Recent content by David J. Marcus

Ratings Central is just ratings. You should be able to use any membership platform and integrate with Ratings Central.

Does Norway really use Elo? I think beginners should be able to improve 100-200 USATT points a year for several years.

If they are going to switch, they should switch to a superior system.

To elaborate a bit, I calculated it from the post-tournament ratings in the USATT data set described in my "New table-tennis rating system" paper. I first tried to use the pre-tournament ratings. This gave a rather different graph (greater probability of upset), which didn't work in the...

Even assuming the USATT system was based on the Elo system (better to say it was inspired by it, i.e., chess has ratings, so table tennis should too and let's use similar numbers), there is no reason why the rating scales should be the same. It is like feet and meters: Not only do you need to...

Note that even if the ratios in the rating chart matched the probabilities, and you just use the rating chart (i.e., don't do the "adjustments"), this won't ensure that the ratings don't inflate/deflate. In such a system, the rating chart does not change the total points (summed over all...

That can happen. But, usually the standard deviation goes down when you play. It depends. If the main part of the player's law was a narrow bump and the results smush that away, then a wider bump may be all that's left. But, usually the results just remove part of the main bump.

Almost everything you wrote is correct. But, "consistently beating others with a higher ranking" doesn't get you a greater standard deviation. The standard deviation just measures how certain we are that we know the player's playing strength. We don't attempt to model individual players. The...

I'm not sure what USATT wants. I suspect no one in authority in USATT has looked at the rating system for some time. While some in USATT may want the ratings to be stable, the ratings are not. The USATT rating system has significant inflation. There is no easy fix for this. It is a result of the...

When I read Elo's book, I was not impressed. While he does have a model in there, he doesn't derive the update formula from the model. He spends a lot of his book comparing players through time. His system is not stable enough for those comparisons to be valid.

It wasn't designed that way. However, at one point in the distant past, someone tried to adjust the ratings chart using that criterion. It never made sense to me: For one thing, it only tells you the ratio of the two numbers. For another, a rating system must adjust ratings as players get better...

The USATT rating system is not Elo. Elo is not the gold standard. Also, the USATT rating system is more than the rating chart: Initial ratings and adjustments make a big difference to the ratings. Chess organizations that use Elo often do more than just use the basic Elo formulas. In Ratings...