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LIFE TABLES

INTRODUCTION

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 tables in this spreadsheet 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 for the Australian and state and territory life tables are based on death registrations and estimated resident population for the period 2010–2012. The life tables do not take into account future assumed improvements in mortality.

A life table may be complete or abridged, depending on the age interval used in the compilation. Life tables in this spreadsheet are complete life tables—they contain data by single years of age. Abridged life tables contain data for five-year age groups. Life tables are presented separately for males and females.

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 in size.

To construct a life table, data on population, deaths and births are 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 publication 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.

The 2010-2012 national and state/territory life tables have been compiled using the revised ERP based on the 2011 Census data. A small refinement has also been 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 Technical Note 1: The Effect of Rebasing on Estimates of Life Expectancy and Technical Note 2: Improvements to Mortality Estimation at the Highest Ages, 2010-2012.

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

State and territory life tables produced by the ABS are available for:
• 1994-1996 to 1999-2001: published in the Demography set of publications (cat. nos. 3311.1-3311.8);
• 2000-2002: available on request;
• 2001-2003 to 2008-2010: published in Life Tables (cat. nos. 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).

LIFE TABLES BASED ON ASSUMED IMPROVEMENTS IN MORTALITY

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's official life tables and are only used as inputs to ABS population projections. For further information see Population Projections, Australia, 2006 to 2101 (cat. no. 3222.0).