Title
Skew-normal/independent linear mixed models for censored responses with applications to HIV viral loads
Date Issued
01 May 2012
Access level
open access
Resource Type
research article
Author(s)
Bandyopadhyay D.
Lachos V.
Dey D.
Publisher(s)
Wiley-VCH Verlag
Abstract
Often in biomedical studies, the routine use of linear mixed-effects models (based on Gaussian assumptions) can be questionable when the longitudinal responses are skewed in nature. Skew-normal/elliptical models are widely used in those situations. Often, those skewed responses might also be subjected to some upper and lower quantification limits (QLs; viz., longitudinal viral-load measures in HIV studies), beyond which they are not measurable. In this paper, we develop a Bayesian analysis of censored linear mixed models replacing the Gaussian assumptions with skew-normal/independent (SNI) distributions. The SNI is an attractive class of asymmetric heavy-tailed distributions that includes the skew-normal, skew-t, skew-slash, and skew-contaminated normal distributions as special cases. The proposed model provides flexibility in capturing the effects of skewness and heavy tail for responses that are either left- or right-censored. For our analysis, we adopt a Bayesian framework and develop a Markov chain Monte Carlo algorithm to carry out the posterior analyses. The marginal likelihood is tractable, and utilized to compute not only some Bayesian model selection measures but also case-deletion influence diagnostics based on the Kullback-Leibler divergence. The newly developed procedures are illustrated with a simulation study as well as an HIV case study involving analysis of longitudinal viral loads. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Start page
405
End page
425
Volume
54
Issue
3
Language
English
OCDE Knowledge area
Estadísticas, Probabilidad
Scopus EID
2-s2.0-84862230773
PubMed ID
Source
Biometrical Journal
ISSN of the container
03233847
Sources of information: Directorio de Producción Científica Scopus