About Global Priority Settings: Due Date vs. Critical Ratio

Use the Global Priority Settings form to assign priorities to jobs either by using critical ratio calculations or based on the number of calendar days until the job is due. The priority number represents the job's priority (priority cannot be less than zero). Use the Scheduler's Job Release Rule to specify how the priority value is interpreted during scheduling. The Global Priority Setting does not reassign new priorities to jobs with frozen priorities (from the Job header).

You must set priorities before running APS Planning or the Scheduler. The system plans and schedules jobs and loads them into the resource groups in order of priority.

The differences between Due Date and Critical Ratio options are discussed below.

Due Date

The system simply sets each job's priority to the number of days until the job is due + 1000. A job due 3 days from now would therefore have a higher priority (1003) than one due 6 days from now (1006).

Note:  The number 1000 is added to the priority because the Scheduler cannot process negative priority values (priority can be from 100-9999, leaving 0-99 open for you to freeze job priorities on the Job Orders form).

Critical Ratio

The system assigns a priority to jobs based on the amount of work yet to be done on the job in relationship to the number of days until the job is due. The basic calculations used are:

  • If job not past due: (critical ratio *100) + 1000
  • If job past due: (days remaining until due date - days of process time remaining / average work hours per day) + 1000
Note:  This utility uses the work center's scheduling shift in its critical ratio calculations (the scheduling shift selected in the Work Center form's Shift ID field).