Table of Contents
International Journal of Population Research
Volume 2012, Article ID 419824, 16 pages
http://dx.doi.org/10.1155/2012/419824
Research Article

Forecast Accuracy and Uncertainty of Australian Bureau of Statistics State and Territory Population Projections

Queensland Centre for Population Research, School of Geography, Planning and Environmental Management, The University of Queensland, Chamberlain Building, Brisbane, QLD 4072, Australia

Received 21 May 2012; Revised 31 August 2012; Accepted 12 September 2012

Academic Editor: Oliver Duke-Williams

Copyright © 2012 Tom Wilson. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Errors from past rounds of population projections can provide both diagnostic information to improve future projections as well as information for users on the likely uncertainty of current projections. This paper assesses the forecast accuracy of official Australian Bureau of Statistics (ABS) population projections for the states and territories of Australia and is the first major study to do so. For the states and territories, it is found that, after 10-year projection durations, absolute percentage errors lie between about 1% and 3% for the states and around 6% for the territories. Age-specific population projections are also assessed. It is shown that net interstate migration and net overseas migration are the demographic components of change which contributed most to forecast error. The paper also compares ABS projections of total population against simple linear extrapolation, finding that, overall, ABS projections just outperformed extrapolation. No identifiable trend in accuracy over time is detected. Under the assumption of temporal stability in the magnitude of error, empirical prediction intervals are created from past errors and applied to the current set of ABS projections. The paper concludes with a few ideas for future projection rounds.