Forecasting Origin-Destination-Age-Sex Migration Flow Tables with Multiplicative Components

In this chapter, we show how multiplicative components that capture the underlying structures of migration flow tables can be used to inform forecasts of interstate migration in Australia. For our illustration, we decompose 5-year census migration flow tables by state or territory of origin, state or territory of destination, 5-year age group and sex for seven census time periods from 1981–1986 to 2011–2016. The components are described over time and then fitted with time series models to produce holdout sample forecasts of interstate migration with measures of uncertainty. Goodness-of-fit statistics and calibration are then used to identify the best fitting models. The results of this research provide (i) insights into the different migration patterns of an important aspect of subnational population growth in Australia and (ii) potential inputs for standard or multiregional cohort component projection models.