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Table 11 Sample size for powering trials using WURSS-21 and WURSS-44

From: Validation of a short form Wisconsin Upper Respiratory Symptom Survey (WURSS-21)

  one-tailed α = 0.005
(two-tailed α = 0.01)
one-tailed α = 0.025
(2-tailed α = 0.05)
one-tailed α = 0.05
(two-tailed α = 0.10)
β = 0.05 0.10 0.20 0.05 0.10 0.20 0.05 0.10 0.20
Power 95% 90% 80% 95% 90% 80% 95% 90% 80%
Sample size per group needed to detect day-to-day MID (using Guyatt's responsiveness coefficient)
WURSS-21 72 60 47 52 43 32 44 35 25
WURSS-44 64 53 42 47 38 28 39 31 22
WURSS-21 – Sample size per group needed to detect between group AUC differences of:
10% 2348 1961 1540 1712 1385 1035 1426 1129 815
20% 578 483 379 421 341 255 351 278 201
30% 259 217 171 189 153 115 157 124 90
40% 147 123 97 107 87 65 89 71 51
50% 95 80 63 69 56 42 57 46 33
WURSS-44 – Sample size per group needed to detect between group AUC differences of:
10% 2787 2328 1828 2033 1644 1228 1693 1340 967
20% 697 583 458 508 411 307 423 335 242
30% 312 261 205 227 184 138 189 150 108
40% 176 147 116 128 104 78 107 85 61
50% 113 95 75 82 67 50 69 55 40