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“Save the pies for dessert”?

Included in Stephen Few’s very interesting visualization blog (perceptual edge) is the provocatively titled “Save the Pies for Dessert” post.   Pie charts are notoriously bad for perceptually judging magnitude. Here is an annotated excerpt from Few’s post, giving just one example of how hard it can be to judge scale using pie charts…

Not everyone hates pie charts, though…for example, here is a blog post from “Junk Charts” on the downside of discouraging pie charts.

Bonus: An amusing pie chart which shows the shadow illusion featured in the Categories question is this fascinating little image. Once you see the pyramid, you cannot unsee it:

 

Pyramid pie chart art.

I did not manage to identify the original maker of this -sort of- meme at this point, if you know, please tell me in the comments. Image above is copied from Rebecca Barter here: http://www.rebeccabarter.com/blog/2015-07-23-pie/

Another case made against the rainbow colors

Rainbow colors are pretty, and many of us like them. However, go to any visualization-related conference, and you’ll hear a lot of ‘rainbow-hate’. Where does that come from? Below is an excellent example that shows how rainbow color tables might mislead and make us see categories, or patterns, that might not be there. The image below is featured in a blog post titled “How The Rainbow Color Map Misleads” by Robert Kosara, in his wonderful visualization and visual communication blog eagereyes:

There is more to the art and science of choosing colors. Here is another informative post by Lisa Charlotte Rost: https://blog.datawrapper.de/colors/

Maybe a treemap would be better?

Consider this infographic about imprisonment, from this article on the American Legislative Exchange Council blog.   Most people would look at it and find it very engaging and attractive, which it is.  But, as a visualization expert, one wonders if the odd coloring variations in the outer ring of the main figure and in the “Juvenile” block at right, which just show how the larger wedges (categories) divide up more finely  (into sub-categories) wouldn’t be better shown in a Tree Map, using the ideas about showing hierarchical categories proposed by Ben Shneiderman in the 199os.   A Tree Map version of these data would almost certainly show the area of sub-categories and categories relative to each other (context) better than the snazzy graphic shown here.

Why (and what is) a “3D PDF”?

For hundreds of years, scientists have published their results in scientific journals that were printed on paper.  Today, though, most journals have gone entirely online.  Articles less and less frequently printed out and read on paper, so why should they still look and funciton exactly the way they did in the 1600s?

Josh Peek and I, and our colleagues wrote a fully online paper presenting The ‘Paper’ of the Future back in 2014, which highlights (with embedded demonstrations) many of the technologies available to scientists publishing today, and in the near future.   One particularly important technology–“3DPDF”– discussed in that paper of the “future” was actually first deployed in a Nature article by my “Astronomical Medicine” collaborators and me, way back in 2009.

Our challenge was to show the difference between two “segmentation” techniques used to define salient structures inside of star-forming regions.  The science isn’t important here (sorry).  What’s important is that we wanted to offer the “reader” multiple, interactive, views of high-dimensional data, inside of a journal article.

To see the PDF in action, take a look at this video, or download the “nature_demo” file and open it, on any Mac or PC, with an Adobe PDF viewer of any kind (not Preview).

Other authors (e.g Peek 2012) have since published methods for creating these 3D PDFs using free software, and a (perhaps too small!) number of authors have now embedded these 3D images inside of the scholarly articles.   Even though interactive images are clearly seen to add value to articles, they are not (yet) widely used.  3D PDF as a format may be short-lived, as articles move more and more to a fully online environment, where other (e.g. javascript-based) technologies can offer superior options.  BUT, the general idea of embedding data and interactive views of it, be they “3D” or not, is extremely valuable, and we will return to it in future posts–for now go have a look at The ‘Paper’ of the Future (Goodman at al. 2014).

But what about software!?

We knew this might be the first question you’d ask! One of the 10VizQ founders (Alyssa Goodman) is quite involved in making new visualization software, and in the scientific software world in general, so she promised to make posts about software from time to time. At present, Alyssa’s pet project is “glue,” which is a python-based (but GUI enabled) tool for exploring diverse data sets using linked views. She’ll make a separate post on glue soon–it’s utility applies across all 10 Questions.