Interpretation of differential item functioning analyses using external review

N.W. Scott, P.M. Fayers, N.K. Aaronson, A. Bottomley, A. de Graeff, M. Groenvold, C. Gundy, M. Koller, M.A. Petersen, M.A.G. Sprangers

Research output: Contribution to journalArticleAcademic


Differential item functioning (DIF) analyses are used to determine whether certain groups respond differently to a particular item of a test or questionnaire; however, these do not explain the reasons for observed response differences. Many studies have used external reviews of items, sometimes using blinded reviewers, to help interpret these results. The authors conducted a literature review of this topic to describe the current usage of external reviews alongside DIF analyses. It concentrated on studies of health-related quality of life instruments, but studies in other fields were also considered. Relatively few examples of blinded item reviews were identified, and these were mostly from educational studies. A case study using blinded bilingual reviewers alongside translation DIF analyses of a health-related quality of life instrument is described. Future researchers should consider conducting external item reviews alongside DIF analyses
Original languageEnglish
Pages (from-to)253-258
JournalExpert review of pharmacoeconomics & outcomes research
Issue number3
Publication statusPublished - 2010

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