Similarity, Dissimilarity, and Distance, Measures of

We discuss definitions and properties of similarity and dissimilarity coefficients, including their metric and Euclidean status. Among the plethora of available coefficients, we give details of some of the more commonly used with binary and quantitative variables. First, we discuss measures for evaluating similarity between a pair of units, showing that some coefficients are monotonic functions of each other and that many coefficients are particular instances of an overall measure of similarity. We end with measures that can be used to assess interpopulation similarity