DEFINITIONS

Some algebraic properties of the cophenetic correlation coefficient (CPCC) are derived. Conditions under which the CPCC is maximized for a phenogram are calculated, and a strategy for finding a phenogram with largest CPCC is described. The desirability of the CPCC as an optimality criterion for classifications is discussed. Since its introduction by Sokal and Rohlf (1962), the cophenetic correlation coeffi-cient (CPCC) has been widely used in numerical phenetic studies, both as a mea-sure of degree of fit of a classification to a set of data and as a criterion for evaluating the efficiency of various clustering tech-niques. Paradoxically, little effort has been devoted to analysis of the properties of the CPCC. The present paper attempts partly to fill this gap in the theory of numerical taxonomy. I shall discuss the problems of producing a phenogram with optimal CPCC and the effect that optimizing the CPCC may have on the ability of the classification to retrieve information about operational taxonomic units (OTUs)