The same code works OK with the new supposition: if all values of PWPUMAS are the same then MAX(PWPUMAS) is this value for each IN_PUMA_ID You can also use the following code assuming both files are sorted by IN_PUMA_ID and PWPUMAS has the same value for each IN_PUMA_ID: Data new;   merge Agearank (in=in_rank) Agea (keep=IN_PUMA_ID PWPUMAS);   by IN_PUMA_ID;   if in_rank; run; CTorres ... View more