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99% of the time pie charts suck (see my rant). However, there is a situation where it can be useful: when you are trying to convey a general idea of part-to-whole relationships among 3-5 entities which are meaningful parts of a whole unit. There’s an excellent breakdown of how this works, why it works, and dos and don’ts here.
This image has to be the best use of a pie chart I’ve ever seen.
I’ve been working on the physical side of my ambient display for a Barclay’s Cycle Scheme docking station on Theobald’s road – one that I use pretty often. The challenge for this display is that it uses a motor and drive assembly harvested from an obsolete HP printer. Properly, anything requiring precise positioning should use a stepper motor, but that’s not what I found inside the printer. It uses a simple cheapie induction motor. So, I’m considering it a design challenge/constraint.
There was a plastic optical calibration strip somewhere in the assembly but that’s long gone. So precise positioning will be rudimentary, as the vagaries of induction drive do not always yield reliable results. My tradeoff for the display is to zero-out the motor for every display cycle instead of skipping directly from one number to the next. Each number will have its own drive time and the motor supply is regulated to keep it as constant as possible to minimise the likelihood that the motor will be slower or faster depending on supply voltage.
This test is just to make sure the drive times for digits and the serial communication are all working properly. Next steps are connecting it to the web API and making it look pretty!
In the US, there’s recently been a great furore over a planned Islamic Community Center to be built near Ground Zero in New York. Inflammatory rhetoric from detractors and anti-Muslim fanatics fans the flames. Inspired by a graphic sketch by Mark Schmidt on Facebook, I created an Infographic which shows the approximate relative sizes of the various parties involved. The chart illustrates the absurdity of gross generalisations which lump all Muslims together with Al Qaeda and discount the fact that lost of americans are Muslims, too. (Many Muslims would also argue the red dot should not be included in the circle containing all Muslims.)
Just came across Adobe’s Kuler, an excellent online tool for creating and exploring colour palettes. I’m using it for making some aesthetic choices for some prototype GUIs in Processing…nifty!
Presentation graphics packages like PowerPoint have always been slightly irritating to me. Although they can make it easy to present ideas, this doesn’t mean that the presentation will be meaningful to an audience. Information design heavyweight Edward Tufte has offered scathing critiques of presentation software and argues that they lead to a different kind of thinking for both present and audience.
This funny poster on BoingBoing (thanks Cory) encapsulates this love-hate relationship and pokes fun at Tufte as well. I’m still chuckling…
For an added knee-slapper, check out the Gettysburg Address as a PowerPoint presentation by Peter Norvig.
I’ve been honing my houghts on this for a while, because many people have been asking me why pie charts are problematic. On the surface, they seem like a good way of presenting part-to-part and part-to-whole relationships. And hey, everybody uses them, so they must be good, right? Unfortunately, they make little use of our best capabilities for visual perception and rely on comparing angles and areas – two of our weaker visual tasks, according to many perceptual studies.
Their principle faults are:
For example, take the pie chart below. Imagine that you had to determine the quantities represented by the slices or even easier, to simply rank order them from biggest to smallest. Think about how long it would take to make your best guesses and how much you’d have to rely on rough estimates by either: 1) evaluating the relative sizes of the slices or 2) comparing the angles of the slices where they converge at the centre of the pie:
It’s pretty tough going. Just how much bigger is the red slice than the orange slice, expressed as a percentage? Furthermore, adding labels actually complicates matters because your eyes have to bounce back and forth in order to know what you are making comparisons about. In this case, perhaps the number of animals adopted from a pet shelter:
It’s visual ping-pong folks, and it’s not fun. What, you say? Just add the percentages into the slices and that will help you to solve the estimation problem. Let’s take a look:
It does indeed make it easier to see that there were almost twice as many Rabbits adopted as Hamsters. It might even be easier if my version of Excel allowed me to put the labels in the slices (though it doesn’t!). However, this misses the final point: that if we have to rely on displayed numerical values to get the answers, it would be better (and easier) to just show them without all of the visual nonsense:
There is is. Simple, straightforward, and easy to read. It might not make for pretty pictures in the boardroom. But ask yourself if you are really just trying to entertain your audience or whether you are trying to communicate something effectively, precisely, and meaningfully. And in that case, it doesn’t matter if that last line is a Platypus or a Profit Margin.
I have just got my copy of Stephen Few’s new book “Now You See it”, which I had bought from Amazon without even cracking the cover for a preview and I have to say it’s a very impressive effort. Following on from Few’s previous excellent books Designing Information Dashboards and Show Me the Numbers, this new book carries on his excellent work on data representation and quantitative presentation. Even better, the new book makes specific recommendations regarding user interaction with interfaces. Best of all, it provides a practical methodology for grappling with data representation problems, something which has been sorely lacking in the literature (e.g., the work of Tufte). Go. Buy. Now.
Last year at Dorkbot London I gave a demonstration of the Brockenspiel and fielded a few questions afterwards. Some clever guy in the audience asked if I could hook up a bar code reader – a thought I’d had but not implemented. When I said it would probaly work just fine, as long as the serial protocol is the same, someone in the audience called out “Hang on a minute, I’ve got a barcode reader around here!” (Only at Dorkbot!) Hidden in the depths of Limehouse Town Hall, he hauled out the reader, and by a stroke of luck, it worked. We were playing the music on beer bottles in a matter of minutes. Later, I made a quick video to demonstrate the concept.
Brockenspiel Bar Codes from Brock Craft on Vimeo.
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