On a closed-form expression and its approximation to Gompertz life disparity

Abstract

BACKGROUND In the literature, there exists a closed form solution to the remaining life expectancy at age x when mortality is governed by the Gompertz law. This expression contains a special function that allows us to construct high-accuracy approximations, which are also helpful in assessing the elasticity of life expectancy with respect to the model parameters. However, to my knowledge, a similar formulation for life disparity does not exist, and as a consequence, it does not exist for life table entropy either.