## Lesson 17, The Difference Between Two Population Means, Summary Notes

For Lesson 17 here are some summary notes, Lesson 17 Summary Notes.

## Exam Three is Tuesday

The Exam Three is Tuesday, November 12, at 2pm, in 313 CLB.  The summary page that was shown in class during the exam review is here, Summary Page Inferences on Mean and Proportion.    Best on the TEST!

## Z and t hypothesis tests and confidence intervals

The detailed class notes that we viewed in class are here:   Class Notes Z test and t test, with CI equations .

## Compare the Z and t distributions

Lesson 14 covers Inferences on the Population Mean when the Population Standard Deviation is known.  The resulting hypothesis test and confidence interval are based on the Z-distribution, also called the Standard Normal Distribution. Lesson 15 covers Inference on the Population Mean when the Population Standard Deviation is unknown.   The sample standard deviation, S, will be used as an estimator for sigma, the population standard deviation, but when that occurs the test statistic is not Z, but t and the confidence interval form is also based on t, not Z.   Here are some details, Class Notes Z test and t test, with CI equations .