The information in this FAQ applies to the following:

• ProHelp® EPM, Releases 6.2.0, 6.1.0, 6.0.0


• ProHelp® EPM, Releases 5.2.2, 5.2.1, 5.2.0, 5.1.0, 5.0.0

When running system reports, it is possible that the subtotals may differ slightly from the sum of the detail lines. There are commonly two causes for this difference.

Rounding Error

This difference is normal and is the result of "rounding error". For example, assume that a report displays the run time for 20 machines. The value is displayed in the format "hours:minutes". At the bottom of the report, a subtotal for run time is also displayed in the format "hours:minutes". When you add each individual run time for all 20 machines, it is possible that this value will be different than the subtotal that is displayed at the bottom of the report.

The reason for this "error" is that the "display resolution" for the data (run time) differs from the "actual resolution" of the data. For example, run time is stored internally in seconds. However, for simplicity, the value on the report is shown in "hours:minutes". For most users, this is sufficient resolution. Extra seconds are rounded to the nearest minute using standard mathematical practices.

Subtotals are not merely the sum of the individual detail lines. Instead, to ensure that subtotals are accurate, the extra resolution (seconds) is not rounded off until all machines are added in. The result is that the subtotal that is displayed on the report may differ from, but be more accurate than, the sum of each detail line that is displayed on the report.

In the example that is given, the actual subtotal that is displayed may differ from the sum of the detail lines by as much as 30 seconds per machine times 20 machines. This is the maximum deviation that can occur. Keep in mind, however, that both the detail lines and the subtotals that are displayed are probably correct.

Family Molding

This difference is the difference between "job time" and "machine time". For example, assume that a machine is running a job with 3 son jobs. All 3 son jobs run at the same time and each job runs for 8 hours. The detail line for each of the 3 son jobs would show 8 hours of run time. However, the subtotals would show 8, not 24, hours of run time.

In the example that is given, the subtotal that is display differs from the sum of the detail lines dramatically. That is because the subtotal shows "machine time", whereas the detail lines show "job time". You can display "job time" in subtotals lines by creating a custom report.