Reliability modeling involving two Weibull distributions

In this paper, we study three different models, each involving two Weibull distributions, to model failure data. We carry out a characterization of the plots on Weibull plotting paper (WPP). This allows one to decide on the appropriateness of a particular model formulation to model a given data set. For each of the three model formulations, we discuss parameter estimation based on the plots and illustrate their application using real data.