Test Equating Under the NEAT Design: A Necessary Condition for Anchor Items

摘要

This note was concerned with a necessary condition for anchor items (anchor test) used in a NEAT design, which seems to have received less than deserved attention in much of the literature on equating. This condition is measurement invariance, the meaning of which is the identity of the subabilities being measured by the anchor test items in the two groups to which forms 1 and 2 of an overall test have been administered. The note argued that if measurement invariance does not hold for the anchor test (the common items in both forms), it is rather difficult to impart substantive meaning to the results of an application of test equating procedures, in particular those that are based on the NEAT design.