Section 9.6 Summary

1. Under the assumption that is true, the statistic takes the following form:

   The hypothesis test about may be performed using the -value method or the critical-value method. Either way, the test is valid only if we have a random sample from a normal population. The critical-value method compares with one or two critical values.

2. The -value method compares the -value to the level of significance .

3. If we have a confidence interval for , of the form (lower bound, upper bound), and are interested in a two-tailed hypothesis test, using , of the form

   we will not reject for values of that lie between the lower bound and upper bound of the confidence interval. We will reject for values of that lie outside this interval.