Data are obtained from four kinds of sources:
- National sources in the countries of the region;
- National sources in sending countries of immigrants or as provided by the authorities of the sending countries based in the region
- Sources in destination countries as provided by the authorities of the region countries, in particular consular authorities’ registers;
- National sources in major destination countries of migrants originating in the region.
Other sources include: data released in the national press by government officials, academic work, estimates provided by international organizations, original data obtained from reprocessing existing files, etc.
A standardised list of tables on stocks (emigrants and immigrants by main characteristics) and flows (arrivals and departures of migrants and asylum seekers, naturalisations, movements on labour markets, circulation of students, money transfers, etc.) is available. Tables are missing when appropriate data are not available in national statistics.