Some reliability properties of the proportional hazard rate model with upside down bathtub shaped hazard rate

In this paper, a lifetime model with upside-down bathtub shaped hazard rate function has been considered, and the change point of the mean residual life function has been compared with the corresponding point of a proportional hazard model in terms of their locations. It has been shown that like the mean residual life function, the α-percentile residual life function α ∈ (0,1) of an upside-down bathtub shaped hazard rate model is increasing or bathtub shaped. But, unlike the mean residual life function its change points may not be unique. Then, the points minimising the α-percentile residual life have been compared with the corresponding points of a proportional hazard rate model in terms of their locations.