In reply to Bill Baar.

I'm not sure that I understand your question, but I'll try to answer your question anyway. If you have a variable with a TIME format, it is still a numerical variable, it just displays as a string (for example, 12:34:56) when you print it out. SAS time variables are represented as seconds since midnight. Let's say you record the time at which you eat lunch for four days: 11:45:00, 12:00:00, 11:55:00, and 12:05:00. SAS stores these times as the values 42300, 43200, 42900, and 43500. If you want to know the average of these times, you can call PROC UNIVARIATE, but it tells you that the average is 42975. You have to apply a TIME8. format to that value if you want to see the corresponding time-of-day (11:56:15).

When I compute with elapsed times, such as the time it takes to walk home, I won't use a TIME. format. I'll just choose a convenient unit (seconds, minutes, hours,...) and express all times in terms of that unit. In this blog post, I am not concerned with the "time of day," only with elapsed times.