Sentry Page Protection
Processing BY Groups
(SBS Module 13)

The (first.variable) and (last.variable) are two temporary variables created in the PDV.

They are used to identify the first and last observation in each BY group.

In this module, you will learn:
  • How the (first.variable) and (last.variable) are created.
  • How to identify the first and last observation within each BY group.
  • How to perform cumulative summation over BY groups.