City Research Online

Abstract

Engineering judgement has an important role in safety or reliability assessment. This paper focuses on the use of engineering judgement for integrating diverse evidence into an assessment of the safety or reliability of a product. In many cases of stringent safety requirements, this form of engineering (or "expert") judgement, i.e., "informal inference from complex evidence", is the crucial resource for the decision maker, for lack of more solid, objective evidence. This dependence on judgement is especially evident in the assessment of the unreliability due to possible design faults in complex products, and computer software in particular. Although engineering judgement plays an essential role in the assessment, there are good reasons to doubt the ability of experts in some of the judgement tasks in which they are usually employed. Experimental research both about the way humans think and integrate evidence, and about the performance of experts in tasks similar to engineering judgement, support the idea that the ability of experts may be overrated. This paper summarises some literature about common fallacies and ways to guard against them, and argues for a more disciplined use of expert judgement.

Publication Type:	Report
Additional Information:	This document has been provided by the author as a means to ensure timely dissemination of scholarly and technical work on a noncommercial basis. Copyright and all rights therein are maintained by the author, notwithstanding that they have offered their works here electronically. It is understood that all persons copying this information will adhere to the terms and constraints invoked by each author's copyright. These works may not be reposted without the explicit permission of the copyright holder.
Publisher Keywords:	expert judgement, judgement under uncertainty, cognitive bias, probabilistic reasoning, heuristics, dependability assessment, safety case, design faults
Subjects:	B Philosophy. Psychology. Religion > BF Psychology Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Departments:	School of Science & Technology > Computer Science > Software Reliability

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