inst/app/www/doc_methods.md

In mpascariu/MortalityCauses: Life expectancy monitor upscaled in R

How we estimate demographic indices

Life expectancy

From observed age-specific death rates at a given time, a life table is constructed with life expectancy as one of its elements. Life expectancy, or the average number of years lived by a population, is an easily interpretable metric, clinically meaningful, and simple to understand. Life expectancy can be calculated at birth and at other ages, in all cases representing an age-aggregated measure of mortality in a given time. Life expectancies are particularly useful for comparisons across time and populations, since they are not affected by population size or age-structure. (Preston et al. 2001)

Cause reduced

Associated single decrement life tables are used for the hypothetical scenario where mortality from one cause of death is deleted. A similar procedure can be applied for life tables in which one or various causes of death are reduced partially at the same time. Those new life tables will have higher life expectancies than the original, which allows to quantify the impact of reducing specific causes of death on increasing life expectancy (Chiang et al. 1968).

Decomposing the change in life expectancy over time

To better understand differences in life expectancy of the original population vs its cause-reduced version, we decomposed those differences into age- and cause-specific contributions. We used the stepwise decomposition to disentangle the age and cause of death contribution to comparisons of life expectancy across time or populations. This methodology assumes that causes of death are exhaustive, not allowing mortality to be duplicated, and independent. This independence refers to the situation where the removal of one cause leaves the risk of dying from all other causes unchanged (Andreev et al 2002).

Sources

• Andreev EM, Shkolnikov VM, and Begun AZ. Algorithm for decomposition of differences between aggregate demographic measures and its application to life expectancies, healthy life expectancies, parity-progression ratios and total fertility rates. Demographic Research 7: 499-522. 2002.
• Chiang CL. Introduction to Stochastic Processes in Biostatistics. Wiley Publishers, New York, 1968.
• Preston SH, Heuveline P, and Guillot M. Demography: measuring and modeling population processes. Blackwell Publishers, Oxford, 2001.

mpascariu/MortalityCauses documentation built on April 17, 2025, 8:31 p.m.