Chapters1. Introduction2. The principles of experimentation, illustrated by a psycho-physical experiment3. A historical experiment on growth rate4. An agricultural experiment in randomised blocks5. The latin square6. The factorial design in experimentation7. Confounding8. Special cases of partial confounding9. The increase of precision by concomitant measurements. Statistical Control10. The generalisation of null hypotheses. Fiducial probability11. The measurement of amount of information in general