Two Sample Proportion Sample Size Calculator
Two sample proportion sample size calculation is a crucial step in designing clinical trials or any study involving two groups. It helps determine the number of participants needed to detect a significant difference between the two groups with a given level of confidence.
How to Use This Calculator
- Select the significance level (α).
- Enter the desired power (1 – β).
- Enter the proportions in Group 1 (p1) and Group 2 (p2).
- Click “Calculate”.
Formula & Methodology
The formula used in this calculator is based on the work of Campbell and Gardner (1988). It involves calculating the non-centrality parameter and then solving for the sample size using numerical methods.
Real-World Examples
Data & Statistics
| Significance Level (α) | Power (1 – β) | Sample Size per Group |
|---|---|---|
| 0.05 | 0.8 | 64 |
| 0.05 | 0.9 | 106 |
Expert Tips
- Always round up the calculated sample size to the nearest whole number.
- Consider using a software tool for complex calculations.
- Regularly review and update your sample size calculation as new data becomes available.
Interactive FAQ
What is the significance level (α)?
The significance level (α) is the probability of rejecting the null hypothesis when it is true. It is typically set at 0.05.