Table 9.
Number of replications, readers, and cases needed to achieve .80 power to detect a .04 AUC difference between soft- and hard-copy radiographs using a factorial study design, based on estimates from the Kundel et al [9] data, an assumed within-reader within-replication correlation of 0.60, and alpha = .05.
| replications (n) | readers (r) | cases (c) | power |
|---|---|---|---|
| 1 | 4 | 585 | 0.800 |
| 1 | 5 | 366 | 0.801 |
| 1 | 6 | 266 | 0.800 |
| 1 | 7 | 210 | 0.802 |
| 1 | 8 | 173 | 0.801 |
| 2 | 4 | 348 | 0.800 |
| 2 | 5 | 218 | 0.801 |
| 2 | 6 | 158 | 0.800 |
| 2 | 7 | 125 | 0.802 |
| 2 | 8 | 103 | 0.802 |