Date Calculation - Duration

[jnmorrison]

I do a lot with schedules. Due dates & times, end dates and times, etc. I would like to create a calculation field which signifies one of three things: On Schedule, Completed On Time, Completed Late. To do this, it will need to compare the end date and time with the due date and time. Can anyone suggest a way to accomplish this? If it were just a matter of "days" I would have no problem, but this involves "time" as well. Here are my field names:

"Due_date", "Due_Time", "End_Date", "End_Time"

thanks,

Jeff

[Ocean West]

I would recommend

[jnmorrison]

Is there no way to do this without additional plug-ins? I'm not opposed to that, but I would rather learn this myself, since I do this quite a bit.