For example, a quality engineer at an automobile manufacturer wants to compare the variance in the diameters of the camshafts produced by two different vendors. If the variances from the two vendors are different, the engineer uses the confidence interval to determine whether the difference is practically significant.
The 2 variances test is useful for quality improvement situations. You can use this test to compare the variance within subgroups to the variance between subgroups. Also, you can use this test to compare the process variance before and after you implement a quality improvement program.
To perform a 2 variances test, choose.