So I'm reading this (below) in the documentation... In BY-group processing, you can use data that is arranged in an order other than alphabetic or numeric, such as by calendar month or by category. To do this, use the NOTSORTED option in a BY statement when you use a SET statement. The NOTSORTED option in the BY statement tells SAS that the data is not in alphabetic or numeric order, but that it is arranged in groups by the values of the BY variable. You cannot use the NOTSORTED option with the MERGE statement, the UPDATE statement, or when the SET statement lists more than one data set. I'm trying to wrap my head around the idea of when to use NOTSORTED. So, is NOTSORTED literally only used when you haven't sorted your data-set so you are indicating that the values themselves dictate grouping not the order?
... View more