Economic order quantity models for postponed payment of stored commodities

In inventory theory the inventory holding cost per unit plays an important part. In most transactions concerning selling and buying a certain postponement of payment is offered or accepted by the seller. This should have some consequences for the order size and can be regarded as a kind of discount. Traditionally, when average costs (AC) are used, these kinds of effects are not explicitly incorporated in the classical formulas for economic order quantities (EOQs). On the other hand, such effects have been treated to a certain degree in the literature when a present value criterion (PVC) is used to estimate the inventory holding costs over a certain time interval. However, in these models one does not differentiate between the holding costs incurred by the capital tied up in the inventory and other costs incurred by storing an item. Approaches this problem in an AC manner, but, opposed to the PVC, splits the inventory holding costs into two parts. Offers an EOQ formula for the simple case of a single item stored; enhances this formula for a situation where a family of items are ordered in a co-ordinated way, and into a situation with stochastic demand for a single item. Finally, interprets the postponed payment in terms of an all unit discount.