Design with a Purpose in Mind

The merits of something’s design cannot be determined without first understanding the purpose for which it is used and the nature of those who will use it, including their abilities. When looking at the photo below, you no doubt see two poorly designed chairs. The seats are far too low and the backs are far too tall for comfort. Imagine sitting in one of these ill-proportioned chairs.

If these are chairs, they are poorly designed for all but humans of extremely odd proportions, but they are not chairs. Rather, they are kneelers, used for prayer. Here’s a more ornate example:

And here’s one that looks more like those that are typically found in churches:

Not only are we not able to evaluate the merits of something’s design without first understanding its use and users, we cannot design something ourselves without first understanding these things. This is definitely true of data visualizations. We must always begin the design process with questions such as these:

  • For whom is this data visualization being designed?
  • What is the audience’s experience/expertise in viewing data visualizations?
  • What knowledge should the audience acquire when viewing this data visualization?

The point that I’m making should be obvious to anyone who’s involved in data visualization. Sadly, it is not.

Data visualizations should not be designed on whim. Based on the knowledge derived so far from the science of data visualization, if you understand your purpose and audience completely, you can determine the ideal way to design a data visualization. You can only determine this ideal design, however, to the extent that you know the science of data visualization and have developed the skills necessary to apply it. Our knowledge of data visualization best practices will change and improve as the science advances, and when it does our designs will change as well. In the meantime, we should understand the science and apply the practices that it informs with skill. None of us do this perfectly—we make mistakes—but we should strive to do it better with each new attempt. Data visualization is a craft informed by science, not an art driven by creative whim.

Take care,

6 Comments on “Design with a Purpose in Mind”

By Jonathon Carrell. October 24th, 2017 at 6:41 pm

Wonderful example Stephen. As much as it is a reminder of the necessity of skill and context for good design, it is also a reminder that we shouldn’t be dismissive of unfamiliar design concepts without similarly understanding their context/purpose.

That being said, the data viz community at large seems to ride wave after wave of design fads that come and go as with the changing of the tides. One has to wonder how much careful thought is being exercised in comparison to a “monkey see, monkey do” approach. I have my suspicions.

By Stephen Few. October 24th, 2017 at 6:48 pm

“Monkey see, monkey do” is the modern law of the jungle. It’s one of the few laws that can apply when you don’t take time to understand anything. It’s defintely a jungle out there.

By GMF. October 25th, 2017 at 7:10 am

The old saying…

The fool opens his mouth not knowing what he will say.
The smart man opens his mouth knowing exactly what he will say.
The wise man opens his mouth knowing exactly what the listener will hear.

By Andrew. October 25th, 2017 at 9:53 am

“…when you don’t take time to understand anything.”

Pretty much the problem with everything these days.

By Jeff. November 1st, 2017 at 11:08 am

Science in general and the science of data visualization in particular depend on the knowable natures and communicability of things. It is only because we can know the natures of things, at least in part if not in total, that we can not only communicate but communicate effectively what we know and have learned. If ‘the things’ were subject to random, arbitrary change (i.e. in an evolutionary sense), then no knowledge or communication would be possible. Design and purpose are indeed two peas in the same pod.

By Neil. November 20th, 2017 at 4:20 am

I tend to agree — though design with a purpose in mind is equivalent to the ‘form [should] follow function’, where the function is the purpose.

Interestingly, although each of the above chairs has been built with kneeling in mind, each of them also make artistic decisions that presumably give people a little bit of the warm and fuzzies. E.g. straight legs are easier and quicker to make — why the splay on the first chair, other than to give a sense of lightness and elegance?

Not that you’re saying this at all, but considering how people *feel* about the graphs and displays we design is important, too, if its the have the desired impact. Perhaps a fourth question that should be added to your list is, “How would the audience feel when viewing this visualization?”

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