You'd better to post some dummy data to explain your question more clear. proc sort data=have; by pid descending age descending visit; run; proc sort data=have out=want nodupkey; by pid ; run; Ksharp ... View more

SEE IF THIS HELPS... counter = 0; *COMPARISON OF ARRAY1 WITH ARRAY2; i= DIM(ARRAY1); j= DIM(ARRAY2); do x= 1 to i;      do y= 1 to j;            Counter + (ARRAY1(x)=1 and ARRAY2(y)=1);      end; end; run; REPEAT THE ABOVE STEPS FOR THE OTHER ARRAY COMPARISONS... KEEP THE COUNTER RUNNING WITHOUT RESETTING AND YOU SHOULD HAVE YOUR RESULT ... View more