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Objective This study investigated whether items on the simplified version of the Beck Depression Inventory (BDI-S) exhibited differential functioning across age, gender, and clinical status, possibly compromising the fairness and diagnostic accuracy of its scores.Method To identify differential item functioning (DIF) of the scale, partial credit tree (PCtree) model was used. The PCtree uses respondents’ covariates to detect DIF in a data-driven manner. The analysis was conducted on responses from 4,521 German respondents (both clinical and non-clinical).Results The PCtree analysis yielded 17 non-predefined nodes, with different item difficulty patterns. DIF was observed as a function of the interaction between gender and age, with clinical status showing no significant impact on item performance. The results indicated that four items (Items 1 (sadness), 10 (crying), 14 (look unattractive), and 18 (changes in appetite)) exhibited large DIF.Conclusion The findings suggest the need for age- and gender-specific scoring norms to improve diagnostic accuracy.
Effatpanah et al. (Tue,) studied this question.