How do our European neighbours collect population data?
In 2011, a register-based census will be conducted in Germany. With that survey, Germany will participate in a census round of the European Union. In fact, how do our European neighbours collect their population data?
Variety of census types
As regards the census, Europe shows a multi-faceted picture: The data on the population and its working and housing conditions are collected in different ways in the various countries. First, there are countries conducting traditional population censuses where the entire population is directly questioned. There are also register-based censuses »drawing« data from the relevant administrative registers. Some countries apply combinations of the two census models. Such mixed forms combine, for example, traditional population censuses with register use or sample surveys. And there is a fourth type: the rolling census. With that type, every year part of the population is interviewed – how many inhabitants that are depends on the size of the municipality.
(Census types in Europe - chart as PDF)
Which census type is applied where?
Register-based censuses
Using registers is not entirely new in Germany because already for the traditional population census of 1987 extracts from population registers were used. European pioneers in purely register-based surveys are the Nordic countries Denmark, Finland, Sweden, Norway and Iceland, where today the population data are collected only by evaluating existing registers. For a specific reference day, data are »drawn« from various administrative registers and are then combined. This is based on central registers of individuals and personal identification numbers of every individual citizen, introduced in the 1960s. Every citizen lives with such a number from birth to death. Entirely register-based censuses following the recommendations of the United Nations have been conducted in Scandinavian countries since the 1980s. The reason why those countries did not directly start register-based censuses when they introduced the personal identification numbers is that registers of buildings and dwellings and register-based labour market statistics were not available at the time. Since then, register-based censuses have proved their worth in Scandinavia.
Mixed forms
Other European countries prefer combinations of traditional census and register evaluation: In the census round 2001, Spain, Belgium and Austria as well as Latvia and Slovenia used such a mix of methods. What is interesting is that the two latter countries are new EU members which conducted a population census for the first time since (re)gaining their independence. In addition to Switzerland and Luxembourg – the grand duchy held a conventional census last time – Belgium and Austria are among the countries which are in a transitional phase on the way towards a purely register-based population census system. In Spain, Belgium and Switzerland, registers were in part adjusted on the occasion of traditional surveys. This means that the information taken from registers was printed on the questionnaires and had to be checked by the citizens concerned.
The Netherlands have developed a register evaluation system which, for specific information, is complemented by sample surveys. With the so-called »social insurance and tax code«, our neighbour country – unlike Germany – has a code which is contained in nearly all registers and which allows easy linkage of the various data sources.
Traditional surveys
Some European countries still conduct traditional population censuses. In 2001, the South European countries Greece, Italy and Portugal as well as Ireland and the United Kingdom in Western Europe belonged to that group. The countries of Central, East and South-East Europe, with the exception of Slovenia and Latvia, also rely on traditional censuses today. However, traditional surveys may be shaped quite differently: What is applied apart from classical interviews and paper questionnaires is self-completion questionnaires that are distributed and collected by enumerators or sent by post, and various combinations of the two variants. In Belgium and Switzerland, surveys are conducted also via internet today; in the United Kingdom, a telephone survey is currently under consideration. In Macedonia, abandoning paper questionnaires is planned for the near future, and enumerators will be equipped with hand-held computers instead. This will allow, first, direct electronic data entry, second, reduction of interview time because for example specific questions will no longer have to be asked, depending on the answers given before and, third, plausibility checks can be integrated. »Traditional« thus can also be modern and innovative.
Rolling census in France
In France it is planned to apply a method which is unique in Europe: With a rolling system, data are collected only from part of the population every year. Within a survey cycle of five years, a full census will be conducted in the municipalities with less than 10,000 inhabitants; in municipalities with 10,000 inhabitants and more, only sample surveys will be conducted, covering about 40 percent of the municipality’s inhabitants. As half of the French live in smaller municipalities, some 70 percent of the population will entirely be covered with this method. For the remaining 30 percent, expansions will be required. The first publication of a population figure based on the new method is scheduled for 2008, referring to 2006. Then, annual results will be available.