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Tau-Equivalence and Equipercentile Equating

Published online by Cambridge University Press:  01 January 2025

Wendy M. Yen
Wendy M. Yen*
Affiliation:
CTB/McGraw-Hill
*
Reprint requests should be addressed to Wendy M. Yen, CTB/McGraw-HilI, 2500 Garden Road, 93940, Monterey, California, 93040.
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Abstract

Test scores that are not perfectly reliable cannot be strictly equated unless they are strictly parallel [Lord, 1980]. This fact implies that tau-equivalence can be lost if an equipercentile equating is applied to observed scores that are not strictly parallel. Seventy-two simulated testing conditions are produced to simulate equating tests with different difficulties and discriminations. Number-correct and trait metrics are examined. When an equipercentile equating is applied to these data, locally biased (i.e., non-tau-equivalent) results are produced for tests of unequal difficulty. Differences between the criteria of tau-equivalence and equipercentile equivalence are discussed.

Keywords

item response theory
Type
Original Paper
Information
Psychometrika , Volume 48 , Issue 3 , September 1983 , pp. 353 - 369
Copyright
Copyright © 1983 The Psychometric Society

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References

Reference Notes

Lord, F. M. A survey of equating methods based on item characteristic curve theory (RB-75-13), Princeton, NJ: Educational Testing Service, 1975.Google Scholar
Sympson, J. B. The Assessment of Basic Competencies: A New Test Battery. Paper presented at the meeting of the American Psychological Association, New York, 1979.Google Scholar
Yen, W. M. Use of three-parameter item response theory in the development of CTBS, Form U, and TCS. Paper presented at the meeting of the National Council of Measurement in Education, New York, March 1982.Google Scholar

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