| Full text | |
| Author(s): |
Matos, Larissa A.
;
Castro, Luis M.
;
Lachos, Victor H.
Total Authors: 3
|
| Document type: | Journal article |
| Source: | TEST; v. 25, n. 4, p. 627-653, DEC 2016. |
| Web of Science Citations: | 2 |
| Abstract | |
In some acquired immunodeficiency syndrome (AIDS) clinical trials, the human immunodeficiency virus-1 ribonucleic acid measurements are collected irregularly over time and are often subject to some upper and lower detection limits, depending on the quantification assays. Linear and nonlinear mixed-effects models, with modifications to accommodate censored observations, are routinely used to analyze this type of data (Vaida and Liu, J Comput Graph Stat 18:797-817, 2009; Matos et al., Comput Stat Data Anal 57(1):450-464, 2013a). This paper presents a framework for fitting LMEC/NLMEC with response variables recorded at irregular intervals. To address the serial correlation among the within-subject errors, a damped exponential correlation structure is considered in the random error and an EM-type algorithm is developed for computing the maximum likelihood estimates, obtaining as a byproduct the standard errors of the fixed effects and the likelihood value. The proposed methods are illustrated with simulations and the analysis of two real AIDS case studies. (AU) | |
| FAPESP's process: | 11/22063-9 - APPLICATIONS OF THE SCALE MIXTURES OF SKEW-NORMAL DISTRIBUTIONS IN FACTOR ANALYSIS MODELS |
| Grantee: | Larissa Avila Matos |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 14/02938-9 - Estimation and diagnostics for censored mixed effects models using scale mixtures of skew-normal distributions |
| Grantee: | Víctor Hugo Lachos Dávila |
| Support Opportunities: | Regular Research Grants |