Comment on Levy’s “An Empirical Comparison of the Z-variance and Box-Scheffé Tests for Homogeneity of Variance”

An alternative selection of subsample sizes for the Box-Scheffé test is compared to the single m used in Levy, “An empirical comparison of the Z-variance and Box-Scheffé tests for homogeneity of variance.” Use of the alternative subsample sizes is shown to suggest greater power for the Box-Scheffé test, although the test would still be less powerful than the Z-variance test. Because of the nonrobustness of the Z-variance test and the robustness of the Box-Scheffé test, the latter is recommended as a general technique unless an experimenter has assurance that all populations in the experiment are normal. Alternative techniques are also considered.