New Chart Junk: Squaring The Pie

The purpose of graphics for data visualization is communication, not decoration, which is often forgotten in publications as well as on company performance dashboards. A case in point is the chart on yesterday’s cover of the New York Times. It shows that solar energy currently accounts for more than twice as many jobs as coal. It also shows the numbers of jobs in different sectors and uses a color code to mark some as based on fossil fuels versus renewable and low-emission technologies. 

Until recently, most publications would have used a pie chart. Now, graphic artists have found a way to square the pie chart into yet another style that will most likely trickle down to slideware and office walls, in spite of a low data-to-ink ratio and the use of two-dimensional shapes to display one-dimensional data.

If we agree that a picture is worth 1,000 words, then you don’t need a picture if your information fits in 50 words. The numbers in the chart are from the 2017 US Energy and Employment Report, Table 1, p. 28, which I would summarize as follows:

It is, perhaps, less flashy but more informative. The emphasis on Solar vs. Coal is given by the red frame. As in the New York Times picture, the fill color indicates the type of source. Unlike the New York Times, however, I used a special color for Nuclear. Uranium sure isn’t a fossil fuel, so it doesn’t belong with oil, gas, and coal, but that doesn’t make it renewable. As for Nuclear being a low-emission technology, the inhabitants of Chernobyl and Fukushima might disagree.

The other issue with the New York Times chart is that it uses 2D objects — rectangles — to display 1D data — numbers of employees. If you absolutely want to show this data graphically, you could do it with a horizontal bar chart, which would make the relative sizes of the sectors more visually clear than rectangles. With rectangles, for example, it is not visually obvious that the Other category employs more people than Wind; on the bar chart, on the other hand, it is, because the bar for Other clears the 100,000 mark while the bar for Wind doesn’t.

In slideware and business reports, the most common graphic for this kind of data is the pie chart, where the one-dimensional Employment variable is represented a the one-dimensional wedge angle, but it is still not as information-rich nor more visually clear than the table or the horizontal bar chart, as you can see in the visually indistinguishable wedge sizes for Wind and Other.

In conclusion, for the purpose of communication, yesterday’s New York Times squared pie chart is the worst. and the traditional pie chart is not much better. The table, and the horizontal bar chart work best.

#DataVisualization, #PerformanceBoards, #Dashboard, #ChartJunk


10 comments on “New Chart Junk: Squaring The Pie

  1. Michel, your article begs the question: when would one use a pie chart? The situations where pies make sense are comparing something with a well-known, fixed capacity. How does an employee spend their work day? What composes the surface area of the earth? It is difficult to think of other good examples…

  2. Mr Trumps pitch on coal was designed to be understood by the heart, not the head. He was promising ‘clean coal’, would give the miners their jobs back. I think the New York Times article was trying to disprove that position.
    A good lesson here for managers – logic will not overcome emotions. Logic enters through the head/intellect, emotion enters through the heart.
    An extreme example of this mechanism we have all experienced, is explained in a Chinese proverb, ‘Anger blows out the candle of the mind.’ Why is it only after an argument you think of the brilliant thing you could have said.

    Leadership is about engaging and focusing the 3 H’s, possessed by all our people.
    The HEAD – to think, dream & conceive.
    The HEART – to feel & believe.
    The HANDS- to take action & achieve. – .
    “The hand is the cutting edge of the mind.” Jacob Bronowski – author ‘Ascent of Man’.
    Our ultimate goal is to engage physically and emotionally the Heads, Hearts and Hands of all our people, to create an organisation* that can compete successfully on the global battlefield now and in the future. It must also be a secure challenging, fulfilling & enjoyable/fun place to work.

    *Team, department, company, community or nation.

    There is a dark side to the use of people’s emotions.
    “There was no point in seeking to convert the intellectuals. For intellectuals would never be converted. Our target must always be ‘the man in the street.’ Arguments must therefore be crude, clear and forcible, and appeal to emotions and instincts, not the intellect. Truth is unimportant and entirely subordinate to tactics and psychology. A lie told once remains a lie, but a big lie told a thousand times becomes the truth.” Josef Goebbels.


    • My post was only about a graphic tool, not about the politics of energy sources. I do have opinions on this subject, but this blog is not the place to express or discuss them. Regardless of political leanings, we can agree on what constitutes effective graphic communication.

  3. I’d say, it depends if the graph is intended to entertain or to educate. If it’s the latter, then the NYT graphic “art” doesn’t work. I once heard that the attention span of many executives today is not longer than that of a toddler, around 8 seconds. I don’t know if this is true, but since then I am telling team members to simplify their presentations so that the content can be understood within that short timeframe. Squared charts don’t make it in those presentations.

  4. My apologies Michel.
    I thought there was a valuable leadership lesson. The exact method of logical data presentation does not matter if people are listening on the emotional level.

  5. Michel,
    I like the challenge of disagreeing with you for once. Since you like accurate data, I have to say your statements are not accurate. This is not new chart junk: this chart is not new chart junk and can not be attributed to the New York Times designers. It is known as a heat map and according to a decently documented Wikipedia definition:
    “A heat map (or heatmap) is a graphical representation of data where the individual values contained in a matrix are represented as colors. The term ‘heat map’ was originally coined and trademarked by software designer Cormac Kinney in 1991, to describe a 2D display depicting financial market information,[1] though similar plots such as shading matrices have existed for over a century.[2]”
    In terms of learning styles, it is widely recognized that out of visual, auditory and kinesthetic, visuals are prevalent in populations. I personally belong to this population and therefore am more sensitive to a chart (pie or heat) than to a table and this is the target for the NYT audience. When was the last time they had a table as a cover page? Which style are you?
    By the way, this debate is not new. You had opened my chakras about the Visual Display of Quantitative Information by Edward Tufte. There is an interesting post from Tufte about this very topic.
    Tufte leaves it as an open discussion saying it would be good to have both the chart and the table especially for complex stock market data.

    • If this is a heat map, where is the matrix? The following example is of a heat map on Wikipedia. It’s about DNA, but I have no idea what it means.

      Rather than about a matrix, I have seen the term used more frequently for spatial information. On a map of the city, for example, you can represent variables like per capita income, real estate prices, or crime rate by gradations of color, usually from cold blue to hot red. The following, for example, is a heat map from WalkScore, of bike scores in San Francisco, where green mean best for bikes:

      I don’t have a set style. I’ll use graphics or tables, whichever one I feel is most effective to what I want to say across to the people I want to say it to.

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