Univariate Choropleth Maps

http://www.geog.le.ac.uk/russianheartland/DemographicMaps/Raions.html

Univariate choropleth maps only show one set of data. Like other choropleth maps the range of, in this case, just one variable, is shown by a spectrum of color. In this example map, dark brown regions indicate areas of high population, while pale yellow areas have a low population.