Edward Tufte’s “Slopegraphs”
charliepark.org/slopegraphs
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
What’s interesting is that over 20 years before sparklines came on the scene, Tufte developed a different type of data visualization that didn’t fare nearly as well. To date, in fact, I’ve only been able to find three examples of it, and even they aren’t completely in line with his vision.