It IS the Elo system, the method which is employed by most grading bodies in the world. For a full description see the FIDE
(Federation International des Echecs) Laws of Chess. The Win Expectancy formula quoted here under Help is taken from the
FIDE book. FIDE themselves say that this formula gives an "approximation" to the table which they recommend. I'm not a
mathematician, so I don't know whether it is merely an approximation. The table is certainly easier to use and FIDE may be
recommending it as a matter of convenience.
Other questions which have been raised on this website (eg Exactly what are the criteria for rateable games?) would have to be
answered by the RedHotPawn people.
I'm not entirely convinced that's the whole explanation. Hardly any - if
any at all - of my games were specified as unrated at the beginning.
Very few were defaulted before the third move. But in my record there
are a fair number of unrated games. I suspect that there is some
other rule I haven't detected - or that there is some randomness in
the system.
Originally posted by gordonDude: are you ever going to respond to my PM?
I'm not entirely convinced that's the whole explanation. Hardly any - if
any at all - of my games were specified as unrated at the beginning.
Very few were defaulted before the third move. But in my record there
are a fair number of unrated games. I suspect that there is some
other rule I haven't detected - or that there is some randomness in
the system.