Martin Szibalski Grid Data in Official Statistics of Europe A Survey about the Storage, Analysis and Publication of Census Data and Business Statistics Working Party Meeting "Geographical Information Systems for Statistics" from 15th to 16th March 2007

Agenda Aims and motivation Framework conditions Realisation Results Summary Perspective

Aims und motivation Census data Business statistics Small-area grid data for internal and external analyses as well as for publications. Business statistics Data with coordinates of adresses for internal analyses. Small-area grid data for publications and external analyses. There are no practical experiences with statistical grid data. Therefore the official statistics in Germany would like to participate in the knowledge of the European neighbours by an e-mail survey.

Framework conditions I Census data The permanent storage together with adresses or with a reference to adresses is prohibited. Adresses have to be deleted as soon as possible after a survey. The spatial relation may be stored long-term only together with identifiers of lattice cells. Business statistics The permanent storage with adresses or with a reference to adresses is allowed. The dissemination of the data together with adresses is prohibited.

Framework conditions II In Germany it is necessary to establish a concept especially for the storage of the spatial relation of data concerning natural persons. A B C D E F G 1 2 3 4 5 Geographic Lattice Data Coordinates xxxx yyyy zzzz ... ... 34111, 52111 34222, 52222 34333, 52333 34444, 52444 Input data about persons with coordinates Data Lattice-ID xxxx yyyy zzzz ... ... D2 D3 Output data with identifiers of lattice cells

Realisation Survey from late October to early December 2006 Three batteries of questions broken down by census data and business statistics Storage (only census data) Analysis Statistical confidentiality and dissemination E-mail survey in 33 countries 18 feedbacks

Results

Results

Results

Disclosure control based on grid cells Results Census data Min. grid size [m] Disclosure control based on grid cells Estonia 500 Less than 3 enumeration units Finland * 250 - Less than 10 enumeration units - Less than 2 residential buildings Austria 125 / 250 From 125 m no limitation for absolute values From 250 m limitations for subdivisions of attributes: - less than 31 enumeration units (census data) - less than 5 enumeration units (building or household attributes) Norway Less than 20 persons Switzerland ** 100 Less than 4 enumeration units * Disclosure control only for sensitive attributes ** Disclosure control for a predefined variable set. Sensitive attributes will not be published.

Disclosure control based on grid cells Results Business statistics Min. grid size [m] Disclosure control based on grid cells Estonia - Finland 250 - Classification of personnel and turnover data - Economic data of buying behaviour, income or consumer structure are protected like census data Austria 125 / 250 - From 125 m no limitation for absolute values - From 250 m no limitation for subdivisions of attributes Norway Less than 50 employees Switzerland * 100 Less than 4 units * Disclosure control for a predefined variable set. Sensitive attributes will not be published.

Summary Permanent storage of adresses or adress references is allowed in countries which apply grid data. Germany has a unique position regarding its storage concept for census data. In Europe statistical grid data are already frequently applied for analyses and publications espacially of population data. The minimal grid sizes are very different. Supressing grid cells is a common method to guarantee statistical confidentiality. Methods like overlap contigency or low-pass filtering are not applied.

Perspective Census grid data Business statistics grid data The preparations for the next census (2010/11) are made. The legal dicisions concerning the use of the spatial reference of statistic data are not carried out at present. Study about disaggregation of the population density with data of the national map agencies. Business statistics grid data Up to now there are only case scenarios and feasibility studies. Methods to standardise adresses and to add geographic coordinates to these adresses are being developed at present.

Perspective Input data Output data Intended improvement Official map agency data about residential areas and mixed zones Inhabitants per municipality Output data Grid map with inhabitants per square kilometre Intended improvement Using of building adresses to define residential areas more exact