Here is what a first time viewer needs to go through when looking at a data chart:

  • What's the unit on the y-axis
  • What's on the x-axis
  • What do the legend colours stand for
  • What is "good" or "bad", are things supposed to go up or down?
  • What is actually happening
  • Is the y-axis broken or does it start on zero?
  • Why is this unexpected, interesting, counter-intuitive, amazing, terrifying?

If you did the analysis then you live and breathe the data in the chart, the only thing you watch out for is how the line/column/bar looks different from the previous version of the chart you saw. For a completely new audience it is a different story.

There are 2 types of data charts:

  1. Charts to ponder and refine research and analysis
  2. Charts to communicate the result of the pondering and refining

If you make a presentation of result, you deal with scenario 2. Make a diagram completely from scratch. Start with "what is actually happening" and only put that piece of data on the chart.

For example if a complex stacked line diagram shows that the % of returning visitors gets smaller over the past 5 years, you can replace all that monthly visitor data with 3 data points: % of return visitors in the last 3 years.

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