MEPX
Chapter 2 of 10All chapters
  1. 1What correlation measures
  2. 2The five explanations
  3. 3Confounders
  4. 4Experiments
  5. 5Natural experiments
  6. 6Weighing causal evidence
  7. 7Selection effects
  8. 8Regression to the mean
  9. 9Language and reporting
  10. 10Acting under uncertainty

Chapter 2 of 10

The five explanations

A checklist before concluding.

Run through them

A causes B. B causes A. A third factor causes both. Selection decided who is in the data. Or it is chance. Only after eliminating four is the fifth a candidate.

  • Write them out explicitly; the discipline is in not skipping any.
  • Most published overclaims skip the third and fourth.

Plausibility is not evidence

A convincing mechanism makes a causal story easier to believe and does not make it true. Many plausible mechanisms have turned out to run the other way.