Discipline: Information Design
With graphs and infographics, it can be fairly easy to add designs and elements that serve no purpose. The graphic below does a great job of illustrating how to clean up a design, and use the date-ink ratio properly. The graph becomes so much more effective when it is trimmed down from all the extras.
Here are some examples of graphs that were done using a good data-ink ratio:
The examples above are simple and extremely easy to follow. I think the Stopping Power chart does a great job of showing the different golf balls, and visually seeings how the balls rolls with simple lines. The TP5 graph has a good use of color, to show the TP5 and makes it really simple to see the ball flight compared to the other. The graph could use some more information on what the TP5 is being compared to.
Here is an example of a graph that could improve the data-ink ratio:
The graph is not bad but could use some improvements similar to what the animated graphic did above. Lightening the lines, and possibly getting rid of the background could be enough to greatly improve the graph and give the user a better opportunity of viewing and understanding the graph.