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Comparison of the Effects of Discrete Anchor Items and Passage-Based Anchor Items on Observed-Score Equating Results NEAT CE

Zu, Jiyun; Liu, Jinghua
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ETS Research Report
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Subject/Key Words:
Passage-Based Anchor Items, Discrete Anchor Items, Testlet Model, Non-Equivalent-Groups Anchor Test (NEAT) Design, Chain Equating (CE), Post-Stratification Equating


Equating of tests composed of both discrete and passage-based items using the nonequivalent groups with anchor test (NEAT) design is popular in practice. This study investigated the impact of discrete anchor items and passage-based anchor items on observed score equating via simulation. Results suggested that an anchor with a larger proportion of passage-based items and/or a larger degree of local dependence among passage-based items produces larger equating errors, especially when group ability differences are not minimal. Our findings challenge the common belief that an anchor should be a miniature version of the tests to be equated.

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