Use to calculate one of the following parameters for an equivalence test with paired data:

·    Sample size

·    Difference (or ratio)

·    Power

When you enter values for any two of these parameters, Minitab solves for the third. See Power for equivalence tests for further discussion.

You developed a new cleaning solution for contact lenses. You want to verify that your new solution cleans lenses as well as the leading brand. You ask participants to wear contact lenses for a day, and then clean the lenses. Each participant cleans one lens in your solution and the other lens in the leading brand. By pairing the observations, you reduce the amount of variability that is caused by differences between participants. Finally, you assess the cleanliness of each lens by measuring the angle of contact for a drop of fluid on the lens. The angle of contact is affected by film or deposits on the lens.

You want to determine the sample size that is required to achieve a power of 0.9 for the test. From previous samples, you estimate that the standard deviation is 0.42.