Non-Inferiority Sample Size Calculator
Introduction & Importance
Non-inferiority sample size calculation power analysis is a statistical method used to determine the minimum sample size required to demonstrate that a new treatment is not inferior to a standard treatment by a predefined margin.
This is crucial in clinical trials and other research studies to ensure that the study has a high probability of detecting a clinically meaningful difference, if one exists.
How to Use This Calculator
- Enter the significance level (α), power (1 – β), non-inferiority margin (δ), and standard deviation (σ) in the respective fields.
- Click the “Calculate” button.
- View the results below the calculator, including the required sample size and a chart illustrating the power curve.
Formula & Methodology
The formula used in this calculator is based on the one-sided z-test for non-inferiority. The required sample size (N) is calculated as:
N = (Z_α + Z_β)² * σ² / δ²
Real-World Examples
Data & Statistics
| Sample Size (N) | Power (1 – β) |
|---|
| δ | N |
|---|
Expert Tips
- Always consult with a statistician when designing a study to ensure the sample size is appropriate.
- Consider using a software tool for power analysis to account for complex study designs and multiple endpoints.
- Regularly review and update your power analysis as the study progresses to account for any changes in assumptions or parameters.
Interactive FAQ
What is the difference between superiority and non-inferiority trials?
In a superiority trial, the goal is to demonstrate that a new treatment is better than the standard treatment. In a non-inferiority trial, the goal is to show that the new treatment is not worse than the standard treatment by a predefined margin.