Systems Engineering Methodology, Risk Assessment & Management
The need to evaluate alternative solutions, options or proposals involving different degrees of risk and uncertainty has increased with a greater awareness of social responsibilities and the drive for greater efficiency. Many of the comparison problems involve parameters that are difficult or impossible to quantify accurately. Evaluation of such problems is possible using the Comparative Risk Assessment (CRA) approach.
The CRA methodology invokes a systematic and objective approach to organising analysing and evaluating the risks, costs and benefits of the alternatives. It must however be remembered that CRA is a tool to be used as an aid in evaluation, and is not to be considered a precise model that will deliver an unambiguous correct result for all circumstances.
H A Watson developed fault tree analysis (FTA) in the Bell Telephone Laboratories in 1962. Since then it has been used extensively in technological projects and systems, notably aerospace and nuclear. Fundamentally, FTA is the diagrammatical representation of the sequence of conditions necessary to result in the outcome that is being evaluated. Extensions to this concept are the application of probability and cost to establish the cost of avoiding a negative utility - hence cost benefit analysis.
