From: bogin <bogin <at> YAHOO <dot> CO <dot> JP>
Date: 2 jun 2003
Subject: Re: Dual ratings

Sorry, I can't really follow all of the math too well. So, if someone  is
rated 1750 on Shogi 24 then would that make them 2150 on the Pan- Atlantic
System?


Bill Gaudry

PS: Do you play a lot of Nakabisha? It was played quite often in the last
NHK tournament so it's quite in vogue these days.


 --- Larry Kaufman <lkaufman <at> COMCAST <dot> NET>  $B$+$i$N%a%C%;!<%8!' (B
> ----- Original Message -----
> From: "Ross Dickson" <rdickson <at> ACHILLES <dot> NET>
> To: <SHOGI-L <at> TECHUNIX <dot> TECHNION <dot> AC <dot> IL>
> Sent: Sunday, June 01, 2003 10:52 PM
> Subject: Re: Dual ratings
>
>
> > It is with some trepidation that I present the least mean square
> results
> > for the enlarged data set Larry has produced.
> >
> > Pan-Atlantic = 0.6 times ShogiClub24 + 1100 is a close
> approximation to
> the
> > linear regression (lms slope = 0.5962 , lms intercept = 1118.7).
>
>      The slope of .6 is much more plausible than the earlier numbers.
>  If
> you force the slope to .6 (in the interest of ease of calculation),
> the
> intercept should drop to about 1113.  By a curious coincidence, if I
> multiply my very latest ShogiDojo rating (2010) by .6, and add 1113,
> I get
> 2319, which happens to be my exact up-to-the minute Pan-Atlantic
> rating!  I
> feel that we are getting quite close to the "true" formula, given the
> limitations of a linear formula.  Note that since ShogiDojo ratings
> are not
> allowed to go negative, the formula would imply a minimum rating of
> 1100 (or
> 1113) on Pan-Atlantic, but in fact we have many players rated below
> that
> level.  So either the true slope is higher than .6, or else the
> formula
> breaks down below about 5 or 6 kyu Pan-Atlantic.  Maybe we need a
> non-linear
> regression, but perhaps that's getting too complicated for our needs.
>      I note also that the formula implies that the two systems
> converge at
> 2750 (or 2783 if we use 1113), which agress almost perfectly with my
> previous states opinion.
>      Until further notice, I suggest we adopt Ross's formula (.6 SC24
> +
> 1100 ) (or 1113 if you want to be exact) for setting the rating of
> new
> players in our tournaments who have ShogiDojo ratings.
>
> >
> > The original data is in the first two columns, sorted in order of
> > SHogiClub24 score, the calculated Pan-Atlantic follows, and then
> the
> > difference between the calculated and Actual values of the Pan
> Atlantic
> > scores.
> >
> > Actual   Shogi    Calc     Actual
> > PanAtl  Club24    PanAt    - Calc
> > 2422,    2284,    2485,      -63
> > 2455,    2118,    2386,       69
> > 2255,    2013,    2323,      -68
> > 2285,    1993,    2311,      -26
> > 2174,    1925,    2270,      -96
> > 2195,    1753,    2167,       28
> > 2094,    1555,    2049,       45
> > 1980,    1513,    2024,      -44
> > 1660,    1507,    2020,     -360
> > 2118,    1455,    1989,      129
> > 2101,    1465,    1995,      106
> > 2012,    1453,    1988,       24
> > 1926,    1378,    1943,      -17
> > 1852,    1377,    1942,      -90
> > 1973,    1312,    1904,       69
> > 1809,    1298,    1895,      -86
> > 2044,    1181,    1825,      219
> > 1908,    1161,    1813,       95
> > 1599,    1157,    1811,     -212
> > 1769,    1149,    1806,      -37
> > 1924,    1124,    1791,      133
> > 1827,    1091,    1771,       56
> > 1791,    1072,    1760,       31
> > 2074,    1064,    1755,      319
> > 1784,     993,    1713,       71
> > 1772,     933,    1677,       95
> > 1620,     797,    1595,       25
> > 1272,     789,    1591,     -319
> > 1505,     635,    1499,        6
> > 1138,     336,    1320,     -182
> >
> > The large (and possibly periodic) deviation of a number of points
> is
> > interesting. Perhaps the starting rating does have some effect.
> >
>      I don't think starting rating is the problem.  For the SC24
> ratings,
> the 80 game requirement virtually rules that out as a factor.  For
> Pan-Atlantic, it may be a problem for fast-improving players, but not
> for
> the majority of players on the list, who are veterans.
>      The two very large negative deviations belong to the only two
> Swedes on
> my list.  This offers strong support for the
> claim that Sweden is substantially underrated (on Pan-Atlantic)
> relative to
> the rest of Europe (and the U.S.).  The two largest positive
> deviations
> belong to older Japanese players living in the U.S., who are more
> likely
> than others to play on ShogiDojo during breaks from work (where they
> may be
> interrupted) or to play after drinking alcohol at night (at least
> that is my
> perception), so my guess is that these nationality factors may be the
> prime
> cause of large deviations.
>      Thanks Ross for your statistical help.
>
>
> > Ross
>
>            Larry Kaufman


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