Migration data sources

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Definition

Sources of migration data can be broadly grouped into three categories:

Statistical data sources: These sources include national population and housing surveys. Data from these sources are collated, cleaned, edited, imputed, aggregated and used to produce official statistics. 

Administrative data sources: Most countries have administrative procedures to register foreigners or to grant permits to stay in the country. Examples include tourist visas, work visas and study permits. Although still not fully recognized as a source of migration statistics in many countries, these administrative records can, to some extent, identify and analyze migrant stocks and flows.  

Innovative data sources: Fueled by rapid technological advancement, an increasing amount of migration-related information is now available from the private sector. An unprecedented amount of data, commonly known as “big data”, have been generated through the use of digital devices such as mobile phones, internet-based platforms such as social media, and online payment services. A growing body of research attempts to present the various ways in which the use and analysis of big data can help elucidate forced displacement, transnational networks, human trafficking or estimate remittance flows. 

Data sources

Census and surveys collect migration-related data which can be used to produce official statistics. For example: 

• Censuses produce statistics on migrant stocks, socio-economic characteristics, migrant flows (limited) and some emigration figures. The UN Statistics Division recommends including three core variables in population censuses to identify international migrants. They are: (1) country of birth, (2) country of citizenship, and (3) year or period of arrival in the country for foreign-born persons. 
• Household surveys produce statistics on different aspects, such as the drivers and the impact of migration, internal migration, socio-economic characteristics, emigration, migrant stocks and flows of immigrants and emigrants. 
• Labour Force Surveys produce statistics on migrant stocks in the labour market. 

Administrative sources collect data for purposes other than gathering information on migration, but may be useful in the collection of specific indicators. Statistics derived from data in these sources usually refer to administrative records rather than people. Some examples of sources include: 

• Administrative registers that can potentially produce information on certain groups of persons who change their country of usual residence and thus qualify as international migrants.
• Border data collection systems which produce statistics on flows of nationals and non-nationals entering and leaving through official border posts. 
• Visas, residence permits, and/or work permits that produce statistics on migrant flows and stocks, drivers and impact of migration, and socio-economic characteristics

Innovative data sources—Although the availability of migration statistics from traditional sources is useful to some extent, significant gaps remain, as outlined above. Mobile phones, online tools and platforms, such as social media or online payment services, have become a potentially useful source for migration data. For example:

• Big data sources, such as social media and call detail records can produce statistics on migrant flows, drivers and impact of migration, and internal migration.

Information produced by innovative sources includes: migrant flows, drivers and impact of migration, internal migration, public opinion on migration, among others. 

Data strengths & limitations

Depending on the source, various strengths and limitations can present when analyzing available data sources for migration.

Statistical sources: These sources, such as censuses, household surveys and labour force surveys, are universal, and allow cross-country comparability; they can also offer detailed data on small population groups. However, depending on the country, surveys might be infrequent and/or costly. Surveys can also present issues with sample size and coverage, and migration questions tend to be left out.  

Administrative sources: Administrative sources can provide detailed and continuous data on small groups. However, visas, residence permits and work permits, while continuous and comprehensive, lack comparable definitions, coverage and availability between countries or ministries within the same country. Furthermore, they often do not cover naturalized citizens or undocumented residents who overstay their visas. It is also important to note that, for example, if a person receives more than one residence permit in a year, or if the permit granted to the head of the family covers his or her dependents, data may not reflect the total number of migrants in the country of residence. 

Innovative sources: Big data sources are timely and provide real-time data; they also have broad coverage and are automatically collected. Some limitations to these sources are that they can be biased and there are privacy and ethical issues with the collection and use of these data.