Waffle vs. Pie: A visualization showdown!

This post was originally shared on my personal blog.

I, like many of you, never really thought much about pie charts one way or the other. Invented by William Playfair, and popularized by Florence Nightingale who used it to discuss causes of military death in the 1850s, the pie chart has clearly cemented itself in the world of data visualization. In fact, at my elementary school, the pie (along with the line graph and the bar chart) were taught as the only real ways to visually show data. I accepted it, then, and for decades after that.

But then few years ago, when I was teaching a class on dashboard design, a student pointed out the flaws that I'm about to point out in this article. It was an instantly compelling argument, and I haven't recommended using a pie chart since.

The Problem with Pies

Allow me to illustrate the problems that are presented by the pie chart.

I've been asked about a statement I made in my post on VitaraCharts regarding waffle charts. Waffle charts are a much better way of showing the same sort of data that a pie chart would. I will discuss the Waffle Chart in this blog post.

The above paragraph is my data set for looking at the waffle chart, and not, in fact, an accurate portrayal of the reality of this blog. You see no one has asked me about this statement (and only one person asked me why I used "VitaraCharts for MicroStrategy" as a verb in the title of that post, so I assume that everyone just believes I left a word out - which in fairness is more logical, given that using "VitaraCharts for MicroStrategy" as a verb was not as funny as I thought it would be). Anyways, we'll call the words in the first above sentence "Lies".

The second sentence of the paragraph is an opinion, which I believe to be true, but I have stated it as a fact. It's still a hypothesis, which you may disagree with or agree with, so we will call this "Beliefs".

And finally, the last sentence is true, as that is exactly what I'm doing here. Well, it will be once I finish being pedantic. We'll call it "Truth."

So, our data set is:

We could picture this data as a pie chart:

But look at the visualization itself. It seems like there's almost as much belief as lie in the data set, but there's almost 16% more Belief. Here's what 16% of a pie chart looks like :

See - two values, and a pie chart is incredibly clear. However, as you add a third it becomes more difficult to grasp relationships. As you add additional measures, it becomes less and less possible to keep track of detail.

In the end, a pie chart is good for tracking 2 measures, mediocre at tracking 3 measures, or can be used to show how much 1 measure dwarfs all of the others, such as this graph that compares the populations of the Netherlands and Luxembourg to the rest of the world:

(Note: I seem to have run into an issue with display in MicroStrategy Desktop at this point. I had Belgium in the dataset, but every time I added it into the graph, the slice for Belgium would appear as a combination of Belgium, the Netherlands, and Luxembourg - don't worry, Belgium, there's plenty more time to mention you in any post related to waffles).

This capability is good when you need to make a statement. But it's terrible when you need to do analysis, or want people to make a genuine informed decision, which is what data analysis is about. The pie is a tool, no doubt, but not one for analysis.

And a pie chart takes up a lot of space to show that small number of values ineffectively.

Enter the Waffle!

With a waffle chart, you get a more segmented view of the data - so at first glance, you can see the same information, but you can study it a bit longer and really look at how it compares:

As you can see it accomplishes the same at-a-glance insight, but if you take the time to delve deeper, you can see there's a 35:42 ratio between Lies and Beliefs.

And our 16% graph doesn't look much different, either:

It's still not perfect, obviously, as it appears that the world is effectively 0% Benelux, even with Belgium added back in:

That's not all

Joanna Seyfi just put out a video on using the VitaraCharts Waffle chart in MicroStrategy this week. It's worth mentioning that we didn't coordinate this (way to steal my thunder, jerk!), but it's a great video and shows functionality that I'm not discussing here (and manages to do so in about a minute, where my blog is probably going to be about 4 pages), so here it is:

It's not just about the tool

Note that creating a waffle chart is definitely also possible in Tableau, but it takes a bit more doing, and I didn't have the time to really dig into this. If I do have time in the near future, I'll add it in as an update, or maybe I'll include it when I finally do a review of Tableau, itself, or if I get desperate for a topic at some point it might be its own post one day.

My point is, there are certainly other tools and methods to get this specific visualization, and as much as I'd love for you to use VitaraCharts to achieve this functionality, the main thing I want readers to walk away with is that the Waffle chart itself is a better way to show your data in this way. I want to be sure that you add it to your bag of tricks, regardless of the tool you use.

Now to close off this post in a satisfying way

I thought I just did that. There's no additional useful information to add here.

Could you say something nice to appease pie chart fans?

Honestly, the only good thing that can be said about a pie chart is that it's not a gauge - which is the least efficient way of showing a single piece of information I can imagine.

Additional random historical facts are always fun, maybe something pro-pastry?

Sure... uh... The pie itself is probably about 2500 years old as a concept, and delicious. My dislike of the pie chart should not be taken as an insult to the pie. Nor should it seen to say that I believe waffles are better than pies as food. While I owe the Belgians something for leaving them out of the pie chart above, and they invented the modern form of the waffle some time in the 1400s, I've always been fond of both foods.

Okay, can you tie that information into the blog post somehow?

And, of course, as the waffle is a much more modern food (almost 2 millennia newer, in fact), it should be no surprise that the waffle chart is supplanting the pie chart in our modern world. You see waffle charts all around the news and social media these days.

Okay, now fizzle out with a failed catch phrase at the end

So modern up, and get with the waffle, already!

David Schieber is a freelance Business Intelligence and Data specialist working in the European Union and the United States. You can contact him at schieber@barefootdatascience.com

He's also proud partner of VitaraCharts which provides the missing visualizations for MicroStrategy and Microsoft Power BI. Contact Dave for a demo, or contact Vitara directly here.

He also added this sales text after several people had already liked and commented on this article. Don't judge them.