On GEE for Mean-Variance-Correlation Models: Variance Estimation and Model Selection

Fuente: arXiv
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Main Authors: Xu, Zhenyu, Fine, Jason P., Song, Wenling, Yan, Jun
Format: Preprint
Published: 2024
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author Xu, Zhenyu
Fine, Jason P.
Song, Wenling
Yan, Jun
author_facet Xu, Zhenyu
Fine, Jason P.
Song, Wenling
Yan, Jun
contents Generalized estimating equations (GEE) are of great importance in analyzing clustered data without full specification of multivariate distributions. A recent approach jointly models the mean, variance, and correlation coefficients of clustered data through three sets of regressions (Luo and Pan, 2022). We observe that these estimating equations, however, are a special case of those of Yan and Fine (2004) which further allows the variance to depend on the mean through a variance function. The proposed variance estimators may be incorrect for the variance and correlation parameters because of a subtle dependence induced by the nested structure of the estimating equations. We characterize model settings where their variance estimation is invalid and show the variance estimators in Yan and Fine (2004) correctly account for such dependence. In addition, we introduce a novel model selection criterion that enables the simultaneous selection of the mean-scale-correlation model. The sandwich variance estimator and the proposed model selection criterion are tested by several simulation studies and real data analysis, which validate its effectiveness in variance estimation and model selection. Our work also extends the R package geepack with the flexibility to apply different working covariance matrices for the variance and correlation structures.
format Preprint
id arxiv_https___arxiv_org_abs_2401_08172
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On GEE for Mean-Variance-Correlation Models: Variance Estimation and Model Selection
Xu, Zhenyu
Fine, Jason P.
Song, Wenling
Yan, Jun
Methodology
Generalized estimating equations (GEE) are of great importance in analyzing clustered data without full specification of multivariate distributions. A recent approach jointly models the mean, variance, and correlation coefficients of clustered data through three sets of regressions (Luo and Pan, 2022). We observe that these estimating equations, however, are a special case of those of Yan and Fine (2004) which further allows the variance to depend on the mean through a variance function. The proposed variance estimators may be incorrect for the variance and correlation parameters because of a subtle dependence induced by the nested structure of the estimating equations. We characterize model settings where their variance estimation is invalid and show the variance estimators in Yan and Fine (2004) correctly account for such dependence. In addition, we introduce a novel model selection criterion that enables the simultaneous selection of the mean-scale-correlation model. The sandwich variance estimator and the proposed model selection criterion are tested by several simulation studies and real data analysis, which validate its effectiveness in variance estimation and model selection. Our work also extends the R package geepack with the flexibility to apply different working covariance matrices for the variance and correlation structures.
title On GEE for Mean-Variance-Correlation Models: Variance Estimation and Model Selection
topic Methodology
url https://arxiv.org/abs/2401.08172