Nonsense associations in Markov random fields with pairwise dependence

Fuente: arXiv
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Autores principales: Bhattacharya, Sohom, Mukherjee, Rajarshi, Ogburn, Elizabeth
Formato: Preprint
Publicado: 2024
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author Bhattacharya, Sohom
Mukherjee, Rajarshi
Ogburn, Elizabeth
author_facet Bhattacharya, Sohom
Mukherjee, Rajarshi
Ogburn, Elizabeth
contents Yule (1926) identified the issue of "nonsense correlations" in time series data, where dependence within each of two random vectors causes overdispersion -- i.e. variance inflation -- for measures of dependence between the two. During the near century since then, much has been written about nonsense correlations -- but nearly all of it confined to the time series literature. In this paper we provide the first, to our knowledge, rigorous study of this phenomenon for more general forms of (positive) dependence, specifically for Markov random fields on lattices and graphs. We consider both binary and continuous random vectors and three different measures of association: correlation, covariance, and the ordinary least squares coefficient that results from projecting one random vector onto the other. In some settings we find variance inflation consistent with Yule's nonsense correlation. However, surprisingly, we also find variance deflation in some settings, and in others the variance is unchanged under dependence. Perhaps most notably, we find general conditions under which OLS inference that ignores dependence is valid despite positive dependence in the regression errors, contradicting the presentation of OLS in countless textbooks and courses.
format Preprint
id arxiv_https___arxiv_org_abs_2402_03249
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Nonsense associations in Markov random fields with pairwise dependence
Bhattacharya, Sohom
Mukherjee, Rajarshi
Ogburn, Elizabeth
Statistics Theory
62E20, 62F03
Yule (1926) identified the issue of "nonsense correlations" in time series data, where dependence within each of two random vectors causes overdispersion -- i.e. variance inflation -- for measures of dependence between the two. During the near century since then, much has been written about nonsense correlations -- but nearly all of it confined to the time series literature. In this paper we provide the first, to our knowledge, rigorous study of this phenomenon for more general forms of (positive) dependence, specifically for Markov random fields on lattices and graphs. We consider both binary and continuous random vectors and three different measures of association: correlation, covariance, and the ordinary least squares coefficient that results from projecting one random vector onto the other. In some settings we find variance inflation consistent with Yule's nonsense correlation. However, surprisingly, we also find variance deflation in some settings, and in others the variance is unchanged under dependence. Perhaps most notably, we find general conditions under which OLS inference that ignores dependence is valid despite positive dependence in the regression errors, contradicting the presentation of OLS in countless textbooks and courses.
title Nonsense associations in Markov random fields with pairwise dependence
topic Statistics Theory
62E20, 62F03
url https://arxiv.org/abs/2402.03249