Courses / Assessment Methods & Selection
36. Differential Item Functioning (DIF)
Detecting whether specific test items function differently across demographic groups, indicating potential bias.
Assessment Methods & Selection
Differential Item Functioning (DIF)
DIF is a statistical check to see if a test question gives different probabilities of success to equally able people from different demographic groups.
"If two people with the same job-relevant skill have different chances to answer one question correctly because of their group membership, that item is unfair."
DIF identifies items where individuals matched on overall ability have different expected performance across groups (e.g., gender, ethnicity), suggesting potential bias in that item. It doesn't prove bias by intent, but flags items that function differently and need review.
"If two people with the same job-relevant skill have different chances to answer one question correctly because of their group membership, that item is unfair."
DIF identifies items where individuals matched on overall ability have different expected performance across groups (e.g., gender, ethnicity), suggesting potential bias in that item. It doesn't prove bias by intent, but flags items that function differently and need review.