The role of translations of verbal into numerical probability expressions in risk management: a meta-analysis

Translations of verbal into numerical probability expressions play a central role in risk management, for instance when assessing risks or when choosing appropriate measures to handle them. Despite the fact that the issue of probability translations has been widely studied in the past, results have remained quite isolated. The present work sets out to provide a meta-analysis of previous work, focussing on the most frequently used expressions. It turns out that the numerical ratings for verbal expressions differ considerably between studies. Subsequent analysis is devoted to distances between the results and to differences in methodology. Although there is significant disagreement on which figure represents a particular verbal probability best, methodology was not found to be a decisive factor. The study clearly shows that there is no consensus about probability translations and that attempts to codify word-number-pairs come too early. For such general purposes, the present study helps to distinguish between similarly versus inconsistently rated expressions instead.