A large of the data presented in business presentations is uncertain: future forecasts, market (share) estimates, competitive comparisons. Many people express that uncertainty by presenting numbers as ranges: cost per bottle as between $1.50 and $2.00.

While working with ranges might be required in a spreadsheet calculation, I don't like to use them in presentations:

  • It clutters the slides with double the amount of data labels, and/or double the amount of text in tables
  • It becomes hard to work with totals, add things up. Five of these 1.5 to 2 becomes 7.5 to 10. Adding negative numbers into the equation will give totals that nobody can work out from the top of their head.

So what to do? I would stick the mid point of the ranges as a point estimate in the presentation, and makes sure it is a nice, rounded number (7.49544 looks to certain). Much simpler and much clearer.

Art: a painting depicting women inspecting silk, early 12th century, ink and colour on silk, by Emperor Huizong of Song.

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