Navegando por Autor "Ortega, Edwin M. M."

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    Log-Burr XII regression models with censored data.
    (2007-05) Silva, Giovana Oliveira; Cancho, Vicente Garibay; Ortega, Edwin M. M.; Barreto, Mauricio Lima
    In survival analysis applications, when the failure rate function has an unimodal shape7 that is a common situation, the log normal or log-logistic distributions are used. In this paper, a regression model based in the Burr XII distribution is proposed for modeling data what has a unimodal failure rate function. The Burr XII distribution has a advantage over the log-normal that the Burr XII survival function is written in closed form and the leg-logistic distribution is a special case of the Burr XII distribution. Assuming censored data, we considered a classic analysis, a Bayesian analysis assuming no informative priors and jackknife estimator for the parameters of the model. The Bayesian approach is considered using Markov Chain Monte Carlo Methods with Metropolis-Hasting algorithms steps to obtain the posterior summaries of interest. Besides, we used the sensitivity analysis to detect influential or outlying observations and residual analysis is used to cheek assumptions in the model such as departures from the error assumptions. The relevance of the approach is illustrated with a real data set.
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    Log-new Weibull extension regression models with censored data.
    (2006-05) Oliveira, Giovana; Ortega, Edwin M. M.; Cancho, Vicente Garibay
    In this paper we introduced a regression model considering the new Weibull extension distribution. This distribution can be used to model bathtub-shaped failure rate function assuming censored data, we considered a classic analysis and a Bayesian analysis assuming informative priors for the parameters of the model. A Bayesian approach is considered using Markov Chain Monte Carlo Methods, where Gibbs algorithms along with Metropolis steps are used to obtain the posterior summaries of interest. We illustrated methodology with two numeric examples.
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    The geometric exponential poisson distribuition.
    (2011) Nadarajah, Saralees; Cancho, Vicente Garibay; Ortega, Edwin M. M.
    Many if not most lifetime distributions a.re motiveted only by mathematical interest. Here, a new three parameter distribution motivated mainly by lifetime issues is introduced. Some properties of the new distribution including estimation procedures, univeriate generalizations and bivariate generalizations are derived, Two real data. applications are described to show superior performance versus at least five of the known lifetime models.
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    The geometric exponential poisson distribution.
    (2011-11) Nadarajah, Saralees; Cancho, Vicente Garibay; Ortega, Edwin M. M.
    Many if not most lifetime distributions are motiveted only by mathematical interest. Here, a new three parameter distribution motivated mainly by lifetime issues is introduced. Some properties of the new distribution including estimation procedures, univariate generalizations and bivariate generalizations are derived, Two real data applications are described to show superior performance versus at least five of the known lifetime models.