Groups Variable Use thi option to indicate a variable that associate observations with groups. Each group will have its own variance component for the residual error. Refer to the BGLR R Package documentation for further details. To Specify a Group Variable: Specify the Input SAS Data Set. All of the variables in the specified input data set are displayed in the Available Variables field. Examine the list of available variables. Highlight the variable whose values indicate how the samples are grouped. Click to add the highlighted variable to the Groups Variable field, as shown below: