Key Concepts

• A test of a single variance can be a one-tail test or a two-tail test.
• The degrees of freedom for the test of a single variance is $n-1$.
• The test statistic is $\frac{(n-1)s^2}{\sigma ^2}$.

Glossary

Standard Deviation: A number that is equal to the square root of the variance and measures how far data values are from their mean; notation: $s$ for sample standard deviation and $\sigma$ for population standard deviation.