From: olounela@klaava.Helsinki.FI (Olli Lounela)
Newsgroups: rec.games.go
Subject: Re: ratings algorithm (LONG)
Date: 1 Oct 92 14:13:49 GMT
Organization: University of Helsinki

In article <1992Sep29.190411.9149@dvnspc1.Dev.Unisys.COM> mdobbins@dvnspc1.Dev.Unisys.COM (Michael Dobbins) writes:
>In article <wekpniO00Woh54aEN_@andrew.cmu.edu> wjh+@andrew.cmu.edu (Fred Hansen) writes:
>>Paul Matthews describes below a statistically sound rating method that 
>>he claims a competent numerical programmer who knows elementary 
>>probability and statistics could implement in a weekend.  (I'm neither a 
>
>For usage in the IGS we should be able to pull out a table of values
>from Paul's system (say averages over the past year of rated games) and
>create a very simple non-iterative algorithm for modifying rankings
>based on the results of each game. The winner's rank would increase
>some fraction of a rank and the loser's rank would decrease some

I think that most any ranking system would be good enough.  The only
things we need are for it to converge, and be automated.  This would
ensure some degree of accuracy in ranks, and at least a little
coherence.  The situation as it is now cannot be made any worse, except
by being too strict as explained later.  Generally, the simpler the
system the better, although I most assuredly would not oppose a complex
system, as long as it takes no extra effort from the average J. Random
Player. 

>IGS, it does not make sense to do any heavy number crunching to
>calculate ranks when a simpler, though less accurate mechanism would
>suffice.  The simpler algorithm would be adequate for sorting
>individuals into a reasonable skill hierarchy.  Nothing better is
>needed.

Excellent thinking.  To me it would not immediately be apparent to think
of the crunching load imposed to the machine hosting the server. 
However, I believe these updates could be scheduled to such a time of
the day when there is little load to the machine otherwise.  This would,
of course, make implementing the system that much more complex, so I
have no idea wheter this would be feasible. 

>As far as the higher level question of should the IGS use the results
>of game to rank people, I would have no objection to it doing it all of
>the time as long as the individuals have the choice of selecting
>handicap values different from what the relative rankings would
>indicate.  

Yes, I see absolutely no reason for restricting handicaps.  I have the
habit of teaching some weaker (weaker than me, at least :-) players in
fuseki and strategy by playing them a game or two every now and then,
with no handicap. 

>The IGS is for fun and we should not get caught up in worrying about
>our rankings on it (that is what sanctioned tournaments are for.)  If
>you just play for fun and don't "try your hardest to win" then the IGS
>ranking will tend to move to that level and people will know that is
>the level you tend to play at on the IGS.  That should in no way be
>interpreted as how well you play in tournaments or what your real
>ranking is. I think it would be fun to see statistics on people.  

I think that there are two kinds of people playing in the IGS.  One
group is those, who just want to play, perhaps have an interesting game,
and not worry overmuch about the result or the quality of play.  As per
my experience these are fast players and usually prefer shortish games. 
The other consists of those who really want to try and learn (we should
remember that not everywhere are there (really) strong players around),
who really are willing to spend effort for it, and also of those who
think winning and losing is a matter of honor and/or ego.  These players
play slow and careful (and there actually is a third kind of players:
those who play slowly by habit, IMHO).  As IGS is for fun, we should try
and accommodate these, mostly conflicting points of view. 

However, I also would want to see statistics, and the individual results
usually just are not enough of an indication of anything. 

>Along those lines, maybe we should allow people to adjust their ranking
>up if they think that they under-rated.  
>
>Actually I wouldn't mind if we had total freedom to adjust ranks, and
>still had IGS adjust it a bit each game. Those who want to play with
>their ranks would be allowed and those who wanted the IGS to track
>their record could do that as well.  Yeah, that's the ticket :-)

I think this would be the perfect solution.  To be able to adjust your
ranking despite what the automagical ranking says.  This opinion of mine
comes down to (yet another) imperfect categorization of the IGSers. 

There are those, who know their "real" ranking (according to some system
or other, more often official than not), and prefer to use that.  There
are those, who prefer to use a rank not bearing any resemblance to their
real skill.  And there are those who really don't know what their rank
would be, or perhaps just don't know how to set it and keep it
reasonably accurate. 

There is nothing we can do to the people who want to use some
such-and-such rank, nor do we need to IMHO.  To force people to any such
practice could seriously decrease the pleasure of playing in the IGS. 
However, with an automatic ranking, some rank could be fairly quickly be
established to those who have no idea of their rank relative to the
server.  I speculate they may constitute as much as one third of all the
IGS players. 

In short: if I were asked, I would prefer an automagical system with
ranks adjustable by the player in question. 

(Sorry for the length, but I wanted to try for some unemotional analysis
of the situation.  Also apologies for the mass of quotations.  Insert
lots of 1/2 ;-)'s.)

-- 

	Olli, 3 dan
--
E-mail: olounela@cc.helsinki.fi           ! .sig still under construction.
Newsgroups: rec.games.go,kw.general