On the decomposition of life expectancy and limits to life

Relationships between best-practice and greatest possible life expectancies

This paper investigated the relationships between the best-practice and the greatest possible life expectancies by means of gaps, lags and decomposition analyses, from 1950-1955 up to 2095-2100. The data were gathered from the United Nations' World Population Prospects (2017), containing abridged period life tables, for both sexes combined, for 201 countries or areas, which allowed the identification of low-mortality regions that are sometimes omitted in previous studies. It was observed that both best-practice and greatest possible life expectancies rose and are expected to continue to rise linearly in a very similar way. Moreover, the average gap between the best-practice and the greatest possible life expectancies was of about 1.14 years and the average lag was 7.59 years. Finally, it was found that major contributions to the gap are typically due to age groups beyond 65 years.

Trends in the Quantiles of the Life Table Survivorship Function

We offer a new approach for modeling past trends in the quantiles of the life table survivorship function. Trends in the quantiles are estimated, and the extent to which the observed patterns fit the unit root hypothesis or, alternatively, an innovative outlier model, are conducted. Then a factor model is applied to the detrended data, and it is used to construct quantile cycles. We enrich the ongoing discussion about human longevity extension by calculating specific improvements in the distribution of the survivorship function, across its full range, and not only at the central-age ranges. To illustrate our proposal, we use data for the UK from 1922 to 2013. We find that there is no sign in the data of any reduction in the pace of longevity extension during the last decades.

On the decomposition of life expectancy and limits to life

Life expectancy is a measure of how long people are expected to live and is widely used as a measure of human development. Variations in the measure reflect not only the process of ageing but also the impacts of such events as epidemics, wars, and economic recessions. Since 1950, the influence of these events in the most developed countries has waned and life expectancy continues to lengthen unabated. As a result, it has become more difficult to forecast long-run trends accurately, or identify possible upper limits. We present new methods for comparing past improvements in life expectancy and also future prospects, using data from five developed, low-mortality countries. We consider life expectancy in 10-year age intervals rather than over the remaining lifetime, and show how natural limits to life expectancy can be used to extrapolate trends. We discuss the implications and compare our approach with other commonly used methods.