# Data considerations for Multi-Vari Chart

To ensure that your results are valid, consider the following guidelines when you collect data, perform the analysis, and interpret your results.

The response should be numeric
To calculate the mean response at different factor levels, the multi-vari chart requires numeric response data.
Each factor should have at least 2 levels
You may have up to four numeric, text, or date/time factors. Each factor must have at least 2 levels.
You must have observations for enough factor level combinations
You need observations for at least 60% of all possible factor level combinations for Minitab to create the chart.
Suppose you are studying two factors, A and B. Factor A has three levels and Factor B has two levels. There are six possible combinations of factor levels (cells) in this design. If data are not included for one of these combinations, it creates an empty cell (*).
Three of the six factor level combinations, do not have observations. Thus, Minitab cannot create a multi-vari chart.
C1 C2 C3
A B Observations
A 1 *
B 1 20
C 1 *
A 2 22
B 2 *
C 2 21
A 1 *
B 1 23
C 1 *
... ... ...