Table 2 Sample size calculations to detect a 10 minute difference in child weekend day moderate-to-vigorous physical activity between intervention and control groups
SD (mins) | α | β | N required per group | Total N required for analysis | Total N inflated for attrition | Total N rounded and based on 10 participants per course group | Number of intervention groups$ | Number of control groups$ |
|---|---|---|---|---|---|---|---|---|
12 | .80 | .05 | 23 | 46 | 62.1 | 80 | 4 | 4 |
12 | .80 | .01 | 34 | 68 | 91.8 | 100 | 5 | 5 |
12 | .90 | .05 | 31 | 62 | 83.7 | 100 | 5 | 5 |
12 | .90 | .01 | 43 | 86 | 116.1 | 120 | 6 | 6 |
17 | .80 | .05 | 46 | 92 | 124.2 | 140 | 7 | 7 |
17 | .80 | .01 | 68 | 136 | 183.6 | 200 | 10 | 10 |
17 | .90 | .05 | 61 | 122 | 164.7 | 180 | 9 | 9 |
17 | .90 | .01 | 87 | 174 | 234.9 | 240 | 12 | 12 |
20 | .80 | .05 | 63 | 126 | 170.1 | 180 | 9 | 9 |
20 | .80 | .01 | 94 | 188 | 253.8 | 260 | 13 | 13 |
20 | .90 | .05 | 85 | 170 | 229.5 | 240 | 12 | 12 |
20 | .90 | .01 | 120 | 240 | 324 | 340 | 17 | 17 |