arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2012.03758math.PRmath.STstat.TH

中心极限定理与高维自归一化和的近似Berry-Esseen速率

Central Limit Theorem and Near classical Berry-Esseen rate for self normalized sums in high dimensions

Debraj Das

AI总结:

本文研究高维自归一化和的中心极限定理及Berry-Esseen速率,证明多项式矩条件下的最优截断速率和最优Berry-Esseen速率。

摘要:

本文关注在高维空间R^p中,对于T_n=(∑_{i=1}^nX_{i1}/√(∑_{i=1}^nX_{i1}^2),…,∑_{i=1}^nX_{ip}/√(∑_{i=1}^nX_{ip}^2))的高维正态近似,其中T_n在超矩形类A^{re}={∏_{j=1}^p[a_j,b_j]∩R:-∞≤a_j≤b_j≤∞,j=1,…,p}上均匀。假设X_1,…,X_n是非退化的独立p维随机向量,其分量相互独立且同分布。我们研究在均匀中心极限定理(UCLT)中T_n在A^{re}上的最优截断速率log p。目标是将通常在高维CLT中假设的指数矩条件,一般假设指数增长的维度相对于样本量,减少到某些多项式矩条件。确实,我们证明仅存在某些多项式矩阶为[2,4]的条件就足以使p呈指数增长。然而,log p的增长速率无法进一步从o(n^{1/2})作为n的幂来改进,即使X_{ij}在(i,j)上独立同分布且X_{11}有界。我们还建立了在高维下,当X_{ij}存在(2+κ)阶绝对矩时,T_n的近似Berry-Esseen速率为n^{-κ/2}。当κ=1时,所得到的Berry-Esseen速率也被证明是最佳的。作为应用,我们找到了相应于分量的Student's t统计量的版本,这可能在高维统计推断中很有用。

英文摘要:

In this article, we are interested in the high dimensional normal approximation of $T_n =\Big(\sum_{i=1}^{n}X_{i1}/\Big(\sqrt{\sum_{i=1}^{n}X_{i1}^2}\Big),\dots,$ $\sum_{i=1}^{n}X_{ip}/\Big(\sqrt{\sum_{i=1}^{n}X_{ip}^2}\Big)\Big)$ in $\mathcal{R}^p$ uniformly over the class of hyper-rectangles $\mathcal{A}^{re}=\{\prod_{j=1}^{p}[a_j,b_j]\cap\mathcal{R}:-\infty\leq a_j\leq b_j \leq \infty, j=1,\ldots,p\}$, where $X_1,\dots,X_n$ are non-degenerate independent $p-$dimensional random vectors. We assume that the components of $X_i$ are independent and identically distributed (iid) and investigate the optimal cut-off rate of $\log p$ in the uniform central limit theorem (UCLT) for $T_n$ over $\mathcal{A}^{re}$. The aim is to reduce the exponential moment conditions, generally assumed for exponential growth of the dimension with respect to the sample size in high dimensional CLT, to some polynomial moment conditions. Indeed, we establish that only the existence of some polynomial moment of order $\in [2,4]$ is sufficient for exponential growth of $p$. However the rate of growth of $\log p$ can not further be improved from $o\big(n^{1/2}\big)$ as a power of $n$ even if $X_{ij}$'s are iid across $(i,j)$ and $X_{11}$ is bounded. We also establish near$-n^{-κ/2}$ Berry-Esseen rate for $T_n$ in high dimension under the existence of $(2+κ)$th absolute moments of $X_{ij}$ for $0< κ\leq 1$. When $κ=1$, the obtained Berry-Esseen rate is also shown to be optimal. As an application, we find respective versions for component-wise Student's t-statistic, which may be useful in high dimensional statistical inference.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑