  The peculiar properties of the Inverse Weibull (IW) distribution are shown.
It is proven that the IW distribution is one of the few models having upside-
down bathtub (UBT) shaped hazard function. Three real and typical de generative
mechanisms, which lead exactly to the IW random variable, are formulated. So a
new approach to proper application of this relatively unknown survival model is
supported. However, we consider also the case in which any knowledge about
generative mechanism is unavailable. In this hypothesis, we study a procedure
based on the Anderson-Darling statistic and log-likelihood function to
discriminate between the IW model and others alternative UBT distributions. The
invariant properties of the proposed discriminating criteria have been proven.
Based on Monte Carlo simulations, the probability of the correct selection has
been computed. A real applicative example closes the paper.
