United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Spatial Analysis & Dissemination of Census Data

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Outline Geographic Database Spatial Analysis Techniques Examples

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Geographic Database  Geographical features (Conceptual Model) Components selection Attributes Structure  Spatial Relationships (explicit -Topolgy)

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Spatial relationships  Logical connections between spatial objects represented by points, lines and polygons  e.g., - point-in-polygon - line-line - polygon-polygon

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 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 Amman, Jordan, May, 2011 Spatial Operations  “adjacent to”  “connected to”  “near to”  “intersects with”  “within”  “overlaps”  etc.

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Spatial Analysis Techniques  the main use of spatial analysis is for census products and services  Techniques include: queries, distance measurements, buffering, linear interpolation, point pattern analysis, and cartograms, etc.  All offer functionality beyond standard thematic mapping, with many tools now available in both commercial and open-source software programs.

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Spatial Analysis: Query  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

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Examples: What is at…? Features that meet a set of criteria

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 “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 Amman, Jordan, May, 2011 “is near to”: Buffer Operations Point buffer Affected area around a Hospital Catchement area of a water source

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 “is near to”: Buffer Operations Point buffer Affected area around a polluting facility Catchement area of a water source

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 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 Amman, Jordan, May, 2011 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 Amman, Jordan, May, 2011 Spatial Analysis Techniques  point-in-polygon analysis Determines whether a point lies inside or outside a polygon. Can be used to compare geo-coded village centroids lying inside and outside hazardous areas such as tropical storm tracks or earthquake zones.  Polygon overlay analysis Involves comparison between the locations of two different polygonal data layers. For example, the boundaries of two administrative districts could be compared to troubleshoot errors in the field enumeration process

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 “ 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 Amman, Jordan, May, 2011 Problem: We may have a set of point coordinates representing clusters from a demographic survey and we would like to combine the survey information with data from the census that is available by enumeration areas. Solution: “Point-in-Polygon” operation will identify for each point the EA area into which it falls and will attach the census data to the attribute record of that survey point.

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Spatial aggregation  Example of Spatial aggregation: fusion of many provinces constituting an economic region

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Spatial data transformation: interpolation Example 1: Based on a set of station precipitation surface estimates, we can create a raster surface that shows rainfall in the entire region

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Example of linear interpolation creating contours

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Thiessen polygons illustrated  Thiessen polygons Have the unique property that each polygon contains only one input point (e.g. settlements), and any location within a polygon is closer to its associated point than to the point of any other polygon. This method assumes that the values of the unsampled data are equivalent to those of the sampled points. Spatial Analysis Techniques

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Areas of influence  Commuting distances: daily commuters flow

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Modeling/Geoprocessing  modeling: identify or predict a process that has created or will create a certain spatial pattern diffusion: how is the epidemic spreading in the province? interaction: where do people migrate to? what-if scenarios: if the dam is built, how many people will be displaced?

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Modelling: smoothing  Evolution of the population beetwen two censuses

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Spatial Analysis Techniques  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

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Location-allocation problems  Site selection  Optimal allocation  Multicriteria Analysis

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 Conclusion  Geographic Database  Topology  Although spatial analysis is sometimes used during the enumeration phase (clustering, for example, can aid in identifying housing units to be canvassed), the main use of spatial analysis is for census products and services.  Variety of techniques: buffering, overlay, modelling  GIS: Decision making tool

United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, May, 2011 THANK YOU!