Hi,   I am very new to sas an trying to search within a concatenated var ("COMBINATION") which is in the form (product1 + product2 + product 3) for any part of the previously used combination.  I am trying to establish how many changes in combinations are a complete change (vs an addition to an existing regimen);   data completley_new_products; set combination_products; by cust_id combination; lag_combination= lag(combination); where combination not contains lag_combination; run;   Any help or guidance much appreciated!   ... View more