Belzunce, Félix; Martínez-Riquelme, Carolina; Ruiz, … - In: Computational Statistics & Data Analysis 61 (2013) C, pp. 199-210
A well known sufficient condition for the mean residual life order of two random variables is the hazard rate order of the two random variables. The hazard rate order is characterized by the monotonicity of the ratio of the two survival functions. However in many cases this ratio is non monotone...