Table of Contents
Advances in Statistics
Volume 2014, Article ID 853090, 5 pages
http://dx.doi.org/10.1155/2014/853090
Research Article

On Agreement Tables with Constant Kappa Values

Institute of Psychology, Unit Methodology and Statistics, Leiden University, P.O. Box 9555, 2300 RB Leiden, The Netherlands

Received 8 July 2014; Accepted 14 August 2014; Published 24 August 2014

Academic Editor: Chin-Shang Li

Copyright © 2014 Matthijs J. Warrens. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Kappa coefficients are standard tools for summarizing the information in cross-classifications of two categorical variables with identical categories, here called agreement tables. When two categories are combined the kappa value usually either increases or decreases. There is a class of agreement tables for which the value of Cohen’s kappa remains constant when two categories are combined. It is shown that for this class of tables all special cases of symmetric kappa coincide and that the value of symmetric kappa is not affected by any partitioning of the categories.