Revisiting Life Expectancy Rankings in Countries that Have Experienced Fast Mortality Decline
In this chapter, we propose a simple procedure for making international comparisons of life expectancy. This procedure builds on the theoretical advantages of using actual cohorts (as opposed to synthetic cohorts) for building life tables, but uses all the available mortality information up to the present. Specifically, for each non-extinct cohort present in the population at time t, we calculate the cohort’s truncated life expectancy at birth, with the truncation age being the age reached by the cohort at time t. We calculate truncated cohort life expectancies for 17 countries using data from the Human Mortality Database, and compare them with their period, synthetic-cohort equivalent. We find that a number of countries, including Italy and Spain, rank consistently lower in terms of cohorts vs. periods. The US, however, ranks more favorably in terms of cohorts as opposed to periods. We argue that the examination of truncated cohort life expectancies offers a simple solution for summarizing complex time- and age-specific mortality trajectories in a way that is meaningful for real cohorts of individuals, and thus enriches international mortality comparisons. This approach is particularly relevant for countries that have experienced fast mortality change. We also introduce the concept of “momentum of mortality disadvantage,” which states that some countries currently ranking high in terms of period life expectancy have accumulated such cohort mortality disadvantages up to the present that these disadvantages are not likely to be reversed, even if currently-observed mortality advantages persist in the future.
KeywordsCohort mortality Period mortality International mortality comparisons Life tables Life expectancy Momentum
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