Animated Charts: Pretty, Useless, and Not Entirely Safe

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Animated charts look modern and alive: the Bars slowly grow from zero to their actual size, and the Pies spin handsomely around on the screen. Why would a customer not find a stimulating chart like this more interesting than your run-of-the-mill static one? Especially when presenting a product for the first time. But at the end of the day, are animated charts really worthwhile data analysis features?

Obviously, animated charts, with their pretty snapshot, are of no real use when it comes to real analysis. Neither can the moving Pie chart do anything to help users understand the structure of their sales, or the growing bars compare results of sale managers. For all that, the uselessness of the feature would not appear to be in itself a big problem; it's quite normal to want to spruce up your dashboards. Unfortunately, appearances can be deceiving. By moving and changing the chart elements (however beautifully) while the person is trying to understand the data, you can can easily mislead him/her, creating a wrong impression, and ultimately - a wrong decision. The situation is compounded when the decision maker is pressed for time and dealing with large quantities of data. 

Just imagine your car dashboard showing animated speed levels every time you glance at it. So that even though your speed is constant, you see first 10 mph, then 20 mph, then 30 mph, and then ... you have to get your eyes back on the road. Your real speed is 80 mph, but you're unlikely to figure that out, because while you were speeding along, your mind was working on averaging out the numbers you were seeing.

Anyway, the idea is clear: animated charts look nice but are completely useless and perhaps even dangeorus. And the same thing can be said about 3D charts. The way 3D charts change the aspect ratio can just as easily confuse and mislead the user.

There are also technical reasons for why animated charts might best be avoided when attempting serious analysis. The implementation of web animation calls for the use of client-side software, like Javascript, and for the transfer of all data to the client, leading to serious limitations in chart performance. It's not a problem if you're only dealing with a hundred points, but if you're dealing with a hundred thousand? You have to send everything to the browser through the Internet, which can create some serious problems. At the same time, static charts can be implemented server side, so the server always sends the chart to the browser as an image, which makes it possible to visualize virtually unlimited numbers of points.

Now, having said all of that, let's come back to the main question: should we absolutely never animate? Of course not. In some cases an animated chart is a must, like for monitoring a process in realtime. In other cases, animation can actually help people understand the data in question properly, as with visualisations of changes in time, as with the Earth's population over the centuries on a map, or with the changing structure of energy production over the last few decades. When the animation is used as a visualisation tool showing processes, it can be really helpful.