I'll add 2 "but if"s to Paige's post. If you are concerned about missing values in response_date: data _null_;      set old(where=(response_date ne .)) end=eof;      if _n_=1 then call symputx('start_date',response_date);      if eof then call symputx('end_date',response_date); run; If you want the chronological start and end dates, and aren't sure that your dataset is sorted: proc summary data=old ;      var response_date ;      output out=new min=day1 max=day2 ; quit; data _null_ ;      set new ;      call symputx('start_date',day1) ;      call symputx('end_date,day2) ; run; ... View more