Differential Item Functioning

Item bias represents a threat to the validity of test scores in many different disciplines. An item is considered to be biased if the item unfairly favors one group over another. More specifically, an item is considered to be biased if two conditions are met. First, performance on the item is influenced by sources other than differences on the construct of interest that are deemed to be detrimental to one group. Second, this extraneous influence results in differential performance across identifiable subgroups of examinees.

The use of the term bias refers to various contexts, both statistical and social. From a statistical point of view, an item is said to be biased if the expected test or item scores are not the same for subjects from different ...