Requirements elicitation using STAMP/STPA and CATWOE when adding another service to an existing service

Abstract

When adding another service to an existing service, focusing on the stakeholders who have a need for the additional service may omit consideration of the impact on other stakeholders when eliciting requirements. On the other hand, stakeholders who do not have a direct need for additional services may be less interested in adding services, making it difficult to elicit their needs through interviews. In addition, service additions may cause problems due to the interaction between services, but it is generally difficult to anticipate such problems, and it is difficult to elicit problems and countermeasures through interviews. Therefore, we devised a method to identify the needs of stakeholders using the CATWOE analysis, a requirements analysis method, and to elicit requirements using the STAMP/STPA safety analysis method, which focuses on interactions by considering failure to satisfy needs as a loss. A case study is presented in which the devised method is applied to a past accident case, and the results are shown to confirm its effectiveness.