Letter to the Editor—Some Characteristics of a Special Joint-Order Inventory Model

Joint ordering strategies are of extreme importance in many inventory control situations. This paper considers a situation involving two items having identical characteristics including unit Poisson demand. The joint ordering rule is to order both items up to a level Q each time the level of either of them drops to zero. Expressions for the probability mass function of the remnant stock, the expected value of the remnant stock, the expected time between orders, and the long-run cost per unit time are shown. The joint ordering strategy is compared with the situation where the two items are treated independently. When the cost of placing an order for two items is equal to that for a single item, it turns out that it is never preferable to use the independent strategy.