OPS.10.1:1 - Problem frame

Use this when a capacity decision has a service question and an operating arrangement, but the calculation needed to compare its alternatives is missing or misleading. A faster machine produces longer queues. Two staffing plans have the same average hours but different completion risks. A workload controller changes an aggregate smoothly while the customer is waiting for one complete order.

Model how the available resources produce the required result, then calculate the consequence of each proposed change. Keep the arrival, service, resource and completion meanings attached to the quantities. The result can be a finite schedule, an obstruction, a mean estimate, a conditional probability or a useful bound.

First useful move. Select one result and its time criterion. Recover who or what must serve it, what is already waiting and what prevents the next service from starting. A resource-time shortfall may settle the question immediately.

The reader needs to interpret rates, durations and elementary probability for the branches used. A practitioner can obtain a specialist calculation while retaining the operating assumptions and result interpretation. Use an adequate existing model directly; reconstruct it when a changed resource, arrival process or question invalidates a needed relation. OPS.10 selects the wider capacity/service decision. This method develops the model used in that decision.