This is a nominal area choropleth because there are no classifications or numerical data being presented, it is simply a map displaying places and oceans, it is choropleth because of the different colors used for different countries.
Univariate choropleth maps are choropleth maps displaying only one type of data. This map focuses only on water withdrawals in the United States.
A Bivariate Choropleth map is one that shows multiple pieces of data on one choropleth map. This map of Africa shows its land use, life expectancy, and GNP per Capita, all together with only one map.
Range graded circle maps have only a particular range of circles used, the are not infinite. In this map it shows the exact size of the circles being used and what they represent, and these are the only circle sizes used.
In a continuously graded circle map like this one there are infinite circle sizes used to represent approximate numbers. In this map there are 5 circles shown in the key to give a visual aid to what each size represents, however on the map there are many in between sizes to closer represent their number. This cartographer also conveniently wrote the actual amount by the circle.
Multivariate maps display 2 or more types of data in one map. This map is also a proportional circle map, however it is multivariate because it shows proportional population of each region with the circles, but also uses a pie chart method to separate each minority and show how many of each are in particular regions.
