The one sentence summary

You can make sense of a complex world by carrying out quick plausibility tests, understanding how numbers are reported and separating experts from pseudo-experts.

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  • We live in a world of information overload. Facts and figures on absolutely everything are at our fingertips, but are too often biased, distorted or outright lies. In a world where anyone can become an expert at the click of a button, being able to see through the tricks played with statistics is more necessary than ever before.
  • We need to ask ourselves: (a) Can we really know that? and (b) How do they know that? Doing this effectively allows us to evaluate numbers, words, and the world generally.
  • Statistics are not facts. They are interpretations, because people gather statistics. Sometimes the numbers are simply wrong Always ask yourself whether a claim is broadly plausible. Look at how the numbers were collected, interpreted and presented graphically.
  • There are three ways of calculating an average, and they often yield different numbers. People with statistical acumen usually avoid the word average in favour of the more precise:
  1. Mean: add up all the observations or reports and divide by the number of observations or reports.
  2. Median: the middle number in a set of numbers (half of the observations are above it, and half below)
  3. Mode: the value that occurs most often.
  • Many graphs mislead and distort with a variety of tricks, including not labelling the axes, truncating the vertical axis, and messing around with scale. They can be made to tell almost any story.
  • How numbers are collected is essential to whether they tell an accurate story. The sample size is vital (too small and the results are invalid), samples can be biased to reflect certain groups with certain views and may be subject to participation bias in which those inclined to participate are more inclined to certain opinions. There is also measurement error, lack of standardization, and vague definitions or categories. On top of all that there are some things that are simply unknowable or unverifiable.


  • When seeing information, always ask: Who is behind it?
  • When evaluating a claim or argument, ask yourself if there is another reason. What has been overlooked? Which information is undervalued? What are the alternative explanations?
  • Counterknowledge, coined by journalist Damian Thompson, is misinformation packaged to look like fact that some critical mass of people has begun to believe. Its spread is helped by the intrigue of imagining what if it were true? Adding a few true elements to an otherwise incorrect piece adds to the deception.
  • We can clarify Donald Rumsfeld’s 4 possibilities like this:
  • What we know that we know: good – put it in the bank
  • What we know that we don’t know: not bad, we can learn it
  • What we don’t know that we know: a bonus
  • What we don’t know that we don’t know: danger – hidden shoals


  • There is a lot of detail that will probably be skipped by the lay reader.