How to read a chart

Reading a chart is reading data. We’re subjected to the angle of vision of the chart’s author. What data is included? What’s excluded? Reading a chart is just like reading a paragraph. A good chart is simple. But sometimes it’s beneficial to tell a robust story in the chart that a simple chart can’t tell.

  • Read the title: what am I looking at?
  • Look at the legend: what is being plotted or compared?
  • What is the line? Average? Who does it represent?
  • Look at the aces: what’s the magnitude of the change? Range?
  • Look at the trend. Up, down?


  • Why is the trend this way? Do we like the trend? Do we want to change it?
  • What does this imply? So what? How many people are affected by this?

Questions to ask/critical thinking:

  • Year over year? Compare to last year.
  • Compare to benchmark?