The age separating early deaths from late deaths

Abstract

Averting deaths may either increase or reduce life disparity, as measured by e†. The sign of the effect depends on the age at which the deaths are averted. We show that there may, depending on the entropy of the life table, be an age such that averting deaths before that age reduces disparity, but averting deaths after that age increases disparity. We say that this age separates "early" from "late" deaths (in terms of their effect on disparity) and investigate the factors determining this threshold age. If life table entropy is less than one, a unique threshold age separating early and late deaths always exists. If life table entropy is greater than one, averting deaths at any age increases disparity. If entropy equals one, averting deaths at age zero has no effect, but averting a death at any age after zero increases disparity. © 2009 Zhen Zhang & James W. Vaupel.