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On the Use, the Misuse, and the Very Limited Usefulness of Cronbach’s Alpha

Published online by Cambridge University Press:  01 January 2025

Klaas Sijtsma
Klaas Sijtsma*
Affiliation:
Tilburg University
*
Requests for reprints should be sent to Klaas Sijtsma, Department of Methodology and Statistics, Faculty of Social Sciences, Tilburg University, PO Box 90153, 5000LE Tilburg, The Netherlands. E-mail: k.sijtsma@uvt.nl
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Abstract

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This discussion paper argues that both the use of Cronbach’s alpha as a reliability estimate and as a measure of internal consistency suffer from major problems. First, alpha always has a value, which cannot be equal to the test score’s reliability given the interitem covariance matrix and the usual assumptions about measurement error. Second, in practice, alpha is used more often as a measure of the test’s internal consistency than as an estimate of reliability. However, it can be shown easily that alpha is unrelated to the internal structure of the test. It is further discussed that statistics based on a single test administration do not convey much information about the accuracy of individuals’ test performance. The paper ends with a list of conclusions about the usefulness of alpha.

Keywords

Cronbach’s alphainternal consistencyreliabilityunidimensionality
Type
Theory and Methods
Information
Psychometrika , Volume 74 , Issue 1 , March 2009 , pp. 107 - 120
Creative Commons
Creative Common License - CCCreative Common License - BYCreative Common License - NC
This article distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Copyright
Copyright © 2008 The Author(s)

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