Nominal scale response agreement as a generalized correlation

A further discussion of Brennan & Light's (1974) measure of nominal scale response agreement between two raters is given. Specifically, a monotonic function of Brennan & Light's statistic is obtained in terms of a generalized correlation coefficient and provided with a descriptive probabilistic interpretation. Under the different assumptions of fixed and variable marginal frequencies, simple numerical illustrations of the appropriate mean and variance formulae are included. The fixed marginal assumption was used by Brennan & Light, and thus our formulae in this case merely suggest convenient algebraic simplifications.