Use this field to specify a BY variable from the
Experimental Design SAS Data Set to use in your analysis. Separate analyses are conducted for distinct levels of the
BY group variable.
BY variables are optional (in most processes) variable specifications whose values define groups of
observations, such as hour, month, or year. BY variables can enable analyses to be performed separately on different groups as defined by that variable. Choosing a BY variable such as gender, for example, groups the subjects by gender and conducts two separate analyses: one for males and one for females.