Abstract: | A new four-parameter distribution is introduced. It appears to be a distribution allowing for and only allowing for monotonically increasing, bathtub-shaped and upside down bathtub-shaped hazard rates. It contains as particular cases many of the known lifetime distributions. Some mathematical properties of the new distribution, including estimation procedures by the method of maximum likelihood are derived. Some simulations are run to assess the performance of the maximum-likelihood estimators. Finally, the flexibility of the new distribution is illustrated using a real data set. |