Quality assurance 2: check for multiple registration in the population registers
A major source of information for the 2011 Census is the data from the population registers. As they are maintained in a decentralised way in every municipality, however, it may happen that a person is registered in several municipalities at the same time to have his/her main or sole residence there. It may also happen that a person is only registered to have one or several second residences. Ascertaining and correcting such discrepancies was the main goal of the check for multiple registration. This is because, in the 2011 Census, every person must be counted with exactly one main or sole residence.
Therefore, in municipalities with 10,000 or more inhabitants, the register data of persons with several main or sole residences were corrected electronically. Persons for whom one or several second residences were registered were questioned on their housing status by means of the questionnaire to clarify the residence (PDF, 836KB, file not barrier free).
In municipalities with less than 10,000 inhabitants, all people who on 9 May 2011 were registered to have several main residences or only a second residence were asked for clarification in the survey to clarify the residence.
This ensured that all people for whom implausible data were identified in the population registers are correctly counted. The results of the survey are included in the calculation of the official number of inhabitants.
Of course, the data were not transferred back to the registration offices or other authorities because, for the 2011 Census, it is prohibited to transfer such data back to any authorities.