1996 Volume 8 Issue 6 Pages 1066-1072
In order to assess the uncertainty, verbal probability judgement is a more natural and easier device than the direct numerical assessment. We propose a new procedure to measure subjective probability by means of verbal probability judgment. This procedure provides the assessment of subjective probability in terms of the distribution rather than the unique value of estimate.There are two aspects of uncertainty involved in this judgment. The one is the uncertainty of subjects' belief, which means it cannot be represented by a unique value and instead we assume subjects' belief is distributed as a truncated normal distribution. The other is the unvertainty associated with each of verbal expressions. This uncertainty is represented as trapezoidal membership functions. Based on these two assumptions, we obtain the likelihood of probability (belief) value when subjects rate the appropriateness of each of verbal expressions for a particular event. Assuming that the prior distributions for parameters are uniform, we finally obtain the subjective probability distribution for each of eight events which we assigned.We measured subjective probabilities about various unvertain events. They agreed with our intuitions and they were more consistent than direct numerical assessments when available.
