In each case, ask yourself what it is you want from each process (a goal or goals), then measure the degree to which you achieved that goal. You need to decide what is the best measure for your company and situation. For example, for purchasing it could be accuracy of purchase orders, improvement in payment terms or cost from vendors, cycle time for PO's, degree of internal customer service/happiness, etc. For production it could be yield, cycle time, efficiency, etc.