摘要
Two grade measures of monotone dependence, Spearman's ρ* and Kendall's τ, can be expressed as weighted averages of monotone Gini separation indices for pairs of conditional distributions of Y on X. This fact is used to show an important property of the measures of absolute dependence ρmax* and τmax, defined, respectively, as the maximal values of ρ* and τ over the set of pairs of all the possible one-to-one Borel-measurable transformations of X and of Y. Namely, if (X,Y) are totally positive of order two (TP2) then ρ*(X,Y)=ρmax*(X,Y) and τ(X,Y)=τmax(X,Y). Moreover, another index τabs(X,Y) of absolute dependence is introduced as weighted average of Gini (absolute) separation indices for the pairs of conditional distributions of Y on X. Indices τabs and τmax are used to measure the irregularity of dependence. All facts proved in this paper hold for the general case of the mixed discrete-continuous variables.