The Nolan Index: A Quantitative Measure of List Similarities

Abstract

Several ethnobiological studies have used the Jaccard Index, a qualitative, binary measure, to compare group similarities and differences in lists of plant and animal species, medicinals, foods, cultural utilities, and so on. We extend this effort by formulating the Nolan Index, a new, more precise quantitative measure of the relative frequency of listed items to compare similarities and differences between groups . It is deployed here to evaluate the degree of similarity of free-listed, wild plants between novices and experts in rural Missouri.