Annex A. Statistical annex

OECD countries seldom have tools specifically designed to measure the inflows and outflows of the foreign population, and national estimates are generally based either on population registers or residence permit data. This note describes more systematically what is measured by each of the sources used.

Population registers can usually produce inflow and outflow data for both nationals and foreigners. To register, foreigners may have to indicate possession of an appropriate residence and/or work permit valid for at least as long as the minimum registration period. Emigrants are usually identified by a stated intention to leave the country, although the period of (intended) absence is not always specified.

In population registers, departures tend to be less well recorded than arrivals. Indeed, the emigrant who plans to return to the host country in the future may be reluctant to inform about his departure to avoid losing rights related to the presence on the register. Registration criteria vary considerably across countries; in particular the minimum duration of stay for individuals to be registered ranges from three months to one year, which poses major problems of international comparisons. For example, in some countries, register data cover many temporary migrants, in some cases including asylum seekers when they live in private households (as opposed to reception centres or hostels for immigrants) and international students.

Statistics on permits are generally based on the number of permits issued during a given period and depend on the types of permits used. The so-called “settlement countries” (Australia, Canada, New Zealand and the United States) consider as immigrants persons who have been granted the right of permanent residence, and this right is often granted upon arrival. Statistics on temporary immigrants are also published in this annex for these countries. In the case of France, the permits covered are those valid for at least one year (excluding students).

Another characteristic of permit data is that flows of nationals are not recorded. Some flows of foreigners may also not be recorded, either because the type of permit they hold is not included in the statistics or because they are not required to have a permit (freedom of movement agreements). In addition, permit data do not necessarily reflect physical flows or actual lengths of stay since: i) permits may be issued overseas but individuals may decide not to use them, or delay their arrival; ii) permits may be issued to persons who have in fact been resident in the country for some time, the permit indicating a change of status.

Ireland provides estimates based on the results of Quarterly National Household Surveys and other sources such as permit data and asylum applications. These estimates are revised periodically on the basis of census data. Australia and New Zealand conduct passenger surveys, which enable them to establish the length of stay on the basis of migrants’ stated intentions when they enter or exit the country.

Statistics on asylum seekers published in this annex are based on data provided by Eurostat and the United Nations High Commission for Refugees. Since 1950, the UNHCR, which has a mission of conducting and co-ordinating international initiatives on behalf of refugees, has regularly produced complete statistics on refugees and asylum seekers in OECD countries and other countries of the world (https://www.unhcr.org/data.html).

These statistics are most often derived from administrative sources, but there are differences depending on the nature of the data provided. In some countries, asylum seekers are enumerated when the application is accepted. Consequently, they are shown in the statistics at that time rather than at the date when they arrived in the country. Acceptance of the application means that the administrative authorities will review the applicants’ claims and grant them certain rights during this review procedure. In other countries, the data do not include the applicants’ family members, who are admitted under different provisions (France), while other countries count the entire family (Switzerland).

The figures presented in the summary table (Table A.3) generally concern initial applications (primary processing stage) and sometimes differ significantly from the totals presented in Tables B.3, which give data by country of origin. This is because the data received by the UNHCR by country of origin combine both initial applications and appeals, and it is sometimes difficult to separate these two categories retrospectively. The reference for total asylum applications remains the figures shown in summary Table A.3.

There are major differences in how immigrants are defined across OECD countries. Some countries have traditionally focused on producing data on foreign residents (European countries, Japan and Korea), whilst others refer to the foreign-born (settlement countries, i.e. Australia, Canada, New Zealand and the United States). This difference in focus relates in part to the nature and history of immigration systems and legislation on citizenship and naturalisation.

The foreign-born population can be viewed as representing first-generation migrants, and may consist of both foreign and national citizens. The size and composition of the foreign-born population is influenced by the history of migration flows and mortality amongst the foreign-born. For example, where inflows have been declining over time, the stock of the foreign-born will tend to age and represent an increasingly established community.

The concept of foreign population may include persons born abroad who retained the nationality of their country of origin but also second and third generations born in the host country. The characteristics of the population of foreign nationals depend on a number of factors: the history of migration flows, natural increase in the foreign population and naturalisations. Both the nature of legislation on citizenship and the incentives to naturalise play a role in determining the extent to which native-born persons may or may not be foreign nationals.

Four types of sources are used: population registers, residence permits, labour force surveys and censuses. In countries which have a population register and in those which use residence permit data, stocks and flows of immigrants are most often calculated using the same source. There are exceptions, however, with some countries using census or labour force survey data to estimate the stock of the immigrant population. In studying stocks and flows, the same problems are encountered whether population register or permit data are used (in particular, the risk of underestimation when minors are registered on the permit of one of the parents or if the migrants are not required to have permits because of a free movement agreement). To this must be added the difficulty of purging the files regularly to remove the records of persons who have left the country.

Census data enable comprehensive, albeit infrequent analysis of the stock of immigrants (censuses are generally conducted every five to ten years). In addition, many labour force surveys now include questions about nationality and place of birth, thus providing a source of annual stock data. The OECD produces estimates of stocks for some countries.

Some care has to be taken with detailed breakdowns of the immigrant population from survey data since sample sizes can be small. Both census and survey data may underestimate the number of immigrants because they can be missed in the census or because they do not live in private households (labour force surveys may not cover those living in collective dwelling such as reception centres and hostels for immigrants). Both these sources may cover a portion of the unauthorised population, which is by definition excluded from population registers and residence permit systems.

Nationality law can have a significant impact on the measurement of the national and foreign populations. In France and Belgium, for example, where foreigners can fairly easily acquire the nationality of the country, increases in the foreign population through immigration and births can eventually contribute to a significant rise in the population of nationals. On the other hand, in countries where naturalisation is more difficult, increases in immigration and births among foreigners manifest themselves almost exclusively as growth in the foreign population. In addition, changes in rules regarding naturalisation can have significant impact. For example, during the 1980s, a number of OECD countries made naturalisation easier and this resulted in noticeable falls in the foreign population (and rises in the population of nationals).

However, host-country legislation is not the only factor affecting naturalisation. For example, where naturalisation involves forfeiting citizenship of the country of origin, there may be incentives to remain a foreign citizen. Where the difference between remaining a foreign citizen and becoming a national is marginal, naturalisation may largely be influenced by the time and effort required to make the application, and the symbolic and political value individuals attach to being citizens of one country or another.

Data on naturalisations are usually readily available from administrative sources. The statistics generally cover all means of acquiring the nationality of a country. These include standard naturalisation procedures subject to criteria such as age or residency, etc., as well as situations where nationality is acquired through a declaration or by option (following marriage, adoption or other situations related to residency or descent), recovery of former nationality and other special means of acquiring the nationality of the country.

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