Area is calculated for Collection Districts (CDs) in square kilometres using digital boundary data which define the CD. The areas of other spatial units used in the Census are usually calculated by aggregating the areas of the component CDs.
The digital CD boundaries are only representations of the 'real world' bounds of a collector's area. The real world boundary is complex, where the digital version is simplified. This results in a less than perfect measurement of the true area of the CD. The degree to which the measured area is inaccurate is, in most cases, only slight.
Calculation of the actual area of a CD is two dimensional. The effects of changes in elevation are not considered in the area calculations provided by the ABS. CDs that consist of bodies of water only i.e. 'Water CDs', are excluded from the area calculation.
For Census purposes, the area of a Local Government Area (LGA) is calculated by aggregating the areas of component CDs (excluding Water CDs). This area may not correspond to the legally determined area.
See also Collection District (CD).