Use this field to specify the design
variables
whose values distinguish the groups of desired columns.

Select this option when you want to compute
means
within groups of columns in the input data set. Means within each group will be computed and considered to be the data columns for all

distribution
calculations.

An output data set with suffix
_dgm
will be created containing the mean columns, and an output experimental design data set with suffix

_dge
will also be generated to accompany it.

When you specify grouping variables,
standard deviation
versus Mean plots can also be constructed for each group. These are useful for quality control when columns within a group are replicates of one particular set of treatment conditions. In this case, specify the treatment variables of interest here as the grouping variables.