Or if Iyama is under-rated, which with him down in 45th place last year I think was the case.

Iyama has a double advantage: not only is he playing in all the big-money (overweighted) Japanese titles but as the defending titleholder he is seeded directly into the finals (overweighted), which are longer in Japan than in China or Korea. I assume this also helps explain Yamashita's position. I would expect Kono Rin to make a disproportionate jump in the ratings later this year as well.

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Dave Sigaty
"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21

I assume the KBA weighting factor is not trivial, otherwise why put it in? The larger point here is that I don't think the KBA rating system was intended to be used for international pro rankings given the different tournament systems of each country.

Our case study - Iyama Yuta - has a single international tournament title to his name over his entire professional career (2013 Asian TV Cup). In fact, outside of that single international title, he's never made it to the final round of any other international tournament. Nevertheless, he's ranked 5th on the list above Lee Sedol (ranked 8th) who has won and defended 6 international titles 14 different times. On the face of it, something just doesn't seem right here.

For comparison: The highest paying national tournaments in both Korea (Myeongin) and China (Qisheng - created in 2013) are just shy of $100,000 each in U.S. dollars.

Here's the list for Japan's top five paying tournaments in U.S. dollars (today's exchange rate, rounded off):

Kisei --- $434,000
Meijin --- $357,000
Honinbo --- $308,000
Tengen --- $135,000
Oza --- $135,000

Here's the list for the top five paying international tournaments in U.S. dollars (today's exchange rate, rounded off):

ING --- $400,000
Samsung --- $293,000
Bailing --- $293,000
LG --- $244,000
Chunlan --- $195,000

Given the KBA weighting factor, Iyama Yuta has effectively won the weighted equivalent of the top 5 international tournaments - and then some - over the past two years without leaving Japan. Having said all of this, It would be interesting to run the numbers again without the tournament weighting factor to see how the rankings differ.

Note: someone please correct me on my tournament prize figures if I've miscalculated, or any other factual error.

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"This is a game that rewards patience and balance. You must think like a man of action and act like a man of thought."
-Jonas Skarssen

The weighting factor increases the importance of a game, so if Iyama plays a lot of heavily weighted slow games and a few lightly weighted fast games, his rating will be determined disproportionally by the slow game results.

I understand that longer thinking time helps a pro play better, but does it actually increase his winning probability against a weaker pro who is given the same thinking time? If anything, I would think it would go the other way, that short thinking time accentuates strength differences.

This argument would say that Iyama has a disadvantage, having to maintain a high win/loss ratio in slow games to earn his rating But then again, I guess you could argue that if his weaker opponents benefit from the long thinking time, they are likely are over-rated (compared to fast game players), helping Iyama obtain an inflated rating when he beats them Rating systems are tricky.

Whichever way the above argument goes, the rating system is certainly not comparing Iyama's strength at slow play to a Korean player's strength at fast play; to first order at least, that time limit effect is taken out by the system.

I think there is a slight misunderstanding going around about the role of the weighting factor.

As I understand it, it simply means more of Iyama's games are weighted heavily, hence for Iyama it basically cancels out.

Where it makes a difference is if you have someone who wins a major title, but then finishes poorly in a couple blitz TV tournaments. Their rating will give more consideration to the performance in the title than the blitz events.

The weighting factor is about scaling the effect of games *within one player's rating calculation*, not about scaling one person's rating relative to another.


Also, for a player like Iyama, number of international titles won is a poor metric to use, especially when comparing to Korean and Chinese counterparts. A better evaluation would be overall win rate in international events. I'm not at my computer right now so I can't look up that comparison...

Thanks for the clarification, Mef. This makes more sense and highlights my misunderstanding, which I'm sure Mitsun was pointing out as well.

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"This is a game that rewards patience and balance. You must think like a man of action and act like a man of thought."
-Jonas Skarssen

I don't think that distinction makes sense. The system does assign individual ratings to every player, but the use of those ratings is to predict win/loss probabilities when two players compete against each other.

Imagine two parallel rating systems for the same group of players, one for slow games and one for fast games. It is entirely plausible that some players would be ranked higher under one system, while other players would be ranked higher under the other system. Now combine the two systems by lumping all the games together with some weighting factors. If the slow games are given high weights, then the final ratings will be skewed toward the slow game ratings. I guess we all agree on this?

I agree with everyone that Iyama's rating mostly describes his strength at slow play, but I do not think this gives him any particular rating advantage in the combined system. For all we know, he might have an even higher win/loss ratio, against the same set of opponents, if they played blitz games.

I always thought that faster time settings give the weaker player a better chance (like when Ishida Yoshio 9p played Crazystone, read the GGG article). Think about the Globis Cup and Asian tv cup! It's only natural that as Japanese players improve, the first succesess would be in HayaGo tournaments.

It's similar to two pros playing on a 9x9-- one "average" level and one a top pro-- the game would be pretty much even.

To me, it seems, despite the fact that you're not rated for winning titles but for winning games, the fact of the matter is that according to Dr Bea Taeil's system, winning a national title with twice as much prize money as an international one would mean that if someone's rated 1000 and wins a National tournament with 2x prixe money and play opponent's with an average of 750 points, and then you also rated with 1000 points play in an international with the same amount people played and same winning percentage, they'd have to have an average rating of 1500 for you to increase your rating by the same amount.

Losing in some international tournaments 10 times against one person can be rectified by beating that same person once in a some Japanese tounaments.

If not many top Japanese players compete in international cups, but the up and coming japanese players do and frequently lose, if the K factor for international tournaments is doubled, the up and coming players ranks would be lower an when top japanese players play the up and coming players, the top players ranks wont increase much if they beat them, but decrease a lot if they lose to them.

I persnally think would be fairer, because rising stars in Korea and China would hold a better position.

Hope this helps!

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On Go proverbs:
"A fine Gotation is a diamond in the hand of a dan of wit and a pebble in the hand of a kyu" —Joseph Raux misquoted.

I am not an expert on ratings, but if one wanted a rating, the initial assumption would be to not bother with a K-factor, and just run some sort of algorithm (e.g. whole history ratings) on the raw games.

Perhaps that wouldn't work for international comparisons, but I've never read any non-speculative reason it wouldn't.

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Occupy Babel!

There is a video on WeiQiTV from the recent 58th European Go Congress (only ~2 weeks ago).
A top Chinese pro (Liu Xing) gave a European high dan 3 stones, 10-second blitz.
Liu Xing won (twice). The other board is another Chinese pro vs. another
European high dan, same settings. Later, a top Chinese woman pro gave 2 stones.
The Chinese pros won all the blitz games on this video.

It also seems that on KGS, some players can achieve 9 dan ratings by playing lots of high handicap blitz games against weaker players, but can't hold that rating in even games against other top players.

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Occupy Babel!

It's an interesting dynamic. If Iyama is over-rated, I suspect the mechanism is this:

Most games are played in country, so we'd expect the most significant sorting to occur in country. This would be especially true in Japan with more high-purse tournaments and so a larger average weight to Japan-Japan games. A rising star will "steal" most of his points from countrymen.

Internationally, the sorting should tend to be strongest in the upper echelons of players. They last longer in international tournaments, getting more games and more high weight, late round games.

Those combine to make top echelon players significant points of score diffusion. If a new player is added to each country and one is stronger than the other, then the differential is going to tend to flow through the top players to equalize the two new players. Players from the stronger pool will tend to be slightly underrated, players in the weaker pool will tend to be slightly overrated for this diffusion to occur. So if the average new Korean and Chinese professional is stronger than the average new Japanese professional, it would make sense for Iyama to experience some overrating.

That said, there are at least two possible contravening factors. First, flow also occurs with changes in relative strength between pools as well. So if, say, Japanese players are weaker than Korean players, but the difference were diminishing, Iyama would experience some rating deflation. If the gap were growing, that would inflate him.

Second, this assumes that the highest weight international games are between top players. In many systems new players get a big weight boost to all their games to facilitate them quickly getting to the appropriate level. If that's so in this system, and if new players play a meaningful number of international games, the surface area between the pools would be much larger, and there would be no players on diffusion hotspots, so the rankings would be much more accurate in general.

That sounds like fun. Does WeiQiTV allow views/purchase of individual videos (like BadukTV) or must one have general subscriptions? Do you have a link?

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"Tsumegos are for reading power and Tesujis for knowing which moves to read"

http://weiqitv.com/index/live_back?vide ... 6d4d8b4567
It should be this one.
Currently no registration or purchase or subscription is needed for watching videos at WeiQiTV.

Very cool, thank you. Am eager to view more of their videos.

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"Tsumegos are for reading power and Tesujis for knowing which moves to read"

Wow, those aren't just any high Dans, those are two of the strongest players in the whole of Europe. One is an EGF 7 dan, strong enough to be a pro, who used to be an yuengsueng,, the other is an EGF 6 Dan and also EGF pro... 3 stones is still a relatively unchallenging game for the top pro? XO strong

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On Go proverbs:
"A fine Gotation is a diamond in the hand of a dan of wit and a pebble in the hand of a kyu" —Joseph Raux misquoted.