Use the Time ID Creation – 1,2,3 window to add a time ID variable to an input data set with observation numbers as the ID values. The interval for the series will be 1. Use this approach if the data frequency does not match any of the system’s date or date-time intervals, or if other methods of assigning a time ID do not work. To access this window, select “Create from observation numbers” from the Create pop-up list in any window where you can select a Time ID variable. For more information, see Chapter 4: Date Intervals, Formats, and Functions, in this book.