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dc.contributor.authorWentzel-Larsen, Toreen_US
dc.contributor.authorNorekvål, Tone M.en_US
dc.contributor.authorUlvik, Bjørgen_US
dc.contributor.authorNygård, Ottaren_US
dc.contributor.authorPripp, Are Hugoen_US
dc.PublishedBMC Medical Research Methodology 2011, 11:137en
dc.description.abstractBackground: Questionnaires are used extensively in medical and health care research and depend on validity and reliability. However, participants may differ in interest and awareness throughout long questionnaires, which can affect reliability of their answers. A method is proposed for “screening” of systematic change in random error, which could assess changed reliability of answers. Methods: A simulation study was conducted to explore whether systematic change in reliability, expressed as changed random error, could be assessed using unsupervised classification of subjects by cluster analysis (CA) and estimation of intraclass correlation coefficient (ICC). The method was also applied on a clinical dataset from 753 cardiac patients using the Jalowiec Coping Scale. Results: The simulation study showed a relationship between the systematic change in random error throughout a questionnaire and the slope between the estimated ICC for subjects classified by CA and successive items in a questionnaire. This slope was proposed as an awareness measure - to assessing if respondents provide only a random answer or one based on a substantial cognitive effort. Scales from different factor structures of Jalowiec Coping Scale had different effect on this awareness measure. Conclusions: Even though assumptions in the simulation study might be limited compared to real datasets, the approach is promising for assessing systematic change in reliability throughout long questionnaires. Results from a clinical dataset indicated that the awareness measure differed between scales.en_US
dc.publisherBioMed Centraleng
dc.rightsAttribution CC BYeng
dc.titleA proposed method to investigate reliability throughout a questionnaireen_US
dc.typePeer reviewed
dc.typeJournal article
dc.rights.holderCopyright 2011 Wentzel-Larsen et al; licensee BioMed Central Ltd.
dc.subject.nsiVDP::Medical disciplines: 700::Health sciences: 800::Health service and health administration research: 806eng

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