David Kane wrote:
"Kenneth Sloan" wrote in message
...

In any Elo-based system, the only "correct" rating for a player who truly
knows nothing is: -infinity.

This is only true if "knows nothing" equates to "never wins" which you
haven't proven. In fact, if we rated a tournament filled only
with unrated "know-nothings", they'd end up with the rating arbitrarily
assigned to their class by the rating system. No system that I know
of uses -infinity.

uses -infinity as *what*? As the initial rating for a first-time
player? Well, of course not - THAT WAS MY POINT!

As the lowest possible rating? USCF does. In *calculating* ratings,
any value (even negative values) are permitted. Only at the end is
an administrative floor imposed.

At one time, the programming assumed a minimum of 0000 - but did not
really impose it (actually, it assumed a minimum of 0001, because 0000
was reserved to mean "UNR". That is, until it was noticed that ratings
for some players were fast approaching 0000, and it was only a matter of
time until a computed rating was actually negative. That's what sparked
the discussion of the Absolute Floor.

Participants in that discussion may recall that I argued for a Floor
of 0400. The end result was a floor at 0100. The official reason
given: "players are embarassed to have double-digit ratings".

The lowest rating ever published (if memory serves) was 0040. There
are now hundreds of players who are being propped up by the floor at
0100 (properly so, in my opinion - for reasons beyond the scope of this
thread), but the basic Elo computation
takes absolutely NO NOTICE of ZERO, for any purpose whatsoever (don't
believe me? read Elo!). There is nothing at all in the current
USCF rating system that prevents a rating from going negative (and,..as
negative as you please, which is a pretty good definition of -infinity).
The ONLY reason you don't see negative ratings reported is the
politically determined Absolute Floor at 0100.

Exercise for statistics journeymen: look at the distribution of USCF
ratings and estimate the lowest "true" USCF rating as of today.


--
Kenneth Sloan
Computer and Information Sciences +1-205-932-2213
University of Alabama at Birmingham FAX +1-205-934-5473
Birmingham, AL 35294-1170 http://www.cis.uab.edu/sloan/