Finally, a proper cartogram of covid-19

A population-based cartogram as the basis for a choropleth of covid-19 infection in the Netherlands. See text for link.

The problem with any mapping of absolute values with a choropleth, is that areas of large territory receive great visual prominence, and small areas are hard to see, and the prominence (or lack thereof) is generally misleading. The solution, as I mentioned with respect to the CDC’s choropleth is to standaradize the values in some way, by population or by area.

An alternate, and better, solution for choropleth mapping is to use regions that have been adjusted so that their area is proportional to their population: areas of high population get larger, areas of small population get smaller, and the resultant visual impact of the coloring in the choropleth is appropriate.

Here is an excellent set of population-based cartograms showing the spread of covid-19 in the Netherlands. I’ve copied from twitter, where it was originally posted by Josse de Voogd @Jossedevoogd on 20 March, and promptly shared by Martijn Storms @MapStorms. Thanks, Martijn!

Prompted by this, I searched around, and found other cartograms online. Here’s a great one from World Mapper:

World Mapper’s population-cartogram of the world, with areas proportional to population. Click on map to go to source.

It looks weird, which is one of the issues with some algorithms for constructing cartograms, but it gets across the point that the US and Europe have high rates of known infection. Note that the scale has also been standardized as infection rates per 100,000 people.