Makeham Mortality Models as Mixtures

Mortality modeling is crucial to understanding the complex nature of population aging and projecting future trends. The Makeham term is a commonly used constant additive hazard in mortality modeling to capture background mortality unrelated to aging. In this manuscript, we propose representing Makeham mortality models as mixtures that describe lifetimes in a competing-risk framework: an individual dies either according to a baseline mortality mechanism or an exponential distribution, whatever strikes first. The baseline can describe mortality at all ages or just mortality due to aging. By using this approach, we can estimate the share of non-senescent mortality at each adult age, which is an essential contribution to the study of premature and senescent mortality. Our results allow for a better understanding of the underlying mechanisms of mortality and provide a more accurate picture of mortality dynamics in populations.