How does the census work?

01 How are the official population figures calculated?

In contrast to traditional censuses, not every household is interviewed for the register-based census. Nevertheless, all inhabitants ultimately have to be recorded. How does that work?

02 Register data and sample size

Interview with Steffen Seibel Register data and sample size

In this interview, Steffen Seibel from the Federal Statistical Office in Wiesbaden explains the changes to the sampling methodology for the next census and the differences to the 2011 census. How will the 2022 census differ from the 2011 census? What are the challenges? And why are municipalities with under 10,000 inhabitants now also being surveyed?

read the interview

03 Data protection and information security

Data protection and information security are much more than just legal obligations. After all, the institutions responsible for official statistics thrive on the trust and acceptance of the population. For this reason, the Statistical Offices of the Federation and the Länder will implement strict and comprehensive security measures to ensure the protection of your data during the census.

04 The method used for the 2022 census

The method used for the 2022 census

The results of the 2011 census now form the basis of the official statistics. The data is constantly updated using information on births, deaths and changes of address, but the sources of such adjustments (the official registers) are not always accurate. As a result, the updated figures become less accurate from year to year.

The classic census

The last classic census took place in the former territory of the Federal Republic of Germany in 1987. As with the 2022 census, it was a survey of statistical population data that was required by law. However, the total population was not determined on the basis of a random sample; a full census was conducted – and all citizens were obliged to provide information.

The modern census

Following on from the 2011 census, the 2022 census is conducted as a “register-based census”, a method developed by the Statistical Offices of the Federation and the Länder. In contrast to a traditional census, not all citizens had to be interviewed in a register-based census, as most of the data was already available in administrative registers such as those kept by residents’ registration offices.

In the 2022 register-based census, copies of that data were submitted to the official statistics, where they are stored separately under strict data protection requirements. However, some individuals or families may have recently moved house and not yet registered their new address. In such cases, the information in the population registers are incorrect. In order to iron out such inaccuracies in the statistics, less than 10% of the population were surveyed in a short interview. This survey, based on a random sample, was also necessary to collect data that is not available in the registers, such as information on education, training and employment.

As there are no comprehensive registers for buildings and housing in Germany, approximately 17.5 million owners of dwellings or residential buildings were surveyed by post. A further survey was conducted in residential establishments (e.g. student halls of residence) and collective living quarters (e.g. old people’s homes, nursing homes and homes for children and young people). The registers are particularly inaccurate for such addresses, as there are frequent changes of residents.

The register-based census will provide reliable results for the whole of Germany – even though the entire population was not surveyed.

Differences to the microcensus

The microcensus is an official statistical survey that has been conducted every year since 1957 using a representative sample of 1% of households in Germany.

In comparison to the census, the microcensus is more detailed and contains more questions. Due to the wide range of data collected during the microcensus, it is suitable for analysing small sub-populations (e.g. occupational groups). As the microcensus is conducted on a more regular basis, it also enables data and trends to be analysed over time which, in turn, leads to the discovery of historical developments. The microcensus can also be used for longitudinal analyses. The microcensus is also suitable for drawing comparisons in an international context, as there are international standards for various areas. In addition, the microcensus is an important tool for extrapolating, adjusting and controlling the data collected in a number of surveys in the fields of empirical social research, opinion polling and official statistics. However, the results can only be shown for Germany, its federal states, large cities and districts / regions, because the sample of 1% of households is too small for more detailed results to be presented. In contrast to the microcensus, the census includes interviews with all owners of buildings and housing in Germany, and the information obtained from registers is supplemented by a survey of 10% of households and a survey of people living in dormitories and shared accommodation. This means that results will be available for all towns, cities and municipalities.

So, unlike with the census, the aim of the microcensus is not to determine the official number of inhabitants, but to provide annual data on the economic and social situation of the German population. This includes information on household and family structures, the labour market and employment, training and further education, income and many other aspects. In contrast to the census, the microcensus provides much more detailed information about important changes in society and the economy. It can be used to determine key figures, structural data and their changes at short intervals, which helps to fill data gaps between large censuses of the entire population (i.e. the 2011 census and 2022 census).

05 Confidentiality during the census

When publishing the results of the census, those responsible must ensure that the information provided by individual persons or other entities cannot be inferred, in order to safeguard each citizen’s fundamental right to informational self-determination and to comply with the Federal Statistics Act (BStatG ). At the same time, the published data should provide as much general information as possible. This is ensured by maintaining an appropriate level of confidentiality.