William Playfair (1759-1823) was a political economist and data visualizer in Britain who was “against the ‘ruinous folly’ of the British government policy of financing its colonial wars through debt” (Tufte, 65). Below is one of his charts where he tried to visualize this “ruinous folly” by comparing three different variables (population, revenue (taxes), and area of country) among fifteen principal European nations during the 1800s.
For our first assignment, we had to redesign the chart so that it better represented the information that Playfair was trying to convey. In the first diagram, I utilized all three variables. The size of the circles represented the area of each country, the x-axis represented the population, and the y-axis represented the total taxation. The diagonal line that runs from the bottom left to the upper right is the best fitting line (average) for the points plotted.
Although the diagram above was visually interesting and included all three variables, it wasn’t completely apparent that Britain was being unfairly taxed compared to other countries. After doing some quick tests with people, everyone’s first observation was that Russia was a lot bigger than all the other countries.
In this second diagram (below), I removed the area variable because I felt that it was irrelevant since Russia’s population-to-area ratio was disproportionate to all the other countries. With one less variable to consider, the chart was simplified, as shown below.
Sticking to two variables, population and taxation, I switched from the scatter plot to a bar graph. Again, I tested these two graphs with people and everyone thought that the scatter plot was a bit confusing, while in the bar graph, the first thing people noticed was Britain’s level of taxation compared to everyone else. Success!
Some of my fellow classmates were able to further simplify this graph by cutting out the area variable along with combining the population and taxation variables (tax/person). Although this was a perfectly good solution, I kept the population and taxation variables separate because the people of Britain wanted to disassociate themselves from heavy taxation, hence the separation.