On Aggregating Second-Level Software Estimation Cost Drivers: A Usability Cost Estimation Case Study

Software estimation cost drivers are in many cases abstract concepts that are better estimated by breaking them down in a number of second– level aspects. This raises the need for inquiry regarding the most appropriate aggregation processes for them, since they significantly impact in the final cost estimates. Recent research on aggregation operator design has resulted in a number of families of operators that should ideally be considered for each concrete situation. In this paper, we illustrate this philosophy through a concrete case study in which the required usability of a given system is modeled in terms of three second–level aspects, and the OWA operator is introduced as a realistic and configurable summarization tool. The results illustrate the influence of the design of cost driver aggregation schemes in the resulting economical decisions.