Article: An evaluation of an index of affinity for comparing assemblages, in particular of Foraminifera

An index of affinity which is related to the city block metric is described. Its values are found to be comparable with values derived from Pearson's coefficient of contingency when model sample assemblages are used. The value of the index of affinity which indicates that samples are taken from the same assemblage varies with the type of assemblage being sampled. This critical value can be calculated by using a simple formula. Analyses of samples of recent foraminiferal assemblages from the coast of California and the Western Approaches to the English Channel agree, in general, with results obtained using traditional techniques and factor analysis. The index of affinity is very simple to calculate and is equally effective if one or many pairs of samples are being compared.