Censuses are not a solely American phenomenon: governments everywhere rely on accurate, up-to-date assessments of their populations to determine the distribution of funds, placement of schools, allocation of seats in their governing bodies, and other critical aspects of government function. When a country conducts a census, it is mandatory for residents to complete, and ultimately allows for a more comprehensive understanding of a country’s demographics.

Despite their importance, getting an accurate count of all the people living in a country can be difficult. The process is time consuming, takes months of preparation, and requires large numbers of workers to complete the census quickly and efficiently. Because of this, countries are constantly looking for new ways to refine their census processes.

Read on for summaries of the three major types of censuses from around the world and the advantages and disadvantages of each system.

The Traditional Census

The traditional census is by far the most common way for countries to compile accurate national demographics. A traditional census occurs at a set time interval, and is largely defined by a “survey” that is sent to each resident. Many nations, like the United States and Brazil, conduct their censuses every ten years in this manner; others, like Japan and Ireland, use a five-year interval.

In a traditional census, each address is mailed a census form that asks certain demographic questions about the people that live at that address. Once census forms are completed, residents can submit their responses by mail or, increasingly, over the internet. Census workers may approach residences who have not submitted their forms by the deadline to ensure that the forms are completed and submitted.

A traditional census can allow for the most accurate and complete report of a country’s demographics at a moment in time. Having these complete counts conducted at regular intervals allows governments to more easily track complete trends over time. The greatest downside of traditional censuses is that it can be difficult to get all residents to complete a census form. In particular, people experiencing homelessness and people with low literacy may struggle to be reached by census workers. Traditional censuses are also expensive and may not always be a feasible use of funds.

The Register-Based Census

The register-based census was pioneered by Nordic countries in the 1970s and has since expanded to cover many European countries. In a register-based census, governments do not individually canvas the residents of each address. Instead, they combine the information that they already have on file about residents, including social security, taxes, education records, and other individual records, to create comprehensive profiles of each resident of a country. Through a register-based census, households do not need to complete any surveys at all.

Register-based censuses are considerably less expensive and less complex than traditional censuses. However, they are only a realistic option for countries that already have extensive, accurate, and well-maintained records of their country’s residents. Many countries without these records cannot do a fully register-based census, and instead supplant information from traditional census surveys with the information that they already have on record in a combined census approach. In Estonia’s 2011 census, where existing registers did not include information on occupation and definitions had not been consistent across registers, the government conducted a traditional census and used registers for verification.

The Rolling Census

France is unique in the world with its “rolling census,” first implemented in 2004. Where traditional census taking techniques limit their assessment to get a single snapshot of a country’s demographics, France continually assesses segments of its population over time.

Addresses within each administrative region are chosen at random and surveyed just as they would in a traditional census. Census takers then move onto another set of randomly selected addresses until the entire population has been surveyed. Most addresses are surveyed multiple times throughout the census process. The entire population is surveyed over the course of seven years, with the next census beginning immediately at the end of the previous census.

The primary advantage of this mode of census taking is that data is updated much more frequently than in traditional censuses. The rolling census also spreads out the cost burden of operating the census across several years rather than concentrating in one. However, as the rolling census only surveys about 70% of the country’s population within a given year, it never gives a complete assessment of the country at one given point in time, which can make comparisons between different divisions of the country more difficult.

Counting a Population is Important

It is important to appreciate the fact that any census is an enormous undertaking. No matter which method you employ, it is extremely challenging to assess the population of an entire country, but we hope you found this information helpful in appreciating the different approaches used throughout the world.

Image Credits: 2020 census form with envelope (Laura Short); U.S. Census worker goes door-to-door (2020census.gov); Crowd in Estonia (Eesti Eesti by Aivar Ruukel is licensed under CC BY-SA 2.0)