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Ratings - Chess.com VS Chess South Africa Rating System

Ratings - Chess.com VS Chess South Africa Rating System

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Malan77
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Often the question is asked how to convert your online rating to your actual ratings.  I have found some answers and will show you how you can make your online rating be a measure of your over the board strength.

The questions will be:

  • Can you use Blitz
  • Can you use Rapid
  • What formulas can you use

Can you use Blitz - YES

t-Test: Paired Two Sample for Means
  CHESSA BLITZ
Mean 1308.26 1336.52
Variance 107847.7065 141929.0302
Observations 50 50
Pearson Correlation 0.832887415
Hypothesized Mean Difference 0
df 49
t Stat -0.956056195
P(T<=t) one-tail 0.17186856
t Critical one-tail 1.676550893
P(T<=t) two-tail 0.343737119
t Critical two-tail 2.009575237  

The Blitz Correlate well over a sample of 50 players.  Pearson Correlation 0.83.

Can you use Rapid - YES

t-Test: Paired Two Sample for Means
  CHESSA RAPID
Mean 1287.057692 1355.769231
Variance 106863.1535 115707.632
Observations 52 52
Pearson Correlation 0.891775235
Hypothesized Mean Difference 0
df 51
t Stat -3.182183539
P(T<=t) one-tail 0.001244818
t Critical one-tail 1.67528495
P(T<=t) two-tail 0.002489635
t Critical two-tail 2.00758377  

The RAPID Correlate well over a sample of 52 players.  Pearson Correlation 0.89.

What formulas can we use for Blitz:

CHESSA = 0.726 BLITZ + 337.9

What formulas can we use for Blitz:

CHESSA = 0.857 RAPID + 125.14

SIMPLIFIED TABLES:

Chess.com: Rapid Chessa Variance Chess.com: Blitz Chessa Variance
800 811 -11 800 919 -119
1000 982 18 1000 1064 -64
1200 1154 46 1200 1209 -9
1400 1325 75 1400 1354 46
1600 1496 104 1600 1500 101
1800 1668 132 1800 1645 155
2000 1839 161 2000 1790 210
2200 2011 189 2200 1935 265
2400 2182 218 2400 2080 320
2600 2353 247 2600 2226 375
2800 2525 275 2800 2371 429
3000 2696 304 3000 2516 484

But how do I translate Chessa to FIDE or other systems:

t-Test: Paired Two Sample for Means
  CHESSA Rating FIDE Rating
Mean 2075.163934 2042.721311
Variance 19411.50601 20605.57104
Observations 61 61
Pearson Correlation 0.9101917
Hypothesized Mean Difference 0
df 60
t Stat 4.217180735
P(T<=t) one-tail 4.23698E-05
t Critical one-tail 1.670648865
P(T<=t) two-tail 8.47395E-05
t Critical two-tail 2.000297822  

The Rating systems Correlate well over a sample of 61 players.  Pearson Correlation 0.91.

FORMULA:

CHESSA = 0.857 RAPID + 125.14

OR

CHESSA = 0.726 BLITZ + 337.9

THEN

FIDE = 0.9378 CHESSA + 125.14

SUMMARY LOOKUP TABLES:

Chess.com: Rapid Chessa FIDE Variance Chess.com: Blitz Chessa FIDE Variance
800 811 885 -85 800 919 987 -119
1000 982 1046 -46 1000 1064 1123 -64
1200 1154 1207 -7 1200 1209 1259 -9
1400 1325 1368 32 1400 1354 1395 46
1600 1496 1528 72 1600 1500 1531 101
1800 1668 1689 111 1800 1645 1668 155
2000 1839 1850 150 2000 1790 1804 210
2200 2011 2011 189 2200 1935 1940 265
2400 2182 2171 229 2400 2080 2076 320
2600 2353 2332 268 2600 2226 2212 375
2800 2525 2493 307 2800 2371 2348 429
3000 2696 2654 346 3000 2516 2485 484

GO TEST IT ON YOUR RATINGS AND LET ME KNOW!

Remember the more you play the lower your RD and the more accurate your rating...