Skip to main content
. Author manuscript; available in PMC: 2012 Feb 1.
Published in final edited form as: Acad Radiol. 2011 Feb;18(2):129–142. doi: 10.1016/j.acra.2010.09.007

Table 5.

Combinations of cases and readers having .80 power to detect a .05 AUC difference between spin-echo and cine MRI based on the Van Dyke et al [21] data. The pilot-study estimate of σ^TR2 was negative. The left-hand-side results are for a planned study that has the same normal-to-abnormal ratio as the pilot study; the right-hand-side results are for a planned study that has equal numbers of normal and abnormal cases.

normal/abnormal ratio = 69/45 = 1.53
normal/abnormal ratio = 1
σ^TR2=0
σ^TR2=.0001
σ^TR2=0
σ^TR2=.0001
Readers Cases Power Cases Power Cases Power Cases Power
3 559 0.800 1898 0.800 374 0.800 1282 0.800
4 343 0.800 491 0.800 229 0.800 328 0.800
5 266 0.801 330 0.801 177 0.801 220 0.801
6 225 0.800 263 0.800 150 0.801 176 0.802
7 200 0.800 227 0.801 133 0.800 151 0.801
8 183 0.800 203 0.801 122 0.801 135 0.801
9 171 0.801 187 0.802 114 0.802 124 0.801
10 162 0.802 174 0.800 108 0.803 116 0.802
11 154 0.800 165 0.801 103 0.803 110 0.803
12 148 0.800 158 0.802 99 0.803 105 0.803
13 143 0.800 151 0.800 95 0.801 101 0.803
14 139 0.801 146 0.800 93 0.804 97 0.801
15 136 0.802 142 0.801 90 0.801 94 0.800