The Map of Population Density is based on the file of mandatorily registered residents who have stated Berlin to be their main place of residence. This file was current as of 31 December 2009 and is managed by the State Statistical Agency Berlin-Brandenburg (Amt für Statistik Berlin-Brandenburg) (Berlin is both a city and a German state, but in this case there is one agency for Berlin and its surrounding state of Brandenburg). This file contains, among other things, the total of inhabitants registered by the Resident Registration Agencies for all statistical blocks in Berlin which have at least one inhabitant. The file is updated every six months on the basis of registrations, cancellations, and transfers.
As an administration register, the register of residents cannot completely satisfy the criteria of statistics. So, the abstract of the reference dates contains unavoidably some inaccuracies caused by removal, births or death cases for example. An improvement of the quality of all registers of residents in Germany is to be expected through the introduction of the uniform tax number.
For the here available map a special operation was arranged: all 381,000 address data of Berlin were attributed to the blocks or block segments of the use data base of the Information System Urban and Development (ISU). By these means it was possible to aggregate the inhabitants data not only to the level of the blocks but also to the segment blocks of the ISU and to reach the same detailed presentation of the population density as in the edition 2009.
For data protection reasons it is not allowed to publish the true data for all areas with less than 3 inhabitants. Thus an automatic procedure is used to make those blocks anonymous (normally 3 or more inhabitants are displayed in those cases).
The sizes of the individual blocks and block segments were taken from the map ISU5 1: 5000 of the Information System Urban and Development (ISU) (cf. Map 06.07, SenStadt 2008).