A comment: "Integrated single vendor-single buyer model with stochastic demand and variable lead time"

Ben-Daya and Hariga [2004. Integrated single vendor single buyer model with stochastic demand and variable lead time. International Journal of Production Economics 92, 75-80] proposed a single vendor-single buyer integrated inventory model where they assumed that the vendor delivers the lot in equal-sized batch shipments to the buyer. In this note, we modify the model proposed by Ben-Daya and Hariga to permit batch shipments increasing by a fixed factor. We show that it is necessary to consider different reorder-points for each batch shipment and illustrate the benefit of considering unequal-sized batch shipments in a numerical example.