Junkchart and pistongeekery on the same page!

The sites I refer to when I talk about charting, data analysis and good (and bad) charting techniques are normally quite different from the ones where I satisfy my gearhead lust with the news from the latest car models in the market. This time the guys at motortrend did it for me in their article “Finding the best-handling car in the US”: both fixes in just one page

Look at the following chart: well, it’s easy to tell the winner on their tests is the yellow line (if you are curious, the Porsche 911GT3). But can you tell from the green and red lines in the middle of the pack which one is better?

If you go to their gallery, you’ll see many other charts that fight fiercely for the top place in the Junk Chart museum. Just a couple of samples below

 

Spider charts may be useful, but only in very limited cases. Leave the webs to the guy in the custome, enjoy the movie, and stick to other chart types in your professional reports. You would be better off. Your audience will get it faster.

Read on to see a proposal on how this chart could be better.

Here is the proposal:

What makes (IMHO) this chart much better? These principles usually work well to improve your charts:

• Key message first: The article was about which car was best. True, one may be better than other in one aspect and viceversa, but readers want to know at a glance who the winner was. The large bar charts on the left achieve that
• Sorting: Few things are more powerfult than sorting to make your message clear. The entries are sorted from best to worse. The “dust of dots” to the right of the bars may be hard to read, but at least sorting will come to the readers’ help, since they are sorted following the legend
• Grouping: All the steering items share the diamond shape. All the chassis items share the asterisk shape. That makes mental grouping easier
• Frame of reference: On the original spider chart it’s hard to judge if the score for a given aspect for a car is below or above average. The vertical line on the right side gives some frame of reference

I hope I convinced you against the spider charts. In this particular case, the chart was supposed to show 80 datapoints in 8 categories or dimensions, at the same time. The bars with a “dust of dots” that I shown is just one way to show it. Perhaps having 8 bar charts side by side could look even better.

The chart shown, in case you wonder, was fully done in Excel. It uses primary and secondary axes, and the sliding technique I had previously mentioned on this post