A number of indices have been used in recent years to calculate lifespan variation, each with different underlying properties. Although these indices are assumed to be interchangeable, little research has been conducted to show under which conditions this assumption is appropriate, or how to...

This note provides some earlier history of the relationship given in FormalRelationships1, "Life left equals life lived in stationary populations," (Goldstein2009) and shows that while the expectation of life at the mean age of the population is close to the mean age, this is not exactly so.

Many studies have examined Keyfitz’s population momentum, a special case of inertia in long-term population size resulting from demographic transition to the stationary population growth rate. Yet, population inertia can be produced by any demographic perturbation (i.e., not just perturbations...

What does tempo-adjusted period life expectancy measure? Taking a cohort perspective, I show that under conditions of constant linear mortality shifts the tempo-adjusted period indicator translates exactly to the cohort born e¤0 (t) years earlier. I discuss the implications of cohort...

Adult mortality decline was the driving force of life-expectancy increase in many developed countries in the second half of the twentieth century. In this paper we study one of the most widely used models to capture adult human mortality - the Gompertz proportional hazards model. In its standard...

Formal demography has yet to move beyond assuming that demographic rates are constant over time, an assumption that is both unrealistic and constraining. To generalize the fixed rate stable model to the changing rate dynamic model, this paper explores the mathematical regularities that underlie...