Weekly Data Viz #5
Each Tuesday, Eurry Kim, a student in our class, will pick one example of data visualization to share with us. Eurry writes:
I have a Sankey Diagram from ProPublica this week! What’s more is that the authors wrote about how they made it! You’ll see that they employed the NYT API to obtain the data (we can all relate to that one!) and then used jQuery to draw the flows.
http://www.propublica.org/special/a-tangled-web, by Al Shaw, Kim Barker and Justin Elliott, ProPublica. You have to go to the page to get the full interactive effect.
A Sankey diagram is a flow chart that displays the “flows” from one category to the next. The size of the bars refer to the magnitude of the movement. In some diagrams, the angle at which the flow is directed represents another aspect to the data. I think Sankey diagrams are really cool. Several months ago, while at work, I came up with an excuse to draw a Sankey diagram showing the money amounts reported in corporate tax returns and the amount of money that was “supposed” to be reported in certain lines. It turned out that there was a better method in which to visualize the story, but it was a good learning experience nonetheless. I drew it manually employing the use of Bezier curves in Illustrator. Then I drew several vertical lines to represent the “size” of money that was reported within each line.
This may sound familiar? Have you seen Napoleon’s March? The one Edward Tufte said “may well be the best statistical graphic ever drawn” (The Visual Display of Quantitative Information, p.40)? Yeah, that’s a Sankey.