I would probably hard code it, since you don't seem super familiar with formats/recoding.   data tedsa_puf_2021_combined; set tedsa_puf_2021; length sub1_combined$100.; if sub1 in (2, 14, 15) then sub1_combined = 'Alcohol, Barbiturates, Other Tranquilizers'; else sub1_combined= put(sub1, sub.); run; proc freq data=tedsa_puf_2021_combined; table sub1_combined*region; run;   ... View more

That looks like a basic counter.   data want; set have; by ID; if first.id then count_events=0; count_events+1; run; Note your want data set does not match the have and is missing a variable. Please ensure you test the code you post.   @ANKH1 wrote: This is the dataset we have: data have; input ID age; datalines; 1 131 1 0 1 0 2 22 2 76 3 0 3 48 3 48 3 3 ; run; How do you create a variable that counts how many times the variable "age" has appeared up until that age. This means that the same ID can have multiple ages. The output should look like this: data want; input ID count_events; datalines; a1 131 1 a1 0 2 a1 0 3 b2 22 1 b2 76 2 c4 0 1 c4 48 2 c4 48 3 c4 3 4 ; run;   ... View more

I highly recommend looking into the TABLEN macro from Jeff Meyers. https://communities.sas.com/t5/SAS-Communities-Library/Demographic-Table-and-Subgroup-Summary-Macro-TABLEN/ta-p/634030 ... View more