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Subject: Rerun for 2400+ and 2400-

Author: Andrew Dados

Date: 06:42:06 02/05/01

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On February 04, 2001 at 13:58:11, Andrew Dados wrote:

>
>I decided to find out 'true chance' of draw outcome from real games.
>The below is summarized output from my twic game files.
>Rdiff means difference of players ratings in the (range, range+25).
>Integrestingly around range of 0 draws approaches 50% and better won about 25%.
>
>Now if you take 2 tosses of coin you'll get total score of 2 heads in 25%, 1
>head in 50% and 0 heads in 25%...
>
>
> files: 176      games: 170464   decisive (counted) : 128803
>
>Rdiff+  games   %draws  %better won
>=======================================
>0       14480   48.82   25.67
>25      15365   46.57   31.45
>50      15784   44.60   35.52
>75      15429   41.80   39.62
>100     14092   38.68   44.26
>125     12121   35.08   49.18
>150     9926    31.92   54.47
>175     8129    28.34   58.89
>200     6478    25.39   63.71
>225     4707    22.82   67.94
>250     3443    20.65   69.82
>275     2575    18.45   73.67
>300     1879    15.59   77.38
>325     1370    15.62   78.83
>350     970     10.52   85.46
>375     687     9.32    86.90
>400     453     7.06    89.18
>
>Is one chess game statistically equivalent of 2 coin tosses? :)
>
>-Andrew-

Since Vincent and Hermano raised valid point about expected different draw
distribution among different strength of players, I post a re-run...
While I wanted to provide tables down to 400 elo difference I decided to simply
divide my small pgn sample in 2 with regard to 'average game rating'.

Hi_won and Lo_won are respectively wins for higher and lower rated.
Expected %score is practical achieved score (which according to rating system
should not depend upon players ratings). Rdiff is difference of opponents
ratings.

1) Data for games where average combined (R_white+R_black)/2
   rating is 2400+ :
==========================================================
files: 176      games: 170464   counted: 59172
Avg rating: 2500.76 Total draws %:  44.64

 Rdiff  games   %draws  Hi_won  Lo_won   | Expected %score
=======================================
0       8329    55.31   23.26   21.43    |  50.91
25      8745    53.06   28.03   18.91    |  54.56
50      8699    50.34   32.64   17.02    |  57.81
75      7989    47.90   36.48   15.62    |  60.43
100     6712    44.80   41.15   14.05    |  63.55
125     5282    40.57   47.03   12.40    |  67.31
150     3863    35.78   52.58   11.65    |  70.46
175     2976    31.42   57.73   10.85    |  73.44
200     2262    28.47   62.78   8.75     |  77.01
225     1427    24.60   67.90   7.50     |  80.20
250     951     20.08   72.13   7.78     |  82.18
275     665     18.35   76.69   4.96     |  85.86
300     427     16.63   76.58   6.79     |  84.89
325     302     14.57   79.47   5.96     |  86.75
350     203     12.32   85.71   1.97     |  91.87
375     112     13.39   83.04   3.57     |  89.73
400     61      9.84    85.25   4.92     |  90.16

2) Data for games where average combined rating is below 2400 :
==========================================================

 files: 176      games: 170464   counted: 69227
 Avg player: 2278.28 Total draws %:  30.36
 Rdiff  games   %draws  Hi_won  Lo_won   | Expected %score
=======================================
0       6105    39.89   31.47   28.65    |  51.41
25      6594    37.99   35.99   26.02    |  54.98
50      7032    37.47   39.12   23.41    |  57.86
75      7393    35.20   42.99   21.82    |  60.58
100     7336    33.04   47.18   19.78    |  63.70
125     6817    30.81   50.86   18.34    |  66.26
150     6017    29.47   55.66   14.87    |  70.39
175     5139    26.52   59.60   13.87    |  72.86
200     4169    23.72   64.21   12.07    |  76.07
225     3269    22.09   67.94   9.97     |  78.98
250     2471    20.84   68.88   10.28    |  79.30
275     1904    18.49   72.58   8.93     |  81.83
300     1445    15.36   77.58   7.06     |  85.26
325     1062    15.91   78.63   5.46     |  86.58
350     763     10.09   85.45   4.46     |  90.50
375     575     8.52    87.65   3.83     |  91.91
400     390     6.67    89.74   3.59     |  93.08

Indeed there is huge difference in draw distributions... and very little in
expected score. Note that around difference of 250 elo draw % converges.
More games needed...

-Andrew-



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