The purpose of this exercise is to introduce you to three common ways of classifying data for representation as a choropleth map. Thus, the choropleth map is used to illustrate the relative magnitude of places. The cartographer will normally represent different magnitudes by the use of colors or shading - having each class represented by a variance in color or grey tone. The main objective of a choroplethic classification procedure is to reduce the number of individual data values transmitted to the map reader. Ther eis no one best way of devising class intervals and class boundaries for choropleth maps.
Simplicity is a major goal.
It is also worth considering that the class interval system should include the full range of the data and reflect some logical division of the data array in order to portray both the data distribution and the purpose of the map. Developing class intervals and class boundaries for conventional choropleth maps remains largely an experimental activity. Each geographical phenomenon being mapped presents a unique set of circumstances. Mapping purposes vary, as does the intended readership. The cartographer must look at each new choropleth map from a fresh perspective, without feeling constrained to follow a given method of classification.