A guide to gathering expert estimates The treatment of unscientific data

For various reasons, decision makers are often forced to use unscientific data-personal estimates made by experts using existing objective data plus personal insights. Some persons feel the use of "guesstimates" should be avoided or minimized. The author, however, feels that decision making in the face of uncertainty inevitably requires personal judgments and estimates, and believes that there are advantages to explicating and quantifying them. He examines three problems in gathering and using such data. The first concerns the methods used to obtain estimates from a single expert. The second deals with the problem of pooling estimates. The third concerns explicating the assumptions to increase confidence in the reliability of the expert.