Author: Odd Gunnar Malin
Date: 23:30:40 04/20/05
Go up one level in this thread
Well, hard to stop when first started :)
Here is a graphic picture of each curve:
http://home.online.no/~malin/sjakk/elo.gif
The numbers:
Score FIDE Log10 Norm.dist. Schmitt W-L Groot
0,50 0 0 0 0 0 0
0,51 7 7 7 7 8 7
0,52 14 14 14 14 16 14
0,53 21 21 21 21 24 21
0,54 29 28 28 28 32 28
0,55 36 35 36 36 40 36
0,56 43 42 43 43 48 43
0,57 50 49 50 50 56 50
0,58 57 56 57 57 64 57
0,59 65 63 64 65 72 64
0,60 72 70 72 72 80 72
0,61 80 78 79 79 88 79
0,62 87 85 86 87 96 86
0,63 95 92 94 94 104 94
0,64 102 100 101 102 112 101
0,65 110 108 109 110 120 109
0,66 117 115 117 117 128 117
0,67 125 123 124 125 136 124
0,68 133 131 132 133 144 132
0,69 141 139 140 142 152 140
0,70 149 147 148 150 160 148
0,71 158 156 157 158 168 156
0,72 166 164 165 167 176 165
0,73 175 173 173 175 184 173
0,74 184 182 182 184 192 182
0,75 193 191 191 193 200 191
0,76 202 200 200 202 208 200
0,77 211 210 209 211 216 209
0,78 220 220 218 221 224 218
0,79 230 230 228 231 232 228
0,80 240 241 238 241 240 238
0,81 251 252 248 251 248 248
0,82 262 263 259 262 256 258
0,83 273 275 270 273 264 269
0,84 284 288 281 284 272 280
0,85 296 301 293 296 280 292
0,86 309 315 306 309 288 304
0,87 322 330 319 322 296 316
0,88 336 346 332 336 304 330
0,89 351 363 347 350 312 343
0,90 366 382 362 366 320 358
0,91 383 402 379 383 328 373
0,92 401 424 397 401 336 389
0,93 422 449 417 421 344 405
0,94 444 478 440 443 352 423
0,95 470 512 465 469 360 441
0,96 501 552 495 499 368 461
0,97 538 604 532 539 376 480
0,98 589 676 581 597 384 500
0,99 677 798 658 685 392 520
1,00 757 400 539
Your formula put into Excel format (basic):
Function phi(x)
p = 0.2316419
c1 = 0.31938153
c2 = -0.356563782
c3 = 1.78147937
c4 = -1.821255978
c5 = 1.330274429
Pi = 3.14159265358979
sndf = Exp(-(x * x) / 2) / Sqr(2 * Pi)
t = 1 / (p * x + 1)
phi = ((((c5 * t + c4) * t + c3) * t + c2) * t + c1) * t * sndf
End Function
Function Rtdiff(Performance)
tol = 0.0001
sdev = 200 * Sqr(2)
Rtdiff = (Performance - 0.5) * 700
delta = 1
Do While delta >= tol
Iteration = phi(-Rtdiff / sdev)
delta = Performance - Iteration
Rtdiff = Rtdiff + delta * 700
Loop
End Function
Put these in a macro and set a sell to f.ex. '=Rtdiff(0,68)'
Odd Gunnar
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Last modified: Thu, 15 Apr 21 08:11:13 -0700
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