DATA LIST LIST /date1(ADATE12). BEGIN DATA 12-28-1959 12-01-1958 12-23-1959 01-01-1960 12-31-1959 12-27-1959 12-22-1959 END DATA. LIST. COMPUTE date2=date1. FORMATS date1 date2 (ADATE12). * Next lines recodes dates between 23 DEC 1959 and 31 DEC 1959 as missing. IF (date1>=DATE.DMY(23,12,1959) & date1