Jordan and Graves (1995) initiated a stream of research on supply chain flexibility, which was furthered by Graves and Tomlin (2003), that examined various structures for achieving horizontal flexibility within a single level of a supply chain. In this paper, we extend the theory of supply chain flexibility by considering placement of vertical flexibility across multiple stages in a supply chain. Specifically, we consider two types of flexibility–logistics flexibility and process flexibility–and examine how demand, production, and supply variability at a single stage impacts the best stage in the supply chain for each type of flexibility. Under the assumptions that margins are the same regardless of flexibility location, capacity investment costs are the same within and across stages, and flexibility is limited to a single stage of logistics (process) flexibility accompanied with necessary process (logistics) flexibility, we show that both types of flexibility are most effective when positioned directly at the source of variability. However, although expected profit increases as logistics flexibility is positioned closer to the source of variability (i.e., downstream for demand variability and upstream for supply variability), locating process flexibility anywhere except at the stage with variability leads to the same decrease in expected profit.
