Elicitation: State of the Art and Science

Abstract

This book is about elicitation, which may be defined as the facilitation of the quantitative expression of subjective judgement, whether about matters of fact or matters of value. To motivate, we review case studies from human health (swine flu); provision of public services (airport location); natural hazards (assessment of the risk of earthquakes) and environmental protection (in the case of radioactive waste) where elicitation was or could have been profitably used to inform decisions. It is often argued that uncertainties are too deep or human values are too profound for quantitative thinking to be applicable: we argue on the contrary (drawing again on cases) that it is impossible to think about important problems without dealing with problems of “how big” and “how much”. We provide an overview of chapters in the book, which, we argue, shows that there is a huge body of knowledge and expertise about how to elicit both probabilities and preferences in important social problems, and conclude with future trends that make the subject of this book (in our view) particularly timely.

I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be.

Lord Kelvin (1891, pp. 72–72)