Reading charts and tables
Examine axes, categories and missing context before interpreting a visual.
Covered in this guide
- Check scales, units and time periods.
- Identify omitted categories and aggregation effects.
- Match a chart to the decision being made.
Charts direct attention, but design choices can magnify or conceal differences. Begin with the axis range, unit, time period, group definitions and source before interpreting the shape.
Read the axes before the story
Charts direct attention, but design choices can magnify or conceal differences. Begin with the axis range, unit, time period, group definitions and source before interpreting the shape.
A chart whose truncated axis overstated change
A bar chart beginning at 94 shows satisfaction scores of 96 and 98 as dramatically different. The two-point difference may matter, but the truncated axis exaggerates its visual size.
Try this
List the checks needed before recommending action from the chart.
Review answer guidance
Check the full scale, sample size, response rate, question wording, uncertainty, subgroup composition and whether a two-point difference is operationally meaningful.
What chart items actually test
Check units, scale, time range and what is omitted. Then answer the question asked, not the impression the graphic is selling.