Differential Item Functioning

Differential Item Functioning (DIF) occurs when individuals from different groups (e.g., gender, ethnicity) with the same overall ability or skill level have different chances of answering a specific test question correctly. This suggests the question may be biased or unfair toward one group. In essence, DIF highlights when a test item doesn't measure the intended skill equally across diverse groups, potentially leading to unfair advantages or disadvantages. Identifying and addressing DIF helps ensure tests are fair and accurately assess all individuals, regardless of their background.