Verbal uncertainty expressions: Literature review

Marek J. Druzdzel
Department of Engineering and Public Policy
Carnegie Mellon University
(currently with: University of Pittsburgh
School of Information Sciences
and Intelligent Systems Program

This paper summarizes findings of a literature review on verbal uncertainty expressions. There have been several studies in this field in the last twenty years. The main motivation behind these studies is that using verbal expressions is preferred by humans in certain situations and may be practically applied in decision making. It is postulated to reflect better non-numerical nature of the data, avoid the misleading impression of precision by being implicitly vague, and be easier for people to deal with.

Two major findings of this research are that people are internally consistent in their use of these expressions and that there is a great between-subject variability. The probabilistic meaning of the phrases is also shown to be highly context sensitive, with an asymmetry and a large overlap between different phrases. Variability of verbal expressions is severly underestimated by people using them and verbal communication poses the danger of considerable misunderstandings. On the other hand, there exist phrases that most of the people agree upon and a careful choice of a small vocabulary is able to facilitate precise communication. Appendix gives a list of all verbal uncertainty phrases encountered in the literature.

The full paper is available in PostScript (127KB) and PDF (247KB) formats.
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