title: Medicine in words and numbers: a cross-sectional survey comparing probability assessment scales.
abstract: BACKGROUND
  In the complex domain of medical decision making, reasoning under uncertainty can benefit from supporting tools. Automated decision support tools 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.
  
  
  METHODS
  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.
  
  
  RESULTS
  No differences in assessments over the three response scales were found. Preferences for type of scale differed: the less experienced GPs preferred the verbal scale, the most experienced preferred the numerical scale, with the groups in between having a preference for the combined verbal-numerical scale.
  
  
  CONCLUSIONS
  We conclude that all three response scales are equally suitable for supporting probability assessment. The combined verbal-numerical scale is a good choice for aiding the process, since it offers numerical labels to those who prefer numbers and verbal labels to those who prefer words, and accommodates both more and less experienced professionals.
authors.affiliation: Diagnostic Decision Making, Behavioural Science Institute, Faculty of Social Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands. c.witteman@socsci.ru.nl <c.witteman@socsci.ru.nl>
authors.forename: Cilia L M
authors.initials: CL
authors.lastname: Witteman
authors.forename: Silja
authors.initials: S
authors.lastname: Renooij
authors.forename: Pieter
authors.initials: P
authors.lastname: Koele
mesh_terms: D000328:Adult; D002983:Clinical Competence; D003430:Cross-Sectional Studies; D003657:Decision Making; D005194:Family Practice / Q000592:standards* / Q000639:trends; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D010817:Physician-Patient Relations; D010818:Practice Patterns, Physicians'; D011336:Probability; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires