Power Analysis to Determine Sample Size Calculator
Expert Guide to Power Analysis for Sample Size Determination
Introduction & Importance
Power analysis is a crucial step in designing a study. It helps determine the sample size required to detect an effect of a given size with a specified level of confidence…
How to Use This Calculator
- Enter the desired significance level (α).
- Enter the desired power.
- Enter the expected effect size.
- Click ‘Calculate’.
Formula & Methodology
The formula used in this calculator is based on Cohen’s power analysis…
Real-World Examples
Example 1: A Clinical Trial
Suppose you’re planning a clinical trial to test a new drug for lowering cholesterol…
Data & Statistics
| Formula | Description |
|---|---|
| n = (Z_α/2 + Z_β)^2 / E^2 | Sample size formula |
| β = Z_α/2^2 / (Z_α/2^2 + E^2 * n) | Type II error probability formula |
Expert Tips
- Always round up the calculated sample size to the nearest whole number.
- Consider using a power analysis software for more complex designs.
Interactive FAQ
What is power in the context of power analysis?
Power is the probability of detecting an effect when there is one…
CDC’s StatCalc and UNC’s Power Analysis are excellent resources for further learning.