Paper 3 · Module
Inference
The sample mean and the Central Limit Theorem
The mean of a random sample is itself a random variable. It is centred on , its spread shrinks like , and for large samples it is approximately normal whatever the population looks like.
≈ 35 minConfidence intervals
A single estimate is almost certainly a little wrong. A confidence interval gives a range, , built so that in, say, of samples the range would capture the true mean.
≈ 40 min