Quantitative reasoning of goal satisfaction in the i∗ framework

In requirement analysis, goal models play an important role in assessing alternative design options of a software system. Many qualitative and quantitative goal reasoning approaches have been proposed for goal models such as Knowledge Acquisition in Automated Space (KAOS), Non- Functional Requirements (NFR), and Goal Oriented Requirement Language (GRL). However, for i∗ goal model only qualitative reasoning has been proposed in Requirement Engineering literature. The aim of this paper is to present a quantitative goal reasoning for i∗ goal model. The proposed approach was validated with case studies from existing literature and offers a guide in the decision process. To support the validation a simulation was developed in Visual C++.