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Article
Differential item functioning in the Danish translation of the SF-36
Quantitative Health Sciences Publications and Presentations
  • Jakob B. Bjorner, University of Copenhagen
  • Svend Kreiner, University of Copenhagen
  • John E. Ware, Jr., University of Massachusetts Medical School
  • Mogens T. Damsgaard, University of Copenhagen
  • Per Bech, Frederiksborg General Hospital
UMMS Affiliation
Department of Quantitative Health Sciences
Date
11-17-1998
Document Type
Article
Medical Subject Headings
Adolescent; Adult; Aged; Cross-Cultural Comparison; Denmark; *Health Status Indicators; Humans; Middle Aged; Psychometrics; *Quality of Life; Questionnaires; *Translations
Abstract

Statistical analyses of Differential Item Functioning (DIF) can be used for rigorous translation evaluations. DIF techniques test whether each item functions in the same way, irrespective of the country, language, or culture of the respondents. For a given level of health, the score on any item should be independent of nationality. This requirement can be tested through contingency-table methods, which are efficient for analyzing all types of items. We investigated DIF in the Danish translation of the SF-36 Health Survey, using two general population samples (USA, n = 1,506; Denmark, n = 3,950). DIF was identified for 12 out of 35 items. These results agreed with independent ratings of translation quality, but the statistical techniques were more sensitive. When included in scales, the items exhibiting DIF had only a little impact on conclusions about cross-national differences in health in the general population. However, if used as single items, the DIF items could seriously bias results from cross-national comparisons. Also, the DIF items might have larger impact on cross-national comparison of groups with poorer health status. We conclude that analysis of DIF is useful for evaluating questionnaire translations.

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Citation: J Clin Epidemiol. 1998 Nov;51(11):1189-202. Link to article on publisher's site
Related Resources
Link to Article in PubMed
Citation Information
Jakob B. Bjorner, Svend Kreiner, John E. Ware, Mogens T. Damsgaard, et al.. "Differential item functioning in the Danish translation of the SF-36" Vol. 51 Iss. 11 (1998) ISSN: 0895-4356 (Linking)
Available at: http://works.bepress.com/john_ware/96/