The forecast accuracy of Australian Bureau of Statistics national population projections

This paper examines the forecast accuracy of Australian Bureau of Statistics national population projections produced from the 1960s to the early 2000s. As well as total populations, the accuracy of the following is assessed: age-sex-specific populations, the Total Fertility Rate, life expectancy at birth and net international migration. It is shown that forecasts of the 1960s and 70s were the most inaccurate; forecasts of the 1980s and later proved to be much more reliable. The paper goes on to take an alternative perspective on population forecast error through the use of an adapted percentage error measure which accounts for offsetting errors in births, deaths, net migration and the jump-off population. This measure also permits an assessment of the relative contributions of the components of demographic change to overall inaccuracy. It is shown that errors in forecasting net international migration have generally contributed most to inaccuracy followed by births and then deaths and jump-off error. ABS projections of total population are also compared to those produced using a simple naive model. The paper concludes by arguing that the new error measure could prove valuable in other studies of population forecast accuracy