Table 4 Power calculation
Treatment group mean / Treatment effect (contrast) | Width of two-sided 95 % confidence interval from point estimate to limit (units in standardized ODI) | Power of pairwise t-test to detect a difference in change from baseline of 10 units in ODI | |
|---|---|---|---|
ODI sum score (SD = 12 points) | Change in ODI (SD = 14.7 points = 12*sqrt (2(1-r)) when r = 0.25 | Change in ODI (SD = 14.7 points = 12*sqrt (2(1-r)) when r = 0.25 | |
SC (n = 24) | 4.80 | 5.88 | – |
NDbasic (n = 36) | 3.92 | 4.80 | – |
NDplus (n = 60) | 3.04 | 3.72 | – |
NDbasic (n = 36) versus SC (n = 24) | 6.20 | 7.59 | 71 % |
NDplus (n = 60) versus SC (n = 24) | 5.68 | 6.96 | 79 % |
NDplus (n = 60) versus NDbasic (n = 36) | 4.96 | 6.07 | 89 % |