The role of Population and Housing Census for a country

UNFPA is a lead UN agency providing support for the population and housing census globally. During the 2010 census round, UNFPA provided support to 135 countries through, inter alia, technical assistance, capacity strengthening, procurement of equipment or services, financial and operational support, coordination and management of financial resources for the census on behalf of partner governments, and facilitation of South-South cooperation.

Ms. Naomi Kitahara, UNFPA Representative for Vietnam responded to the questions raised by the General Statistics Office providing an in-depth information about the purpose of population and housing census.

1. What is the purpose, meaning and role of the Population and Housing Census for the country?

A Population and Housing Census is conducted to count everyone in the country on the Census date, which is therefore a fair, independent, and accurate source of information which is essential for the country’s direction, policy-making, planning, risk management, social welfare, and business market analysis. By definition, a Population and Housing Census is an enumeration of the total population of a given country on a given date, and provides data on key characteristics of people, such as the number, people’s spatial distribution, economic activities, age, gender, ethnicity, household compositions and living conditions, education, and internal/international migration, as well as other key socio-economic characteristics. It counts everyone on the given Census date, which usually includes foreigners resident in the country regardless their immigration status, but does not necessarily include nationals who do not reside in the country on the Census date.

The essential principles of the population and housing census are universality, independency, fairness, simultaneity, and defined periodicity. It should be noted that a traditional population and housing census is a unique opportunity for making statistics visible, both in terms of operations and results, which also allows for international comparison per internationally recognized standards, which must be used for reporting on international obligations, instruments, and documentations. In addition, it must be underlined that the Census information is a key data source for SDG reporting. Up to 107 out of the 232 indicators of the Sustainable Development Goals require population data to be calculated, with the census providing population denominators for many of the indicators. At least 19 SDG indicators can be fully calculated from census data alone. Because the census covers every individual in the country, census data allows for more granular disaggregation of indicators, thereby facilitating a more comprehensive analysis of inequalities for locating those left behind i.e., Leaving No One Behind (LNOB) analysis.

Census is a key pillar of national statistical systems, as it is the basis of sampling frames for national surveys. In addition, census data are used to assess the completeness of civil registration systems and validation of administrative data. Census also provides base data for population projections, including sub-national projections, which are the basis for Common Operational Datasets on Population Statistics – a key resource in humanitarian settings.

Independent, reliable, and accurate data derived from Census form a foundation for evidence-based policy and decision making, which is essential for the country’s socio-economic growth. Moreover, the Census data are treated with confidentiality, in line with Principle 6 of the Fundamental Principles of Official Statistics, which states: “Individual data collected by statistical agencies for statistical compilation, whether they refer to natural or legal persons, are to be strictly confidential and used exclusively for statistical purposes.” 

2. How has the global population and housing census round 2020 been conducted?

Most countries in the world including Viet Nam to date conducted a Population and Housing Census, and it has been the international norm.  Most countries conduct the Population and Housing Census every 10 years, and some conduct every 5 years (Canada, Japan, Ireland, etc.). A few countries conduct every year (France, Finland, Italy, Switzerland, etc.).

The 2010 round of the population and housing censuses (censuses conducted between 2005 and 2014) had the largest global coverage to date. Approximately ninety-three percent of the world population was covered, across 214 of 235 countries and territories. Only twenty-one countries and territories, mainly in Africa and the Arab States, did not have the census for various reasons which include internal political/conflict situations. During the 2000 round of the censuses, twenty-six countries and territories did not conduct a census.

For the 2020 round of population and housing censuses (censuses conducted between 2015 and  2024): the 2020 World Population and Housing Census Programme was approved by the United Nations Statistical Commission at its 46th session and adopted by the United Nations Economic and Social Council (ECOSOC) in its resolution E/RES/2015/10. The Programme recognizes population and housing censuses as one of the primary sources of data needed for formulating, implementing and monitoring policies and programmes aimed at inclusive socio-economic development and environmental sustainability. It further recognizes population and housing censuses as an important source for supplying disaggregated data, and also as the reliable data source to report on the progress towards the 2030 Agenda for Sustainable Development, especially in the context of assessing the situation of people by income, sex, age, race, ethnicity, migratory status, disability and geographic location, or other characteristics.

To support countries to conduct a population and housing census, the Department of Economic and Social Affairs Statistics Division of the Unites Nations issued in 2017 the Material: “Principles and Recommendations for Population and Housing Censuses, revision 3”. It provides international recommendations and technical guidance to countries in census operations, and compiling and disseminating census results. The previous global census recommendations were published in 2008 under the title “Principles and Recommendations for Population and Housing Censuses, Revision 2”. 

In general, there exist three different types of a Population and Housing Census: 

• The traditional census, which is a full field enumeration, whether in person or online (registers and administrative sources may be used to support the enumeration but not directly to obtain census data). The majority of countries in the world (71.8% for the 2020 census round) applying a traditional census modality include USA, UK, Portugal, Mexico, China, and countries in Southeast Asia including Viet Nam. It is noted that some developed countries with a strong administrative data system such as USA and Japan still conduct the traditional Census. The traditional census is not free from disadvantages however, particularly its cost and complexity. Some countries have addressed some of such disadvantages either by using sampling or by facilitating an online/postal self-response option, which may result in field cost savings and improved quality but requires very careful planning and implementation so as to avoid any irregularities.
• The second type of a Census is the register-based census, which uses administrative data held in various registers (population register, building/address register, social security register, etc.) through a matching process, normally making use of personal identification numbers. This type does not require field data collection and permits the census operation at a much-reduced cost and with relatively limited manpower, fewer non-response rate, a possibility of a continuous census once a good quality system of statistical registers has been established. Denmark was the world’s first country to conduct a fully register-based population and housing census in 1981. For the 2020 round of population census, about 11.4% countries applied the register-based census including Belgium, Denmark, Finland, Iceland, the Netherlands, Norway, Spain, Sweden, and the Republic of Korea. However, this type requires a robust population register, well capturing the entire population dynamics (birth, death, migrations).
• The combined census allows some data obtained directly from registers or administrative sources while other data are collected through field data collection conduced specifically for census purposes, covering the whole population or only a sample. Since the 1990s, some countries in Europe have developed innovative methods to conduct the census, combining the use of administrative data with a limited collection of data from a field enumeration of the population for specific variables. Often this approach is adopted in the transition from a traditional to a register-based censu Some countries have used a combined census, for example Germany, Italy, Luxembourg, Switzerland, and Singapore. For the 2020 round of population census, about 8.6% countries applied the combined census modality. However, as the second type above, it is a pre-requisite to have a robust and complete register system, and normally it takes years for the register system to mature to be used for the purpose of conducting a Census.

Impact of COVID-19

The 2020 census round has been negatively impacted by the COVID-19 pandemic, which has caused many delays and postponements. Prior to COVID-19, 63% of countries were scheduled to conduct census enumeration in the years 2020 & 2021, with 70 countries expected in 2020 and 69 countries in 2021. However, following the outbreak of the pandemic, only 19 countries successfully conducted census enumeration in 2020 with the rest postponing to 2021 or later. Similarly, the year 2021 has been characterized by further postponements. Moreover, fertility, mortality and migration are likely to be affected by COVID-19, and it is critical to assess the demographic impact of COVID-19 through census data. This is known only after a few years from now, as it tends to lag behind a crisis like COVID-19.

3. Currently, have countries with good administrative data systems in the world conducted the population and housing census? If yes, how was the information being collected? 

As mentioned above, the majority of countries including developed or developing countries conducted a full census for the reasons explained under Question 1 above. Where a robust and complete registers and administrative systems exist, some developed countries (mostly in Northern Europe with a smaller population size) started the combined or register-based census. For the 2020 round of population censuses, out of 48 member countries of the United Nations Economic Commission for Europe (UNECE), 14 countries plan for a register-based census (29 per cent), and 12 countries with a combined census (25 per cent). A near majority 22 countries are still continuing with the traditional and full census (46 per cent).

Countries which conducted a register-based census thus far are those having a robust system of administrative registers that are consistent, easily usable and of high quality (i.e., all units are uniquely identified using a common identifier), and this system satisfies all required features for census information. That means the data obtained from the registers/administrative sources must allow obtaining information on each person separately (according to the census principle of individual enumeration), for the entire defined territory (universality), with the same reference-time (simultaneity) and with a certain periodicity (which in the case of registers will be less than the period of 10 years that usually separates traditional censuses). All these principles can potentially be fulfilled through a system of interconnected registers. If the list of administrative data sources cannot achieve the required quality for the whole range of such census variables, it may still be possible and useful to apply a combined census or continue with the traditional and full census.

Basic pre-requisites for implementing a register-based census or combined (traditional enumeration and use of registers), include:

a. Appropriate legal framework- To be able to conduct a register-based or combined census there must be legal provisions that prescribe the access to, and protection of, such administrative data. This legal framework needs to consider legal considerations not only for the National Statistics Office (NSO), but also for the administrative data suppliers, as well as for wider government frameworks covering privacy/data protection and data security.

b. Stakeholder and political support- This includes support for the overall approach, given stakeholder and public views, as well as for the necessary legal changes (discussed above) and for removing any barriers to accessing administrative registers, cooperation between Statistics Office and register owners.

c. Availability of appropriate data sources- Every country has an extensive range of administrative records and registers. Many of these may be suitable for use in a register-based statistical system.  To determine whether they can be used in this way, it is necessary to identify the availability of sources, and then assess the suitability of each source and the variables within each source. A universal personal identification (unique identity) system should be in place to facilitate proper linking of data.

d. Methods systems and processes- Administrative registers exist (by definition) mainly for administrative purposes, and not for statistical purposes. This means that the units, variables and updating frequency follow administrative rules and demands, and may not meet all statistical purposes.  The NSO will need to prepare methods, systems and processes to assess each data source and then, where appropriate, transform the data into the relevant statistical registers.  In addition, the NSO needs to have in place robust and well-trusted data protection systems and techniques

e. Appropriate resources and expertise- In order to move to a register-based system, it will be necessary to develop the full range of specific skills. These include relationship management, information management, data analysis and associated subject matter skills. Specialized statistical skills may also be needed to support linking processes.  While NSOs generally have a long-standing expertise in information management, it is important to recognise that a register-based statistical system will require statistical expertise, particularly in the linkage and matching of data in general, as well as specific subject matter knowledge and experience.

4. What is the orientation of the Global Population and Housing Census round 2030?

The Population and Housing Census will continue to be conducted by most countries in the world. It should be noted that this is an essential exercise for national governance and development. However, different countries may explore different types of a census (as explained above) depending on the country’s capacity, coverage, robustness and quality of the registers and administrative data sources, and population size, among others. In trying a different type of a census, it is critical not to compromise on the principles of the census as above.

The 2030 round expected to be characterized by the continuation of the census modernization, which was already seen in the 2020 round including the increased use of new technologies and methodologies such as the use of handheld devices, satellite imagery and use of GIS across the different phases of the census, and more innovative analysis methods. Whilst several countries with well-developed registry systems and those meeting the census pre-requisites are likely to consider mixed methods for the 2030 round, the traditional census is expected to remain as the dominant approach in the large majority of countries, for a variety of reasons.

5. What are your recommendations for Viet Nam?

As mentioned above, the full population and housing census is scheduled to be conducted by most countries in the world in the next decades. Even with the presence of a strong national register system, most countries, including developed countries, plan to conduct a full census in the future, recognizing the importance of having a solid statistical foundation for national policy and decision-making. In this respect, given Vietnam’s level of various register systems, as well as the population size and rapidly evolving socio-economic growth characteristics of the country, UNFPA Viet Nam thinks it prudent not to replace a Census with a register, and such an attempt is still premature for Viet Nam. We firmly advise Viet Nam to continue with a Census. However, Viet Nam may wish to elaborate on some options for different types of censuses as above, examining experience and lessons learned from other countries. UNFPA will be able to facilitate this process.

In the context of the 4^th industry revolution in Viet Nam, digital transformation and innovation for data technologies and communication platforms can be fully explored to speed up the data generation process and minimise human errors. Vietnam’s population and housing census 2019 was a very good example, as cited in many occasions at regional and international fora. Other countries are learning from Vietnam’s Census experience, because for the first time, Viet Nam applied ICT in all stages of the Census, especially at data enumeration phase that has substantially helped improve the quality and transparency of data collected, shorten the time for data processing, reduce human errors, and disseminate census results within an excellent record of 7 months.

Currently Viet Nam has developed the national population database managed by the Ministry of Public Security, sectoral databases (e.g., civil registration and vital statistics – CRVS – managed by the Ministry of Justice, etc.) and other administrative data sources. We highly appreciate such efforts to establish and strengthen national population database. However, it is our opinion that such database is not yet sufficient or fully matured to replace the population and housing census as necessary conditions are not yet met to ensure the essential features of census, i.e., individual enumeration, simultaneity, universality, small area data, defined periodicity, and quality.

We understand that key information to be collected in the Viet Nam population and housing census such as reproductive history of women, education, death, migration, imbalance of sex ratio at birth, disability, marriage including child marriage and customary marriage, education, labour forces, housing conduction, etc. are not available or designed in these databases or administrative sources to meet with Census requirement.  In addition, it is important to recognize that such national database, once set, are not flexible enough to change, add, or delete indicators and questions (as change in the database would also mean the difficulty in conducting trend analysis and comparisons of data at different point of time), while the Census can be flexible for questionnaires to be adjusted as different population characteristics emerge over time. Moreover, it usually takes decades to improve and mature such national data systems to be used for the population and housing census.

It is against this background that we strongly advise Viet Nam assess and prepare the transition with extreme caution, if any, from traditional to different types of censuses, ranging from data needs availability, technological viability, and legal and stakeholder considerations. It is highly likely that such a transition can give rise to some unexpected challenges, which can possibly increase the cost in the end.