The Equivalence of Multiple Rater Kappa Statistics and Intraclass Correlation Coefficients

Using the Gini-Light-Margolin concept of partioning variance for qualitative data, correspondences are established between various kappa statistics and intraclass correlation coefficients under general conditions (multiple raters and polychotomous category systems). A measure of marginal symmetry for multiple ratings is also developed and is shown to have a proportion-of-variance explanation.