Data-Ink Ratio: Tufte principle of Data Visualisation

In his seminal  book “The Visual Display of Quantitative Information” published in 1983, Edward Tufte, an American statistician and professor emeritus of political science, statistics, and computer science at Yale University, said the following:

“The interior decoration of graphics generates a lot of ink that does not tell the viewer anything new. The purpose of decoration varies—to make the graphic appear more scientific and precise, to enliven the display, to give the designer an opportunity to exercise artistic skills. Regardless of its cause, it is all non-data-ink or redundant data-ink, and it is often chartjunk.”

Chartjunk refers to useless visual elements in any quantitative display that distract us from understanding the intended messages. The purpose of decluttering  data visualizaton is to maximize the data-ink ratio so that the proportion of ink that is used to present the data can be kept to a minimum, resulting in every pixel counts.

The following YouTube video (source: https://www.youtube.com/watch?v=JIMUzJzqaA8 by Tomasz Przechlewski) provides a simple and clear explanation of the principle.