Graphical comparison of changes in large populations with “volcano plots”

I recently rediscovered a volcano plot — a scatter plot that aims to visualize changes in large populations.

Volcano plots are very technical and specialized and, most probably, are not a good fit for explanatory data visualization. However, they can be useful during the exploration phase, and they come with a set of well-established metrics.

Moreover, if you are lucky enough to have well-behaved data, the plots look very cool

Visualization of RNA-Seq results with Volcano Plot
From here

Of course, in real life, the data is messy. Add bad visualization practices to the mess and you get a marvel like this one

From here

The bottom line: if you have two populations to compare, consider volcano plots. But do remember dataviz good practices.

Data giraffe is sometimes a feature, not a problem

I wrote about data giraffes two weeks ago. Usually, “data giraffes” are a problem and we need to work hard in order to solve it. Sometimes, they are a useful feature. Take a look at this NYT front page that shows the number of new unemployment applications in the United States over the time

And this is the pseudochartchart version of the same data

Credits: I’ve found these examples on Stott Berkun’s page.