30 May 2025

How to help your readers' intuition, or lack thereof, when talking about probabilities

Bayes' famous theorem is widely regarded as the most important theorem in statistics. But that doesn't mean that it is easy to understand or interpret; not by any means.

Today, trying to come to grips with it myself, I stumbled on a vital piece of information for any technical writer or into-English technical translator who wants to make any text that mentions probabilities more accessible to their readers.

Fortunately, you can use this tip whether or not you've managed to understand the theorem, so feel free to jump to the shortcut.

Optional: Want to know more about Bayes' theorem?

Here are three links:

Shortcut

From An Intuitive (and Short) Explanation of Bayes’ Theorem:

People prefer natural numbers. Say “100 in 10,000″, or something similar, rather than “1%”. This helps people work through the numbers with fewer errors, especially with multiple percentages (“Of those 100, 80 will test positive” rather than “80% of the 1% will test positive”).

How to help your readers' intuition, or lack thereof, when talking about probabilities

Bayes' famous theorem is widely regarded as the most important theorem in statistics. But that doesn't mean that it is easy to under...