Gauges are the devilPosted: August 14, 2011
BI dashboard builders almost always seem to offer a speedometer or gauge as a favourite way of visualising your most important data. Like this:
Pretty enough to look at, I suppose. But an absolutely shocking example of data visualisation, which will absolutely not help people to run their businesses and will make using the dashboard a source of stress rather than a helpful and calm tool of control.
What’s so wrong with having a business dashboard that literally looks like a car dashboard, with a series of gauges showing you how you’re doing?
- Awful, awful use of screen space. All that the gauge above conveys to me is that the current value of something is 126, and that a value of 126 is not very good. Here is a great way to convey exactly the same message in less than 1/100th the space: 126
- Misleading visual signals. People use the angle on a gauge before they use the actual numbers to judge performance. In this case, a natural interpretation might be that anything to the right of the vertical is high/bad, and to the left is low/good. Probably not true, just an accidental artefact of the range on the gauge.
- No context. Unless you have an extremely good memory, you probably don’t know if 126 is better, worse, or about the same as the last few values. That’s just as important as knowing today’s value.
- No interpretation. For example, say that in this case any value under 140 is fine and doesn’t need action, 140-150 is worrying as it may be a danger signal, and 150+ means that something is about to break. You have no way of knowing this from the gauge. Wouldn’t it be more useful to use the screen space on communicating this instead of making a pretty gauge? You could do it as simply as adding a note below the written number to explain where the danger threshold stands.
And if your desktop now feels a bit too empty without all the dials and buttons, you can fill it up again with some pictures of kittens.