I think this solution should work: DATA new;   Set old;   By subjid;   Retain visit_r 0;   If first.subjid Then visit_r = visitnum;   If visit = "Unscheduled" Then visitnum = visit_r + 0.01;   visit_r = visitnum;   Drop visit_r; RUN; For a similar example see http://www.mwsug.org/proceedings/2009/stats/MWSUG-2009-D14.pdf ... View more

Hi RW9, I am working on a HW exercise similar to the OP. The solution you posted only partialy worked for me, SAS produces the vector lstvist such that if visit is (1, 2, ., .,3, ., 4) then lstvisit is (1, 2, 2, 2, 3, 3, 4), which is a step in the right direction. However, the lstunsch produces a vector of missing values. I have been trying to debug for a while but have had little success,  any chance you might know what is going on there? Also, I am assuming that your use of "visit" refers to the OP's use of  "visitnum", and "type" refers to  "visit". Message was edited by: Kevin Adams ... View more