Hello. I want to retain a variable value across multiple observations in order to do comparisons. ID          Date1          Date2 1          20100101     20100201 1          20100110 1          20100115 1          20100215   2          20100115     20100215   2          20100130   2          20100201 ... I want to create a new variable with value=1 if Date1<=Date2 and value=0 if Date1>Date2 for each ID. I think it requires "retain" but I cannot find the solution. ... View more