Hi Assuming the input data is sorted by var_1, then the following code should do what you want: data want;   set have;   by Var_1;   if first.var_1 = 1 then do;     retain checkForA;     checkForA = 1;   end;   if checkForA = 1 and var_2 = "A" then do;     var_3_sas = 1;     checkForA = 0;   end;   var_3_sas = coalesce(var_3_sas, 0); run; ... View more