Use the test for equal variances to determine whether the variances or the standard deviations of two or more groups differ. You must have at least one categorical factor and a continuous response.
For example, a lumber distributor wants to compare the variation of beam lengths that are cut by three sawmills. If any sawmill produces beams that have significantly more variation, the distributor may stop selling lumber from that sawmill.
To perform a test for equal variances, choose .