Compactness is having the minimum distance between all the parts of a constituency. The most compact districts form either a circle, square, or a hexagon.
There are a number of data quality checks contained in Esri Redistricting that allow you to measure whether a district plan adheres to certain standards.
Note:
Esri Redistricting uses WGS 1984 Web Mercator Auxiliary Sphere WKID: 102100 projection when calculating compactness tests.
You can perform a compactness test that measures the following:
- Polygon Area Test compares the areas of each district. The area is reported in square miles.
- Perimeter calculates the perimeter of the district, including inner holes. The perimeter is reported in miles.
- Reock Test calculates the ratio of district area to the smallest circle containing the district.
- Area / Convex Hull Test determines the ratio of the area of the district to the convex hull area of the district.
- Grofman Test calculates the ratio of the district perimeter to the square root of the area.
- Schwartzberg Test is the ratio of the perimeter of the district to the perimeter of a circle of an equal area to that of the district.
- Polsby Popper Test calculates the ratio of the same area of the district to the area of a circle with the same perimeter.
- Holes determines the number of holes (geography clusters that are fully enclosed) within each district.
The compactness test can also be run when you have two plans open for comparison. The comparison plan's compactness results are displayed in parentheses.
- On the Review ribbon, click Compactness Tests.
The Compactness Tests dialog box appears. Results from the compactness test are displayed.
Note:
It may be necessary to click Refresh to update the compactness tests if you make changes to your district plan.