|
Designs with minimum cost among designs with 80% power of detecting the interaction |
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| Gene-surrogate |
Flexible two-phase design options |
Expected Phase One counts |
Power# |
Cost* |
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|
|
|||||||||
| Spec |
Sens |
n0 |
n1 |
ρ0† |
ρ1‡ |
N0 |
N1 |
||
|
|
|||||||||
| 70% |
80% |
700 |
500 |
90% |
80% |
5163 |
1525 |
81% |
1534 |
| 70% |
90% |
600 |
500 |
90% |
80% |
4412 |
1472 |
80% |
1394 |
| 80% |
60% |
700 |
300 |
90% |
90% |
7721 |
1491 |
80% |
1461 |
| 80% |
70% |
600 |
300 |
90% |
80% |
6585 |
1259 |
80% |
1292 |
| 80% |
80% |
500 |
300 |
90% |
80% |
5461 |
1200 |
80% |
1133 |
| 80% |
90% |
400 |
400 |
90% |
80% |
4348 |
1528 |
81% |
1094 |
| 90% |
60% |
400 |
400 |
70% |
50% |
6667 |
1683 |
81% |
1217 |
| 90% |
70% |
500 |
300 |
50% |
50% |
5896 |
1169 |
80% |
1153 |
| 90% |
80% |
500 |
300 |
40% |
60% |
4673 |
1307 |
80% |
1099 |
| 90% |
90% |
500 |
300 |
40% |
50% |
4630 |
1019 |
82% |
1082 |
|
# Analysis approach: Maximum likelihood * the study cost is computed as the sum of the number of screened subjects divided by 20 plus the number of subjects included in Phase Two. † ρ0 is the proportion of SG+ controls included in Phase Two ‡ ρ1 is the proportion of SG+ cases included in Phase Two | |||||||||
Wild et al. Epidemiologic Perspectives & Innovations 2008 5:4 doi:10.1186/1742-5573-5-4 |
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