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Impact on estimates of life expectancy at birth
3 Population estimates, together with deaths data, are a critical input into the method used to derive life tables and life expectancy estimates. Any major downward revision to population estimates will inevitably have an impact on estimates of life expectancy, as the mortality experience in the population references a smaller number of people (or larger number when estimates are revised upward).
4 Unlike most demographic series the ABS produces, the time and resources required to derive life tables are such that they are never revised, even after a rebasing period is concluded. This means that estimates of life expectancy are not strictly comparable across intercensal periods, though the differences are usually so small as to not limit their effective use as a time series. This is less true for comparisons between the 2009-11 and 2010-12 life tables.
5 The following table shows the difference between recent estimates of state and territory life expectancy at birth, and the new 2010-12 estimates, which used rebased and recasted ERP. The largest impact of the rebasing and recasting process on life expectancy at birth estimates is expected to be for Queensland, given it also experienced the greatest relative revision during rebasing. The ABS plans to undertake further analysis to explore the impact of changing denominators (e.g. unrebased, preliminary rebased and final rebased ERP) on life tables and life expectancy estimates. The results of this analysis will be released in Life Tables, States, Territories and Australia, 2011-2013 (cat. no. 3302.0.55.001) in November 2014.
6 For more information see Technical Note 2: Improvements to Mortality Estimation at the Highest Ages, 2010-2012, Final Rebasing of Australia's Population Estimates, September Quarter 2006 - June Quarter 2011 and Recasting 20 Years of ERP.
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