Determine the minimum sample size needed to estimate a population proportion or population mean with a given confidence level and margin of error.
Estimates sample size to determine a population proportion p within margin of error E.
Formula: n = z²·p·(1−p) / E²
| Parameter | Value |
|---|---|
| Confidence Level | 95% |
| Critical value (z*) | 1.96 |
| Proportion (p) | 0.5 |
| 1 − p = q | 0.5 |
| Margin of Error (E) | ±0.05 (5.0%) |
| Unadjusted n₀ | 385 |
| Required n | 385 |
| Margin of Error | n (95% CI) | n (99% CI) |
|---|---|---|
| ±1% | 9,604 | 16,587 |
| ±2% | 2,401 | 4,147 |
| ±3% | 1,067 | 1,843 |
| ±4% | 600 | 1,037 |
| ±5% | 384 | 664 |
| ±10% | 96 | 166 |