Even if you don’t run a full usability test for your charts, have a fresh set of eyes look at what you’ve done and give you feedback. You may be surprised by what is confusing – or enlightening! – to others.
6. Don't use 3D or blow apart effects.
Studies show that 3D effects reduce comprehension.
Blow apart effects likewise make it hard to compare elements and judge areas
Colour choice is often culturally determined. For example, red is often used to represent loss, so it should not be used to reflect a positive value.
Avoid rainbow palettes as they create visual artifacts such as stripes which make it look as though there are dramatic patterns that do not exist. They also result in loss of detail particularly in the yellow to light green range due to low contrast.
Different colors should be used for different categories (e.g., male/female, types of fruit), not different values in a range (e.g., age, temperature).
If you want color to show a numerical value, use a range that goes from white to a highly saturated color in one of the universal color categories.
Use the same colors, axes, labels, etc. across multiple charts.
One of the easiest ways to get the most out of charts is to rely on comparison to do the heavy lifting.
Our visual system can detect anomalies in patterns. Try keeping the form of a chart consistent across a series so differences from one chart to another will pop out.
9. Don't make users do "visual math."
If the chart makes it hard to understand an important relationship between variables, do the extra calculation and visualize that as well.
This includes using pie charts with wedges that are too similar to each other, or bubble charts with bubbles that are too similar to each other.
Our visual processing system is not well suited to comparing these types of visual areas.
We are also not good at holding precise visual imagery in our memory and comparing it to new stimuli; if you are giving a presentation and want the audience to be able to compare two charts, they need to be on the same slide.
10. Don't overload the chart.
Adding too much information to a single chart eliminates the advantages of processing data visually; we have to read every element one by one!
Try changing chart types, removing or splitting up data points, simplifying colors or positions, etc.
This guide has been adapted by the University of Guelph Library. The original guide was created by the Duke University Libraries and is licensed under a Creative Commons Attribution-Share-Alike 3.0 Unported license unless otherwise marked.