Chartjunk

Edward Tufte coined the word in The Visual Display of Quantitative Information in 1983, and it has outlived most of the charts it was aimed at. Chartjunk is ink on a chart that carries no data: bars extruded into blocks, gradient fills behind the plot, hatch and moiré patterns, drop shadows, heavy frames, redundant legends, thickets of gridlines, and the clip-art mascot somebody added because the slide looked empty. The test is simple and physical. Erase a mark and ask whether any number got harder to read. If nothing was lost, the mark was decoration, and it was competing for attention with the marks that were doing the work.

The word travels with its measure. Chartjunk names ink that carries no data; the data-ink ratio measures how much of a chart’s ink does. One is a category you can point at and delete, the other is the arithmetic that tells you how much deleting is left to do, and Tufte published them together as two views of the same argument.

Two cautions keep the word honest. First, not all non-data ink is junk. An axis line, tick labels, and a light gridline are all non-data ink that earn their place by making position readable as quantity, which is why the charge is really “ink that competes” rather than “ink that is not a datum”. Second, the empirical record is less one-sided than the polemic. Bateman and colleagues found in 2010 that heavily embellished charts were remembered better over a delay than plain ones, with no measurable cost to accuracy at reading time, so a chart made to be recalled from a poster and a chart made to be read closely are not obviously subject to the same rule. What survives every study is the specific harm: decoration that distorts the encoding. An extruded bar makes the reader choose between the front face and the back face of the same value, and a gradient fill makes two equal bars look unequal.

Distinguish it from its neighbours by where the damage lands. A truncated axis is a lie in the geometry itself, so the marks misreport their values while the chart stays visually clean, whereas chartjunk usually leaves the geometry honest and buries it. Maximalism is a register that means its excess, chosen for a poster or a brand where more is the point, while chartjunk is excess arriving by default from a spreadsheet’s chart wizard and paid for by the reader. The practical correction is not austerity for its own sake. It is one pass of deletion at the end, keeping whatever a reader would miss.