Assessing the Overall Sufficiency of Safety Arguments

Safety cases offer a means for communicating information about system safety among the system's stakeholders. Recently, the requirement for a safety case has been considered by regulators for safety-critical systems. Adopting safety cases is necessarily dependent on the value added for regulatory authorities. In this presentation, the speaker outlines a structured approach for assessing the level of sufficiency of safety arguments. She uses the notion of basic probability assignment to provide a measure of sufficiency and insufficiency for each argument node. She uses the concept of belief combination to calculate the overall sufficiency and insufficiency of a safety argument based on the sufficiency and insufficiency of its nodes. The application of the proposed approach is illustrated by examples.