Objectives Test the difference between two large sample means using the z test. Test the difference between two variances or standard deviations. Objectives (cont'd.) Test the difference between two means for small independent samples. Test the difference between two means for small dependent samples. Test the difference between two proportions. The Difference Between Two Means Assumptions for the test to determine the difference between two means: The samples must be independent of each other; that …showed first 75 words of 1373 total…

…showed last 75 words of 1373 total…the variances are not know or one or both sample sizes are less than 30, then the t test must be used. For independent samples the F test must be used to determine whether or not the variances are equal. For dependent samples the dependent samples t test is used. A z test is used to compare two proportions. Conclusions Special z and t tests allow researchers to compare population parameters, such as means or proportions.