Sensitivity Analysis of Conflicting Goals in the i* Goal Model

Requirements engineering (RE) has been developed as a discipline to identify and then translate stakeholders’ needs into system requirements. Hence, RE is used to produce a set of specifications for developing a software system. The specifications can be applied to satisfy stakeholders and can be implemented, deployed and maintained by using their alternative design options. The past several years have seen significant improvements in RE, whereby the discipline supports the modelling and analysis of stakeholders’ goals (objectives) beyond merely incorporating these goals. Goals further help in deriving functional and non-functional requirements (NFRs) of a system. Goals play an important role in the RE process by helping elaborate the requirements. Goal-oriented requirements engineering (GORE) refers to the use of goals in RE for eliciting requirements. GORE is then used in the process of elaboration, organization, specification, analysis, negotiation, documentation and evolution of the elicited requirements. To model the software system requirements, GORE is implemented by using goals in view of goal models. Stakeholders’ goals are then represented through these goal models to assess their non-functional needs. We developed a technique for analysing conflicting goals of inter-dependent actors in a goal model. In this proposal, to ascertain stakeholders’ NFRs, we applied the cost-effectiveness analysis (CEA) to a multi-objective optimisation model in the i* goal model. This optimisation model can handle large, sophisticated systems. The requirements analyst can use information derived from the input data. The CEA further facilitates the requirements analyst by including the sensitivity of conflicting goals in the i* goal model. Based on the inter-dependency relationships, the proposed approach includes the optimisation of each objective function. This approach also uses sensitivity analysis based on the economic evaluation of derived optimal values to prioritize design options. The most cost-effective design option can hence be chosen and used to further the aim of achieving conflicting goals. This proposal uses a Telemedicine System case study, making evaluations through a simulation-based analysis.