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)
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
Subjects
Scopus EID
2-s2.0-84862230773
PubMed ID
Source
Biometrical Journal
ISSN of the container
03233847
Sources of information:
Directorio de Producción Científica
Scopus