Purpose: Questionnaires used in hearing screening should be short and demonstrate measurement equivalence across groups defined by hearing impairment and hearing aid experience. The measurement equivalence of 2 scales addressing functionality (experienced hearing ability) and social hearing (social barriers due to hearing problems) was investigated. Method: Measurement equivalence was assessed using the differential item functioning and differential test framework within item response theory. Three comparisons were considered: (a) persons with normal hearing versus persons with hearing impairment either owning or not owning a hearing aid; (b) hearing aid users versus individuals who do not use hearing aids; (c) hearing aid users versus persons with hearing impairment who do not use a hearing aid. A protocol of differential item detection was applied consisting of ordinal regression and the log-likelihood ratio test to flag suspect items, followed by applying the log-likelihood ratio test using anchor items (items not suspect of differential item functioning). Results: The 11-item functionality scale was reduced to 9 items, whereas the 10-item social hearing scale was reduced to 7 items. Conclusions: Applying the differential item functioning framework resulted in shorter questionnaires displaying measurement equivalence relative to hearing impairment and hearing aid use without loss of reliability.
Chenault, M., Anteunis, L., Kremer, B., & Berger, M. (2015). An Investigation of Measurement Equivalence in Hearing Response Scales: Refinement of a Questionnaire for Use in Hearing Screening. American Journal of Audiology, 24(2), 188-203. https://doi.org/10.1044/2015_AJA-14-0036