Select True or False from each pull-down menu, depending on whether the corresponding statement is true or false.

? True False  1. A political analyst in Iowa surveys a random sample of registered Democrats and compares the results with those obtained from a random sample of registered Republicans. This is an example of two independent samples.

? True False  2. In comparing two means when samples are dependent, the variable under consideration is $\bar{x}_D$, where the subscript D refers to the difference.

? True False  3. Two samples of sizes 25 and 20 are independently drawn from two normal populations where the unknown population variances are assumed equal. The number of degrees of freedom of the equal-variances $t$ test statistic is 44.

? True False  4. The number of degrees of freedom associated with the $t$ test, when the data are gathered from a matched pairs experiment with 10 pairs, is 9.