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Nominal Scale Agreement Among Observers

Published online by Cambridge University Press:  01 January 2025

Hubert J. A. Schouten
Hubert J. A. Schouten*
Affiliation:
Institute of Biostatistics, Erasmus University Rotterdam
*
Requests for reprints should be sent to Hubert J. A. Schouten, Department of Medical Informaties and Statistics, University of Limburg, PO Box 616, 6200 MD Maastricht, THE NETHERLANDS.
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Abstract

Experiments are considered where each of a sample of subjects is assigned to one of C categories separately by each of a fixed or varying group of observers. Building on earlier publications, general procedures are proposed to analyze agreements and disagreements among observers. In the case of a varying group of observers, it is shown that it is not necessary to demand a constant number of observers per subject. In the case of a fixed group of observers, the problem of missing data is considered.

The procedures are illustrated within the context of two clinical diagnosis examples. In the first example it is investigated which categories are relatively hard to distinguish from one another; a new theorem is applied that shows a useful property of the statistic kappa. In the second example it is investigated if a subgroup of observers can be found with a significantly higher degree of interobserver agreement.

Keywords

agreementkappamissing data
Type
Original Paper
Information
Psychometrika , Volume 51 , Issue 3 , September 1986 , pp. 453 - 466
Copyright
Copyright © 1986 The Psychometric Society

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Footnotes

The author gratefully acknowledges the valuable suggestions by W. Molenaar, R. van Strik, R. Popping and the referees.

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