Employment and Activities poster for the Federal Art Project, presenting a breakdown of total employment based on statistics available November 1, 1936
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
This is the isotype method: one repeated identical figure with a stated unit, so quantity is read from the length of a row rather than from a number, and rows can be compared without arithmetic. Fixing the unit in a printed line - each figure represents 100 project workers - is what stops the chart being decoration and makes it evidence. The outline map behind the rows makes a national claim without a second data set or a second colour. Everything is one ink, which is why the display face is built from geometric cuts instead of shading, and why the vignettes are pure outline.
Steal this when
Use this when you have to defend a budget or a headcount to a sceptical audience: convert spend into counted people, fix one icon to one unit, print the unit on the page, and let row length do the arguing instead of a paragraph.