Differential Item Functioning (DIF)

Differential Item Functioning (DIF) occurs when individuals from different groups (e.g., based on gender, ethnicity, or language) with the same underlying ability respond differently to a specific test question. This suggests that the item may favor one group over another, not because of true ability differences but due to factors like cultural bias or wording. Identifying DIF helps ensure assessments are fair and valid for all groups, by highlighting questions that may need revision to prevent unintended advantages or disadvantages.