Asymptotic representations for Spearman's footrule correlation coefficient

Abstract: In order to address the theoretical challenges arising from the dependence structure of ranks in Spearman's footrule correlation coefficient, we propose two asymptotic representations under the null hypothesis of independence. The first representation simplifies the dependence structure by replacing empirical distribution functions with their population counterparts. The second representation leverages the H\'{a}jek projection technique to decompose the initial form into a sum of independent components, thereby rigorously justifying asymptotic normality. Simulation study demonstrates the appropriateness of these asymptotic representations and their potential as a foundation for extending nonparametric inference techniques, such as large-sample hypothesis testing and confidence intervals.