Key Concepts

• The steps for performing a hypothesis test for two population means with known standard deviation are generally the same as the steps for conducting a hypothesis test for one population mean with known standard deviation, using a z-distribution.
• It is recommended that calculations for the test statistic and degrees of freedom be done using technology.
• The sampling distribution for the difference between the means is normal and both populations must be normal.

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 σ for population standard deviation.