The improvements outlined in this chapter are designed to capture some immediate gains to NOM estimation. However, additional investigations are being undertaken to make further gains and build upon the improvements identified in this chapter.
The ABS continues to investigate ways to improve the quality of the input data (i.e. overseas arrivals and departures data) used in the calculation of preliminary NOM. By using additional data provided by the Australian Government's Department of Immigration and Citizenship, improvements may be made to the quality of the 'initial category of travel' variable. It is on the 'initial category of travel' that the propensity model currently bases its migration adjustments to help estimate preliminary NOM. If successful, the ABS plans to implement these changes to further improve preliminary NOM estimation and publish in a future edition of Australian Demographic Statistics (cat. no. 3101.0).
With a longer time series of final NOM estimates now available, the ABS is also undertaking an examination to improve the cross-classified groupings of travellers that are used by the propensity model. Currently, groupings are made by the following variables: initial category of travel, age, country of citizenship and state or territory of usual/intended residence. The effectiveness of additional variables such as visa class will be examined and other areas of research such as the use of time series analysis may be undertaken. However, their use for improving preliminary NOM estimation will depend on the operational feasibility for the ABS to implement.
International migration is a volatile phenomenon caused by a wide range of demographic, social, economic and political determinants and consequences. With the improvements being implemented to estimate preliminary NOM, combined with the impact of the GFC and changes being observed in recent traveller behaviour, the ABS advises users to take care when making future assumptions based on the large upward revisions recently experienced between preliminary and final NOM estimates.