Data quality

Lineage
Positional accuracy
Attribute accuracy
Logical consistency
Consistency with other products
Completeness

Spatial data quality elements provide information on the fitness-for-use of a spatial database by describing why, when and how the data are created, and how accurate the data are. The quality elements include information on the lineage, positional accuracy, attribute accuracy, logical consistency and completeness. This information is provided to users for all spatial data products disseminated for the census.

Lineage

Lineage describes the history of the spatial data, including descriptions of the source material from which the data were derived, and the methods of derivation. It also contains the dates of the source material, and all transformations involved in producing the final digital files.

The National Geographic Database (NGD) is a joint Statistics Canada-Elections Canada initiative to develop and maintain a spatial database which serves the needs of both organizations. The focus of the NGD is the continual improvement of quality and currency of spatial coverage using updates from provinces, territories and local sources. The source files used for the creation of the boundary files reside on Statistics Canada's Spatial Data Infrastructure (SDI) which is derived directly from data stored in the NGD.

The 2011 Census standard geographic area unique identifier, name, type, and the relationships among the various geographic levels are found on the SDI. The data for administrative areas are updated using information from provincial and territorial sources.

Positional accuracy

Positional accuracy refers to the absolute and relative accuracy of the positions of geographic features. Absolute accuracy is the closeness of the coordinate values in a dataset to values accepted as or being true. Relative accuracy is the closeness of the relative positions of features to their respective relative positions accepted as or being true. Descriptions of positional accuracy include the quality of the final file or product after all transformations.

The Spatial Data Infrastructure is not Global Positioning Systems (GPS)-compliant. However, every possible attempt is made to ensure that the 2011 Census standard geographic area boundaries maintained in the Spatial Data Infrastructure respect the limits of the administrative entities that they represent (e.g., census division and census subdivision) or on which they are based (e.g., census metropolitan area or census agglomeration). The positional accuracy of these limits is dependent upon source materials used by Statistics Canada to identify the location of limits. In addition, due to the importance placed on relative positional accuracy, the positional accuracy of other geographic data (e.g., road network data and hydrographic data) that are stored within the Spatial Data Infrastructure is considered when positioning the limits of the 2011 Census standard geographic areas.

Attribute accuracy

Attribute accuracy refers to the accuracy of the quantitative and qualitative information attached to each feature (e.g., census division unique identifier, name).

As noted under Lineage, the attributes (UIDs, names, types and codes) for all 2011 Census standard geographic areas are sourced from the Spatial Data Infrastructure. The names and types for administrative 2011 Census standard geographic areas have been updated for the 2011 Census using source materials from provincial and territorial authorities.

The attribute data associated with the polygons in the boundary files were independently verified against the data in the Spatial Data Infrastructure and found to be accurate.

Logical consistency

Logical consistency describes the fidelity of relationships encoded in the data structure of the digital spatial data.

All 2011 Census standard geographic areas contained in the four files have been verified to have a unique identifier that is valid for the 2011 Census.

The ecumene mask boundary file was verified to ensure that every census division with agricultural data contains an ecumene pocket.

Consistency with other products

As a result of the generalization of the shoreline, the boundaries in the Province and Territory and Census Division files of this product are not necessarily consistent with the shoreline of the 2011 Census Cartographic Province and Territory and Census Division Boundary Files.

Topology checks were performed with the road network file and boundary files to measure the degree of integration amongst these products. The results indicated the degree of integration was within the default tolerance parameters as defined below.

  • XY Resolution: 0.000000001 degrees
  • XY Tolerance: 0.000000008983153 degrees

Completeness

Completeness refers to the degree to which geographic features, their attributes and their relationships are included or omitted in a dataset. It also includes information on selection criteria, definitions used, and other relevant mapping rules.

All non-amalgamated census divisions with reported agriculture (16 or more farms) were represented in the ecumene.

The Agricultural Ecumene Boundary File contains two standard geographic area boundary files that are generalized: census division; province and territory. The census division generalized boundary file contains all 293 census divisions which cover all of Canada. The province and territory generalized boundary file contains the 10 provinces and 3 territories covering all of Canada.

Date modified: