Overview for Power and Sample Size for 2-Sample Equivalence Test

Use Power and Sample Size for 2-Sample Equivalence Test to examine the relationship between power, sample size, and difference when you want to evaluate the equivalence between the test mean and the reference mean of independent samples.

Use these calculations for the following reasons:

Before you collect data for a 2-sample equivalence test, to ensure that your design has an adequate sample size to achieve acceptable power
After a 2-sample equivalence test, to improve the design for the next study

For example, a quality analyst wants to determine whether the mean amount of active ingredient in a generic brand of pain reliever is within 1 mg of the mean amount in a popular brand of pain reliever. Before collecting the data for a 2-sample equivalence test, the analyst uses a power and sample size calculation to determine how large the sample size must be to obtain a power of 90% (0.9).

Where to find this analysis

To perform a power and sample size calculation for a 2-sample equivalence test, choose Stat > Power and Sample Size > Equivalence Tests > 2-Sample.

When to use an alternate analysis

If you have paired or dependent data, such as pairs of observations for the same person, use Power and Sample Size for Equivalence Test with Paired Data instead. For more information, go to How are dependent and independent samples different?.