A simple method for estimating a regression model for kappa between a pairof raters

Agreement studies commonly occur in medical research, for example, in the r eview of Xrays by radiologists, blood tests by a panel of pathologists and the evaluation of psychopathology by a panel of raters. In these studies, o ften two observers rate the same subject for some characteristic with a dis crete number of levels. The kappa -coefficient is a popular measure of agre ement between the two raters. The kappa -coefficient may depend on covariat es, i.e. characteristics of the raters and/or the subjects being rated. Our research was motivated by two agreement problems. The first is a study of agreement between a pastor and a co-ordinator of Christian education on whe ther they feel that the congregation puts enough emphasis on encouraging me mbers to work for social justice (yes versus no). We wish to model the kapp a -coefficient as a function of covariates such as political orientation (l iberal versus conservative) of the pastor and co-ordinator. The second exam ple is a spousal education study, in which we wish to model the kappa -coef ficient as a function of covariates such as the highest degree of the fathe r of the wife and the father of the husband. We propose a simple method to estimate the regression model for the kappa -coefficient, which consists of two logistic (or multinomial logistic) regressions and one linear regressi on for binary data. The estimates can be easily obtained in any generalized linear model software program.