Defining 'Foreign Born' and 'Foreigner' in International Migration Statistics
By Elizabeth Grieco
Migration Policy Institute
July 1, 2002
Contrary to popular belief, numbers are not always "just numbers." As social scientists point out,
many official statistics released by government agencies reflect the culture and history of the
country in which they are generated. All aspects of a data collection system—from what data are
collected, to the questions asked on surveys and censuses, even to what data are ultimately
analyzed and disseminated—are influenced by this same context. Thus, official statistics
actually embody socio-cultural influences that can prove to be problematic when attempting to
compare data from different countries.
Like other official numbers, international migration statistics also reflect the culture and
history of the country in which they are generated. Throughout the world, countries demarcate
their national identities by defining what seem to be immutable migration-related concepts, such
as "migrant," "immigrant," or "citizen," in distinct ways. This variability has a direct impact on
the way the governments of those countries collect, process, and present migration data—and on
the ability of data users to make direct comparisons among countries.
Models of Citizenship: Jus Soli and Jus Sanguinis
The influence of socio-cultural norms and historical experiences on migration statistics is best
illustrated in the similar-yet-different concepts of "foreign born" and "foreigner," both of which
are rooted in and reflect very different models of citizenship. In general, the majority of people
around the world acquire citizenship in one of two ways: "by birth" (jus soli) or "by
blood" (jus sanguinis). Although these are "ideal types," they remain useful in explaining
the divergent outcomes of citizenship policies. In a jus soli system, citizenship is based on place of birth. Although there are exceptions to this rule, in
general, people born in these countries are citizens, while people born outside are non-citizens.
Thus, in a jus soli context, the term "foreign born" refers to residents of a country who
were born in another country. Foreign-born residents can, under certain circumstances, change
their status and become citizens through naturalization. When combined, both place of birth and
citizenship status can be used to divide the population into three categories—native-born
citizens, foreign-born citizens, and non-citizens—and define who among the foreign born has
acquired the full rights and responsibilities bestowed on all citizens.
In a jus sanguinis system, descent and heritage play a pivotal role in
defining who is, and can become, a citizen. Where people were born is not as important as
how they can trace their ancestry back to the origin country. In this context, the term
"foreigner" refers to those in the population whose heritage cannot be traced back to the host
country. In general, under jus sanguinis citizenship policies, it is often difficult—though not
impossible—for foreigners to naturalize, even if they are long-term residents or were native
born to the country. Those foreigners who do naturalize typically have to demonstrate that they
meet the required "integration" criteria, such as language skills or knowledge of the country's
culture and history. While it is often difficult for resident foreigners to naturalize, it is
usually easier for foreign-born ethnics to obtain citizenship after immigrating back to their
ancestral "homeland," in some cases even if their families have lived abroad for generations. In
this sense, the concept of foreigner divides a country's resident population—and, indeed, the
world's population—into two groups: nationals, who have the right of citizenship by virtue of
their ancestry, and foreigners, who must earn the right to naturalize.
Foreign Born v. Foreigner: Reflecting Alternative Views of Citizenship
These outlines of jus soli and jus sanguinis citizenship policies are, as noted, ideal
types. In fact, most countries, while generally emphasizing one or the other, have increasingly
blurred the distinction between the two by including elements of both in their broader
procedures. However, the preeminence of either a "by birth" or "by blood" citizenship policy
simultaneously reflects and defines how a country views "membership" and who does,
and does not, belong. This, in turn, influences how individuals in a country's population are
classified administratively and how they are counted in official statistics.
The influence of varying citizenship policies on migration statistics can be clearly seen when
data from the United States and Germany are put side-by-side. Two examples will be presented here,
with the first focusing on "stock" data and the other on "flow" data. Both the United States and
Germany data discussed in these examples are available in The Source's
Global Data Center.
Stock data represent "snapshots" of a population at a single point in time by counting (as in a
census) or estimating (as in a survey) the distribution of that population according to some
characteristic, such as age, income, or sex. An example of stock data would be the distribution of
all foreign persons in a population by their country of origin. However, who is included in the
category of "foreign persons" will depend on whether the dominant citizenship policy of a country
is jus soli or jus sanguinis.
In the United States, where the citizenship policy is predominantly jus soli,
"foreign persons" refers to all foreign born in the resident population and includes both
naturalized citizens and non-citizens. In Germany, where a jus sanguinis policy dominates,
"foreign persons" generally refers to anyone in the resident population who is a non-citizen and
not of German descent, that is, both foreign-born and native-born foreigners who have not
naturalized. However, it does not include either ethnic Germans who were born abroad and were
awarded citizenship after immigration or non-German foreign-born persons who have naturalized; these
individuals are considered to be, or to have become, nationals. As a result, while the concepts of
foreign born and foreigner initially appear similar, they actually categorize people in
fundamentally different ways. This makes it difficult to compare directly the migration stock data
of the United States and Germany.
A similar problem exists when attempting to compare flow data. Flow data are collected and
produced by governmental administrative agencies. Unlike stock data, they are collected
continuously but are usually presented in an aggregate form for a point in time, such as monthly
or annual statistics. A good example of flow data is the number of immigrants entering a country,
since immigration is a process that occurs continuously and is catalogued year-round. Depending on
whether the citizenship policy of a country is predominantly jus soli or jus sanguinis,
the term "immigrant" can include very different categories of people.
In the United States, immigrant inflow data include foreign-born persons who are non-citizens
entering the country for lawful permanent residence. In Germany, immigrant inflow data also
include foreign-born persons who are non-citizens entering the country legally, but not all
foreign born are considered immigrants. Specifically, Aussiedler, or ethnic Germans born in
eastern Europe and the former Soviet Union, who meet certain requirements, have the right to enter
Germany virtually as citizens. While they are enumerated in the inflow data, the Aussiedler are not
considered immigrants but rather "returning nationals." This orientation also helps to explain why
German citizens who have returned to Germany after long-term stays abroad are also included in the
inflow data. In the United States, immigrant inflow data documents the arrival of the foreign
born, while in Germany it documents both the arrival of the foreign population and the "return" of
Implications for the Comparability of International Migration Data
While it is generally assumed that statistics passively and objectively reflect the event or
process they measure, in reality, they do so subjectively—in the context of the history and
culture of the society in which they are produced. These socio-cultural influences can be seen in
the varied concepts, legal definitions, and administrative classifications used to generate and report migration data—
and this variation means that international migration statistics are often difficult to compare.
Concepts and terms that may initially appear to include the same categories of people, such as
"foreign born" and "foreigner" or even "immigrant," may actually encompass very different groups.
This means that the rate and trend statistics generated from these data, such as "percentage of
foreign persons in the total population" or "annual number of immigrants," are often not directly
Do these differences mean that comparative analyses of international migration trends and levels
should not be pursued? Of course not. Fortunately, many governments recognize the problems
associated with these differences and, encouraged by support from various international agencies,
are moving their statistics in the direction of greater comparability. However, change takes time
and, as of today, there are still migration-related concepts and terms that remain problematic in
an international context. It is therefore essential for users to be aware of the existence of
differences and to make every effort to understand how those differences affect the comparability
of the data. This is important, because it is the degree of comparability that will determine the
qualifications associated with any conclusions drawn.
Aleinikoff, T. Alexander and Douglas Klusmeyer (eds.) (2000) From Migrants to Citizens: Membership
in a Changing World. Washington, DC: Carnegie Endowment for International Peace.
Aleinikoff, T. Alexander and Douglas Klusmeyer (eds.) (2001) Citizenship Today: Global
Perspectives and Practices. Washington, DC: Carnegie Endowment for International Peace.
Aleinikoff, T. Alexander and Douglas Klusmeyer (eds.) (2002) Citizenship Policies for an Age of
Migration. Washington, DC: Carnegie Endowment for International Peace.
Starr, Paul (1987) "The Sociology of Official Statistics." Pp. 7-57 in William Alonso and Paul
Starr (eds.), The Politics of Numbers. New York: Russell Sage Foundation.
2002-2013 Migration Policy Institute.
All rights reserved.
Migration Information Source, ISSN 1946-4037
MPI · 1400 16th St. NW, Suite 300 · Washington, DC 20036
ph: (001) 202-266-1940 · fax: (001) 202-266-1900