###### EASILY CONFUSED CHARTS

#### VENN vs EULER

*Welcome to my first article about **easily confused charts!**Let's break down the difference between a Venn diagram and an Euler diagram.*

It’s safe to say everyone is familiar with a Venn diagram, but have you heard of Venn’s more sophisticated cousin, the Euler diagram? Once you meet an Euler, there’s no going back. Euler is where the magic happens.

A Venn diagram shows *all possible relationships* between sets, even if the relationships don’t exist. An Euler diagram, on the other hand, shows *only the relationships that actually exist* between sets. It's like a more complicated, grown-up Venn.

When I discovered Euler diagrams, my mind was blown. It had never hit me why certain sections of a Venn diagram are left blank and unlabeled—because nothing exists there. There is no overlap between those sets.

A Venn diagram is good for a small number of data points (at least two items, no more than four, generally), while an Euler can handle many more categories and complicated inter-connectedness. I find them both to be pleasing to look at and intuitive to understand.

Below is my favorite Venn of all time, the overlap of life purposes known as *ikigai*, the Japanese idea of living life with purpose and joy. There is a __bestselling book__ about this concept. But the original Venn is flawed. See below.

In other words, a Venn diagram is more limited. It can have *empty relationships.* An Euler diagram will *never* have empty relationships. Who wants an empty relationship? Not me. Below I have applied the *ikigai* concept to better, 4-set Venn:

An Euler diagram sometimes resembles a lopsided Venn because it distorts its shape only to show overlaps that actually exist. Below is an Euler diagram I recreated on the confusing hierarchy of the British Isles, a common example of the Euler at work:

The Euler diagram is named after 1700’s Swiss mathematician **Leonhard Euler **(pronounced “oiler”). He contributed more to mathematics than probably anyone in history. **John Venn** was an English mathematician born in 1834. He published his namesake diagrams in the 1881 book *Symbolic Logic*. Leave it to the mathematicians to come up with these awesome logic diagrams!

**To recap:** A Venn shows all possible overlaps.

An Euler can show **nested** and **excluded sets.** It’s more flexible and versatile.

All Venns are Eulers, but not all Eulers are Venns.

Congratulations, if you’ve read this far, you know now a little bit more about Set Theory!

Try making a Venn for yourself. At what intersection of interests do you sit? How elaborate can you get with the overlaps? Are there any empty ones?

**EPILOGUE:** There is another data visualization technique called a **Rainbow Box**, which shows overlapping sets in a completely different way from an Euler diagram. It uses spanning horizontal bars in a box. But that’s a post for another day…

*Cheers,*

*Julie*

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