Hello,   I have a dataset with multiple observations for some participant IDs. I am wondering if there is a way to populate the first observation (by ID) with data in a subsequent observation for multiple variables, without using a different data step for each variable? For example:   ID     Var1     Var2 1        8           9 2        .            4 2        3           2 3        5           7 4        0           . 4        6           10   For the first observation of ID #2, I would want to populate Var1 with 3; for the first ID #4, I want to populate Var1 with 6 and Var2 with 10. I have tried retain (for the first observation) and creating an output dataset with only the populated observations to merge back with the original, but I am trying to find a simpler way that works across multiple variables. Thank you. ... View more