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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