poverty-ratios-skyscraperTextures. 3D. Pie charts. Primary colors. Trends hidden behind labels. Backgrounds. Pie charts again.

Clear signs of a bad chart, right? Right. It is so easy to spot a badly designed chart that you can use a computer to do it. Don’t waste your time.

Let’s stop discussing the obviously wrong and start discussing the useless right. Like this chart here. (I’ve borrowed the dataset Nathan used in one of his visualization challenges – some interesting entries and great discussion there, by the way).

There may not be anything really, really wrong with this chart, but it reflects a bureaucratic way of thinking about data and data presentation where every single data point must be clearly shown and labeled. Just like a table.

Listen, unless you work for a statistics office, you should never create a chart like this. I know, it’s irresistible to check how well my state ranks, but identifying each and every data point in a virtually limitless bar chart makes no sense in most cases.

Do you read the labels between the top five and the bottom five? Charts like this encourage look up of individual data points, and for that a table is probably a better option. If anything, a skyscraper bar chart is a clear sign of loss aversion.

A Flexible Bar Chart: Introducing the Accordion Bar Graph

How do you graph a categorical variable with more than, say, 20 data points without creating a skyscraper? This is what I have in mind:

  • You must retain the overall pattern, so you can’t remove data from the chart;
  • Create one or more focus area (top five and bottom five, for example);
  • Gaps between bars should be larger in these focus areas, so that labels can easily be added.
  • Minimize the height of the remaining bars and remove the labels;

The chart should look like this:

focus-context-bar-chart

 

I like the accordion metaphor and I’m playing with it. An interactive version could use a simple event to create a focus inside the context area, so when the user moves the mouse the bar is enlarged and the label is shown.

What do you think? Do you agree that skyscraper bar charts are (almost) useless or should we focus on reducing the number of data points instead? How would you improve this design? Please share your comments and charts below.

Update

Well, if you want to know how to do this in Excel and read a great discussion about it, Jon wrote Accordion Chart for Jorge. He not only discusses some of the options but also shares the Excel file with us. Thanks Jon! And Dick, over the Daily Dose of Excel wants to make sure that your state is automatically highlighted (Ego Charts). Nice “quarter step”!