Why was 9 May 2011 chosen as the census reference date?

WIESBADEN – The reference date for the 2011 Census is 9 May 2011. On that day, the statistical offices of the Federation and the Länder will count the population in Germany. Thus the information to be provided by people who will be directly interviewed in the context of the modern population census must as a rule refer to the situation on 9 May 2011.

But why is it that the 2011 Census Act defines just that day as the reference date? As a matter of fact, there are several reasons why that date was chosen. A number of organisational, but also very practical considerations played a role in that respect. School holidays or religious holidays such as Easter or Christmas could not be taken as the Census reference date. In addition, it would have been inappropriate to choose as the Census date a day directly before, during or after a major political event, such as the elections to the Länder parliaments.

Generally, a reference date at the beginning of a year would be inappropriate, too. At that time, public authorities often update or carry out changes in their software and consequently have to cope with a higher workload in the IT area. Furthermore, the authorities usually adjust their registers as of 31 December of a year. For that reason, register excerpts might include errors in relation to an end-of-the-year reference date. The data of register excerpts taken in spring are more up-to-date.

And finally, the reference day should be in a season with longer daylight hours as the approximately 80,000 interviewers will have to contact people at home in the evenings, too.

As a result of all the above considerations, 9 May 2011 - a day in spring time - was determined as the reference date.

For further information please contact the Federal Statistical Office.

© Statistisches Bundesamt (Destatis)

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