| Texto completo | |
| Autor(es): |
Garay, Aldo M.
;
Castro, Luis M.
;
Leskow, Jacek
;
Lachos, Victor H.
Número total de Autores: 4
|
| Tipo de documento: | Artigo Científico |
| Fonte: | STATISTICAL METHODS IN MEDICAL RESEARCH; v. 26, n. 2, p. 25-pg., 2017-04-01. |
| Resumo | |
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. (AU) | |
| Processo FAPESP: | 13/21468-0 - Modelos com erros nas variáveis para dados censurados usando distribuições de misturas da escala skew-normal |
| Beneficiário: | Aldo William Medina Garay |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 14/02938-9 - Estimação e diagnóstico em modelos de efeitos mistos para dados censurados usando misturas de escala skew-normal |
| Beneficiário: | Víctor Hugo Lachos Dávila |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 14/11831-3 - Métodos computacionais modernos em modelagem estocástica |
| Beneficiário: | Víctor Hugo Lachos Dávila |
| Modalidade de apoio: | Auxílio à Pesquisa - Pesquisador Visitante - Internacional |
| Processo FAPESP: | 12/19445-0 - Modelagem flexível de modelos longitudinais complexos usando distribuições skew-elípticas |
| Beneficiário: | Víctor Hugo Lachos Dávila |
| Modalidade de apoio: | Auxílio à Pesquisa - Pesquisador Visitante - Internacional |