Tuesday, December 13, 2005

Of ducks and doubt

I'm not a big fan of the bar chart, although it has its uses (for more on this topic see the discussion on the blog Junkcharts and a previous post of mine). But if the ordinary bar chart is less than inspiring, what to make of this graphic from today's issue of an Ottawa newspaper called "Dose":
In discussing "self-promoting graphics", Edward Tufte writes:
"When a graphic is taken over by decorative forms or computer debris, when the data measures and structures become Design Elements, when the overall design purveys Graphical Style rather than quantitative information, then that graphic may be called a duck ..." (The Visual Display of Quantitative Information, 2nd ed., p.116)

Why a duck? In his book, Tufte showed a rather remarkable building shaped like a duck where "the whole structure is itself decoration". I think Tufte's words are particularly applicable to the figure above. A simple table gives the same information in a much more straightforward way:

Hmmm ... I wonder if the kind of graphical nonsense the press routinely produce has something to do with their credibility problem?
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Blogger Nick Barrowman said...

Kaiser over at Junk Charts has bestowed a very fitting name on this duck:

We shall call this genre "racetrack graphs". If Italy and Japan both traversed 20 metres in distance, it'd appear as if Italy's curve was longer than Japan's because Italy has the inside track! This bias is well known to anyone who has run track.

Check out Kaiser's very clear analysis of the resulting distortion.

9:49 PM, December 14, 2005  

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