3302.0.55.001 - Life Tables, States, Territories and Australia, 2013-2015  
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EXPLANATORY NOTES


LIFE TABLES

1 A life table is a statistical model used to represent mortality of a population. In its simplest form, a life table is generated from age-specific death rates and the resulting values are used to measure mortality, survivorship and life expectancy. The life table depicts the mortality experience of a hypothetical group of newborn babies throughout their entire lifetime. It is based on the assumption that this group is subject to the age-specific mortality rates of the reference period. Typically this hypothetical group is 100,000 persons in size. For more information, see Demographic Methods and Concepts (Rowland, 2003).

2 Life tables in this release are current, or period, life tables, based on death rates for a short period of time during which mortality has remained much the same. Mortality rates used in the Australian and state and territory life tables are based on the occurrence of deaths in the 2013-2015 period and the estimated resident population at the mid-point of that period. The life tables do not take into account future assumed improvements in mortality.

3 Life tables may be complete or abridged, depending on the age interval used in the compilation. Life tables in these spreadsheets are complete life tables—they contain data by single years of age. Abridged life tables contain data for five-year age groups.

4 Life tables for males and females are released for Australia and states/territories. However, only the life expectancy at birth estimates for males, females and persons are released for the Statistical Area level 4 (SA4).

5 To construct a life table, data on population, deaths and births is needed. Mortality rates are smoothed to avoid fluctuations in the data. The mortality rate (qx), is the main function of the life table, all other functions are derived from it. The life tables presented in this release contain four columns of interrelated information. These functions are:

    • lx - the number of persons surviving to exact age x;
    • qx - the proportion of persons dying between exact age x and exact age x+1. It is the mortality rate, from which other functions of the life table are derived;
    • Lx - the number of person years lived within the age interval x to x+1; and
    • ex - life expectancy at exact age x.

Life tables based on assumed improvements in mortality

6 Life tables based on assumed improvements in mortality are produced by the ABS using assumptions on future life expectancy at birth, based on recent trends in life expectancy. These are not the ABS' official life tables and are only used as inputs to ABS population projections. For further information see Population Projections, Australia, 2012 (base) to 2101 (cat. no. 3222.0).

Australian life tables

7 The 2013-2015 national and state/territory life tables have been compiled using the revised ERP based on the 2011 Census data.

8 With the release of the 2010-2012 life tables, a small refinement was made to the method to bring Australia's mortality rates (qx values) into line with other comparable countries. The impact of these changes in life expectancy at birth estimates is minimal, though caution should be applied when interpreting changes to life tables over time. For more information, see:
State and territory life tables

9 Life tables for the states and territories are produced on the same principles as the Australian life tables with the exception of the crude death rate, m(x). Crude death rates are smoothed using the Australian life table through the application of the Hodrick-Prescott filter (Hodrick and Prescott, 1977). This overcomes problems associated with excessive noise in the single year of age rates. In addition, some minor smoothing and suppression of outliers is often required to achieve reasonable mortality curves with satisfactory goodness-of-fit statistics.

10 State and territory life tables produced by the ABS are available for:
    • 1994-1996 to 1999-2001: published in the Demography set of releases (cat. no. 3311.1-3311.8);
    • 2000-2002: available on request;
    • 2001-2003 to 2008-2010: published in Life Tables (cat. no. 3302.1.55.001-3302.8.55.001);
    • 2009-2011 onwards: published in Life Tables, States, Territories and Australia (cat. no. 3302.0.55.001).

Statistical Area Level 4 life tables

11 Life expectancy at birth estimates for Statistical Area Level 4s are released for males, females and persons. They have been calculated with reference to state and territory life tables, using the Brass' Logit System (Brass, 1975). These small area life tables are based on age-specific death rates for each area, some of which may be zero where no deaths are recorded at these ages. The Brass' Logit technique enables the calculation of smooth abridged life tables for regions which have deficient age-specific death rates, by adjusting them with reference to a standard life table. The technique does not alter the overall level of mortality, but the age-specific functions of the life table are smoothed.

12 The Brass' Logit technique essentially compares mortality between the regional and standard life tables across ages, then a line of best fit is calculated to describe that relationship by age. The line of best fit is then used in conjunction with the standard life table to determine death rates for the small area life table. For a more detailed description of the Brass' Logit System, see Methods for Estimating Fertility and Mortality from Limited and Defective data (Brass, 1975).

Aboriginal and Torres Strait Islander Australian life tables

13 Life tables for the Aboriginal and Torres Strait Islander population were most recently published in November 2013 in Life Tables for Aboriginal and Torres Strait Islander Australians, 2010-2012 (cat. no. 3302.0.55.003).

14 Estimates of life expectancy at birth for the total population released in Life Tables, States, Territories and Australia, 2010-2012 (cat. no. 3302.0.55.001) are constructed differently to estimates presented in Life Tables for Aboriginal and Torres Strait Islander Australians, 2010-2012 (cat. no. 3302.0.55.003). Estimates of life expectancy at birth for the Aboriginal and Torres Strait Islander population are derived from abridged life tables with an upper age limit of 85 years and over, using numbers of deaths registered in 2010-2012 and the population as at 30 June 2011. Estimates of life expectancy for the total population are based on complete life tables with an upper age group of 120 years and over, using deaths according to month of occurrence in 2010-2012 and quarterly population estimates. In addition, smoothing processes applied to both sets of life tables differ.

ACKNOWLEDGEMENTS

15 The ABS' releases draw extensively on information provided freely by individuals, businesses, governments and other organisations. The efforts of each state and territory's Registries of Births, Deaths and Marriages to improve the data quality, coverage and timeliness of death registration information, processes and systems are noted and valued by the ABS. Their continued cooperation is very much appreciated. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.

RELATED PRODUCTS

16 Other ABS products which may be of interest to users include:
17 ABS products and releases are available free of charge from the ABS website <http://www.abs.gov.au>. Click on Statistics to gain access to the full range of ABS statistical and reference information.

ADDITIONAL STATISTICS AVAILABLE

18 More detailed life table information can be obtained from data cubes (in Microsoft Excel format) available electronically, from the Downloads tab of this release.

Data cubes
    • Table 1: Life tables, States, Territories and Australia, 2013-2015
    • Table 2: Life tables, Statistical Area Level 4, 2008-2010 to 2013-2015

Australian Historical Population Statistics (cat. no. 3105.0.65.001)
    • Life expectancy

PRIVACY

19 The ABS Privacy Policy outlines how the ABS will handle any personal information that you provide to us.

INQUIRIES

20 For further information about these and related statistics, contact the National Information and Referral Service on 1300 135 070.

21 The ABS also issues a daily Release Advice on the website which details the products to be released in the week ahead.