The quiet cost of a beautiful chart
Every decision that makes a figure prettier is also a decision about what the reader will believe.
A chart is an argument. Every choice in it, from where the axis starts to which line gets the bright colour, is a claim about what matters.
That is fine. It is the job. The trouble starts when the choices are made for how the chart looks rather than for what it says.
Three pretty lies
The cropped axis. Starting a bar chart at 80 instead of zero makes a small difference look like a large one. It also looks cleaner, which is why it keeps happening.
The smooth line. Smoothing turns noisy data into an elegant curve, and in doing so invents a trend the data never showed.
The highlight. One line in colour, the rest in grey. The reader now believes the coloured line is the story, whether or not it is.
A test I use
Before publishing a figure, I describe it in one sentence, then look at the raw numbers and ask whether that sentence is true. If the chart makes a stronger claim than the data, I change the chart, not the sentence.
Beautiful and honest are not opposites. But when they pull apart, honest has to win.