Geographic unit Unit relationships provide a path for the system to follow when comparing data across different administrative versions, e.g., ML_1983 to ML_2016.
Changes such as a Geographic Unit becoming smaller by splitting in two or three parts, or getting bigger by merging with others, can severely compromise the ability to compare data such as crop statistics over time. For example, you may want to analyze the productivity of that Geographic Unit’s farming activities per unit of area over time.
Geographic Unit relationships provide a record of these changes, and is a fundamental tool in doing spatial analyses that compare statistics with remotely-sensed (e.g. satellite-based) analyses of weather, and rainfall, and a variety of other key indicators.
Geographic Unit relationships can be updated in three ways.
If you need to update a few relationships, this can be done individually within the FDW.
If you need to update many relationships, this is best done by uploading a relationship table.
When adding new Markets and IDP camps, their relationships to admin units can be specified by adding a
parentcolumn that contains the FNIDs to the file. FDW will automatically create the relationships upon upload.
| Info |
|---|
If a Geographic Unit has changed in name only, it does not need a new FNID or re-defined relationships. |
Relationship types
Relationship Types include:
Boundaries stay the same and data can be aggregated both forward and backward in time
Successor: This administrative unit did not change between geographic unit set versionsGeographic Unit Set Versions.
Equivalent: Two units are equivalent between different geographic unit sets Geographic Unit Sets and do not need to be the same unit type, e.g., population and crop production units that are equivalent.
Seceded: Two units are equivalent between different geographic unit setsGeographic Unit Sets, are the same unit type, and can be part of separate countries, e.g., the admin 1 states of South Sudan seceded the admin 1 states of Sudan.
Name change: Only the name has changed between geographic unit set versionsGeographic Unit Set Versions.
Promotion: An administrative unit becomes a higher-level administrative unit, e.g., Admin2 becomes Admin1.
Demotion: An administrative unit becomes a lower-level administrative unit, e.g., Admin1 becomes Admin2.
Boundaries change
Data can be aggregated forward in time
Merge: Parts of, or the whole of, two or more administrative units were joined together to create a new administrative unit version in the same geographic unit set.
Aggregate: Parts of, or the whole of, two or more administrative units were joined together to create a new administrative unit. However, unlike merge, this relationship doesn’t indicate anything about the relationship between the geographic unit sets.
Data can be aggregated backward in time
Split: One administrative unit was divided to form two or more new administrative units.
Split_demotion: One administrative unit was divided to form two or more new administrative units and the new units are demoted to a lower admin level.
Data can not be aggregated
Redistribute: Parts of more than one administrative unit were divided and redistributed into more than one new administrative unit.
Definition of one unit within another, e.g., admin1_0 indicates the unit is an admin1 within a specific admin 0.
...
Preparing and uploading relationship tables
A relationship table defines the evolution of geographic units year by year, and the type of changes that occur to them, for every Geographic Unit a country has had over a defined period of time.
Preparing tables
To prepare a relationship table for upload, you will need to copy the relationship data from one tab to another in the relevant spreadsheet.
...
Go to Metadata Management > Spatial > Geographic Unit Relationships.
Click Import Geographic Unit Relationships.
Click Choose File.
Choose a format from the dropdown menu. This will likely be xls(x).
Click Submit.
Confirm the import.
Troubleshooting relationship table uploads
Possible errors when uploading relationship tables include:
Extra columns: If the file contains extra columns that are not recognized by FDW, the upload will fail with an error message that notes the unidentified metadata. Remove the extra columns before re-uploading the file.
New Geographic Units: If the file contains units do not already exist in FDW, the upload will fail noting the unidentified units. Upload the new units to FDW before re-uploading the file.