Heterogeneity of Variance Tests

Note: See Example of the Heterogeneity of Variance Test.

The Heterogeneity of Variance Tests option performs a test for comparing variances across groups. The test is an Analysis of Means for Variances (ANOMV) based method. This method indicates whether any of the group standard deviations are different from the square root of the average group variance.

To be robust against non-normal data, the method uses a permutation simulation to compute decision limits. For complete details about this method, see Wludyka and Sa (2004). Because the method uses simulations, the decision limits can be slightly different each time. To obtain the same results each time, hold down CTRL and SHIFT and select the option, and then specify the same random seed.

The red triangle menus for the test reports contain the following options:

Set Alpha Level

Sets the alpha level for the test.

Show Summary Report

Shows or hides a summary report for the test. The values in the report are the same values that are shown in the plot.

Display Options

Shows or hides the decision limits, shading, center line, and needles.