Anybody can tell me how the "hasc = 1 or hasf = 1 " generated during the following programming ? Thank you. Ivy
data test_1 ; set test; by ID lot admin_date drug; retain hasc hasf; if first.lot then do; hasc=0; hasf=0; end; if drug = "CAPECITABINE" then do; if hasf = 1 then drug = "FLUOROURACIL"; else hasc = 1; end; if drug = "FLUOROURACIL" then do; if hasc = 1 then new_drug = "CAPECITABINE"; else hasf = 1; end; run;