Statistical Chart of the Extent, Population and Revenues of the Principal Nations of Europe - the first pie charts and proportional circles
The pattern
This still is filed under Data as proof.
Define
A chart, map, or count that is the argument, not an illustration next to the argument.
Mechanism
Sighted evidence. The reader is asked to believe their eyes: a bar, a share, a spread on a map.
Verdict
The claim is comparative or quantitative and the figure can be read without a caption doing the sell.
Why it works
Three quantities are bound to a single object, so a reader can ask whether a country is rich for its size by looking at the angle of one dashed line instead of dividing two columns of a table. Sorting the circles by descending area turns the plate into a ranking before any value has been read. The wedge cuts appear only on the compound states, Turkey and Germany, because a slice exists here to show a part inside a whole and nothing else; the pie is used where it is the right tool rather than as a house style. Ruling the scale across the entire plate rather than boxing each country separately gives everything one common baseline, which is what makes fifteen unlike states comparable at a glance.
Steal this when
Use it when every item in a comparison carries three linked quantities and the interesting question is the ratio between them. Sort by the quantity that sets the shape, then hang the other two off the same object so the ratio shows up as an angle rather than as arithmetic.