Investigating Repeater Effects on Chained Equipercentile Equating With Common Anchor Items

Abstract

This study investigated the impact of repeat takers of a licensure test on the equating functions in the context of a nonequivalent groups with anchor test (NEAT) design. Examinees who had taken a new, to-be-equated form of the test were divided into three subgroups according to their previous testing experience: (a) repeaters who previously took the reference form, to which the new form would be equated; (b) repeaters who previously took any form other than the reference form; and (c) first-time test-takers for whom the new form was the first exposure to the test. Equating functions remained essentially invariant across all repeaters versus first-time test-takers, supporting score equatability of the two forms. However, when the repeater subgroup was sub-divided based on the particular form examinees took previously, subgroup equating functions substantially differed from the total-group equating function, indicating subgroup dependency of score equating. The results indicate that repeater membership needs to be more clearly specified to assess the impact of repeaters on score equating. Such clarification may be especially necessary for high-stakes licensure tests because repeaters tend to perform more poorly on such tests than first-time test-takers.