Concept Set
Concept System
Life tables are a basic demographic tool for analysing mortality and survival.
They are a tabular numerical representation of death and survivorship rates at each age of life.
The life tables are based on death rates during a specific period, and such tables are called period, current, or cross-sectional life tables.
Period life tables are based on the age-specific death rates of the population during a specific period of time. Life expectancy is a summary measure of those age-specific death rates, but it is a hypothetical life expectancy assuming people experience the age-specific death rates of that period over their lifetime.
In contrast, cohort or generation life tables are based on the age-specific death rates of people over their lifetime. These tables give the actual life expectancy of a particular cohort (eg all people born in the year 1900), although they require data over many years, theoretically until the death of the last survivor.
Every five years, Statistics NZ produces complete life tables using average mortality rates for three successive years centred on a census year.
A complete life table presents functions for each single-year of age. These are currently available for the total, Māori, and non-Māori populations from 1950–52, and for Pacific from 2005–07.
In between complete life tables, Statistics NZ produces abridged life tables using mortality rates for three successive years centred on a non-census year.
These abridged life tables are an interim indication of mortality and survival trends of the total population until complete period life tables are derived. An abridged life table presents functions for five-year age groups rather than by single-year of age, although age 0 and 1–4 years are identified separately.
In 2006, Statistics NZ released cohort life tables for the total population for the first time. These track the mortality and survival trends of people born in each year from 1876, and are updated and extended annually.
Every five years, Statistics NZ also produces abridged life tables for subnational areas using average mortality rates for three successive years centred on a census year. They are available for all 16 regions and most territorial authority areas (where death and population numbers are sufficient to construct reliable life tables). The latest subnational abridged period life tables are for 2005–07. Summary results for 1990–92 to 2005–07 are published while more detailed results are available on request.
Subnational abridged life tables for the 2012–14 period are due out 28 July 2015.
The 2017–19 life tables, using population estimates based on the 2018 Census, are scheduled for release in 2020.
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