Step 1: Examine the average measurement with variation
Use the multi-vari charts as a preliminary tool to investigate variation in your data, including cyclical variations and interactions between factors.An interaction occurs when the change in response from one level of a factor to another level depends upon the level of another factor.
The multi-vari chart displays a mean for each combination of factor levels. In Minitab, each multi-vari chart can display up to eight factors.
Step 2: Examine the standard deviation chart
Multi-vari charts are also used to examine the variability between factor levels.