Before showing any data, explain how your visualization works

When discussing how to make the public more graphically literate (“graphicate”) in recent talks about How Charts Lie, I've been advocating for explaining how unfamiliar visualizations work before we reveal any data. I use this famous Hans Rosling video as an example. I described it in my article for IEEE, too. I emphasized that the part at the beginning, when Rosling talks about the encodings—horizontal and vertical position, bubble size, color,—is crucial. You can see one of those talks here; jump to minute 15'.

That's why I'm happy to see the most recent Lazaro Gamio's visualization about the possible impacts of the coronavirus at The New York Times.  It contains a bubble scatter plot, and it applies Rosling's technique. It's a great use of the annotation layer: (a) “Each bubble on this chart represents an occupation. The bigger the bubble, the more people do that job,” (b) “the vertical position of each bubble is a measure of how often workers in a given profession are exposed to disease and infection,” (c) “the horizontal position is a measure of how close people are to others during their workdays.” Well done.