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Percentage power to detect differences between the three groups at error level (alpha) 0.05 for ANCOVA when there is a small, medium or large effect size according to Cohen (1992) for a range of sample sizes, including the recruited sample size (n = 121) and the number of completions (n = 102)
| n = 140 | n = 121 | n = 102 | n = 80 | |
|---|---|---|---|---|
| Small, f = 0.1 | 17% | 15% | 13% | 11% |
| Medium, f = 0.25 | 75% | 68% | 60% | 49% |
| Large, f = 0.4 | 99% | 98% | 95% | 89% |
