Power Sample Size Calculator Proportion
Introduction & Importance
The power sample size calculator proportion is an essential tool for determining the appropriate sample size for a study. It ensures that your study has a high probability of detecting a significant effect if one exists.
How to Use This Calculator
- Enter the desired significance level (α), power (1 – β), proportion (p), and effect size (d).
- Click ‘Calculate’.
- View the results in the ‘Results’ section.
- Interpret the chart for a visual representation of the calculations.
Formula & Methodology
The formula used in this calculator is based on the work of Cohen (1988) and is as follows:
n = (Z_α/2 + Z_β)² * p * (1 – p) / d²
Real-World Examples
Data & Statistics
| Effect Size (d) | Sample Size (n) |
|---|---|
| 0.2 | 384 |
| 0.5 | 64 |
| 0.8 | 25 |
Expert Tips
- Always round up the calculated sample size to the nearest whole number.
- Consider practical constraints when interpreting the results.
- Regularly review and update your calculations as your study progresses.
Interactive FAQ
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.
For more information, see the power calculator from Simstat.
You can also refer to the sample size calculator from Statistics How To.