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The Use of Two Anchors in Nonequivalent Groups With Anchor Test (NEAT) Equating

Moses, Tim P.; Deng, Weiling; Zhang, Yu-Li
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Report Number:
ETS Research Report
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Subject/Key Words:
Non-Equivalent-Groups Anchor Test (NEAT) Design, Equating, Multiple Anchors, Psychometrics, Standardized Tests


In the equating literature, a recurring concern is that equating functions that utilize a single anchor to account for examinee groups’ nonequivalence are biased when the groups are extremely different and/or when the anchor only weakly measures what the tests measure. Several proposals have been made to address this equating bias by incorporating more than one anchor into nonequivalent groups with anchor test (NEAT) equating functions. These proposals have not been extensively considered or comparatively evaluated. This study evaluates three methods for incorporating more than one anchor into NEAT equating functions, including poststratification, imputation, and propensity score matching. The three methods are studied and compared in two examples. The implications for using the three equating approaches in practice and for developing alternative strategies to incorporate two anchors are discussed.

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