Extensões dos modelos de sobrevivência referente a distribuição Weibull
Vigas, Valdemiro Piedade
MetadataShow full item record
In this dissertation, two models of probability distributions for the lifetimes until the occurrence of the event produced by a specific cause for elements in a population are reviewed. The first revised model is called the Weibull-Poisson (WP) which has been proposed by Louzada et al. (2011a). This model generalizes the exponential-Poisson distributions proposed by Kus (2007) and Weibull. The second, called long-term model, has been proposed by several authors and it considers that the population is not homogeneous in relation to the risk of event occurence by the cause studied. The population has a sub-population that consists of elements who are not liable do die by the specific cause in study. These elements are considered as immune or cured. In relation to the elements who are at risk the minimum value of time of the event accurance is observed. In the review of WP the expressions of the survival function, quantile function, probability density function, and of the hazard function, as well the expression of the non-central moments of order k and the distribution of order statistics are detailed. From this review we propose, in an original way, studies of the simulation to analyze the paramenters of frequentist properties of maximum likelihood estimators for this distribution. And also we also present results related to the inference about the parameters of this distribution, both in the case in which the data set consists of complete observations of lifetimes, and also in the case in which it may contain censored observations. Furthermore, we present in this paper, in an original way a regression model in a form of location and scale when T has WP distribution. Another original contribution of this dissertation is to propose the distribution of long-term Weibull-Poisson (LWP). Besides studying the LWP in the situation in which the covariates are included in the analysis. We also described the functions that characterize this distribution (distribution function, quantile function, probability density function and the hazard function). Moreover we describe the expression of the moment of order k, and the density function of a statistical order. A study by simulation viii of this distribution is made through maximum likelihood estimators. Applications to real data set illustrate the applicability of the two considered models.
Showing items related by title, author, creator and subject.
Oliveira, Cleyton Zanardo de; http://lattes.cnpq.br/2326704083746518 (Universidade Federal de São CarlosUFSCarPrograma de Pós-graduação em EstatísticaCâmpus São Carlos, 2011-12-07)When a group of patients is monitored until a pre-established date for observation of the recurrence time of an event, it is possible that, at the end of the monitoring period, a parcel of such group has not yet suffered ...
Modelos de sobrevivência com fração de cura usando um termo de fragilidade e tempo de vida Weibull modificada generalizada Calsavara, Vinicius Fernando (Universidade Federal de São CarlosBRUFSCarPrograma de Pós-graduação em Estatística, 2011-02-24)In survival analysis, some studies are characterized by having a significant fraction of units that will never suffer the event of interest, even if accompanied by a long period of time. For the analysis of long-term data, ...
Gomes, André Yoshizumi; http://lattes.cnpq.br/0876304287501690 (Universidade Federal de São CarlosBRUFSCarPrograma de Pós-graduação em Estatística, 2009-03-18)The Weibull distribuition is a common initial choice for modeling data with monotone hazard rates. However, such distribution fails to provide a reasonable parametric _t when the hazard function is unimodal or bathtub-shaped. ...