Cilia L.M. Witteman (Radboud University, the Netherlands),
Silja Renooij (Utrecht University, the Netherlands),
Pieter Koele (University of Amsterdam, the Netherlands) (2007).
Medicine in words and numbers: A cross-sectional survey comparing
probability assessment scales
In the complex domain of medical decision making, reasoning under uncertainty
can benefit from supporting tools. Automated tools such as decision support
systems often build upon mathematical models, such as Bayesian networks.
These networks require probabilities which often have to be assessed by
experts in the domain of application. Probability response scales can be
used to support the assessment process. We compare assessments obtained
with different types of response scale.
General practitioners (GPs) gave assessments on and preferences for three
different probability response scales: a numerical scale, a scale with only
verbal labels, and a combined verbal-numerical scale we had designed ourselves.
Standard analyses of variance were performed.
No differences in assessments over the three response scales were found.
Preferences for type of scale differed: the young and less experienced GPs
preferred the verbal scale, the senior and most experienced preferred the
numerical scale, with the groups in between having a preference for the
combined verbal-numerical scale.
We conclude that any of the three response scales is equally suitable for
supporting probability assessment. We advise that the combined verbal-numerical
scale is a good choice for aiding the process, since it offers numerical
labels for those who prefer numbers, while also offering verbal labels to
those who prefer words.