Similarity-based Reasoning with Quality Goals

During the years, softgoals have enjoyed much attention in the requirement engineering (RE) community for handling non-functional requirements (NFRs). As pointed out by RE researchers in recent years, softgoal may not be the right concept for non-functional requirements since it also captures early functional requirements (FRs) that are vaguely defined, e.g., “increase profit”. Alternatively, quality goals have been proposed. However, existing reasoning techniques on softgoals also have some deficiencies and can not be directly adopted: qualitative approaches lack sufficient accuracy and expressiveness for decision making, while the numbers used in existing quantitative procedures are subjective. This paper proposes a two-staged approach to tackle the problem of reasoning with quality goals: in the first stage we measure the satisfaction of leaflevel quality goals based on prototype values and graded membership, and in the second stage we propagate the satisfaction degree using similarity measurement. Our approach aims to address the aforementioned issues in the current reasoning procedures of quality goals.