Data Analyst · Step 6 of 8 · 9 min
Charts that tell the truth
You can choose a chart from the question and avoid the tricks that mislead readers.
Choose the chart by the question
Change over time: a line chart. Comparing categories: a bar chart, sorted, usually horizontal if labels are long. Parts of a whole with two or three parts: a simple stacked bar or, sparingly, a pie. Relationship between two numbers: a scatter plot. Distribution: a histogram.
If you cannot say the question in one sentence, the chart will not answer it either.
Bars start at zero
Bar length represents size, so a bar chart’s axis must start at zero. Cutting the axis makes a 3% difference look like a doubling. Line charts can use a narrower axis when the point is the shape of change, but label it clearly.
Avoid the usual traps
Dual-axis charts let you make any two lines look related by stretching the scales. Use two charts side by side instead. 3D effects and exploded pies distort angles and areas. Too many colours turn a chart into a puzzle; use one highlight colour for what matters and grey for the rest.
Check colour choices for colour-blind readers: avoid relying only on red versus green.
Label directly and write the point
Put labels next to the lines or bars instead of in a distant legend. Give the chart a title that states the finding, like “Online orders overtook in-store in June”, rather than “Orders by channel”.
Note the source and the time period under the chart. A reader should understand it without you in the room.
Try it
Fix a bad chart
- 1.Search for “misleading graph examples” and pick one, or use a chart from a recent report you received.
- 2.Write down the question it should answer and what is misleading about it.
- 3.Redraw it in Google Sheets or Excel with a zero baseline, direct labels and a finding as the title.