Healthy Communities: Avoidable deaths and life expectancies in 2009–2011 - Technical Supplement - Life expectancies at birth

Healthy Communities: Avoidable deaths and life expectancies in 2009–2011

Life expectancies at birth

Life expectancy refers to the average number of years a person of a given age might expect to live if the age-specific death rates, for a given period in a given geographic region, continued throughout his or her lifetime.

Life expectancy in Healthy Communities: Avoidable deaths and life expectancies in 2009–11 is presented as the estimated average number of years a newborn baby is expected to live assuming the average death rates for 2009–2011, for the Medicare Local catchment in which the person lived, continues throughout their lifetime.

Calculating life expectancy involves the use of deaths data to determine length of life. Data were based on the average number of deaths over the three calendar years from 2009 to the end of 2011, while the estimated resident population (preliminary rebased) was as at 30 June 2010.

For this report, life expectancies at birth were calculated with reference to state/territory and Australian life tables (where appropriate), using the Brass Logit method. The Brass Logit method was used as it enables the calculation of smooth abridged life tables for regions which may have a small number of deaths, by adjusting the agespecific death rates with reference to a standard life table. The technique does not alter the overall level of mortality, however, the age-specific functions of the life table are smoothed.

The Brass Logit technique essentially compares mortality between the Medicare Local and standard life tables across ages. A line of best fit is then 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 Medicare Local life table.

For further information, including mathematical notation of the formulae used in the calculation of the data refer to the ABS ( 3302.0.55.001).7

7. Australian Bureau of Statistics (ABS). Life Tables, States, Territories and Australia, 2009–2011 [Internet] [cited 2013 Aug 30]. ABS 2012 3302.0.55.001. Available from: link, opens in a new window.