Optimizing prototyping effort with an evolving product design

The design of a new product usually takes shape gradually over time. Traditionally prototypes follow the design and are concluded before product launch. To decrease the time-to-launch, one may want to start prototype tests in advance of the design completion. However, with a slowly evolving design, modifications (in design) between subsequent prototypes can be significant, thereby increasing the time required for prototyping. This effect would be enhanced further if the prototyping time per unit of design change (sensitivity) is high. Using analytical models, we show how the interaction between the speed of evolution and the sensitivity impacts overlapping strategies. In scenarios where the impact of design changes can only be measured in discrete units, we formulate a shortest-path model and show how discreteness may limit the number of used prototypes.