HIERARCHICAL RICHNESS INDEX (HRI) - A SIMPLE PROCEDURE FOR SCORING RICHNESS, FOR USE WITH GROUPED DATA

The assessment of richness or diversity is complicated by the variety of uses for such assessments and the corresponding plethora of differe nt indices. A more fundamental problem, however, is the overlap betwee n the concepts of diversity and richness, and the loose way the two te rms are used as being effectively equivalent. A procedure is outlined which explicitly combines the two ideas, and provides a simple compara tive estimate of 'richness, the Hierarchical Richness Index (HRI). The procedure is designed for use with any data which can be assigned to mutually exclusive groups, and can in principle be applied at any leve l of a complex hierarchy. The relationship of HRI to other richness an d diversity indices is discussed, particularly in the context of the d istinction between diversity and richness, and it is shown how HRI hel ps to resolve the problems arising from the confusion of richness and diversity. Some possible further extensions and developments are sugge sted.