Population and housing census 2011. International

Different methods - comparable results


Most countries in the world conduct censuses, but the way they carry them out differs from country to country. Nevertheless, it is important that the results can be compared. The bulk of the information that is collected is therefore the same, although there are some variations here too.

Most countries conduct their censuses using the traditional method, with all individuals and households having to provide the information needed. However, this is a costly undertaking, and a growing number of countries are starting to use other methods.

Nordic countries quick off the mark

The Nordic countries were the first to use administrative data as a basis for the census. Denmark (1981) and Finland (1990) were the first countries in the world to create all the required statistics in a census without using a questionnaire. For censuses that were conducted around 2000, these were still the only two countries to have completely register-based censuses. The Netherlands did not have a separate data collection, but created census statistics by supplementing register data with data from statistical sample surveys. A number of other countries, including Norway, combined data collected by using questionnaires with register data.

More countries following suit

In 2009, the United Nations Economic Commission for Europe (UNECE) conducted a survey in its member countries 1 on the censuses around 2010. Substantial changes have taken place in data collection since the censuses 10 years earlier.

Eight countries in the UNECE area now carry out censuses without separate data collection; the five Nordic countries and the Netherlands, Slovenia and Austria. The data sources are mostly administrative registers, but some countries supplement this with data from sample surveys.

Twelve countries combine data from registers with a separate data collection. One such country is Poland, which in 2002 conducted a traditional census with 170 000 enumerators. In 2011, register data is combined with various collection methods: telephone interviews, interviews in the households and questionnaires completed on the Internet. The number of enumerators has been reduced to 18 000, and savings in the region of NOK 400 million will be made.

Traditional not the same as old-fashioned

As many as 30 countries in UNECE, including the bigger ones such as the USA and Russia, carry out traditional censuses where all data is collected by interviewers or by sending out questionnaires. Fourteen countries give the option of submitting the questionnaire via the Internet. The data collection in many countries has been modernised, with the enumerators using laptops during the interview and transferring data to the statistical agency once a day, for instance. Using GPS during the interview is also becoming widespread. This can make the data collection more efficient, but as long as all or most households still need a visit, the costs will remain high.

Lower costs a primary motive

UNECE's survey in 2009 clearly showed that countries using administrative registers have the lowest costs. In the USA, which carries out traditional censuses, the budget for the 2010 census was almost 80 times higher per capita than we spend in Norway. The high costs in the USA are partly due to the special requirements laid down in their constitution. However, other countries that use traditional methods to collect data also have high costs. For instance, the UK spends more than 20 times more per capita than Norway.

Several countries have already started planning the next round of censuses, which will be around 2020. Countries such as Canada and the UK, where using administrative data is not yet regarded as feasible, are starting to consider this as a possibility.

Nordic countries in teaching role

Since the Nordic statistics agencies were first to create register-based statistics, we have received many enquiries about this from our international counterparts over the years. In 2006, the statistical agencies in Denmark, Finland, Norway and Sweden decided to write a report in order to share their experiences in this area with statisticians in other countries. A report in English was published by UNECE in 2007, 2 and this has subsequently been translated to Russian.

Based on the content of this report, Statistics Norway, together with colleagues in Sweden and the Netherlands, has held a total of seven international courses on register-based statistics since 2006. Most of the courses have had participants from European countries, but courses have also been held with participants from the Middle East and North Africa, Central Asia and Latin America.

International cooperation shows that the potential for creating register-based statistics does exist in many countries, but also that there are limitations. The attitudes to such a development also vary from country to country. It is important that each country's work is based on its own circumstances and that they don't try to copy the Nordic countries.

How to ensure international comparability

One crucial question is how is it possible to create comparable census statistics in a scenario where the countries use different methods of data collection. International bodies such as the UN and EU play a key role here.

Every 10 years, the UN draws up recommendations on how the censuses are to be conducted in order to make the results as comparable as possible. The basic information that is collected is the same throughout the world; individuals and dwellings are counted in all countries. However, as regards other data, the need can vary between countries in different parts of the world. It's not necessarily the case that questions on work, education and living conditions should be the same in Norway as in a country in Africa or Asia. The UN therefore places the greatest emphasis on comparisons between countries where the social conditions are relatively similar. From Norway’s perspective, the most important aspect is that the statistics are comparable with the countries in Europe and North America. The United Nations Economic Commission for Europe therefore issues separate recommendations that are adapted to these countries. In the same way, separate recommendations are also devised for other world regions.

New EU legislation improves comparability

In 2008, the EU ratified a law on censuses , which has also been adopted by the EFTA countries. These countries are thereby obligated to create censuses that are fully comparable.

The legislation stipulates that all of the countries must carry out the census in the same year, with the first of these in 2011. The content of the census must also be the same in all of the countries. A number of tables must be created according to a common template, and the EU's statistical office shall ensure through its publishing system that the users can easily access statistics for the countries they want.

However, some areas are optional. The countries are free to choose the data collection method, as long as certain basic criteria are met. The legislation requires comparable results, not a uniform data collection. There is therefore reason to believe that the growing trend towards using register data will continue in the countries where this is possible.