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Doing my duty on Pi Day #onelesspie

Steel tariffs, and my new dataviz seminar

I am developing a new seminar aimed at business professionals who want to improve their ability to communicate using charts. I want any guidance to be tool-agnostic, so that attendees can implement them using Excel if that’s their main charting software. Over the 12+ years that I’ve been blogging, certain ideas keep popping up; and I have collected these motifs and organized them for the seminar. This post is about a recent chart that brings up a few of these motifs.

This chart has been making the rounds in articles about the steel tariffs.


The chart shows the Top 10 nations that sell steel to the U.S., which together account for 78% of all imports. 

The chart shows a few signs of design. These things caught my eye:

  1. the pie chart on the left delivers the top-line message that 10 countries account for almost 80% of all U.S. steel imports
  2. the callout gives further information about which 10 countries and how much each nation sells to the U.S. This is a nice use of layering
  3. on the right side, progressive tints of blue indicate the respective volumes of imports

On the negative side of the ledger, the chart is marred by three small problems. Each of these problems concerns inconsistency, which creates confusion for readers.

  1. Inconsistent use of color: on the left side, the darker blue indicates lower volume while on the right side, the darker blue indicates higher volume
  2. Inconsistent coding of pie slices: on the right side, the percentages add up to 78% while the total area of the pie is 100%
  3. Inconsistent scales: the left chart carrying the top-line message is notably smaller than the right chart depicting the secondary message. Readers’ first impression is drawn to the right chart.

Easy fixes lead to the following chart:



The central idea of the new dataviz seminar is that there are many easy fixes that are often missed by the vast majority of people making Excel charts. I will present a stack of these motifs. If you're in the St. Louis area, you get to experience the seminar first. Register for a spot here.

Send this message to your friends and coworkers in the area. Also, contact me if you'd like to bring this seminar to your area.


I also tried the following design, which brings out some other interesting tidbits, such as that Canada and Brazil together sell the U.S. about 30% of its imported steel, the top 4 importers account for about 50% of all steel imports, etc. Color is introduced on the chart via a stylized flag coloring.








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Hi, Kaiser - I like the remake of the chart with a simple pie chart for the 'Top 10' and then the additional chart on the right for the relative sizes. However, why is that right-side chart made of dots and not bars? If the point is to compare the sizes, we should not make the user consult the axis at the top of the chart, but can just use bars that show the relative sizes.

As for the second chart, I don't see the need to have two charts there at all. If you just eliminate the left column and put the 'Top 4 50%', 'Top 10 80%' and 'Rest of the World' labels right on the stacked chart on the right you get the same data with a simpler chart. Also, I don't understand the 'stylized flag coloring' of that chart - are you saying that the colors are attempting to match the countries' flags? If so, it is too subtle. You'd do better to include a small image of each flag in the bar. Or have I missed something?

Thanks for an intersting article.


Bob: Yes, agree with you on the bar chart.
For the second chart, I am trying to solve the problem of highlighting the main message. On any chart (pie, stacked bar) with country-level details, the reader's attention is immediately on the countries, not the aggregate groups of countries. The two sides could be overlapped on an interactive chart, in which the reader mouses over the aggregate groups to reveal the country details. I want to design a chart in which the reader first pays attention to Top 4, Top 10, and then look at individual countries. Any ideas?


I agree with Bob on both points.

I like the idea of the second chart, but I find it a little confusing to see both side by side. I think if I were to try to create the second chart, I would do something like this:

This is a quick Excel version, and could use some tweaks and cleanup, but is the general idea. I wouldn't fight against the idea of adding flag icons inside the boxes for each country, but I don't think it's necessary either.

(I also did my version of the pie/bar while I was at it: )


JLB: I like your version of the chart, and think that using colors for the Top 4 and Top 10 solves the problem. I'd prefer to keep the building blocks as horizontal 10% slices rather than using treemaps.


Kaiser - thanks. I had tried it is a single stacked bar, and didn't like it, but what you're saying is more like a unit chart. Maybe I'll give that a try.


As a unit chart, just for fun:


JLB: Thanks! I think this is a bit better than the treemap. One other thing I did was to break free from the precision imposed by standard block sizes, so I allowed the blocks to be slightly uneven in lengths. South Korea, Mexico and Russia all had roughly 10% share - that's the message. So I had them in three blocks, with slightly rugged right edges, instead of wrapping around the extra lengths. The next messages are: Turkey plus Japan is roughly 10%. Then, Taiwan, Germany and India form the next 10%. To me, allowing errors of a few percentage points yields talking points that are 10 times clearer.

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