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Scale Drift in Equating on a Test That Employs Cut Scores CE

Puhan, Gautam
Publication Year:
Report Number:
ETS Research Report
Document Type:
Page Count:
Subject/Key Words:
Scale Drift, Standard Error of Equating, Chain Equating (CE), Cut Scores


The purpose of this study is to determine the extent of scale drift on a test that employs cut scores. It is essential to examine scale drift in a testing program using new forms that are often put on scale through a series of intermediate equatings (known as equating chains). This may cause equating error to accumulate to a point where scale scores are rendered incomparable across two parallel chains or time periods. The study examined whether scale drift occurred for two conditions (i.e., parallel equating chains and a single long chain). Data from three tests that employed cut scores were used in this study. Results indicated that although there was some difference observed between the actual equating conversions derived via different equating chains, the effect of these differences on actual pass/fail status of test takers was not large. However, these results may change if new cut scores are introduced. Also, for tests that do not employ cut scores, stability in most parts of the score scale is important, not just at particular cut score points.

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