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of countries close to the boundaries between the regions, like Greenland and Iceland. What it
will do, though, is set us up to create a dashboard with multiple sheets, where regional colors
are cues to link the map with other charts. We'll set that aside for later.
Figure 10-9. Global Internet adoption in 2010, by country
Next, let's consider another way to show data on a map of the world using a choropleth, or a
filled map.
Filled Maps
Filled maps are great ways to show concentration by location, where location is a distinct
area on the map with borders separating it from other areas. We see these very often with
election results data, where certain regions are shaded a certain color according to how they
voted.
The Internet usage statistics are a great example of a data set that is perfect for a filled map,
because the data is in the form of a
rate
: users per 100 in the population. This metric is a type
of density, not mass. If I see a map with circles, and place A has a bigger circle than place B,
