The household survey: how many inhabitants does Germany have, what are their qualifications, and what are their jobs?
The information obtained through the household survey includes data that are not contained in any register. Also, the survey results play a major role in determining the official number of inhabitants.
Determining the number of inhabitants
One of the purposes of the household survey is to determine the correct number of inhabitants in large municipalities with 10,000 or more inhabitants. There the population registers are not always exact because many people move house, so that determining the numbers of inhabitants cannot be based on the population registers as the only data source. The household survey allows identification and statistical correction of outdated and missing entries in the population registers.
Information on education and employment
The household survey was conducted as a sample survey covering only part of the population. It provided variables which in Germany are not, or not sufficiently, available in registers. An example is data on school certificates and vocational qualifications, on employment especially of self-employed people, on religious affiliation, and on migrant background. In addition, the European Union requires employment data according to the definition of the International Labour Organization (ILO). As this requirement cannot be met by data of the Federal Employment Agency alone, the relevant data were collected in the household survey (PDF, 1MB, file not barrier free).
Respondents selected at random
In the household survey conducted as part of the 2011 Census, about 10% of the population were asked for information, that is, a total of about 7.9 million people. The respondents were selected through a mathematical-statistical random method. First of all, addresses were selected at random. Then all persons living at these addresses on 9 May 2011 were questioned by interviewers.
As the data were collected only from part of the population, they are subsequently extrapolated to the total population of the relevant municipality, so that they provide a reliable data basis both for the municipalities and the entire Federal Republic of Germany.
At 5% of the addresses where the household survey had been conducted, the occupants were questioned a second time a few weeks after the first interview. This follow-up survey was held by other interviewers and with a reduced questionnaire (PDF, 1,011KB, file not barrier free) covering just a few variables. It was conducted only in municipalities with 10,000 or more inhabitants.
It is common international practice to check survey results as it allows assessing the quality of the household survey results regarding the number of inhabitants.