Selection of verbal probabilities: A solution for some problems of verbal probability expression

Abstract

A method for verbal expression of degree of uncertainty is described. It requires the subject to select a phrase from a list that spans the full range of probabilities. In a second, optional, step, the subject indicates the numerical meaning of each phrase. The method avoids two problems of verbal probabilities—the indefinitely large lexicon and the individual differences in the interpretation of words. To test whether context and ordinal position might bias subjects' selection or interpretation of the verbal expressions in the list, the list order was varied. When the verbal expressions were arranged in random order, ordinal position had a significant effect on the selection of expressions. However, these effects did not occur when the phrases were listed in ascending or descending order. Considerations of accuracy and interpersonal agreement also support the use of ordered phrase lists.