The statistical qualities of the zone design census output areas

Abstract

The statistical qualities of census output areas are of great importance especially when the purpose of output areas is to understand the statistical properties of the population rather than mapping. If the purpose of creating census output areas is solely for displaying results in a map format, shape compactness of output areas is prioritised. In that case, other statistical characteristics such as population, population mean and social homogeneity are often ignored. This paper explored the statistical qualities of the Automated Zone-design Tool (AZTool) generated census output areas using the 2001 census Enumeration Areas (EAs) as building blocks in South Africa. The statistical qualities were mainly based on population target mean, minimum population threshold, social homogeneity as well as shape compactness. The homogeneity variables that were selected from the 2001 census data were dwelling type and geotype. The results showed that the AZTool generated output areas substantially outperformed the original EAs and Small Area Layers (SALs) in terms of the minimum population threshold and population distribution statistical qualities. It is worth noting though that the AZTool output areas were less compact and homogeneous than the original EAs in both urban and rural settings. The fact that a minimum population threshold of 500 was respected by the AZTool output areas in both rural and urban settings was a huge success from confidentiality point of view. It was concluded that the AZTool could be utilized to produce robust and high-quality optimised output areas for population census dissemination in South Africa.