MEPX
Chapter 1 of 10All chapters
  1. 1Samples and populations
  2. 2The central limit theorem
  3. 3Confidence intervals
  4. 4Hypothesis testing
  5. 5Multiple comparisons
  6. 6A/B testing
  7. 7Causal inference
  8. 8Regression
  9. 9A Bayesian view
  10. 10Reporting results

Chapter 1 of 10

Samples and populations

What you can claim.

The inference

You measure a sample and want to say something about a population. Everything that follows depends on how the sample was obtained, not on how large it is.

  • Random selection is what licenses the generalisation.
  • Logged product data is a sample of your users, not of people.

Sampling distribution

Repeat the sampling and the estimate varies. That variation, quantified as the standard error, is what confidence intervals and tests are built on.