26  Appendix 2

Duncan’s multiple range test is one of the most widely used post-hoc procedures for comparing treatment means once an ANOVA has shown a significant difference among them. Table 26.1 gives the critical values \(r_p (p, df, \alpha = 0.05)\) needed to carry out the test, tabulated against the error degrees of freedom (rows) and the number of means being compared, \(p\) (columns).

Table 26.1: Critical values \(r_p (p, df, \alpha = 0.05)\) for Duncan’s multiple range tests.
\(df \backslash p\) 2 3 4 5 6 7 8 9 10 11 12 15 20
1 17.969 17.969 17.969 17.969 17.969 17.969 17.969 17.969 17.969 17.969 17.969 17.969 17.969
2 6.085 6.085 6.085 6.085 6.085 6.085 6.085 6.085 6.085 6.085 6.085 6.085 6.085
3 4.501 4.516 4.516 4.516 4.516 4.516 4.516 4.516 4.516 4.516 4.516 4.516 4.516
4 3.926 4.013 4.033 4.033 4.033 4.033 4.033 4.033 4.033 4.033 4.033 4.033 4.033
5 3.635 3.749 3.796 3.814 3.814 3.814 3.814 3.814 3.814 3.814 3.814 3.814 3.814
6 3.46 3.586 3.649 3.68 3.694 3.697 3.697 3.697 3.697 3.697 3.697 3.697 3.697
7 3.344 3.477 3.548 3.588 3.611 3.622 3.625 3.625 3.625 3.625 3.625 3.625 3.625
8 3.261 3.398 3.475 3.521 3.549 3.566 3.575 3.579 3.579 3.579 3.579 3.579 3.579
9 3.199 3.339 3.42 3.47 3.502 3.523 3.536 3.544 3.547 3.547 3.547 3.547 3.547
10 3.151 3.293 3.376 3.43 3.465 3.489 3.505 3.516 3.522 3.525 3.525 3.525 3.525
11 3.113 3.256 3.341 3.397 3.435 3.462 3.48 3.493 3.501 3.506 3.509 3.51 3.51
12 3.081 3.225 3.312 3.37 3.41 3.439 3.459 3.474 3.484 3.491 3.495 3.498 3.498
13 3.055 3.2 3.288 3.348 3.389 3.419 3.441 3.458 3.47 3.478 3.484 3.49 3.49
14 3.033 3.178 3.268 3.328 3.371 3.403 3.426 3.444 3.457 3.467 3.474 3.484 3.484
15 3.014 3.16 3.25 3.312 3.356 3.389 3.413 3.432 3.446 3.457 3.465 3.478 3.48
16 2.998 3.144 3.235 3.297 3.343 3.376 3.402 3.422 3.437 3.449 3.458 3.473 3.477
17 2.984 3.13 3.222 3.285 3.331 3.365 3.392 3.412 3.429 3.441 3.451 3.469 3.475
18 2.971 3.117 3.21 3.274 3.32 3.356 3.383 3.404 3.421 3.435 3.445 3.465 3.474
19 2.96 3.106 3.199 3.264 3.311 3.347 3.375 3.397 3.415 3.429 3.44 3.462 3.474
20 2.95 3.097 3.19 3.255 3.303 3.339 3.368 3.39 3.409 3.423 3.435 3.459 3.473
21 2.941 3.088 3.181 3.247 3.295 3.332 3.361 3.385 3.403 3.418 3.431 3.456 3.473
22 2.933 3.08 3.173 3.239 3.288 3.326 3.355 3.379 3.398 3.414 3.427 3.453 3.472
23 2.926 3.072 3.166 3.233 3.282 3.32 3.35 3.374 3.394 3.41 3.423 3.451 3.472
24 2.919 3.066 3.16 3.226 3.276 3.315 3.345 3.37 3.39 3.406 3.42 3.449 3.472
25 2.913 3.059 3.154 3.221 3.271 3.31 3.341 3.366 3.386 3.403 3.417 3.447 3.471
26 2.907 3.054 3.149 3.216 3.266 3.305 3.336 3.362 3.382 3.4 3.414 3.445 3.471
27 2.902 3.049 3.144 3.211 3.262 3.301 3.332 3.358 3.379 3.397 3.412 3.443 3.471
28 2.897 3.044 3.139 3.206 3.257 3.297 3.329 3.355 3.376 3.394 3.409 3.442 3.47
29 2.892 3.039 3.135 3.202 3.253 3.293 3.326 3.352 3.373 3.392 3.407 3.44 3.47
30 2.888 3.035 3.131 3.199 3.25 3.29 3.322 3.349 3.371 3.389 3.405 3.439 3.47
31 2.884 3.031 3.127 3.195 3.246 3.287 3.319 3.346 3.368 3.387 3.403 3.438 3.47
32 2.881 3.028 3.123 3.192 3.243 3.284 3.317 3.344 3.366 3.385 3.401 3.436 3.47
33 2.877 3.024 3.12 3.188 3.24 3.281 3.314 3.341 3.364 3.383 3.399 3.435 3.47
34 2.874 3.021 3.117 3.185 3.238 3.279 3.312 3.339 3.362 3.381 3.398 3.434 3.469
35 2.871 3.018 3.114 3.183 3.235 3.276 3.309 3.337 3.36 3.379 3.396 3.433 3.469
36 2.868 3.015 3.111 3.18 3.232 3.274 3.307 3.335 3.358 3.378 3.395 3.432 3.469
37 2.865 3.013 3.109 3.178 3.23 3.272 3.305 3.333 3.356 3.376 3.393 3.431 3.469
38 2.863 3.01 3.106 3.175 3.228 3.27 3.303 3.331 3.355 3.375 3.392 3.431 3.469
39 2.861 3.008 3.104 3.173 3.226 3.268 3.301 3.33 3.353 3.373 3.391 3.43 3.469
40 2.858 3.005 3.102 3.171 3.224 3.266 3.3 3.328 3.352 3.372 3.389 3.429 3.469
48 2.843 2.991 3.087 3.157 3.211 3.253 3.288 3.318 3.342 3.363 3.382 3.424 3.468
60 2.829 2.976 3.073 3.143 3.198 3.241 3.277 3.307 3.333 3.355 3.374 3.419 3.468
80 2.814 2.961 3.059 3.13 3.185 3.229 3.266 3.297 3.323 3.346 3.366 3.414 3.467
120 2.8 2.947 3.045 3.116 3.172 3.217 3.254 3.286 3.313 3.337 3.358 3.409 3.466
240 2.786 2.933 3.031 3.103 3.159 3.205 3.243 3.276 3.304 3.329 3.35 3.404 3.466
\(\infty\) 2.772 2.918 3.017 3.089 3.146 3.193 3.232 3.265 3.294 3.32 3.343 3.399 3.466