Visualising population distribution with choropleth maps: which classification methods are suitable for South African population data?

Choropleth maps are among the oldest and still one of the most frequently used techniques for visualising quantitative data, such as population density. Today, each geographic information system (GIS) has a plethora of options for categorising data into classes for choropleth maps. Each option has its pros and cons, depending on the data and the use case. This paper presents the results of a user study to assess the suitability of different data classification methods for effectively visualising population distribution with choropleth maps in South African metropolitan areas. The research focused on geographic accessibility as a use case: population density is visualised on choropleth maps, allowing decision makers to identify over- or underserved areas for the provisioning of facilities. Results show that respondents were more likely to provide correct answers when presented with maps visualising data classified according to quantiles and natural breaks (Jenks), suggesting that these are easier to interpret for assessing and understanding population distribution in South Africa.