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Building a Geographic Database and Using GIS for Census Data Dissemination

This seminar highlights the importance of using geospatial technologies and databases for efficient census data dissemination. It covers spatial analysis techniques, the SALB project, and provides a handbook on geospatial infrastructure for census activities.

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Building a Geographic Database and Using GIS for Census Data Dissemination

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  1. Building a Geographic Database and Using GIS and Spatial Analysis for Census Data Dissemination UN Statistics Division United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  2. UN Recommendations/Census Geography Programme • Building a Geographic Database • Spatial Analysis Techniques • SALB Project • Handbook on Geospatial Infrastructure in Support of Census Activities Outline United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  3. The recommendations derived from UN EGM and Workshops on GIS and census mapping emphasized the need for countries to consider the census geography programme as a continuous process, rather than the sequential mapping and dissemination operations. • It was also emphasized that the use of and application of contemporary geospatial technologies and geographical databases is beneficial at all stages of population and housing census process. Geospatial improve the efficiency in the preparatory, enumeration, processing and dissemination phases of the census Census Geography Programme: a continuous process United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  4. Census Cycle United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  5. Geospatial tools at all stages Pre-census Census Post-Census (Pre-enumeration) (Enumeration) (Post-enumeration) GPS/PDA GIS Digital Mapping GPS Photo/Video GIS Digital Mapping Satellite Imagery GIS Internet (Map-Server) Administrative and Reporting Units EAs Units United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  6. Every country has its own specific administrative hierarchy • Definition: A system by which the country and each lower level set of administrative units (except the lowest) are subdivided to form the next lower level. • Administrative areas for which census data will be reported Admininstration Hierarchy United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  7. EA: a basic geographic feature • Need for an identifier: linking the geographic feature to the census data (attributes) recorded for them • EAs and administrative units: coding scheme • A unique code assigned to each EA, used in data processing • Coding scheme: scalability, flexibility, intuitiveness, compatibility • Example of a hierarchical coding scheme Coding Scheme 1 2 0 3 2 4 4 0 1 2 0 0 5 Enumeration area district locality province United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  8. “Geocoding can be broadly defined as the assignment of a code to a geographic location. Usually however, Geocoding refers to a more specific assignment of geographic coordinates (latitude, longitude) to an individual address (UN Report of the EGM on Contemporary Practices in Census Mapping and Use of GIS, 2007) • Geo-coding: not limited to address-matching • Geocoding covers a continuum of spatial scales: from individual housing units to enumeration area level up to higher administrative or national levels. Geocoding Concept United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  9. All large operational GISs are built on geodatabases; • Arguably the most important part of the GIS • Geodatabases form the basis for all queries, analysis, and decision-making. • A DBMS, or database management system, is where databases are stored. Implementation of an EA database United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  10. Complete EA map with all components overlaid on one map display Main components are: Street network, Buildings EA boundaries layer Annotation, Symbols, Labels Building numbers Neatlines Legend United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  11. Components of a Hypothetical urban EA map United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  12. Entity-Relationship Example: EA entity can be linked to the entity crew leader area. The table for this entity could have attributes such as the name of the crew leader, the regional office responsible, contact information, and the crew leader code (CL code) as primary code, which is also present in the EA entity. R 1-1 1-N United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  13. Components of a digital geographic census database United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  14. A geography for data collection: • EA level or even dwelling level • Another geography for data dissemination: • Aggregated level (confidentiality) Different Geographies United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  15. The wide range of potential users of disaggregated census data means that the NSO needs to pursue a multi-leveled digital data dissemination strategy. • Broadly, we can distinguish between the following types of users: • Advanced GIS users • Computer literate users • Novice users Digital Data Dissemination Users United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  16. Exploratory Spatial Data Analysis • Linked Maps, Graphs & Tables • Dynamic Feature Selection • Animation • Visualization over Time Uses of Graphs: Enriching the Understanding of GIS Data Sets United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  17. GIS capabilities: Visualization United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  18. Spatial Relationships (explicit -Topolgy) • Logical connections between spatial objects represented by points, lines and polygons • e.g.,- point-in-polygon; line-line; polygon-polygon • Geographic Database • Geographic features selection • Attributes • Structure Spatial Analysis United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  19. Spatial Operations United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010 “adjacent to” “connected to” “near to” “intersects with” “within” “overlaps” etc.

  20. Spatial Analysis: Query United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010 • select features by their attributes: • “find all districts with literacy rates < 60%” • select features by geographic relationships • “find all family planning clinics within this district” • combined attributes/geographic queries • “find all villages within 10km of a health facility that have high child mortality” Query operations are based on the SQL (Structured Query Language) concept

  21. Examples: What is at…? Features that meet a set of criteria United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  22. “is nearest to” • Point/point • Which family planning clinic is closest to the village? • Point/line • Which road is nearest to the village • Same with other combinations of spatial features United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  23. “is near to”: Buffer Operations • Point buffer • Affected area around a polluting facility • Catchment area of a water source United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  24. Buffer Operations • Line buffer • How many people live near the polluted river? • What is the area impacted by highway noise? United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  25. Buffer Operations • Polygon buffer • Area around a reservoir where development should not be permitted United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  26. “ is within”: point in polygon • Which of the cholera cases are within the containment area United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  27. Spatial aggregation United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010 • Example of Spatial aggregation: • fusion of many provinces constituting an economic region

  28. Spatial data transformation: interpolation Example: Based on a set of station precipitation surface estimates, we can create a raster surface that shows rainfall in the entire region 13.5 20.1 26.0 27.2 12.7 15.9 24.5 26.1 United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  29. Example of linear interpolation creating contours contour lines of elevation can be derived through linear interpolation from a satellite image United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  30. Commuting distances: daily commuters flow Areas of influence United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  31. Evolution of the population beetwen two censuses Modelling: smoothing United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  32. Cartograms • sometimes used to display census results • The areas of the original polygons are expanded or contracted based on their attribute values such as population size or voting habits Spatial Analysis Techniques United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  33. The Second Administrative Level Boundaries data set project (SALB) has been launched in 2001 in the context of the activities of the UN Geographic Information Working Group (UNGIWG) and has for objective to provide access to a working platform for the collection, management, visualization and sharing of sub national data and information in a seamless way from the national to the global level. • unsalb.org The Second Administrative Level Boundaries data set project (SALB) United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  34. http://unstats.un.org/unsd/demographic/standmeth/handbooks/default.htmhttp://unstats.un.org/unsd/demographic/standmeth/handbooks/default.htm Handbook on Geospatial Infrastructure in Support of Census Activities (2009) United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  35. Do you have (or are you considering to have) a full digital Geographic Database for census operations? • Are you considering to use spatial analysis to suit specific user needs? • Are you partnering with other stakeholders (the public and private sector) in order to • Build the NSDI • Work jointly on coding efforts • Produce value added products – higher demand for census data Issues for consideration United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

  36. THANK YOU! United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Bangkok, Thailand, 5-8 October, 2010

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