Immigrant population

National views on the appropriate definition of the immigrant population vary from country to country. Despite this, it is now possible to provide an internationally comparable picture of the size of the immigrant population, based either on nationality or on country-of-birth criteria. Strictly speaking, the immigrant population consists of persons residing in a country but born in another country. The definition based on nationality is commonly used in a certain number of countries and reflects a legal view of immigration.

Definition

Nationality and place of birth are the two criteria most commonly used to define the "immigrant” population. The foreign-born population covers all persons who have ever migrated from their country of birth to their current country of residence. The foreign population consists of persons who still have the nationality of their home country. It may include persons born in the host country.

Comparability

The difference across countries between the size of the foreign-born population and that of the foreign population depends on the rules governing the acquisition of citizenship in each country. In some countries, children born in the country automatically acquire the citizenship of their country of birth (jus solis, the right of soil) while in other countries, they retain the nationality of their parents (jus sanguinis, the right of blood). In others, they retain the nationality of their parents at birth but receive that of the host country at their majority. Differences in the ease with which immigrants may acquire the citizenship of the host country explain part of the gap between the two series. For example, residency requirements vary from as little as two years in Australia to as much as ten years in some countries. The naturalisation rate is high in settlement countries such as Australia, Canada, New Zealand and in some European countries including Belgium, Sweden and the Netherlands. In general, the foreign-born criterion gives substantially higher percentages for the immigrant population than the definition based on nationality. This is because many foreign-born persons acquire the nationality of the host country and no longer appear as foreign nationals. The place of birth, however, does not change, except when there are changes in country borders.

The data shown for the year 2000 come from a special census data collection covering almost all OECD countries. See the next statistic on the following pages for details on this data source. Note that the foreign-born here include persons born abroad as nationals of their current country of residence. The prevalence of such persons among the foreign-born can be significant in some countries, in particular France and Portugal (repatriations from former colonies).

For a number of countries, reliable data on the foreign-born population are available only at time of census. To make up for this deficiency, the OECD Secretariat has developed data series for a certain number of countries, applying two estimation methods, which depend on the auxiliary information available for estimation. These methods are described and evaluated at www.oecd.org/els/migration/foreignborn.

For the foreign-born population the data year shown under the 2000 column is 1999 for France; 2001 for Greece, Italy, the Slovak, Republic, Spain; 2002 for Poland; and 2003 for Belgium and Germany. For the foreign population it is 1999 for France; 2001 for Australia, Canada, Greece; 2002 for Poland; and 2003 for Italy.