Managing the concurrent execution of dependent product development stages

Concurrent product development, the practice of executing dependent product development stages simultaneously, has become the common mode of new product development because of the increasing importance of time-to-market. However, such simultaneous execution of dependent stages may substantially increase the total amount of rework. This research addresses the trade-offs involved in concurrent process, presents analytical models to determine the optimal priority ordering of initial development and rework, and the optimal overlapping duration. We first show that initial development is prior to rework when learning effect is taken into account. Then, based on the general assumption of nonnegative upstream evolution and the clear definition of maximum concurrency, we prove that the total development cost (including rework cost and opportunity cost of time) is convex with respect to the overlapping duration, and so the optimal overlapping duration can be identified by a simple binary search. After that we investigate the Pareto-optimal overlapping strategies for the cases where budget is given or the time to market is predetermined. Finally, the methodology is illustrated with a case study at a handset design company.