Table V. Statistical power of SNAP to distinguish between group means.
Statistical power of SNAP to distinguish between group means. Derivation of the number of animals required to determine significant differences (α = 0.05) between group means at power = 80% (left column) or 90% (right column). ΔSNAP = 2, 3, or 4, is the detectable difference between group mean scores. The overall standard deviation for the entire validation set (sham and injured) was 3.6. The group standard deviations for sham and injured animals were 1.8 (n = 37) and 2.6 (n = 88), respectively. The values were derived from the power curves for ANOVA tests (assumes equal group sizes (Glantz, 1992).
| Δ SNAP | ||||||
|---|---|---|---|---|---|---|
| # Groups compared |
Power = 80% | Power = 90% | ||||
| 2 | 3 | 4 | 2 | 3 | 4 | |
| 2 | 14 | < 6 | < 6 | 19 | 9 | < 6 |
| 3 | 16 | 6 | < 6 | 22 | 12 | 6 |
| 4 | 18 | 9 | < 6 | 26 | 18 | 8 |