Methods used for censuses
‘Statistical offices play a role in the way populations are viewed, both at national and at European level,’ says Francisca Grommé, a postdoctoral researcher at the University of Amsterdam and Goldsmiths (University of London), where the research is being conducted. ‘Sociologists are studying that role. The ARITHMUS project is focused on censuses. Each country has its own methodology and cultural background when conducting the census. Who are included in the population and who are not? How does one arrive at these decisions? What does this mean for policy and public opinion? These are interesting questions, also in light of the emergence of new methods that are based on big data. Another reason is that standardisation of population statistics is currently taking place at the European level.’
Registers popular in the Netherlands
CBS makes frequent use of registers and plays a very active role in discussions about statistical methods within Europe. This is why the Netherlands is among the research countries. ‘Our population register is of a high quality,’ says Eric Schulte Nordholt, census project leader at Statistics Netherlands and member of the international advisory board of ARITHMUS. ‘The Statistics Netherlands Act enables us to use this register. We are also able to combine this register with other data sources. For example, by linking the population register with income data, we are able to map neighbourhood poverty. This does not happen in every country. In many countries, conducting censuses is also a very expensive affair. They do a traditional population count once every ten years, by having interviewers go door-to-door with questionnaires, for example. They do not know their exact number of inhabitants in the meantime. In the Netherlands, however, we know the exact number at any time.’
‘People in the Netherlands have a relatively high level of confidence in public authorities and benefit from proper registration with a view to taxes and social insurances,’ says Grommé. ‘In several other countries, people are reluctant to get registered. The United Kingdom, for example, uses questionnaires to conduct censuses, and citizen interest groups take part in social discussions about who are or are not to be included in the census.’ In order to arrive at a common standard, discussions about definitions and methods are held at the European level. Schulte Nordholt: ‘Countries across the European Union are still counting in different ways. Where do you include students, refugees and employees who temporarily reside abroad? The Netherlands includes every immigrant who intends to stay for at least four months. Some Southern European countries include people who have family ties in the country, even though they have been living elsewhere for years. We need to work towards one common enumeration method.’
In many countries, conducting censuses is also a very expensive affair.
Europe has various overseas countries and territories, including the Caribbean Netherlands. One of the issues is that they often have different systems but they apply statistical methods from Europe. Grommé therefore includes the CBS branch office on Bonaire in her research. ‘It is a challenge to apply the statistical methods of the European Netherlands here,’ explains Quintin Knuf, who heads CBS on Bonaire. ‘The Caribbean Netherlands does keep a register, but proper registration is less important for local residents here than for people in the European Netherlands. A house move is often not reported. Many American students and employees do not deregister when they move back to the United States. Street signs and house numbers are often missing. The census offices therefore correct errors in the register manually and work together with companies and universities to get information on who have graduated or are no longer employed somewhere.’
A dynamic field
‘The professional field of statistics is constantly changing,’ Grommé states. ‘Timeliness, applicability and making projections will play an ever larger role, thanks to data science. In addition, more and more players are entering the data field, not just statistical agencies. The latter devote a great deal of attention to the quality of the figures and to data security. For example, CBS employs methodologists who safeguard data integrity when new developments emerge, also in the field of big data. This includes making choices regarding classifications and categories. Likewise, we see new initiatives being developed at the European level to adopt classifications other than national borders, for instance.’
Book about ARITHMUS
The ARITHMUS project has resulted in several scientific publications, see: www.arithmus.eu. In addition, a book will be published about the findings this year.