Elicitation from Large, Heterogeneous Expert Panels: Using Multiple Uncertainty Measures to Characterize Information Quality for Decision Analysis

Decision analysts are frequently called on to help inform decision makers in cases involving considerable uncertainty. In such situations, expert elicitation of parameter values is frequently used to supplement more conventional research. Expert elicitations typically rely on small panels of experts. However, in cases where the information needed for risk management must draw on a broad range of disciplines or types of professional backgrounds and experience, a larger, more heterogeneous expert panel is needed. In this paper we develop a formal protocol and a suite of uncertainty measures for this work. The protocol uses formal survey methods to take advantage of variation in individual expert uncertainty and heterogeneity among experts as a means of quantifying and comparing sources of uncertainty about parameters of interest. We illustrate the use of this protocol with an expert elicitation on the distribution of foodborne illness in the United States across foods. In the survey, experts are asked to attribute illnesses associated with one of eleven major foodborne pathogens to the consumption of one of eleven categories of food. Results show how the distributions of multiple measures of uncertainty (e.g., agreement of experts and uncertainty in knowledge), made feasible by use of a large panel of experts, can help identify which of several types of risk management actions may be most appropriate.