The more you do, the more you save: the superlinear cost avoidance effect of systems product line engineering

Abstract

Product lines that use automated tools to configure shared assets (e.g., software or requirements or test cases or user documentation) based on product descriptions have long been known to bring about substantial development cost avoidance when compared to clone-and-own or product-specific development techniques. Now, however, it can be shown that the cost avoidance for configuring multiple shared assets is superlinear -- that is, the overall cost avoidance exceeds the sum of the that brought about by working with each of the shared assets in isolation. That is, a product line that configures (for example) requirements and code will avoid more cost than the sum of code-based plus requirements-based cost avoidance. In addition, we also observe a superlinear effect in terms of the number of products in the portfolio as well. This paper explores why these effects occur, and presents analytical and empirical evidence for their existence from one of the largest and most successful product lines in the literature, the AEGIS Weapon System. The result may lead to new insight into the economics of product line engineering in the systems engineering realm.