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Reliability Estimation for a Test with Parts of unknown Lengths

Published online by Cambridge University Press:  01 January 2025

Jerry S. Gilmer
Affiliation:
American College Testing Program
Leonard S. Feldt*
Affiliation:
The University of Iowa
*
Requests for reprints should be addressed to Leonard S. Feldt, 334 Lindquist Center, University of Iowa, Iowa City, Iowa, 52242.

Abstract

The separate questions on an essay test or the individual judges on a rater panel may constitute congeneric parts rather than tau-equivalent parts. Also, it may be necessary to infer the lengths of the congeneric parts from their variances and covariances, rather than from some obvious feature of each part, such as the range of possible scores. Cronbach's alpha coefficient applied to such part-tests data will underestimate total score reliability. Several reliability coefficients are developed for such instruments. They may be regarded as extensions of the coefficient developed by Kristof for a three-part test.

Type
Original Paper
Copyright
Copyright © 1983 The Psychometric Society

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