Lot-sizing decisions under limited-time price reduction

We consider the optimal lot-sizing policy for an inventoried item when the vendor offers a limited-time price reduction. We use the discounted cash flow (DCF) approach in our analysis, thereby eliminating the sources of approximation found in most of the earlier studies that use an average annual cost approach. We first characterize the optimal lot-sizing policies and their properties, then develop an algorithm for determining the optimal lot sizes. We analytically demonstrate that the lot sizes derived using an average annual cost approach for the different variants of the problem are, in general, larger than the DCF optimum. While DCF analysis is more rigorous and yields precise lot sizes, we recognize that the associated mathematical models and the solution procedure are rather complex. Since simple and easy-to-understand policies have a strong practical appeal to decision makers, we propose a DCF version of a simple and easy-to-implement heuristic called the ‘Early Purchase’ strategy and discuss its performance. We supplement our analytical developments with a detailed computational analysis and discuss the implications of our findings for decision making.