Video: Randomised Experiments [5:24]

The gold-standard of making fair comparisons so that we can infer cause-and-effect is the randomised experiment. We’ll introduce you to standard practice for setting up an experiment and show you how large random variation can be.

(See also the Review Questions following the movie)

[Illustrated transcript (pdf)]

After you’ve watched this video, you should be able to answer these questions:

• Why do we want to do randomised experiments? What is the point of them?
• What are the two elements we need to have in place to be able to have a fair test?
• What are treatments?
• What is a treatment group?
• What is the point of random assignment to treatment groups?
• What is the point of random assignment to treatment groups?
• Why is it unethical to do some experiments?
• What does blocking mean? What principle governs the use of blocking and randomisation in designing an experiment?