Editing Go ranks and ratings (section)

=== Winning probabilities ===
The rating indirectly represents the probability of winning an even game against other rated players. This probability depends only on the difference between the two players' ratings, but its magnitude varies greatly from one implementation to another. The American Go Association adopted a uniform standard deviation of 104,<ref>[https://web.archive.org/web/20190214230651/https://www.usgo.org/files/pdf/AGARatings-Simple.pdf Inside the AGA Ratings System] refers to the standard deviation used to calculate winning expectancies as px_sigma.</ref> i.e. slightly more than one rank, while the European Go Federation ratings have a sliding standard of deviation from 200 for beginners down to 70 for top players.<ref name=GoR/> The IGS has a fixed standard deviation for all levels of play, but a non-standard distribution.<ref>[http://www.pandanet.co.jp/English/commands/term/TOC.html The IGS Rating System] {{Webarchive|url=https://web.archive.org/web/20070825012128/http://www.pandanet.co.jp/English/commands/term/TOC.html |date=2007-08-25 }} implies a distribution function which is not a bell curve, but a "pointy hat".</ref> The following table displays some of the differences:

{|class="wikitable"
! rowspan="2" | Rating<br />organisation
! colspan="4" | Rating
! colspan="3" | Winning % of the stronger player
|-
!2 kyu
!1 kyu
!1 dan
!2 dan
!1k vs. 2k
!1d vs. 2k
!2d vs. 2k
|----
|AGA
| −250
| −150
|150
|250
|83.2%
|97.3%
|99.8%
|----
|EGF
|1900
|2000
|2100
|2200
|71.3%
|86.0%
|93.9%
|----
|IGS
|30
|31
|32
|33
|71.9%
|84.2%
|91.1%
|----
|}