"The root of the problem is not technology -- at least not primarily -- but poor visual design."
One element of poor design is what Tufte terms "chart junk."
Most dashboard vendors take chart junk to new extremes, Few writes. They "focus their marketing efforts on flash and dazzle that subvert the goals of clear communication."
Software vendors ought to know how to present information clearly he says. "But they're so exhausted from working ungodly hours trying to squeeze more features into the next release that they're left with no time to do the research needed to discover what actually works."
What are the characteristics of poor design? Of good design? Few provides many examples and descriptions of both.
Perhaps you're using Excel to create your own dashboards. Or perhaps
you're using one of the many commercial dashboard programs. In either
case, Few offers sound advice about ways to design your dashboards to communicate business
Creating More Effective Graphs, by Naomi Robbins
Robbins' book presents graph forms, advice, and commentary on how to implement that command.
When you look at a graph, she continues, "ask yourself 'What is the first thing I notice?' The answer should be 'the data.'"
If you open Creating More Effective Graphs at random, you'll likely see a graph on the left page and a discussion about the graph on the right page. This design makes the book easy to read, and an excellent reference.
This book was not written with Excel in mind. Surprisingly, this turns out to be an advantage for Excel users, because it helps us to discover new ways to present data in Excel.
To illustrate, Excel doesn't offer a "dot plots" chart type. But because Robbins is so convincing about the usefulness of dot plots, I was challenged to create one. I explain the process in, Compare Metrics by Category Using Excel Dot Plot Charts.
Like Few, Robbins dislikes pie charts. She and Few suggest several similar alternatives. But Robbins also recommends the use of dot plots rather than pie charts, and provides an illustration of the information they can reveal.
Although the book isn't about Excel, Robbins does devote part of one chapter to Excel charting. And she includes a link to a workbook that shows one way to create dot plots. This technique, however, requires the use of a quickly written and poorly documented macro, which wasn't written by the author.
The macro aside, Robbins' book provides excellent advice that more
Excel users should follow.
Show Me the Numbers, by Stephen Few
Few provides clear advice that Excel users can apply immediately:
"I don't use pie charts," he writes, "and I strongly recommend that you abandon them as well. My reason is simple: pie charts communicate poorly."
Few supports this conclusion with several examples that quickly demonstrate why pie charts are a poor substitute for other chart types found in Excel.
What's the best way to display budget variances and other deviations from plan?
Few offers several solutions. Some of these work best for categories of variances, like departments or accounts. Others work best for time series data.
When you create tables in Excel, what's the best strategy to follow for using grids (Excel borders) and for shading rows and columns?
Few makes the answer obvious. He offers a series of examples that start with strong grids and gradually decrease the use of grids and rules to a minimum. "Judge for yourself," he wrote, "which table is easiest to read."
He applies a similar lesson to row and column shading, and illustrates the results.
When you create charts in Excel, how often do you use Excel's 3D charting features? Few advises you never to do so.
"Most software makes it far too easy and tempting to add a third dimension to objects in graphs," he writes. "This functionality is thrown in because people expect it, not because it's useful. It is far better to impress your readers with graphs they can easily understand and use, rather than graphs that look like video games and are difficult to interpret."
Edward Tufte's Books
Edward Tufte is widely considered to be the leading expert about how to present data so that readers can understand it quickly and easily. His three books are filled with examples from centuries of visual explanations.
If you're looking for a general grounding in the principles of visual explanations, Tufte still is the leading authority.