Title
Censored linear regression models for irregularly observed longitudinal data using the multivariate- t distribution
Date Issued
01 April 2017
Access level
metadata only access
Resource Type
journal article
Author(s)
Garay A.
Leskow J.
Lachos V.
Universidad de Concepción
Publisher(s)
SAGE Publications Ltd
Abstract
In acquired immunodeficiency syndrome (AIDS) studies it is quite common to observe viral load measurements collected irregularly over time. Moreover, these measurements can be subjected to some upper and/or lower detection limits depending on the quantification assays. A complication arises when these continuous repeated measures have a heavy-tailed behavior. For such data structures, we propose a robust structure for a censored linear model based on the multivariate Student's t-distribution. To compensate for the autocorrelation existing among irregularly observed measures, a damped exponential correlation structure is employed. An efficient expectation maximization type algorithm is developed for computing the maximum likelihood estimates, obtaining as a by-product the standard errors of the fixed effects and the log-likelihood function. The proposed algorithm uses closed-form expressions at the E-step that rely on formulas for the mean and variance of a truncated multivariate Student's t-distribution. The methodology is illustrated through an application to an Human Immunodeficiency Virus-AIDS (HIV-AIDS) study and several simulation studies.
Start page
542
End page
566
Volume
26
Issue
2
Language
English
OCDE Knowledge area
Enfermedades infecciosas
Scopus EID
2-s2.0-85018758717
PubMed ID
Source
Statistical Methods in Medical Research
ISSN of the container
09622802
Source funding
Sponsor(s)
Funding text Victor H. Lachos and Aldo M. Garay would like to acknowledge the support of the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq-Brazil) and the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (Grants 2013/21468-0 and 2014/02938-9 from FAPESP-Brazil). Luis M. Castro acknowledges funding support by Grant FONDECYT 1130233 from the Chilean government and Grant 2012/19445-0 from FAPESP-Brazil. Jacek Leskow would like to acknowledge the support of the grant of Polish National Center for Science, grant number UMO-2013/10/M/ST1/00096. Moreover, while working on this paper Jacek Leskow was also supported by the Grant 2014/11831-3 from FAPESP-Brazil.
Sources of information: Directorio de Producción Científica Scopus