Table 1.
Power estimates for main effects of a continuous predictor and experimental condition
| Continuous Predictor | |||||||||
| Two-tailed p < .05 | One-tailed p < .05 | ||||||||
| N | r = .10 | r = .15 | r = .20 | r = .30 | r = .10 | r = .15 | r = .20 | r = .30 | |
| 50 | 9% | 15% | 26% | 51% | 18% | 26% | 39% | 64% | |
| 100 | 17% | 25% | 46% | 82% | 24% | 40% | 60% | 90% | |
| 150 | 20% | 39% | 63% | 93% | 30% | 52% | 74% | 96% | |
| 200 | 25% | 52% | 79% | 98% | 37% | 64% | 86% | 100% | |
| 250 | 33% | 60% | 86% | 99% | 43% | 73% | 92% | 100% | |
| 300 | 39% | 69% | 91% | 100% | 50% | 78% | 95% | 100% | |
| 350 | 38% | 76% | 93% | 100% | 53% | 85% | 97% | 100% | |
| 400 | 47% | 82% | 96% | 100% | 61% | 89% | 98% | 100% | |
| 450 | 52% | 85% | 98% | 100% | 64% | 92% | 99% | 100% | |
| 500 | 57% | 87% | 99% | 100% | 68% | 92% | 99% | 100% | |
| 750 | 72% | 96% | 100% | 100% | 81% | 98% | 100% | 100% | |
| 1,000 | 83% | 100% | 100% | 100% | 90% | 100% | 100% | 100% | |
| 2,500 | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% | |
| Experimental Condition | |||||||||
| Two-tailed p < .05 | One-tailed p < .05 | ||||||||
| N | d = .20 | d = .30 | d = .41 | d = .63 | d = .20 | d = .30 | d = .41 | d = .63 | |
| 50 | 10% | 19% | 24% | 53% | 16% | 26% | 39% | 65% | |
| 100 | 16% | 30% | 46% | 85% | 25% | 42% | 59% | 90% | |
| 150 | 23% | 45% | 63% | 96% | 32% | 56% | 77% | 98% | |
| 200 | 25% | 48% | 75% | 98% | 36% | 62% | 84% | 99% | |
| 250 | 30% | 62% | 87% | 100% | 41% | 73% | 92% | 100% | |
| 300 | 33% | 71% | 89% | 100% | 50% | 82% | 95% | 100% | |
| 350 | 45% | 73% | 95% | 100% | 57% | 83% | 98% | 100% | |
| 400 | 46% | 78% | 96% | 100% | 56% | 86% | 98% | 100% | |
| 450 | 51% | 88% | 98% | 100% | 63% | 93% | 99% | 100% | |
| 500 | 55% | 89% | 99% | 100% | 66% | 93% | 100% | 100% | |
| 750 | 74% | 97% | 100% | 100% | 81% | 99% | 100% | 100% | |
| 1,000 | 83% | 100% | 100% | 100% | 90% | 100% | 100% | 100% | |
| 2,500 | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% | |
Note: r and d represent the main effect size for continuous predictor and experimental condition, respectively; for the continuous predictor and the dependent variable, we assumed α = .85; for the experimental condition, we assumed α = 1.