Visualizing electoral college politics: exercise in displaying relationships between variables
Aug 03, 2017
Reader Berry B. sent in a tip quite some months ago that I just pulled out of my inbox. He really liked the Washington Post's visualization of the electoral college in the Presidential election. (link)
One of the strengths of this project is the analysis that went on behind the visualization. The authors point out that there are three variables at play: the population of each state, the votes casted by state, and the number of electoral votes by state. A side-by-side comparison of the two tile maps gives a perspective of the story:
The under/over representation of electoral votes is much less pronounced if we take into account the propensity to vote. With three metrics at play, there is quite a bit going on. On these maps, orange and blue are used to indicate the direction of difference. Then the shade of the color codes the degree of difference, which was classified into severe versus slight (but only for one direction). Finally, solid squares are used for the comparison with population, and square outlines are for comparison with votes cast.
Pick Florida (FL) for example. On the left side, we have a solid, dark orange square while on the right, we have a square outline in dark orange. From that, we are asked to match the dark orange with the dark orange and to contrast the solid versus the outline. It works to some extent but the required effort seems more than desirable.
I'd like to make it easier for readers to see the interplay between all three metrics.
In the following effort, I ditch the map aesthetic, and focus on three transformed measures: share of population, share of popular vote, and share of electoral vote. The share of popular vote is a re-interpretation of what Washington Post calls "votes cast".
The information is best presented by grouping states that behaved similarly. The two most interesting subgroups are the large states like Texas and California where the residents loudly complained that their voice was suppressed by the electoral vote allocation but in fact, the allocated electoral votes were not far from their share of the popular vote! By contrast, Floridians had a more legitimate reason to gripe since their share of the popular vote much exceeded their share of the electoral vote. This pattern also persisted throughout the battleground states.
The hardest part of this design is making the legend: