The Chart That Misleads
A sales manager asks you to present quarterly revenue for four regions. The raw figures are Region A: 102, 104, 103, 105 (thousands). Region B: 40, 42, 45, 44. Region C: 20, 19, 22, 21. Region D: 8, 9, 7, 10. The manager wants 'a chart that shows how dramatically Region A is pulling ahead'. A colleague suggests a 3D pie chart of the latest quarter and a bar chart with the vertical axis starting at 100. You have one slide.
1. Evaluate the two suggested charts against the goal of showing Region A pulling ahead, and recommend an alternative.
Read the worked answer
Both suggestions distort or obscure the comparison. A 3D pie of one quarter shows share of a single period, not a trend, and 3D perspective makes slice sizes hard to judge. A bar chart with the y-axis starting at 100 exaggerates small differences: Region A's 102-105 range would look like a steep climb while B, C and D are truncated or invisible, which is misleading even if it flatters the message. A clustered column or line chart with a zero-based axis, all four regions across the four quarters, honestly shows that A is far larger and growing modestly while others are small. If the point is scale dominance, a single chart with a zero baseline communicates it truthfully.
2. If the manager insists the visual must emphasise Region A, what is an ethical way to do it?
Read the worked answer
Emphasise through design, not through a broken scale. Keep a zero-based axis, then use colour and annotation: highlight Region A's series in a strong colour, grey the others, and add a callout stating the actual gap (e.g. 'A is roughly 2.5x B and 5x C in Q4'). You could add a small secondary panel showing A's absolute lead or growth percentage with a correctly labelled axis. This directs attention to A without implying a rate of change that the data does not support. State the axis start and units on the slide so the audience can read it correctly.