Statistics & Probability
Advanced

Confidence Interval (Mean)

Range likely to contain the population mean.

Formula

xˉ±zσn\bar{x} \pm z\frac{\sigma}{\sqrt{n}}

Variables

\bar{x}Sample mean
zCritical value

Example

95% CI uses z=1.96

Did You Know?

A 95% confidence interval does not mean 95% probability the mean is inside — a subtlety that trips up even scientists.

inference