  We evaluate several augmentations to the choropleth map to convey additional
information, including glyphs, 3D, cartograms, juxtaposed maps, and shading
methods. While choropleth maps are a common method used to represent societal
data, with multivariate data they can impede as much as improve understanding.
In particular large, low population density regions often dominate the map and
can mislead the viewer as to the message conveyed. Our results highlight the
potential of 3D choropleth maps as well as the low accuracy of choropleth map
tasks with multivariate data. We also introduce and evaluate popcharts, four
techniques designed to show the density of population at a very fine scale on
top of choropleth maps. All the data, results, and scripts are available from
https://osf.io/8rxwg/.
