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Estimation of the Reliability of a Test Divided into Two Parts of Unequal Length

Published online by Cambridge University Press:  01 January 2025

Leonard S. Feldt
Leonard S. Feldt*
Affiliation:
University of Iowa
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Abstract

In some situations where reliability must be estimated it is impossible to divide the measuring instrument into more than two separately scoreable parts. When this is the case, the parts may be homogeneous in content but clearly unequal in length. The resultant scores will not be essentially τ-equivalent, and hence total test reliability cannot be satisfactorily estimated via Cronbach's coefficient alpha. Limitation on the number of parts rules out Kristof's three-part approach. A technique is developed for estimating reliability in such situations. The approach is shown to function very well when applied to five achievement tests.

Type
Original Paper
Information
Psychometrika , Volume 40 , Issue 4 , December 1975 , pp. 557 - 561
Copyright
Copyright © 1975 The Psychometric Society

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