Over at Nautilus, Becca Cudmore is puzzled by how the same information can be displayed on charts with two entirely different attitudes, or spin. According to Ruth Rosenholtz, a scientist over at MIT, the way you can tell if a chart is trying to deceive you is by how long it takes you to figure out what that visual is trying to say. "A bad chart requires more cognitive processes and more reasoning about what you’ve seen."
Since you are often required to use visuals, including graphs and charts, let's take a look at a couple of Nautilus's examples of what you should NOT do.
The pie chart on the right puts labor up front and closer to you, so it takes up more space. The chart at left puts the labor information farther away from you, so it takes less space (think vanishing point perspective).
In other words, making your numbers look bigger or smaller depends on your perspective.
The red information at the top of the chart on the left is administrative costs and the blue tip of the cone on the right is also administrative costs - do those two bits of visual information look the same to you?
"In both charts, administrative costs take almost a third of each dollar. While this matches reasonably with the left chart, the right chart seems to shrink administrative costs to something much less than a third. 'Anytime you ask anyone to judge just height and ignore the other measurements,' says Rosenholtz, 'it’s going to take extra cognitive load to disregard these other cues.'” In other words, the chart takes more time to figure out--a good sign you are being deceived.
Charts are a great way to take in a lot of information in an instant, but like any other text, they can be rhetorically dishonest. So the next time you read a graph, ask yourself if the material is being displayed honestly? Have you ever created a chart that may have presented your material in a biased way?