Bivariate Choropleth Map

http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap171/p171.htm
Bivariate choropleth maps generally have two different variables with the use of graduated color symbols being incorporated into the map as well. These maps have two geographic variables in the same map, much like the map that is attached above. The map above is a bivariate choropleth map with the use of two variables with graded color symbols.