A log-extended Weibull regression model

A bathtub-shaped failure rate function is very useful in survival analysis and reliability studies. The well-known lifetime distributions do not have this property. For the first time, we propose a location-scale regression model based on the logarithm of an extended Weibull distribution which has the ability to deal with bathtub-shaped failure rate functions. We use the method of maximum likelihood to estimate the model parameters and some inferential procedures are presented.We reanalyze a real data set under the new model and the log-modifiedWeibull regressionmodel.Weperformamodel check based on martingale-type residuals and generated envelopes and the statistics AIC and BIC to select appropriate models. © 2009 Elsevier B.V. All rights reserved.