SAS/LAB software provides facilities for adding a new variable to the current data set. You can specify a formula to be used to assign values to the variable, or you can request blank values so that you can specify values later by editing the data set.
To bring up the window for defining a new variable, select 'Modify' from the File pull-down menu on the main window. Select 'Add a new variable...' from the resulting list.
If you want to create a new variable that is a simple transformation or recoding of an existing variable in the same data set, you may want to select 'Transform a variable...' or 'Recode a variable...' from the Modify list instead.
Note that you must have write access to the data set to be able to add variables. Variables cannot be added to views.