Measures of association for approximating copulas (2505.08045v1)

Abstract: This paper studies closed-form expressions for multiple association measures of copulas commonly used for approximation purposes, including Bernstein, shuffle--of--min, checkerboard and check--min copulas. In particular, closed-form expressions are provided for the recently popularized Chatterjee's xi (also known as Chatterjee's rank correlation), which quantifies the dependence between two random variables. Given any bivariate copula $C$, we show that the closed-form formula for Chatterjee's xi of an approximating checkerboard copula serves as a lower bound that converges to the true value of $\xi(C)$ as one lets the grid size $n\rightarrow\infty$.