Edward Tufte will always be remembered for his “sparklines” (among many other things), but one of his earlier creations “Slopegraphs” has gone largely unnoticed by the community at large. Charlie Park takes a look back at them and some of the neat stuff you can see, and makes a prediction that they may be coming back in a big way.
Imagine you have a line chart, showing the change in European countries’ population over time. Each country has a line, zigzagging from January (on the left) to December (on the right). Each country has 12 points across the chart. The lines zigzag up and down across the chart. Now, let’s say you zoomed in to just the June-July segment of the chart, and you labeled the left and right sides of each country’s June-July lines (with the country’s name, and the specific number at each data point).
