The one research area where our approach clearly does
not work is educational testing. The difficulty with educational
testing is that no matter how carefully you write the common test
questions as anchors, test takers will differ in their responses to
them according to both DIF and their knowledge or achievement.
Anchoring vignettes solve the problem in other areas because a
respondent's answer is only a function of DIF (and estimation
variability), and so can be used to adjust the self-assessments. An
appropriate anchoring vignette in educational testing would be a test
question where all test takers have identical knowledge of the subject
being examined, but this is obviously infeasible.
