Fro example, assume the output of the purchasing activity is measured by the number of purchase orders. Suppose further that the cost of the purchasing activity for one plant is 90,000, and activity output is 4,500 purchase orders. Dividing the cost of the purchasing activity by the number of purchase order prepared gives a unit cost of 20 per order. Now, if the best unit cost is 15 per purchase order, then the plant with the 20 per-unit cost knows it has the ability to improve activity efficiency by at least 5 per unit. By studying the purchasing practices of the best plant, activity efficiency should increase.