rank - absolute levels
Absolute rank
No such thing but see Rank - Worldwide Comparison and the European Go Database (statistics section) for two ongoing attempts. The only way to establish such a thing would be to have a massive tournament, with every player in the world playing many games against other players from around the world, with nobody's skill improving. (The tournament idea sounds like fun, but by the time it was over, i would hope to have improved a stone or three!)
There is not a single rank-setting authority. Rather, there are several rank repositories (each national or continental go association is one such, as is each Go server that tracks ranks), and they do not always quite agree. So one person may be regarded as a 1-kyu in Osaka and as a 1-dan in Tokyo, for example.
Within rank repositories, there may be variation such that a person with a weaker rank can easily beat a person with a stronger rank. This is because ranks do not always keep pace with changes in players' abilities. If a small group of players within a repository mostly play amongst themselves, their ranks may seem stagnant even though the group as a whole is getting stronger. When such a player contests someone from outside the group, s/he will be surprisingly strong for her/is declared rank (which the outsider might regard as sandbagging). The larger the repository, the higher is the chance of isolated pockets of players whose rank isn't accurately compared to the general level of strength.
Jasonred Sometimes, I wonder... are go players in general getting stronger, raising the bar, so to speak? So, a 20 kyu now was equivalent to a 17 kyu 80 years ago? (or whenever the system came into existence).
Someone mentioned to me that once, 25 kyu was the rank given to an absolute beginner who understood the basic rules, with no knowledge of techniques. Apparently, nowadays 25 kyu means you have a certain degree of skill as well. And 30 kyu is the lowest possible rank. Weird.
Possibly, once upon a time, a 1 dan really would have had to give a 25 stone handicap to a 25 kyu...
Bill: I have given a 40-stone handicap based upon ratings. To my surprise it was a close game. ;-)
When I learned go, people did not take double digit kyu ranks seriously. After all, such players can have an insight that advances them several ranks at once.
These days, with internet go servers, double digit kyu players have become more visible. I also gather that they tend to play more with other double digit kyus. (Certainly if you were the only one at the local club you could not do that. ;-)) As a result, I think that two things happen. First, they reinforce each other's bad habits. Second, they get stronger as a group without the rating system reflecting that. So 25 kyus of today are probably stronger than 25 kyus of five years ago.
Mef: I think another problem that has arisen from go servers is that having enough players of similar rank means there are far fewer handicap games, since many players prefer to play even if the option is available. The result is that ranks may no longer be a full stone apart, since one really needs alot of 3 and 4 stone handicap games to make sure the spacing is right. In my experience this problem is not as prevalent at the upper ranks since they play more of such handicap games.
exswoo I don't think Go Theory could really progress if such a thing didn't happen...although I'm not sure how much difference this makes (I would venture to say that the differences in skill would be most evident for the top players but barely at all for the amateur levels). Of course, the relative nature of the rankings makes this point moot. ;)
Ideally, as a kyu ranking is defined in handicaps, but dans are not, the natural point for shodan would be the point at which the handicap=rank difference system broke down?
Andrew Grant: This isn't true. Professional dan grades have no relation to the handicap system, but amateur dan grades certainly do. In any case, to say the handicap=rank difference system breaks down at any point is a circular argument, since all grades are man-made. You could invent a ranking system with a discontinuity at any arbitrary skill level; would that make it a "natural" point to call it shodan?
zinger: One of the dan players at my local club says that the original definition of (amateur) shodan was the weakest player who could beat a professional at nine stones. The other ranks were extrapolated from that, using the one stone per rank rule. If we apply this definition today, where would shodan fall on the various rank scales?
Bill: in one of his books Segoe says that an amateur shodan should take 4 stones from a pro. There has been amateur rank inflation since WWII.
Bob McGuigan: Some venues in which pros and amateurs play with the same ranking scale are various internet go servers (IGS, Tom, Cyberoro, Dashn). On IGS, for example, it seems that the 7d*, 8d*, and 9d* ranks are populated almost entirely by professional players. So on this basis some idea of the relative strengths of amateurs and pros can be determined, but of course there are issues such as the fact that server go does not seem to be directly comparable to "real life go".
Dieter: I'm a 2d. I think I stand a chance against Lee Chang-Ho with 9 stones but I wouldn't bid too high on it. No way I can win with 6 stones if a pro takes it seriously.