No. 251 · Evidence · Statistics and Probability
Randomised Controlled Experiments
Let chance decide who gets the treatment, and any difference left is the treatment’s doing.
In the Almanac
“The Salk vaccine trial”, 1954 · “Ctrip”, 2010–2011
Both stories in full, three ways to use it and where it misleads.
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Questions
What is Randomised Controlled Experiments?
Randomized Controlled Experiments split participants by chance into treatment and control groups, so hidden differences cancel out. The 1954 Salk polio trial involved about 1.8 million children, and Ctrip randomized staff by birthday to test working from home.
How do you use Randomised Controlled Experiments?
Use the idea in daily life by flipping a coin to decide when to try a new habit, tracking the results, and comparing honestly. Randomization stops you fooling yourself, though some questions can't be ethically randomized and small tests can be noisy.
When does Randomised Controlled Experiments matter?
Randomised Controlled Experiments is one of the 68 mental models for evidence, the situations where you ask: Is this really true? Within that, it belongs to “Testing a claim”, alongside False Negative, False Positive and Falsification.
What is an example of Randomised Controlled Experiments?
Two stories show it at work: The Salk vaccine trial (1954) and Ctrip (2010–2011). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to Randomised Controlled Experiments?
A/B Testing, Confounding Factor and Placebo Effect. Randomised Controlled Experiments itself comes from statistics and probability.