Violin Plots
Strictly speaking, 'violin' refers to the internal structure of the data. The external portion visible in the plot is called the 'viola.'
Strictly speaking, 'violin' refers to the internal structure of the data. The external portion visible in the plot is called the 'viola.'
This comic graphs the "suggestiveness" of different visualization types, and the winner is Violin plots, hence the title of the comic. A violin plot is a method of plotting data similar to a box plot, but shows the full probability distribution of the data rather than a "box" showing the central two quartiles. This plot can look like the external opening of a human vulva, as do some of those in the violin plot represented in the comic (strictly speaking, this chart is not purely a violin plot; it is a box plot overlaid onto a violin plot).
The chart compares other visualization types' suggestiveness (as female genitalia) to the violin plots and ranks them after how suggestive they are. In the low end we find pie chart, a circular graph divided into "slices" to show proportions, and line graph or line chart, a graph of points connected by line segments.
Almost as suggestive as violin plots are the paintings by Georgia O'Keeffe, an American painter known for her paintings of flowers. Some of these flowers, Black Iris for example, are said to symbolize female genitalia, though O'Keeffe herself denied those claims.
The title text invokes the fact that many people incorrectly use the word "vagina", which refers to an internal structure, for the vulva, which is the external portion of the female genitals. Meanwhile the viola is an instrument often mistaken for a violin. And the word "viola" shares common letters with "vulva." Mixing pedantic terms like this was also used in 1405: Meteor.
Randall has made several comics with sexual topics, and the vagina has been the center of attention before, as early as in 136: Science Fair. There is even an entire Penis category. However, these topics haven't appeared recently — the last comic in the penis category was posted more than two years ago, and the sex category hasn't had a new comic since December 2017 (more than three months before this comic).
It possible that pie charts were included because this comic was released on Pi Day. Randall has shown fascination with Pi in earlier comics like 1292: Pi vs. Tau. On the other hand, it could be a reference to the film American Pie, which states that putting a finger in a pie feels like putting it inside a Violin... It could of course be both reasons, or none of them...