Comment: Expert Elicitation for Reliable System Design

The paper by Bedford, Quigley and Walls has reviewed the role of expert judgements in reliability assessment within the engineering design process. It differs from many statistically based papers that focus mainly on statistical models, in that it addresses issues related to the process, the concept and principles. The paper itself is comprehensive in coverage and offers general guidance for reliability assessment at the system design stage. However, to some extent, the technical side of the statistical techniques used in expert opinion elicitation in reliability analysis has not been fully explored. A practitioner who wants to conduct research in the area still needs to search methodologies from other recommended sources in the paper to find practical solutions. This is perhaps the purpose of the paper. In my discussion, two techniques that are particularly useful to subjective data elicitation, but are not discussed in the Bedford, Quigley and Walls paper, namely, empirical Bayes (EB; Robbins, 1955) and evidential reasoning (ER; Dempster, 1966), will be briefly discussed. It is hoped that this will shed some light on the problem of expert data elicitation in general and reliability assessment in design in particular.