Don’t get me wrong, I love donuts, the sugary kind. But when a donut shape is used to display information, I’m not a big fan as it’s often just too darn hard to read.
Take the new social network visual below by Zoom Charts. When you click on the face, a donut graph displays social network usage stats in the hover over. You can even drill down on any of the donut parts creating another donut outside of the first one.
I love the designer’s creativity with this, but what I would like to see is for the designer to use his or her creative talents in combination with the fundamentals of graph design to produce something that is the best of both worlds. Good graph design makes use of our ability to perceive certain attributes of visual images pre-attentively. That is prior to us being aware of them. An example of one of these attributes is form such as length. We can easily (pre-attentively) dicern the differences between the lengths of the bars below much easier than the curved shapes of the donut sections above. Could we not for example replace the donut with a bar chart enclosed in a circle? This would retain the circle which appeals to the user but add the bar so it’s easier to interpret the data.
Along with the donut chart, another popular way to display concepts and data is the funnel chart. Below left is an example of a sales funnel chart. While the sales process may represent a funnel shape, the user cannot easily gauge the numeric differences between the areas of trapezoids and rectangles, especially as you go down into the neck of the funnel. If our brain cannot easily use the visual chosen to quickly compare the numbers – why show it? In this case, consider how much easier it is to interpret descending data points using the green bars on the right instead of using a funnel chart.
Tell me what you think – have you found a way to enhance donut and funnel charts to make them more effective in displaying data?