**Expert Judgment, Meta-analysis, and Participatory Risk Analysis**

**Zusammenfassung**

There are three contexts in which one might wish to combine expert judgments of uncertainty: the expert problem, the group decision problem, and the textbook problem. Much has been written on the first two, which have the focus of a single decision context, but little on the third. The textbook problem arises when one needs to draw together expert judgments into a decision analysis when their judgments were made originally in a context-free manner or perhaps for other decision contexts. In many ways the textbook problem parallels that of performing a meta-analysis of empirical studies. However, there are differences. We discuss those difficulties and then focus on two closely related issues: How should expert judgment studies be published so as to facilitate subsequent meta-analyses, and how should such meta-analyses be performed?

**Zur Person**

Simon French is the Director of the Risk Initiative and Statistical Consultancy Unit (RISCU) in the Dept of Statistics at the University of Warwick. Previously he held posts at the Universities of Manchester and Leeds and Manchester Business School. Simon's research career began in Bayesian statistics and he was one of the first to apply Bayesian hierarchical modelling, particularly in the domain of protein crystallography. Nowadays he is better known for his work on decision making, which began with his early work on decision theory and saw several papers on the mathematical foundations of rational decision making and the publication of his 1986 text on Decision Theory. That strand of work still continues in the background: e.g. his book on Statistical Decision Theory, co-authored with David Rios Insua. However, his work has generally become more applied; looking at ways of supporting real decision makers facing major strategic and risk issues, often in the context of emergency management. He has worked in both the public and private sectors. One topic that has fascinated him over the years is that of aggregating expert judgement. How should one combine conflicting or, for that matter, agreeing expert opinion?