chart-designlisted

# Chart Design A chart is an argument about numbers. Its job is to make one comparison faster than a table would — and to make the wrong reading hard. Choose a chart only when it reveals a relationship faster than a table. A chart of four values is slower to read than four labelled numbers, because the reader has to decode the encoding before they get the data. ## The honesty rules These are not stylistic. Breaking them changes what the reader concludes. - **Bar and column charts start at zero.** A truncated bar axis multiplies apparent differences by an arbitrary factor. If small differences matter, use a line chart, a dot plot, or state the values. - **Line charts may use a non-zero axis** — they encode position, not length — but the axis must be labelled and the truncation visible. - **Area encodes one quantity, not two.** Doubling both width and height quadruples the area for a doubled value. - **Percentages name their denominator**, near the chart, not buried in a footnote. - **Equal visual weight means equal comparability.** Do not put two different units on one axis. - **Time on an axis is continuous.** Missing months appear as zero or as a marked gap, never by silently closing up. - **State when a scale is logarithmic**, in the axis label, not the caption. - **Categories are categories, even when they look like numbers.** Years, quarters, ports, and version numbers are labels, not measurements. Put them on a categorical (band) scale. Left on a continuous scale, `