Gini Value-Based Product Line Commonality Index for Benchmarking Product Families

Abstract In the design of product families, assessing how common the components are between products in the family is paramount. The product line commonality index (PCI) is the most common metric to quantify the commonality of components in product families. It is based on three factors: size and shape, materials and manufacturing, and assembly and fastening. Each of these factors is assessed by taking the ratio of the number of the most common type of components to the total number of that type of component. While useful, quantifying the factors with this approach only takes into account the commonality in the primary component type—those shared universally across all product variants—and does not account for the commonality in the secondary, which are shared among some of the products, or tertiary component types that are unique to specific models. This article proposes the use of Gini values as a method to better capture component distribution across all classes. The research focuses on validating the use of Gini PCI for commonality across all component classes and examining its sensitivity to nonprimary component variation relative to the standard PCI approach. The standard PCI method and the Gini PCI method are compared in a case study of Philips Norelco electric shavers from 2012 to 2013 and 2015. The case study found an increase in commonality from 33% to 78.21% using the standard PCI method and from 30.83% to 76.43% using the Gini PCI method. Although both PCI metrics found similar increases in commonality, individual component types were observed to be better quantified using the Gini PCI.