Fault Tree Assessment

Risk assessment through fault tree evaluation

After the fault tree is constructed, both qualitative and quantitative evaluation can be performed. The constructed fault tree itself is a qualitative illustration of the events and relationships that lead to the top event and provides significant insights and understanding into the cause of system failure. The qualitative analysis is conducted from an algebraic point of view, also called logic analysis. Its principal purpose is to determine the structure function of the fault tree concerning the top event, primarily the minimal cut sets and minimal path sets. A cut set is a combination of basic events that can cause the top event; and thus a minimal cut set is the smallest combination of basic

At the system level, the probability of the entire ERP system usage failure can be obtained by quantitative evaluation of the fault tree, thus making it possible for executives of the hosting organisation to make informed decisions on ERP project initiation, termination and high-level system requirement and scope changes. At the component level, the implications of fault tree analysis depend on the approach that was adopted in fault tree construction. There are two basic approaches, which a third one is the mix of them. The difference in these two approaches is that the second requires one to incorporate the root causes to component failures into the fault tree and thus directly assess the impact of these root causes on system failure, while the first approach indicates that the causes are either too elusive to be included in the fault tree or will be identified on a later

Practitioners who carry out fault tree analysis must have the knowledge and experience on the ERP system; involvement and inputs from key stakeholders are essential as well. Considering the complexity of ERP system implementation and the high stakes to the hosting organisation, it is important that consensus on these decisions is reached not only within the ERP project team, but also with key stakeholders outside of the team such as senior management and leading end-users. In summary, with a focus on methodological development that will be followed by further case studies on practical application, this research proposes a probabilistic risk assessment approach based on fault tree analysis that aims to address ERP system usage failure. It is an effort to introduce probabilistic risk assessment techniques into the domain of information system risk management. The approach models the risk relationship between ERP system usage failure, ERP