In comparison to a cross-sectional approach, a longitudinal approach will:
- separate out the effects based on the characteristics of migrants from those due to the circumstances of the time when they arrived
- differentiate between the reasons and circumstances for migrating to another country, and the subsequent events and outcomes of that migration
- provide information about which migrants do not stay
- offer greater potential to add considerable value to existing databases such as the Census database.
A longitudinal survey is a very flexible survey tool as new questions can be added in response to new developments over the life of the survey. The existence of a continually updated longitudinal database with wide coverage removes the need for, and the expense of, a large number of one-off ad hoc cross-sectional studies of migration and settlement.