421. This chapter looks at the way that countries in the UNECE region used the census to identify two different aspects relevant for the measurement of migration:

(a) measurement of stocks and in-flows of international migrants and of other groups relevant to international migration, with information on timing and geographical patterns of their international migrations; and

(b) measurement of stocks and flows of internal migrants, with information on timing and geographical patterns of their internal migrations.

422. In relation to the immigrant stocks the CESR included two core topics that allowed the identification of those born abroad (country of birth) and those with foreign citizenship (country of citizenship). And to aid the measurement of international migration flows the core topic of “ever resided abroad and year of arrival in the country” and the non-core topics of “country of previous usual residence abroad” and “total duration of residence in the country” were also recommended. Additional (non-core) topics would allow the identification of additional groups that may or may not belong to immigrant stock: “citizenship acquisition” and “country of birth of parents”, and, to some extent, “ethnicity”, “religion” and “language” (the latter three being covered in ‎Chapter 20).

423. Internal migration stocks and information about timing and geographical patterns of internal movements are primarily collected using the core topics “previous place of usual residence and date of arrival in the current place of residence” and the non-core topic “place of usual residence five years prior to the census”. One further recommended non-core topic that can provide additional information about both international and internal migration is the “reason of migration”.

424. This chapter reviews the extent to which the CESR for each of these topics in turn were adopted by UNECE countries in the 2020 round.

425. The present section focuses on the core topics relevant to information migration, including country of birth, country of citizenship, ever resided abroad, and year of arrival in the country. Information is also presented on the non-core topic “reason for international migration”, which was also covered in the UNECE survey.

426. It is useful to recall that the CES Recommendations in para. 638 (c) adopt the definition of international migrant as "any person who changes his or her country of usual residence”.⁵ The "country of usual residence" is defined in the same paragraph as “the country where the person usually lives, that is to say, the country in which the person has a place to live where he or she normally spends the daily period of rest.”

427. Information on country of birth is essential for the analysis of international migration, as this information is used to distinguish between native-born and foreign-born residents (CESR para. 649). Information on the collection of data on county of birth in the 2020 census round is presented in Table 77. All the 46 countries that responded to this question adopted the CES Recommendations and collected information on this core topic (similar to the 2010 round).

	Total (out of 46 countries)	Type of census
		Field enumeration (16 countries)	Combined (16 countries)	Register-based (14 countries)
Information collected	46	16	16	14
Main data source:
full enumeration	23	14	9	0
sample data	4	2	2	0
registers/admin.rec.	19	0	5	14
Actual birth or residence of mother:
country of actual birth only	22	10	5	7
country of residence of mother only	13	2	6	5
both	8	3	3	2
Boundaries:
national boundaries as at census	30	12	12	6
national boundaries as at birth	10	3	2	5
other definition	4	1	2	1
Information not collected	0	0	0	0

428. With the advent of administrative data in a number of countries, whether through combined or register-based censuses, it is possible to observe a shift in the country of birth's information source with respect to the 2010 round. The number of countries where the information is sourced from an administrative source has increased (from 13 in the 2010 round to 19 in the 2020 round), whereas the number of countries where the information comes from a full count has decreased (from 32 to 23, respectively). It is also interesting to note that among the 16 countries that use combined census, 11 of them don't use administrative data as an information source for country of birth. This seems to suggest that country of birth is not universally recorded in the administrative system.

429. The CESR allows place of birth to be collected according to either the geographical unit in which the birth took place or to the place of usual residence of the mother at the time of the birth. Twenty two (22) countries adopted the actual birth only, 13 the place of usual residence of the mother only and 8 adopted both criteria.

430. The CESR also stated that for purposes of international comparability, as well as for internal use, information on country of birth should be collected on the basis of international boundaries existing at the census reference time. Thirty (30) countries complied with this, while 10 countries considered the national boundaries as at birth and 4 countries used another definition.

431. The CESR noted that countries with a significant number of immigrants might want to collect data on the second generation of immigrants, especially those countries that did not collect data on ethnic groups. The CESR were to collect information relating to both legal parents. The UNECE survey results showed that 14 countries reported collecting or deriving information on the country of birth of both parents, 1 country collected information on the country of birth on the mother only, and 3 countries collected the information only for part of the population.

432. Information on collecting data on citizenship in the 2020 census round is presented in Table 78. All countries collected information on the country of citizenship, with the exceptions of Israel and the United States, where respondents are asked if they are citizens of the US. Only two countries collected information on the country of citizenship from sample data (Armenia and Canada). Almost the same number of countries used full enumeration (20) and registers or administrative records (21).

433. About half of the reporting countries collected additional data about country of citizenship (non-core topics). Twenty five (25) countries collected information about dual or multiple citizenship, in most cases for all respondents (20 countries), in others for national citizens only (4) or for foreign citizens only (one country). Interestingly, the percentage of countries with a combined census that collected information on dual or multiple citizenship (80%) is significantly higher compared to field enumeration censuses (62%) and register-based censuses (36%).

434. Information on citizenship acquisition was collected by 15 countries (in the 2010 round they were only 7), equally divided by the type of censuses. All those countries considered acquisition by birth, most of them (13) also by naturalization, while acquisition by marriage or other means was considered only by few (5 or less) countries.

	Total (out of 45 countries)	Type of census
		Field enumeration (15 countries)	Combined (16 countries)	Register-based (14 countries)
Information collected
Main data source:	43	14	15	14
full enumeration	20	13	7	0
sample data	2	1	1	0
registers/admin.rec.	21	0	7	14
Information on countries of dual or multiple citizenship?
Yes, for all respondents	20	4	12	4
Yes, only for national citizens	4	4	0	0
Yes, only for foreign citizens	1	0	0	1
No	17	5	3	9
Information on citizenship acquisition?
Yes, including…	15	5	5	5
…acquisition by birth	15	5	5	5
…acquisition by naturalization	13	4	4	5
…acquisition by marriage	5	1	2	2
…following creation of new state	4	0	1	3
…acquisition by other means	10	3	4	3
No	26	8	10	8
Information not collected	2	1	1	0

435. The place of birth covers the migrants who were born abroad, but it does not cover the natives who resided in another country and returned to reside in the country where they were born. Therefore, in order to cover all residents who have ever migrated, it was recommended in CESR (as a core topic) to collect information on whether the resident has ever resided in another country and on the year of arrival in the country. Information on this topic is presented in Table 79.

436. Three quarters of the reporting countries adopted the CESR recommendation to collect data on ever-residing abroad. Only 9 of the reporting countries that conducted traditional census collected the information (60%) against 10 countries that conducted register-based census (77%) and 14 countries with combined census (88%). That seems to indicate that it is easier for countries to derive this information from administrative sources than from questionnaires.

437. The CES recommended that the year (and the month if possible) of the most recent arrival in the country should be collected to provide a measure of duration of residence. The CESR argued that it is preferable to measure duration using the time of arrival rather than the number of years elapsed since arrival in the country because time of arrival is likely to yield more accurate information (paras. 662-663). Furthermore, the year of most recent arrival to the country was recommended rather than the year of first arrival since it provides unequivocal information, and can also provide useful information on recent immigration flows.

	Total (out of 45 countries)	Type of census
		Field enumeration (15 countries)	Combined (16 countries)	Register-based (14 countries)
Ever resided abroad (core topic)
Information collected, of which…	33	9	14	10
…resided abroad for 12 months or more	29	8	13	8
…resided abroad for less than 12 months	4	1	1	2
Information not collected	11	6	2	3

438. Results of the UNECE survey concerning collection in the 2020 census round of data on data of arrival in the country and on other related non-core topics, are presented in Table 80.

	Total (out of 45 countries)	Type of census
		Field enumeration (15 countries)	Combined (16 countries)	Register-based (14 countries)
Date of arrival in the country (when person established usual residence)
Information collected, of which…	41	13	15	13
Most recent arrival	38	11	14	13
Year only	26	8	7	11
Year and month	12	3	7	2
First arrival	7	2	2	3
Year only	4	2	0	2
Year and month	3	0	2	1
Information not collected	4	2	1	1
Country of previous usual residence abroad
Information collected	29	12	13	4
Information not collected	15	3	3	9
Total duration of residence in the country for international migrants
Information collected	9	6	1	2
Information not collected	36	9	15	12

439. In total, 38 countries (84% of those responding to this question) collected information on the most recent arrival in the country, with 26 of them collecting only the year and 12 collecting both year and month. Data on the first arrival were collected by 7 countries, including 4 countries that also collected data on the most recent arrival.

440. For persons who have ever resided abroad, the CESR suggested collecting information on the country of previous usual residence, as a non-core topic. This information was collected by two thirds of the countries, including 80% of those with a field enumeration or combined census and only 30% of those with a register-based census.

441. The non-core topic "total duration of residence in the country" for international migrants was also suggested in the CESR as a non-core topic. This information was collected by only 9 countries (20% of those responding), in most cases through field enumeration. Finland and Norway were the only countries that produced this information as part of a register-based census.

442. The CESR noted that some countries might wish to collect information on reasons for international and/or internal migration. This topic refers to the main reason that drove the respondent to undertake the most recent move (para. 670).

443. Table 81 presents information on the countries that collected information on the main reason for international migration and on the reasons considered. Of the 44 responding countries, 17 (39%) collected this information, in most cases based on field enumeration. The only country with register-based census that produced this information was Norway.

	Total (out of 44 countries)	Type of census
		Field enumeration (16 countries)	Combined (16 countries)	Register-based (12 countries)
Information collected – reasons…	17	10	6	1
Education	16	9	6	1
Employment, of which…	15	8	6	1
long term	14	7	6	1
short term	8	3	5	0
To join family members	15	8	6	1
Refugee (forced migration)	13	6	6	1
Health/medical	10	5	4	1
Asylum	8	4	3	1
Return after emigration	6	3	3	0
Other reasons	9	5	4	0
Information not collected	27	6	10	11

444. The reasons reported by most countries are education (16 countries), employment, and “to join family members” (15 countries), as it was the case in the 2010 census round. Other reasons were reported by more countries compared to the 2010 round: refugee by 13 countries (9 in the 2010 round), health/medical reasons by 10 countries (3 in the 2010 round) and asylum by 8 countries (4 in the 2010 round).

445. Internal migrants, as identified in the census, are specifically defined as those who are usually resident in a civil division at the census reference time and who have previously been resident in another civil division within the country. Persons who are international migrants – who, regardless of country of birth or citizenship, have at some point in their lives been usually resident in another country – may also be counted as internal migrants if, subsequent to their international move, they have also moved internally and they were resident elsewhere in the country prior to the census.

446. The principle means measuring internal migration in the census is by collecting information on place of previous usual residence and the date of arrival in the current place of usual residence. This was assigned as a single core topic in the CESR. However, recognizing the different possible approaches that countries could adopt in collecting the relevant information the CESR recommended that, in practical terms, one of the two modes could be completed:

(a) Extensive mode: by enquiring into “year and month of arrival in the current place of usual residence” plus “previous place of usual residence”; or

(b) Reduced mode: by enquiring into “place of usual residence one year prior to the census”.

447. Table 82 shows what information relating to either the extensive or reduced mode was collected by the countries. Looking at the first three rows it can be noted that 35 countries collected information on place of previous usual residence and 26 countries collected information on year of arrival, but only 25 countries collected both.

448. With regard to the reduced mode, 33 countries collected data specifically on the place of usual residence one year prior to the census as recommended by the CES. In addition, 5 countries collected the information with respect to a period of five years before the census while 10 countries collected the information at some other period prior the census.

	Total (out of 47 countries)	Type of census
		Field enumeration (16 countries)	Combined (17 countries)	Register-based (14 countries)
Extensive mode
Place of previous usual residence	35	14	11	10
Date of arrival (year only)	13	6	4	3
Date of arrival (year and month)	13	1	7	5
Reduced mode
Information on place of previous usual residence, collected….
1 year prior to the census	33	10	11	12
5 years prior to the census	5	2	2	1
Some other period prior to the census	10	5	3	2

449. The survey showed that 25 countries completed the extensive mode and 15 other countries completed the reduced mode, therefore 40 countries in total (85% of those responding) complied with the CESR.

450. In order to provide relevant information on internal migration, the CES recommended that countries should distinguish local, intra-regional or inter-regional moves. Accordingly, the UNECE survey asked countries to report whether or not they identified moves both within and between the country's major and minor civil divisions in any period of time prior to the census (the reduced mode). The results are shown in Table 83. Most of the countries that collected information on previous place of usual residence were able to record whether the person was living in the same or another civil division.

451. Internal migrations within and between minor civil divisions were recognized by half of the countries. Some 20 reported collecting information on moves within the same minor civil division and 20 countries reported moves between minor divisions. Compared with the 2010 round, there is a decrease in the number of countries that collected information on the same minor division (from 28 to 20) and in other minor division (from 30 to 20). The main decrease was in countries that conducted a traditional census.

452. More countries reported collecting information on movements between major civil divisions as the CESR recommendation to collect information on regional migration. Twenty four (24) countries reported collecting information on the same major divisions and 24 counties reported collecting information in other major division.

	Total (out of 47 countries)	Type of census
		Field enumeration (16 countries)	Combined (17 countries)	Register-based (14 countries)
Information collected on whether or not the person was living in…	40	14	14	12
same dwelling where the person was resident at the time of the census	28	12	8	8
same minor civil division where the person was resident at the time of the census	20	8	6	6
another minor civil division	20	9	6	5
same major civil division where the person was resident at the time of the census	24	9	6	9
another major civil division	24	9	8	7
another country	28	11	10	7
other response	11	3	7	1
Information not collected	7	2	3	2

453. Information was also collected in the survey on the level of geography used for measuring internal migration in those 35 countries using the extensive mode of data collection. The equivalent results are shown in Table 84.

	Total (out of 35 countries)	Type of census
		Field enumeration (16 countries)	Combined (17 countries)	Register-based (14 countries)
Information collected on whether or not the person was living in…	35	14	11	10
another dwelling in the same minor civil division where the person was resident at the time of the census	15	6	3	6
another minor civil division	22	10	8	4
same major civil division	21	7	7	7
another major civil division	28	12	9	7
another country	27	12	8	7
other response	6	2	2	2

454. The UNECE survey also asked countries whether they collected or produced census information on other topics related to international migration that were not listed as topics in the CESR. The results are presented in Table 85

455. Of the 39 countries that responded to the question, 22 did not include any other topic, while 11 countries included one or more. The topics included in the census by most countries are emigration (11 countries), reasons for internal migration (10), short-term international migrants (8) and year that permanent residence was granted (5).

Topics	Total (out of 39 countries)	Type of census
		Field enumeration (15 countries)	Combined (14 countries)	Register-based (10 countries)
Emigration	11	4	4	3
Reasons for internal migration (mobility)	10	5	4	1
Short-term international migrants	8	1	7	0
Year that permanent residence was granted	5	3	1	1
Circular migration	1	0	1	0
Remittances	1	0	1	0
Illegal/undocumented migrants	0	0	0	0