Table 2.
Sample sizes required for different combinations of power and relative control versus intervention six-month abstinence rates
| |
|
Trial with 80% power |
Trial with 90% power |
|---|---|---|---|
| % prolonged abstinence in control | % prolonged abstinence in intervention | Number/arm | Number/arm |
| RR = 1.3 |
|
|
|
| 14 |
18.2 |
1249 |
1655 |
| 15 |
19.5 |
1150 |
1524 |
| 16 |
20.8 |
1064 |
1409 |
| 20 |
26 |
805 |
1065 |
| RR = 1.4 |
|
|
|
| 14 |
19.6 |
734 |
970 |
| 15 |
21 |
676 |
893 |
| 16 |
22.4 |
625 |
825 |
| 20 |
28 |
471 |
622 |
| RR = 1.5 |
|
|
|
| 14 |
21 |
490 |
646 |
| 15 |
22.5 |
451 |
594 |
| 16 |
24 |
416 |
549 |
| 20 | 30 | 313 | 412 |