Learn in the textbookData Types by Data Format and Source of Origin
DefinitionChartjunk (チャートジャンク) refers to decoration added to a chart that does nothing for understanding the data and instead gets in the way of reading it.
ExplanationThe term was coined by the statistician Edward Tufte, and 3D effects, flashy backgrounds, and meaningless pictures are typical examples. In a 3D pie chart the front slices look bigger, which easily leads to misreading the proportions. When making a chart, cut back on decoration so that the parts showing the data stand out.
AnalogyIt is like a plate piled so high with garnish that you cannot tell where the actual food is.
Memory hookJunk means rubbish in English, so read it as rubbish on a chart.