I have a dataset where the same sample ID is associated with two components (a and b), it also contains singular data (c). I'm trying to add a column that counts the number of occurrences of the ID so I can identify when I only have one of the two components. I'm trying to create the Count column in the table below so I could identify the unpaired component (in red text) using an if then statement (if Comp eq "a" and Count ne 2 then) and (if Comp eq "b" and Count ne 2 then).   Comp ID Count c 5236 1 a 3298 2 b 3298 2 a 4172 1 a 8723 2 b 8723 2 c 7692 1   If it were in Excel, it could be done using the COUNTIF function and dragging it down (=COUNTIF(B:B,B2)) Unfortunately I don't even know where to begin to do this in SAS and haven't had any luck Googling it. I would appreciate any direction you could give me. ... View more