Sample Size Calculation for Two Sample Proportion Test
Sample size calculation for a two sample proportion test is crucial for ensuring that your study has enough participants to detect a significant difference between two groups. This calculator helps you determine the appropriate sample size for your research.
- Enter the significance level (α), typically 0.05.
- Enter the desired power, usually 0.8 or 0.9.
- Enter the expected proportions in both groups (p1 and p2).
- Click “Calculate” to see the required sample size for each group and the total.
The calculator uses the following formula to calculate the sample size:
n = [(Z_α/2 + Z_β)² * (p1 * (1 - p1) + p2 * (1 - p2))] / (p1 - p2)²
| Power | Sample Size (n) |
|---|---|
| 0.8 | 78.4 |
| 0.9 | 109.6 |
- Always round up the calculated sample size to ensure you have enough participants.
- Consider using a software tool for more complex calculations.
What is the significance level (α)?
The significance level is the probability of rejecting the null hypothesis when it is true. It is typically set at 0.05.