Motif Estimation via Subgraph Sampling: The Fourth Moment Phenomenon

Fuente: arXiv
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Auteurs principaux: Bhattacharya, Bhaswar B., Das, Sayan, Mukherjee, Sumit
Format: Preprint
Publié: 2020
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author Bhattacharya, Bhaswar B.
Das, Sayan
Mukherjee, Sumit
author_facet Bhattacharya, Bhaswar B.
Das, Sayan
Mukherjee, Sumit
contents Network sampling is an indispensable tool for understanding features of large complex networks where it is practically impossible to search over the entire graph. In this paper, we develop a framework for statistical inference for counting network motifs, such as edges, triangles, and wedges, in the widely used subgraph sampling model, where each vertex is sampled independently, and the subgraph induced by the sampled vertices is observed. We derive necessary and sufficient conditions for the consistency and the asymptotic normality of the natural Horvitz-Thompson (HT) estimator, which can be used for constructing confidence intervals and hypothesis testing for the motif counts based on the sampled graph. In particular, we show that the asymptotic normality of the HT estimator exhibits an interesting fourth-moment phenomenon, which asserts that the HT estimator (appropriately centered and rescaled) converges in distribution to the standard normal whenever its fourth-moment converges to 3 (the fourth-moment of the standard normal distribution). As a consequence, we derive the exact thresholds for consistency and asymptotic normality of the HT estimator in various natural graph ensembles, such as sparse graphs with bounded degree, Erdos-Renyi random graphs, random regular graphs, and dense graphons.
format Preprint
id arxiv_https___arxiv_org_abs_2011_03026
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Motif Estimation via Subgraph Sampling: The Fourth Moment Phenomenon
Bhattacharya, Bhaswar B.
Das, Sayan
Mukherjee, Sumit
Statistics Theory
Combinatorics
Probability
62G05, 62E20, 05C30
Network sampling is an indispensable tool for understanding features of large complex networks where it is practically impossible to search over the entire graph. In this paper, we develop a framework for statistical inference for counting network motifs, such as edges, triangles, and wedges, in the widely used subgraph sampling model, where each vertex is sampled independently, and the subgraph induced by the sampled vertices is observed. We derive necessary and sufficient conditions for the consistency and the asymptotic normality of the natural Horvitz-Thompson (HT) estimator, which can be used for constructing confidence intervals and hypothesis testing for the motif counts based on the sampled graph. In particular, we show that the asymptotic normality of the HT estimator exhibits an interesting fourth-moment phenomenon, which asserts that the HT estimator (appropriately centered and rescaled) converges in distribution to the standard normal whenever its fourth-moment converges to 3 (the fourth-moment of the standard normal distribution). As a consequence, we derive the exact thresholds for consistency and asymptotic normality of the HT estimator in various natural graph ensembles, such as sparse graphs with bounded degree, Erdos-Renyi random graphs, random regular graphs, and dense graphons.
title Motif Estimation via Subgraph Sampling: The Fourth Moment Phenomenon
topic Statistics Theory
Combinatorics
Probability
62G05, 62E20, 05C30
url https://arxiv.org/abs/2011.03026