Classed choropleth maps

http://my.ilstu.edu/~jrcarter/Geo204/Choro/Tom/

A classed choropleth map differs from an unclassed choropleth map by combining areal units into a smaller number of groups.  Interval levels may vary, but typically 4 to 7 are used in a map. There is different classification techniques used to divide up the intervals. An example of the different classification techniques used is equal steps, quantities, natural breaks, and minimum variance. The above map shows the percentage of Hispanics per county in Florida and uses 5 natural breaks.