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Decoupling and randomization for double-indexed permutation statistics

Mingxuan Zou, Jingfan Xu, Peng Ding, Fang Han

TL;DR

The paper addresses concentration for double-indexed permutation statistics (DIPS) by decomposing $Q_w$ into a single-indexed component and a degenerate DIPS $Q_d$, and then developing new decoupling and randomization inequalities to bound MGFs. It yields a genuine combinatorial Hanson-Wright-type inequality and a combinatorial Bennett inequality, with dimension-free tails that depend on norms like $\|\mathbf{C}\|_{F}$, $\|\mathbf{C}\|_{op}$, and related Hadamard-structured terms. The framework is illustrated through nonparametric examples (Mann-Whitney–Wilcoxon, Daniels, Chatterjee, Friedman–Rafsky) and an application to causal inference via regression adjustment under complete randomization. Together, these results provide new tools for concentration in design-based inference and broaden the scope of permutation-statistic analysis in statistics and econometrics.

Abstract

This paper introduces a version of decoupling and randomization to establish concentration inequalities for double-indexed permutation statistics. The results yield, among other applications, a new combinatorial Hanson-Wright inequality and a new combinatorial Bennett inequality. Several illustrative examples from rank-based statistics, graph-based statistics, and causal inference are also provided.

Decoupling and randomization for double-indexed permutation statistics

TL;DR

The paper addresses concentration for double-indexed permutation statistics (DIPS) by decomposing into a single-indexed component and a degenerate DIPS , and then developing new decoupling and randomization inequalities to bound MGFs. It yields a genuine combinatorial Hanson-Wright-type inequality and a combinatorial Bennett inequality, with dimension-free tails that depend on norms like , , and related Hadamard-structured terms. The framework is illustrated through nonparametric examples (Mann-Whitney–Wilcoxon, Daniels, Chatterjee, Friedman–Rafsky) and an application to causal inference via regression adjustment under complete randomization. Together, these results provide new tools for concentration in design-based inference and broaden the scope of permutation-statistic analysis in statistics and econometrics.

Abstract

This paper introduces a version of decoupling and randomization to establish concentration inequalities for double-indexed permutation statistics. The results yield, among other applications, a new combinatorial Hanson-Wright inequality and a new combinatorial Bennett inequality. Several illustrative examples from rank-based statistics, graph-based statistics, and causal inference are also provided.
Paper Structure (24 sections, 15 theorems, 225 equations)

This paper contains 24 sections, 15 theorems, 225 equations.

Key Result

Theorem 1.1

Let $N\geq 20$. Assume that $\mathbf{C}$ is doubly centered and $\mathbf{A} =\{a_{ij}\}_{i,j\in[N]}$ has entries in $[-1,1]$. There then exists a universal constant $K>0$ such that the following hold true for any $t>0$.

Theorems & Definitions (34)

  • Theorem 1.1: A combinatorial Hanson-Wright-type inequality
  • Theorem 1.2: A combinatorial Bennett-type inequality
  • Example 1.1: Mann-Whitney-Wilcoxon statistic
  • Example 1.2: Daniels’ generalized correlation coefficient
  • Example 1.3: Chatterjee's rank correlation
  • Example 1.4: Friedman and Rafsky's graph correlation
  • Theorem 2.1: Combinatorial decoupling
  • Theorem 2.2: Combinatorial randomization
  • Theorem 2.3
  • Corollary 2.1
  • ...and 24 more