Tag Archives: Tufte

On the origin of slopegraphs

Slopegraphs are very good ways of viewing both changes in value between two measures over time, and changes in the rank of items for each measure. They can also be used to compare two different dimensions, such as the number of cases and the number of deaths for different diseases (3rd chart), for instance.

Alberto Cairo introduced me to this type of chart in The Functional Art (p 129), and below is the classic example from Edward Tufte’s The Visual Display of Quantitative Information.

A slopechart from Edward Tufte's The Visual Display of Quantitative Information (Graphic Press), on page 158 of the 2013 edition
A slopechart from Edward Tufte’s The Visual Display of Quantitative Information (Graphic Press), on page 158 of the 2013 edition.

I’ve read in many places that Tufte was the inventor of the slopegraph, and I always believed it, although Tufte himself doesn’t claim that in his book.

That was until I visited the Museum of Press and Graphic Communication in Lyon, France, and ran into this :

A slopegraph published in l'Oeuvre on 3 February 1944.
A slopegraph published in l’Oeuvre on 3 February 1944.
Header of the journal where the date is visible.
Header of the journal where the date is visible.
Full page - l Oeuvre - 1944
Full page.

It seems like somebody made a slopegraph during WWII to show how the exports from different French industries had evolved between 1913 and 1935. The subtitle of the chart most likely aims at convincing the readers that the French economy would be better off after the war. The journal L’Oeuvre was apparently collaborationist during the war. The “terroristes” in Haute-Savoie below the header were certainly members of the French Resistance who had been recently massacred by the Nazis.

So that would make the slopegraph 39 years older than the one published by Tufte in 1983. I bet there’s even older examples out there…