From: Pieter Stouten SHOGI NET> Date: 14 dec 2002 Subject: Correlation between ratings and grades Hello Shogi fans, On Thu 12 Dec 2002 14:16 +0100, Daniel Toebbens" HMI DE> wrote: >>Looking at the Elo list, you will notice significant >>correlation between ratings and grades. In fact, I hope >>that Asle can determine the statistical correlation when >>he gets back from vacation. >> >I think he meant that there is no strict relationship >between the current Elo and the grade. Of course there is >a strong correlation between grade and Elo (though it is >not linear, more like exponential growth). > The progressive widening of grade brackets is an arbitrary, but deliberate choice. It was done to reflect the Japanese situation. However, when projecting players' current Elo rating back onto a grade and then comparing that projected grade with their nominal grade, I would expect a linear relationship (although that may be hard to decide with only 20 or so grades). >However, if one looks at i.e. the 2 dan grade, the >corresponding elo points reach from 1546 to 2118! > One should do that only for E-players (i.e., ones with an established rating). I also believe (but am not sure) that the lowest rated 2-dan obtained his grade in Japan, and not through our system. Other grades may have been awarded prior to implementation of the current (Asle's) or even the previous (Eric's) ratings systems. Having said that, I still think it is of interest to investigate the correlation between grades and ratings for all E-players. >>Elo ratings predominantly reflect current strength; >>grades reflect peak performance. I think there is a >>place for both, and I think we should take both >>seriously. Therefore, FESA and USSF need to decide >>how they want to do that. And that may very well >>include accepting NSR grades. >> >This argument only holds, if you see the Elo-based >grades as the 'real' ones. In that case those given >for tournament or club performance are a problem to >the system. Not to speak of those 'honorary' grades >given for other merits. But, since those other grades >exist and, as far as I understood, have existed even >before the Elo system: Is not the whole concept of >purely Elo-based grades flawed from the begin? > At first, players in Europe received grades from visiting professionals, from George Hodges and a little later from national associations. These promotions were all fairly subjective and arbitrary, and a point system was introduced. This system led to inflation as one lost/gained points depending on the nominal strengths of opponents, not on their then current performance. Therefore, FESA decided to replace it by an Elo-based grading system. I think Boris Mirnik's expressed a sentiment shared by many American and European players when he said: "I would like to stay 3-dan. I would prefer to see the 4-dan diploma (which I am very proud of!) as an award for my achievement at the Forum. My true strength is better reflected by my ELO-rating." It is not that an Elo-based grading system is any more real than any other system; it is just that a grade obtained within that system always means the same and reflects sustained peak performance better than any other system. I suspect it is for that reason that Boris and several other players prefer to stay at their Elo-based grade, no matter what diploma they earned in Japan. >Personally, I have no problem in seeing a dan grade >given for great merits due to the promotion of shogi >as as valueable as one achieved through the Elo system. > I don't think it is a matter of value, but of meaning. FESA/USSF grades are different from NSR grades and all of these are different from club grades. Not better or worse, they just measure different things. That's why I suggested to separate FESA/USSF and NSR grades and, if applicable, list them both on the Elo list. Ciao, Pieter