Test bias is the presence of some characteristics of an item in the test, that results in differential performance by individuals of the same ability but different sub-group
When important decisions are made based on test scores, it is critical to avoid bias which may unfairly influence test-takersÃ¢â‚¬â„¢ scores
Fairness and bias are not the same thing.
Fairness has to do with how a test is used.
A biased test may be used fairly.
For a test biased such that males score 5 points higher on average than do females if we simply add 5 points to the observed scores of the females and use that score for making decisions, the biased test will prove to be fair in use.
An item may be biased if it contains content or language that is differentially familiar to different subgroups and/or if the item structure or format is differentially difficult to different subgroups.