The Relationship Between Goal-Function Trees and Value Models

Systems often inspire the development of new models to manage size and complexity challenges in system development. Engineers should be aware of overlap in the models used for systems engineering of systems as it would be inefficient to reiterate overlapping tasks. The objective of this article is to identify consistencies between two models that appear to have overlapping tasks: Goal-Function Trees (GFTs) and value models. Both models are perceived to represent information about the system and stakeholder preferences, but have historically used differing processes and language. An analysis of the functional use and terminology for the two models reveals consistencies. The two models are compared in this article using content analysis of systems engineering academic literature. It is seen that physics-based system representation and stakeholder preference incorporation are often common to both models. A coffee maker is used to illustrate the potential consistencies and overlapping tasks between the models. Extending this simple example, the applicability of the models to space systems is discussed. The findings of this article can be used by systems engineers to improve their efficiency when applying both GFTs and value models.