Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Information Systems and Decision Sciences (Business Administration)

First Advisor

Peter Kelle


Purchasing is a critical, external element of the Just-In-time (JIT) production system. JIT purchasing calls for small delivery quantities which arrive on time, with the quality and quantity required. Economic order quantity models which are adjusted for multiple deliveries or consider the cooperation between the purchaser and the supplier have been published in the literature. The JIT philosophy emphasizes both of these elements. We provide a model for single sourcing which incorporates multiple deliveries and cooperation for the case where there is a single reliable supplier. We call this perfect coordination. The transition to JIT, currently occurring in many companies in the United States, often involves problems with unreliable vendors. In this case we have imperfect coordination. Also provided are extensions of this model for random lead times, random yield, and random demand which can occur in the transition to JIT. If a single, reliable supplier is not available, multiple sources can be used until a reliable source emerges. The question arises as to how to allocate the order among the suppliers. We propose dual sourcing models that allocate the quantity in order to minimize the stockout risk for deterministic and random demand. Sensitivity analysis, factorial analysis, and simulation studies are included.