The strength differences between professional levels is...

[EdLee]

I'm trying to find that answer by myself (with a lot of internet help)

Hi pookpooi, Thanks -- You want a trustworthy little bird.

[Bill Spight]

We don't know how many stone is inside the black box, we can't open it. We've been told (from anonymous) that inside the box is 'believed' to be 2-3 stones. But I don't believe him, and I'm not randomly guess the answer either. Instead, I'm shaking the box to hear what it sounds like, and compare it to another box I made that I put 4 stones in it. When the box is finally open I may be completely wrong, may be there's no stone in it at all, or may be, there are tens of them!

400 years ago an 8 dan, if one existed, would give a ("pro") shodan 4 stones, and a 9 dan would give a shodan 4-5 stones. Over time that handicap diminished, probably because shodans became stronger on average. 100 years ago a 9 dan would give a shodan 3 stones. This difference between ranks lasted until WWII, when 9 dans began to proliferate. The average strength of 9 dans probably diminished by as much as 1/2 stone. It is also possible that the average strength of shodans increased. Around 1980 Ing devised pro ranks such that a 7 dan would give a shodan 2 stones and a 9 dan would give a shodan the equivalent of 2.5 stones. These days pros no longer give handicaps to other pros. Maybe the 2-3 stones you have heard comes from Ing's ranking system.

[pookpooi]

These days pros no longer give handicaps to other pros. Maybe the 2-3 stones you have heard comes from Ing's ranking system.

Now what I need more from these information is that, after given such a handicap, does winrate balanced to around 50:50? (I don't think so)
But I agree that pros shouldn't give handicaps to other pros, and I also strongly agree with the current professional dan system (that the rank never decrease and you can promote by having a good tournament result, or etc.)

[hyperpape]

Lee Sedol beat a group of Western pros down to a three stone handicap, and the Japanese professional vs. amateur Meijin contest often sees the professionals winning with 2 stones.

These are both very weak signals, and your question is still not perfectly defined. Still, I think that >= 2 stones is a safe bet.

[pookpooi]

Lee Sedol beat a group of Western pros down to a three stone handicap, and the Japanese professional vs. amateur Meijin contest often sees the professionals winning with 2 stones.

These are both very weak signals, and your question is still not perfectly defined. Still, I think that >= 2 stones is a safe bet.

Yeah, that's the kind of information I want to hear more. I hope those matches are not play on the internet cause some people might say that they're not playing seriously because the match happen online.

[hyperpape]

The Lee Sedol match was online. The Japanese match is longstanding, you can find an article on Senseis Library. I assume it is played in person.

[Bill Spight]

These days pros no longer give handicaps to other pros. Maybe the 2-3 stones you have heard comes from Ing's ranking system.

Now what I need more from these information is that, after given such a handicap, does winrate balanced to around 50:50? (I don't think so)

Certainly up to WWII the win rate was balanced. That was the idea of handicaps, to balance the win rate. And Ing in 1980 plainly intended the handicaps to balance the win rate.

True, there were exceptional cases where the lower ranked player was markedly stronger than his rank, and up and coming players had to prove themselves by winning more than 50% of the games, but once players had plateaued, the handicaps reflected differences in strength.

[xed_over]

Lee Sedol beat a group of Western pros down to a three stone handicap, and the Japanese professional vs. amateur Meijin contest often sees the professionals winning with 2 stones.

These are both very weak signals, and your question is still not perfectly defined. Still, I think that >= 2 stones is a safe bet.

Yeah, that's the kind of information I want to hear more. I hope those matches are not play on the internet cause some people might say that they're not playing seriously because the match happen online.

While our newly crowned, first ever, American pros had earned the title of "professional", they were still a ways off from being as strong as their Asian counterparts. That was part of the point of the match, to test just how far off they were.

I'm not sure you'll want to use these particular examples in your quest.

[xed_over]

While we have tendencies to rank people and list some as better than others, other cultures not so much. At last year's US Go Congress, Maeda Ryo 6p of the Kansai Kiin told us during one of his lectures that they don't consider lower ranking pros to be any weaker than higher ranking pros. They consider them all on an equal level.

Of course, we all know that actual results speak louder than that, but that's the attitude (and respect) they have toward their professional players of all levels.

[Elom]

The relation of a single stone of difference to a specified rating difference seems to be a measure of convenience.

I don't know how this works too well, but it appears that the winning percentage of a 1kyu against a 3kyu would be less than that of a 7d against a 3d. It's generally assumed that the stronger the players, the higher the winning percentages of the same difference in stones, and the more certain the strength level the stronger the players.

However, if we assume that the winning percentage of a player a certain number of stones stronger is the same across rthe board, then we may come across a slight problem.

If we were to take the winning percentage of a 1k v a 3k, and assume the same for an 8d against a 6d, for example, what could occur is the the rating system believing the higher winning percentage of the 8d against the 6d translates to a higher stone difference between the 8d and 6d than the 1kyu and 3kyu, resulting in a slight inflation of the stronger players rank in dan levels. Therefore, a kgs 10d may not necessarily be 3 stones stronger tyan a kgs 7d in real terms. and using the quota, "100 points of rating for every difference of one stone" may not be quite accurate, as 100p difference refers to a winning percentage, I believe...

Secondly, The Go associations in China, Korea, Japan Taiwan, Europe and North America have different systems in recruiting new professionals. In fact, the Kansai Kiin nominates professionals differently from the Nihon Kiin, and I'm not sure if Taiwanese players must pass the general Chinese professional qualification to become a pro in Taiwan.

Ali 1p and Pavol 1p would not have appeared to have unusually weak strength for a 1p pro in Japan by any case (although they played relatively few official games), according to what I have heard, and taking from that, the majority (at least half) of those taking the recent Winter examinations could say the same-- lthough this doesn't mean the passers were not clearly stronger than the other pro-level players. And if we were referring to 1p in Korea or China, it would be a completely different story.

What may make this more complicated is something I saw on a Chinese weiqi site, along the lines of: "If A > B, and B > C, is A really > C?". It could actually be the case that a certain player may appear weaker than all of the other players in a certain circle of pros, but hen suddenly outperform them in a broader circle of pros.

What is meant by, "Asian counterparts"?

[Bill Spight]

The relation of a single stone of difference to a specified rating difference seems to be a measure of convenience.

Most modern rating systems are built on even game matches and winning percentages. IMO differences in strength measured in handicap stones are quite accurate, even with vast differences in strength. And it is possible to have ratings based upon handicap play, but I doubt if the theory has been much developed.

For instance, if a shodan and a 2 dan play even, maybe the 2 dan will win 60% of the time, but if a 10 kyu and a 9 kyu play even, may be the 9 kyu will win 53% of the time. Still, in both cases if the stronger player plays White and gives komi, the results will be roughly even. Also, even with the great strength difference between shodan or 2 dan and 10 kyu or 9 kyu, the rank difference will indicate a reasonable handicap.

IMO, a rating system designed to predict winning percentages in even games is not as appropriate for go as one designed to predict 50-50 handicaps.

[Bill Spight]

While we have tendencies to rank people and list some as better than others, other cultures not so much. At last year's US Go Congress, Maeda Ryo 6p of the Kansai Kiin told us during one of his lectures that they don't consider lower ranking pros to be any weaker than higher ranking pros. They consider them all on an equal level.

Of course, we all know that actual results speak louder than that, but that's the attitude (and respect) they have toward their professional players of all levels.

I expect that Shusai had a certain regard for Go Seigen, but when he gave him three stones I doubt if he thought of him as even close to his own level.

[EdLee]

They consider them all on an equal level.

Of course, we all know that actual results speak louder than that

If they do, then they have an interesting way of showing it by the teaching fees they charge:
in Japan and China at least (not sure about in Korea), various pros routinely command much higher teaching fees --
50% or higher than other pros. An interesting idea of equal.

[Mike Novack]

They consider them all on an equal level.

Of course, we all know that actual results speak louder than that

If they do, then they have an interesting way of showing it by the teaching fees they charge:
in Japan and China at least (not sure about in Korea), various pros routinely command much higher teaching fees --
50% or higher than other pros. An interesting idea of equal.

Ah, but that is a very different matter. Just because pro A is stronger at playing go than pro B does NOT mean that pro A is a better TEACHER of go than pro B. As long as the teacher is a significantly stronger player than the student, how much the student benefits will depend on the teacher's teaching skills, not go skills.

[EdLee]

Mike, yes, that's common sense.

I wish I had taken photos of the price signs at the Tokyo Go salons in 2011.
The point is that the higher prices are based (partly? primarily?) on their ranks (or current titles), which, as we both agree, are not necessarily corelated to teaching levels.
And yet they were apparently priced as if they are.
So no, it's not a very different matter.