Published Online: 30 JAN 2010
Copyright © 2010 John Wiley & Sons, Inc. All rights reserved.
Corsini Encyclopedia of Psychology
How to Cite
McGrath, R. E. 2010. Kappa Coefficient. Corsini Encyclopedia of Psychology. 1.
- Published Online: 30 JAN 2010
The kappa coefficient was introduced by Cohen (1960) as a reliability statistic when two judges are classifying targets into categories on a nominal variable. It is most commonly used to estimate interrater reliability. Cohen (1968) later described weighted kappa, which considers degree of disagreement. For example, two judges classifying individuals on primary diagnosis could receive greater credit if they choose more rather than less similar diagnoses. Weighted kappa is particularly useful when categories are at least ordinally scaled. Another variant is available when there are more than two judges (Fleiss, 1981).
- psychometric theory;
- intraclass correlation coefficient;
- inter-rater reliability;
- base rate;
- proportion of agreement