Differential item functioning (DIF) and the Mini-Mental State Examination (MMSE). Overview, sample, and issues of translation.

BACKGROUND: Various forms of differential item functioning (DIF) in the Mini-Mental State Examination (MMSE) have been identified. Items have been found to perform differently for individuals of different educational levels, racial/ethnic groups, and/or of groups whose first language is not English. The articles in this section illustrate the use of different methods to examine DIF in relation to English and Spanish language administration of the MMSE.
OBJECTIVES: The aim of this article is to provide a context for interpretation of the findings contained in the following set of papers examining DIF in the MMSE.
METHODS: The performance of the MMSE, when administered in English and Spanish, was reviewed. "Translation" has been discussed in the context of measurement bias, illustrating the variability in Spanish translations. Presented are the readability of the MMSE, description of the translation method, the study design and sample for the data set used, together with treatment of missing data, and model assumptions related to the analyses described in the accompanying set of papers examining DIF.
CONCLUSIONS: The examination of item bias in cognitive impairment assessment instruments has practical and theoretical implications in the context of health disparities. Considerable DIF has been identified in the MMSE. A critical factor that may contribute to measurement bias is language translation and conversion. Once DIF has been established consistently in a measure, decisions regarding adjustments proceed. Perhaps the development of guidelines for appropriate adjustments for DIF correction in self-reported measures represents the next challenge in addressing measurement equivalence in crosscultural research.