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Master's Dissertation
DOI
https://doi.org/10.11606/D.45.1999.tde-20210729-024108
Document
Author
Full name
Maria Paula Zanardi Chicarino
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1999
Supervisor
Title in Portuguese
Modelo semiparamétrico de fragilidade Gama
Keywords in Portuguese
Processos Estocásticos
Abstract in Portuguese
As técnicas inicialmente desenvolvidas em Análise de Sobrevivência supõem independência entre os tempos de ocorrência do evento de interesse. Em problemas multivariados, contudo, é razoável assumirmos que exista dependência entre as observações.Uma das formas para incorporar essa dependência é introduzir um efeito aleatório na modelagem da função de risco. Esses modelos são chamados de modelos de fragilidade e têm sido amplamente estudados desde o início da década de 80. Nesse trabalhoconsideramos modelos de fragilidade supondo distribuição Gama para o efeito aleatório, no contexto do modelo de riscos proporcionais de Cox. Apresentamos quatro diferentes métodos de estimação descritos na literatura e os comparamos através detrês conjuntos de dados diferentes. Além disso, avaliamos o uso das três estatísticas mais populares para testes de hipótese: Wald, Escore e Razão de Verossimilhanças no caso específico do modelo semiparamétrico com fragilidade Gama
Title in English
not available
Abstract in English
The usual methodology in Survival Analysis assume that the times to event are independent. When considering a multivariate framework, such a assumption may not be tenable. One way of incorporating a possible dependence is to consider a randomeffect acting multiplicatively on the risk function. The resulting models are called frailty models and have been studied since the begining of the 80's. This work focus on models which assume a Gamma distribution for the random effects, in thecontext of a Cox proportional hazards model. We present four different estimation methods and compare them using three data sets. We also consider the applicability of a popular procedures for testing hypothesis in Survival Analysis: Wald, Scoreand Likelihood Ratio
 
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Publishing Date
2021-07-29
 
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