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

Tom Wilson, University of Queensland

Errors from past rounds of population projections provide diagnostic information which may be used to improve future projections; they can also form the basis of guidance 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. It is the first major study to do so. The paper assesses projections of total population, population growth, and age-specific populations of the States and Territories. It also examines how ABS projections of total population performed against simple linear extrapolations, and whether they became more accurate over time. 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.