Interpretation of differential item functioning analyses using external review.
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.
Scott
Neil W
NW
Section of Population Health, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen, AB25 2ZD, UK. n.w.scott@abdn.ac.uk
Fayers
Peter M
PM
Aaronson
Neil K
NK
Bottomley
Andrew
A
de Graeff
Alexander
A
Groenvold
Mogens
M
Gundy
Chad
C
Koller
Michael
M
Petersen
Morten A
MA
Sprangers
Mirjam A G
MA
D003431:Cross-Cultural Comparison; D006801:Humans; D015588:Observer Variation; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011788:Quality of Life; D011795:Surveys and Questionnaires