Use of differential item functioning analysis to assess the equivalence of translations of a questionnaire

In cross-national comparisons based on questionnaires, accurate translations are necessary to obtain valid results. Differential item functioning (DIF) analysis can be used to test whether translations of items in multi-item scales are equivalent to the original. In data from 10,815 respondents representing 10 European languages we tested for DIF in the nine translations of the EORTC QLQ-C30 emotional function scale when compared to the original English version. We tested for DIF using two different methods in parallel, a contingency table method and logistic regression. The DIF results obtained with the two methods were similar. We found indications of DIF in seven of the nine translations. At least two of the DIF findings seem to reflect linguistic problems in the translation. ‘Imperfect’ translations can affect conclusions drawn from cross-national comparisons. Given that translations can never be identical to the original we discuss how findings of DIF can be interpreted and discuss the difference between linguistic DIF and DIF caused by confounding, cross-cultural differences, or DIF in other items in the scale. We conclude that testing for DIF is a useful way to validate questionnaire translations.

[1]  J. Davis.  A Partial Coefficient for Goodman and Kruskal's Gamma , 1967 .

[2]  G. J. Mellenbergh.  Contingency Table Models for Assessing Item Bias , 1982 .

[3]  Steven J. Osterlind,et al.  Test item bias , 1983 .

[4]  Dorothy T. Thayer,et al.  Differential Item Performance and the Mantel-Haenszel Procedure. , 1986 .

[5]  Svend Kreiner,et al.  Analysis of Multidimensional Contingency Tables by Exact Conditional Tests: Techniques and Strategies , 1987 .

[6]  H. Swaminathan,et al.  Detecting Differential Item Functioning Using Logistic Regression Procedures , 1990 .

[7]  Keith F Widaman,et al.  Confirmatory factor analysis and item response theory: two approaches for exploring measurement invariance. , 1993, Psychological bulletin.

[8]  H. Kimmel,et al.  An Item Response Theory Evaluation of an English Version of the Trier Personality Inventory (TPI) , 1993 .

[9]  C. Bombardier,et al.  Cross-cultural adaptation of health-related quality of life measures: literature review and proposed guidelines. , 1993, Journal of clinical epidemiology.

[10]  D. Osoba,et al.  The European Organization for Research and Treatment of Cancer QLQ-C30: a quality-of-life instrument for use in international clinical trials in oncology. , 1993, Journal of the National Cancer Institute.

[11]  H. Wainer,et al.  Differential Item Functioning. , 1994 .

[12]  Andrew Bottomley,et al.  EORTC QLQ-C30 Scoring Manual , 1995 .

[13]  J B Bjorner,et al.  Test for item bias in a quality of life questionnaire. , 1995, Journal of clinical epidemiology.

[14]  Timothy R. Miller,et al.  Logistic Regression and Its Use in Detecting Differential Item Functioning in Polytomous Items , 1996 .

[15]  P. Era,et al.  Item bias in self-reported functional ability among 75-year-old men and women in three Nordic localities , 1996, Scandinavian journal of social medicine.

[16]  N. Aaronson,et al.  EORTC quality of life study grouptranslation procedure , 1998 .

[17]  M Sullivan,et al.  Translating health status questionnaires and evaluating their quality: the IQOLA Project approach. International Quality of Life Assessment. , 1998, Journal of clinical epidemiology.

[18]  J. Ware,et al.  Differential item functioning in the Danish translation of the SF-36. , 1998, Journal of clinical epidemiology.

[19]  E. Muraki.  Stepwise Analysis of Differential Item Functioning Based on Multiple‐Group Partial Credit Model , 1999 .

[20]  Mark J. Gierl,et al.  Using Statistical and Judgmental Reviews to Identify and Interpret Translation Differential Item Functioning , 1999, Alberta Journal of Educational Research.

[21]  P. Fayers,et al.  Quality of Life: Assessment, Analysis, and Interpretation , 2000 .

[22]  S. Sireci,et al.  Using Bilingual Respondents to Evaluate Translated-Adapted Items , 2000 .

[23]  Alan D. Mead,et al.  Assessment of the Measurement Equivalence of a Spanish Translation of the 16PF Questionnaire , 2000 .

[24]  J. Teresi,et al.  Modern psychometric methods for detection of differential item functioning: application to cognitive assessment measures. , 2000, Statistics in medicine.