Overview for Power and Sample Size for 2x2 Crossover Design Equivalence Test

Use Power and Sample Size for 2x2 Crossover Design Equivalence Test to examine the relationship between power, sample size, and difference when you want to evaluate the equivalence of a test drug and a reference drug using a 2x2 crossover study.

Use these calculations for the following reasons:

Before you collect data for an equivalence test for a 2x2 crossover design, to ensure that your design has an adequate sample size to achieve acceptable power
After an equivalence test for a 2x2 crossover design, to improve the design for the next study

For example, an analyst plans a 2x2 crossover study to determine whether a generic antacid is equivalent to a name-brand antacid. Two groups of participants will receive a 5-day course of one antacid, followed by a 2-week washout period, and then a 5-day course of the other antacid. Each group will be given the antacids in a different sequence.

Before initiating the study and collecting data, the analyst uses a power and sample size calculation to determine the number of participants that are needed in each sequence of the study to obtain a power of 80% (0.8).

Where to find this analysis

To perform a power and sample size calculation for an equivalence test for a 2x2 crossover design, choose Stat > Power and Sample Size > Equivalence Tests > 2x2 Crossover Design.

When to use an alternate analysis

If your data is not from a 2x2 crossover study, do not use this analysis. For more information, go to What is a 2x2 crossover design?.
If you plan to collect two independent samples (such as samples from two different groups of patients in a parallel study design), use Power and Sample Size for 2-Sample Equivalence Test.
If you plan to collect only one set of paired (dependent) observations on the same person or item, use Power and Sample Size for Equivalence Test with Paired Data.