Shane Schick and pies for many eyes

Yesterday, I blogged about the new collaborative data visualization site called Many Eyes. I am only one among many who have contributed comments to the websphere in the last few days about Many Eyes. In scanning through some of the comments by others, I found an article by Shane Schick, who, although well intentioned, doesn’t seem to understand data visualization. Here’s an excerpt from Shane’s article titled “I’ll believe it when I see it”:

I’m more of a pie chart guy than a bar chart guy. With bar charts you have to read along the bottom to see what the categories are and then back to the bars themselves to determine how much larger one thing is than another. With a pie chart it’s all laid out for you, and it takes only a glance to assess the proportion. To me, pie carts are just easier on the eyes. That won’t necessarily be the case for Many Eyes.

Not being a data visualization expert, Shane’s comments about pie charts vs. bar charts are actually more accurate if you attach what he said about pie charts to bar charts, and vice versa. Unlike pie charts, which typically use a legend to label the slices, bars on a bar chart are labeled directly, just below the bars. You can read a bar’s label without moving your eyes, but with most pie charts your eyes must bounce back and forth again and again between the slices and the legend. Also, visual perception is notoriously bad at comparing 2-D areas, such as pie slices, whereas our greatest perceptual precision is achieved by comparing the lengths of objects that share a common baseline and orientation, such as the bars in a bar chart, or in comparing the 2-D position of objects along a common dimension, such as the ends of bars. Finally, most pie charts are actually harder, not easier on the eyes, because they consist of several colors (one per slice), which are usually (although not necessarily) bright, garish, and therefore jarring to the eyes. When a bar chart is used to display the same information that could also be displayed in a pie chart, all the bars share a single color (unless you unnecessarily make each bar a different color, which is gratuitous nonsense). A considerable body of research has confirmed the superiority of bar charts in supporting all but a few rarely used operations of graph interpretation that can also be performed with pies.

It’s important to mention that pie charts are used for only one type of quantitative comparison, whereas bar charts support many purposes that require the comparison of magnitudes (that is, the relative sizes of the values). Pie charts are used exclusively for part-to-whole comparisons. In fact, the one advantage that a pie chart has compared to bar charts is that when you look at one, you know you are seeing a comparison of the parts of some whole, such as regional sales (the slices), which add up to total sales (the whole pie). Because bar charts can be used to display many types of quantitative relationships, when you look at one that is used to display a part-to-whole relationship, this fact isn’t as obvious, despite a quantitative scale that’s expressed as percentages. All that this means, however, is that you must state this fact, such as in the title “Regional Breakdown of Total Sales.” In other words, even if Shane’s preference for pie charts were backed by the evidence of what actually works best, he would still need bar charts for a host of purposes that pie charts cannot support.

At one point in his article, Shane complains: “If you’re the lone pie chart person among a group of histogram people, how well are you going to be able to articulate a vision?” The truth is, when it comes to presenting data, you can’t be either a pie chart person or a histogram person. To articulate your vision effectively, you must know how to match the data and your message to the appropriate means of display. Pie charts, which exclusively display part-to-whole relationships, and histograms (a specialized version of a bar chart), which exclusively display frequency distributions, don’t align themselves with distinct teams that are trying to reach the same goal. To articulate your vision, you must speak the language—in this case the language of graphs.

Take care,


3 Comments on “Shane Schick and pies for many eyes”

By annoyed. January 31st, 2007 at 11:56 am

I am amazed that someone like yourself can make a career in spending 80% of their time critizing others works while spending 2)5 of their time creating anything of value. I have read all your books, blogs, etc… And I consistently see you demonstrating how NOT to do things while devoting very little attention about the right way to do things. Enough already. We get it.. most people are addicted to their powerpoints and pie-charts, and most “data visualization” does more to distort than inform. But geez, don’t you get tired of pointing this out repeatedly, why not focus on inspiring people to create better desgigns that constantly knocking everyone.

By Stephen Few. January 31st, 2007 at 12:16 pm

Dear Annoyed, 

As a person who understands the best practices of data visualization, you are not one of the people for whom I write these critiques.  Most people don’t know how to present data effectively and need people like me to expose the poor presentation practices that undermine most data communication today. Even those who have developed good data presentation skills often struggle to get others in their organizations to adopt them, and they appreciate my critiques because they are able to use them to make their case.

Your statistics are actually off by quite a bit. Most of my time is spent helping people learn how to analyze and communicate data effectively. Pointing out what doesn’t work is part of teaching people how to do things right, especially when poor practices dominate, as they do today. Unfortunately, as long as poor practices not only dominate, but are also being reinforced and actually advocated by software vendors, constant reminders from people like me that these practices don’t work are necessary.

Despite this, however, a careful review of my work, especially my books, articles, and workshops, reveals a predominant focus on inspiring and equipping people to create better designs. I rarely critique shortcomings or outright errors without going on to explain the effective way to do things. My blog focuses more than my other work on pointing out errors and ineffective practices, which seems appropriate for this venue, with its emphasis on opinion and on responding to things that people are talking about.

I certainly don’t knock everyone–only those who make erroneous or misleading public statements or advocate practices that are harmful. People and organizations that do good work get my attention as well, along with my greatful acknowledgement, but they are unfortunately few and far between.

If you find my critiques repetitive and annoying, you might want to skip them and focus only on the other ways that I contribute to the field. Just be grateful, however, that someone is doing the work of exposing the bad data analysis and presentation practices that do so much harm in the world. If you would be so kind as to take on this role in my stead, I would be able to spend more time doing much more challenging and fulfilling work.


By Russian Sphinx. June 6th, 2010 at 4:32 am

I have just created my first interactive ManyEyes map “Ease of doing business index in different countries” I posted the map as image in my blog Russian Sphinx

ManyEyes is user friendly so you do not need to spend a lot of time to create good chart or map, but I am not sure if it is good solution for me. I need good charts and maps for my blog. Interactive maps looks perfect but I am not able to place them as interactive on my blog, so I just post normal image and add link to ManyEyes. Maybe it will be a bit annoying for my visitors and I will have to focus on static maps.

I also use Tableau Public.