06:08, 12 October 2023 (UTC)