title: The standard gamble demonstrated lower reliability than the feeling thermometer.
abstract: OBJECTIVE
  Participants rated clinical marker states (CMS) to make respondents familiar with the task of preference instruments, ground their ratings in relation to other health states, and help investigators interpret patient ratings. The objective was to assess the reliability of CMS using appropriate reliability statistics.
  
  
  METHODS
  Eighty-one patients rated CMSs for mild, moderate, and severe chronic respiratory disease using the feeling thermometer (FT) and the standard gamble (SG) before and after a 3-month respiratory rehabilitation program. To assess reliability we used (a) intraclass correlation coefficients (ICC) with the variance between CMSs as signal and the variance between raters, the variance within raters, and the signal as noise; (b) scatter plots; and (c) Bland-Altman plots.
  
  
  RESULTS
  ICCs were 0.47 for the FT and 0.37 for the SG. Scatter and Bland-Altman plots showed large between- and within-person variability; 64.2% and 11.3% of the CMSs ratings were in the correct order on both occasions on the FT and SG, respectively.
  
  
  CONCLUSIONS
  Our results suggest moderate reliability of CMSs ratings for the FT and poor reliability for the SG, which may explain their lack of improving the SG's measurement properties. Investigators should use appropriate reliability statistics when addressing related issues.
authors.affiliation: Horten Center, University of Zurich, Zurich, Switzerland.
authors.forename: Milo A
authors.initials: MA
authors.lastname: Puhan
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Guyatt
authors.forename: Victor M
authors.initials: VM
authors.lastname: Montori
authors.forename: Mohit
authors.initials: M
authors.lastname: Bhandari
authors.forename: P J
authors.initials: PJ
authors.lastname: Devereaux
authors.forename: Lauren
authors.initials: L
authors.lastname: Griffith
authors.forename: Roger
authors.initials: R
authors.lastname: Goldstein
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Schünemann
mesh_terms: D000368:Aged; D002908:Chronic Disease; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis* / Q000534:rehabilitation; D008297:Male; D011336:Probability; D011788:Quality of Life; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index