Power properties of the two-sample test based on the nearest neighbors graph

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1. Verfasser: Kanekar, Rahul Raphael
Format: Preprint
Veröffentlicht: 2025
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author Kanekar, Rahul Raphael
author_facet Kanekar, Rahul Raphael
contents In this paper, we study the problem of testing the equality of two multivariate distributions. One class of tests used for this purpose utilizes geometric graphs constructed using inter-point distances. So far, the asymptotic theory of these tests applies only to graphs which fall under the stabilizing graphs framework of \citet{penroseyukich2003weaklaws}. We study the case of the $K$-nearest neighbors graph where $K=k_N$ increases with the sample size, which does not fall under the stabilizing graphs framework. Our main result gives detection thresholds for this test in parametrized families when $k_N = o(N^{1/4})$, thus extending the family of graphs where the theoretical behavior is known. We propose a 2-sided version of the test which removes an exponent gap that plagues the 1-sided test. Our result also shows that increasing the number of nearest neighbors boosts the power of the test. This provides theoretical justification for using denser graphs in testing equality of two distributions.
format Preprint
id arxiv_https___arxiv_org_abs_2504_10719
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Power properties of the two-sample test based on the nearest neighbors graph
Kanekar, Rahul Raphael
Statistics Theory
In this paper, we study the problem of testing the equality of two multivariate distributions. One class of tests used for this purpose utilizes geometric graphs constructed using inter-point distances. So far, the asymptotic theory of these tests applies only to graphs which fall under the stabilizing graphs framework of \citet{penroseyukich2003weaklaws}. We study the case of the $K$-nearest neighbors graph where $K=k_N$ increases with the sample size, which does not fall under the stabilizing graphs framework. Our main result gives detection thresholds for this test in parametrized families when $k_N = o(N^{1/4})$, thus extending the family of graphs where the theoretical behavior is known. We propose a 2-sided version of the test which removes an exponent gap that plagues the 1-sided test. Our result also shows that increasing the number of nearest neighbors boosts the power of the test. This provides theoretical justification for using denser graphs in testing equality of two distributions.
title Power properties of the two-sample test based on the nearest neighbors graph
topic Statistics Theory
url https://arxiv.org/abs/2504.10719