Perform ANOM Levene Robust Variances

How Do I Perform ANOM Levene Robust Variances Test in Excel Using SigmaXL?

The ANOM Levene Robust Variances chart is complementary to Levenes Test for Equal Variance and is also available as an option in the Levenes Test dialog. Since it uses absolute deviations from the median, it is robust to the assumption of normality.

1. Open Customer Data.xlsx, click on Sheet 1 tab.
   
   
2. Click SigmaXL > Graphical Tools > Analysis of Means (ANOM) > ANOM Levene Robust
   Variances. Ensure that the entire data table is selected. If not, check Use Entire Data Table.
   
   
3. Click Next. Ensure that Stacked Column Format is checked. Select Responsive to Calls, click
   Numeric Data Variable (Y) >>; select Customer Type, click Group Category (X) >>; Set Alpha
   Level = 0.05.
   
   
   
   We are analyzing the same nonnormal data used in Levenes Test for Equal Variances.
   
   
4. Click OK. The ANOM Levene Robust Variances chart is displayed:
   
   
   
   
5. The ANOM chart clearly shows Customer Type 1 has significantly higher variance (ADM) than
   overall and Customer Type 2 has significantly lower variance.
   
   
6. The varying decision limits are due to the varying sample sizes for each Customer Type, with
   smaller sample size giving wider limits in a manner similar to a control chart. If the data are
   balanced the decision limit lines will be constant.