For example, managers of a car manufacturer want to compare the variances for the diameters of camshafts for two different vendors. Before collecting the data for a 2 variances test, the manufacturer uses a power and sample size calculation to determine the smallest ratio a test with a specific power value for a given sample size can detect.
This test is useful for quality improvement situations: you can use this test to compare variance within subgroups to variance between subgroups. Also, you can use this test to compare process variance before and after implementation of a quality improvement program.
To perform a power and sample size calculation for a 2 variances test, choose.