A Proposal of Assurance Case Description Method Using Process of ISO 15288

Abstract

Previous studies showed that using assurance cases to increase the feasibility of accomplishing management vision and management strategy. The assurance case description method proposed by previous studies, however, does not take into account the work whose purpose changes in the progress. This study proposes an assurance case description method according to the PROCESS definition defined in this study, for being able to visualize that assuring a task whose purpose changes according to the work progress. The reason we refer to ISO 15288:2015 is that PROCESS defined in ISO 15288:2015 considers Purpose, and thus assumes changes in a certain work's purpose in the progress of the work. This study evaluates the effectiveness of both a) being able to understand the purpose of PROCESS and b) being able to visualize that assuring a work whose purpose changes according to the work progress by using both open coding and paired t-test. Based on the paired t-test result, the proposed description method was judged effective compared with current practice, about a) being able to understand the purpose of PROCESS and b) being able to visualize that assuring a work whose purpose changes according to the work progress. Furthermore, from the open coding results, the results suggested why the proposed description method is effective. This study concludes with future research topics.

Four-Layered Assurance Case Description Method Using D-Case

“…In addition, "Document of medium-term management plan" that is set in the evidence node of the management vision is a prerequisite for the management strategy. The description results of the assurance case description method proposed in the previous study [7] correspond to Figure 1. Step 15, which mainly describe the management strategy model.…”

“…Figure 2 shows that the document set in the evidence node of the management strategy are a prerequisite for the business process. The description results of the assurance case description method proposed in the previous study [7] correspond to Figure 2. Figure 3 shows…”

“…Next, we summarize the above-mentioned steps. Kobayashi et al [7] presented the steps of describing the management vision model. Step 1-Step 7 of this study shows the procedure to decompose the goals set as a management vision until the top goal of management strategy.…”

“…The lowest goal of the management vision model can also be called the top goal of the management strategy model. Kobayashi et al [7] presented the steps of describing the management strategy model. Step 15 of this study shows the procedure to decompose "the top goal of the management strategy" into "the management strategy linked to the business process".…”

“…Kaneko [6] briefly demonstrated models relevant to assurance cases. Kobayashi et al proposed three description methods for describing 1) the layers between management vision and business process [7], 2) the layer of business process [4], and 3) the layers between business process and IT system [8]. The novelty of this study therefore is to show a four-layered assurance case description method using D-Case through connecting four layers of the hierarchical structure of an assurance case, instead of focusing on one layer, in order to improve the feasibility of accomplishing both management vision and management strategy.…”