Highlights from Milan Expo 2015
Visualizing survey results excellently

Taking care of a German pie chart while enjoying German kuchen

I was enjoying this yummy piece of German cake the other day.


I started flipping through the recent issue of Stern magazine, and came across this German pie chart that probably presents results from a poll. In particular, it draws attention to changes between the current and the prior poll, I think.



When a pie chart is used to handle data with more than three or four categories, we frequently encounter objects with a rainbow of colors, and a jumble of text labels. In this case, the order of the labels in the legend doesn't match the order of the pie sectors. 

In addition, such pie charts almost always fail the self-sufficiency test. All of the data are printed on the chart itself, inviting readers to ignore the visual presentation.

A bumps-style chart works well for this type of data. I tried something different here:


The challenge is to elegantly handle the current data plus the change from the last poll.



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As a German I have to at least partially defend this pi chart.
Except for the order of labels.
German governments are usually formed in a coalition of parties that represents more than 50 of the seats.

In this case. Placing black and red (the current coalition) and red, green and then pink together (center left block with die linke as a potential partner) give a German audience, who has minimal background knowledge in the political landscape a quick answer to the question of possible coalitions.


Additionally, the colors used for each party are always the same in Germany. Everyone is associating black with CDU and red with SPD, etc. Using different or no colors at all could even be more confusing. But I agree, the order in the legend could be improved.


@tobias / @heike

Ok, sure, the colors have a particular meaning, and can therefore be useful in the display.

But that doesn't address the mistake of using a (3D) pie chart to display the data. :)


The 3d is awful but the colors are directly identifiable with each party that Germans can organize it in their heads immediately. I think it's one of the few exceptions to the rule, considering the coalition aspect.


This looks more like a Torte to me than a Kuchen, but I could be wrong

Kevin Deegan-Krause

I'd agree that this is an exception to the no-pie-charts rule. Colors here are intuitive and understandable by the desired audience, and the point of the graph that everybody wants to know is whether adjacent segments add up to more than 50%. Circular arrangement of data is actually really good for that because you can give each segment two neighbors (different coalition possibilities) and the eye can easily grasp whether any two sum to 50%. It's not great, however, for time series but for that you really need a series of stacked bars next to one another (though the tradeoff in this is that since they don't start at the same heights, the intuitive calculation of coalition math is much harder.). Any solutions to that challenge???


I love those Edward Tufte-esque white gridlines going across the bars on the chart. I always found that these type of gridlines make it easier to estimate the values displayed.


Things are slow here as I stuff myself with kuchen/torte. Stefan: would love to know what is the difference?

Kevin/Tobias/Heike: Agreed. I actually recommend pie charts in cases where people need to add together different pieces of data. In fact, I hope something would create an interactive pie chart, which would make this exercise of assembling 50% easier. We can include a 50% "box" and users can try to fit different pieces inside the box.

Also, it's quite impressive to be able to associate seven colors. Much harder than red/blue!


Not understanding how a coalition could/would come about, this opens up some interesting ideas on ways to display and/or interact with this data.

As far as how to represent the previous standing, a simple reference line for each bar would suffice on a bar chart.

A set of bar charts representing every potential coalition might be interesting.

The 'mix your own coalition' idea would be great for an interactive piece.


they grey pie (sum of minor parties) should be placed between magenta and blue to seperate left-wing and right-wing parties. The 3D pie-chart however is totally ok for this purpose as it resembles the German parliament.

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