You're right, and that's cool. Hopefully the code above helps to explain what the arrays are trying to do. With arrays it would probably look something like this:   data new(drop=symptom i); set longsort; by id_no; retain sympt1 - sympt5; array new_a (1:5) sympt1 - sympt5; do i = 1 to 5 ; if (first.id_no) then do; new_a(i) =0; end; if symptom=i then new_a(i) =1; end; if (sympt1) and (sympt2) and (sympt3) and ^(sympt4) and ^(sympt5) then disease =1; else disease =0; if (last.id_no); run; proc freq data=new; table disease; run; ... View more

Hi,   Its a little unclear on the structure of your original data, so I've made an assumption that it simply has a single numeric symptom column to start with (with values 1 to 5) and multiple rows per ID depending on number of symptoms. In order to make the logic more transparent i.e. move away from arrays (for now). I reckon it might look something like:   data new; set longsort; by id_no; retain heartburn sickness spasm temperature tiredness; if (first.id_no) then do; heartburn =0; sickness =0; spasm =0; temperature =0; tiredness =0; end; if symptom=1 then heartburn =1; if symptom=2 then sickness =1; if symptom=3 then spasm =1; if symptom=4 then temperature=1; if symptom=5 then tiredness =1; if (heartburn) and (sickness) and (spasm) and ^(temperature) and ^(tiredness) then disease =1; else disease =0; if (last.id_no); run; proc freq data=new; table disease; run; ... View more

Hi, yes I have. Identical issues there as well. ... View more

Couldn't agree more on the importance of good design! Sadly, as is often the case, we're working with what we have. Appreciate the reply. ... View more