After deep introspection, Stephen Few has determined that graphs with dual-scaled axes are fundamentally flawed. Rather than risk the potential for confusion, he believes that there are superior graphing approaches for situations where related data series have different units or magnitudes. His measured and thorough analysis concludes:
“It is inappropriate to use more than one quantitative scale on a single axis, because, to some degree, this encourages people to compare magnitudes of values between them, but this is meaningless.”
I commend Stephen for the courage to start down this path, but he hasn’t gone far enough. Here at Juice, we must often take controversial positions. You may remember that we were among the first to criticize Microsoft’s “databars”, the first to take on the powerful Dashboard Gauge lobby, and the first to challenge the applicability of Tom Davenport’s “Competing on Analytics” sales machine.
While it is true that the second axis can be deceptive, let’s not let the first axis off without asking some tough questions. It is the confusion—nay, the collusion—of the two that causes trouble—who is to say which is the bad seed? We must ask ourselves, do not axes belong in the “Axis of Evil”?
The problem is broader than Stephen suggests: axes are just the tip of the iceberg when it comes to graphic bling that potentially distract or confuse readers:
Take data labels, for example. They encourage users to consider specific values rather than focusing on relative sizes or placement of graph lines or bars.
Legends draw the reader’s eye away from the central storyline of a graphic.
Gridlines… please don’t waste my time with these flat faux-series. One wouldn’t put pinstripping on a Ferrari.
Place your graph in proper context and titles become redundant.
Minimalism is in. Extraneous graph decoration is out. Look no further than Tufte’s sparkline: no excessive graph decoration there.
The world cries out for a new charting aesthetic. One that champions elegance and casts down gaudiness. Let us evoke the pure visual essence of the data. Let us find a pure form to evoke the emotion and hidden meaning of the data. Now is the time for Naked graphs—stripped to the essentials (TM).
Our argument is simple: the visualization of information is the message. The data is but an intermediary form of that visualization. Therefore, any residue from the raw data should be scrubbed from your final graph. Only when you achieve this unadulterated state will the meaning of the graphic burn its way into your consciousness.
Here’s an example of an analysis that casts light on both the relationship of the Fed to hedge funds while simultaneously answering your question about what happened with last month’s sales in the Newark division.
Truly here we see the words of Mark 9:43 made real:
If your hand causes you to stumble, cut it off; it is better for you to enter life crippled, than, having your two hands, to go into hell, into the unquenchable fire.
Gaze in awe, viewers, and find wisdom on this very foolish day.