Table 1 Precision of estimated incidence of stroke for different levels of incidence, and confidence intervals on effect sizes for quantitative measures
| Â | Width of 95% confidence interval | ||
|---|---|---|---|
Expected incidence of stroke | Sample size of retrospective patients: 417 | Cohort size of prospective patients: 833 | Total sample size of 4,582 |
2.5% | ±1.5% | ±1.1% | ±0.5% |
5% | ±2.1% | ±1.5% | ±0.6% |
10% | ±2.9% | ±2.0% | ±0.9% |
20% | ±3.8% | ±2.7% | ±1.2% |
30% | ±4.4% | ±3.1% | ±1.3% |
40% | ±4.7% | ±3.3% | ±1.4% |
50% | ±4.8% | ±3.4% | ±1.4% |
Width of 95% confidence interval | |||
Sample size of retrospective patients: 417 | Cohort size of prospective patients: 833 | Total sample size of 4,582 | |
0.14 | 0.10 | 0.04 | |