From: jhc@iris.uucp (James H. Coombs)
Subject: Re: Looking for improvement suggestions
Reply-To: jhc@iris.UUCP (James H. Coombs)
Organization: IRIS - Brown University
Date: Fri, 10 Apr 1992 18:19:45 GMT

In article <1992Apr9.223815.9082@cis.uab.edu> sloan@cis.uab.edu (Kenneth Sloan) writes:
>In article <1992Apr9.194550.888@cs.brown.edu> jhc@iris.UUCP (James H. Coombs) writes:

>>So, I foresee a serious lag in my rating.

>Of course, there's just the smallest possibility that this same lag is
>in *everyone's* rating.

Yes, I wasn't clear enough.  My idea is that there is a serious lag in
the ratings of most people who are improving and have not hit the
extended plateau that would be required for their ratings to catch up.

As an extreme example, Jorge Zamora went from 1900 to 2400 last year.
He probably did not improve that much in one year but was seriously
underrated to start with.  If a rating can be that far off at high
levels, then I think it could be much worse at lower levels (doesn't
one get fewer points for a win when above 2000?).  Yes, Zamora is a
prodigy, but we can expect a less prodigious lag in many others.  So
when I face an opponent for the first time, I have to take the attitude
that his/her rating is meaningless (i.e., I can't make it the basis for
my plans, and I really shouldn't expect to win/lose).

>But...it makes little sense to put too fine a point on ratings.  They
>are estimates.  On the whole, they are accurate estimates (almost by
>definition).

Well, they are accurate scorings of tournament performance.  From them,
we can estimate future performance, but this is a statistical
estimation.  USCF gives 1 point for every 25 point difference in
rating.  So, player 2000 can be expected to beat player 1800 three
times out of four *over the long run.*  It is too complicated for me to
try to take into account the effect of learning.  I think also that the
published rating system is much simpler than the models used by USCF.
For example, USCF says that the probability of a win increases to 99:1
for a player rated 800 points higher than another, but the lower rated
player gets no more points for beating a +800 than a +400.

I also wonder about relatively closed communities where the same people
play each other over and over.  Couldn't you have Class D players in
one area who are better than Class B players in another?  How does one
make Master when there are no Masters to play against (haven't we heard
this one about Louisiana?)?

>>>as quickly as possible.  If you play book openings, you will just
>>>reach a position that your more experieced opponents knows much better.

>>Yes, but won't you then learn something about that position? 

>Usually not.

Could you explain this?  I would think that you would learn at least
what can happen in that position.  In going over the game later, you
should learn something about how to handle it.

>Obligatory ad hominem attack: 1036 players should not throw around the
>word "neophyte"!

Why not?  I am one, and I certainly expect to learn from the experience
of playing against oldphyters!

>>ratings below 2000 can be wildly inaccurate. 

>Why should we say that?

Emphasis on "can be".  Consider Zamora.

>I predict that the data will not allow you to reject the hypothesis that
>the ratings correctly predict the results - especially if you ignore
>"provisional" ratings. 

Ah, but I think now you are changing the problem from one of predicting
the result of the games that I am about to play to one of predicting
the results of all players over the long run.  It's similar to the
difference between betting on the next coin toss as opposed to the next
100 coin tosses: 50 heads out of 100 is a better bet than 1 head out of
1.

USCF is telling us that 50 of us are heads, but individuals are looking
at each other and wondering who is a head and who is a tail.  It is a
natural response (at least it's common).

I suppose that people who have played "a lot" of tournaments quit
worrying about this sort of thing.  Perhaps you just find that you have
a tendency to beat players below you and lose to those above you.

This discussion reminds me of the difference between most Chinese
martial arts and most Japanese.  The Chinese tend not to have rankings
because they get in the way of the martial art and because they
encourage the ego.  The Japanese, at least teaching in America, are
willing to give the candy that many people need to keep their
interest.

On the other hand, the rating system does make it unlikely that I will
be paired with someone who is twice as good as me.  Thanks for the
discussion.  I concede!  --Jim