1. Which of the following experiments uses independent samples?

a. You want to compare the depression levels of teenage girls before and after attending a weeklong camp focused on improving self-image. So you compare the mean Hamilton depression scores of a randomly selected group of teenage girls before and after they attend a weeklong camp focused on improving self-image.

b. You want to compare the mean SAT score of a randomly selected group of students who took a new SAT preparation course to the national average SAT score.

c. You want to compare the mean SAT score of students who take a new SAT preparation course to that of students who don't take an SAT preparation course. So you compare the mean SAT score of a randomly selected group of students who took a new SAT preparation course to the mean SAT score of a randomly selected group of students who didn't take an SAT preparation course.

2. Which of the following null hypotheses is appropriate for an independent-measures t test?

a. H: =

b. H: 6

c. H: = 0

d. H:

3. According to the theory of stereotype threat,situational pressures can lead to decreased performance on tests of cognitive abilities. Joshua Aronson tested how Caucasian engineering students performed on a math test when placed under a form of situational pressure by randomly assigning 100 of these students to either the control or experimental groups. The control group was told that they were taking a test of general math ability. Members of the experimental group were presented with several news articles discussing the increasing difference in math scores between Asian and Caucasian students and were told that the purpose of the test was to explore these differences.

Would it be valid for Dr. Aronson to use the independent-measures t testto test whether drawing attention to stereotypes about racial groups and math ability affects math scores?

a. No, because the two groups studied are not independent.

b. No, because the two populations from which the samples are selected are not normally distributed.

c. No, because the variances within the two samples are different.

d. Yes, because the sample size is large and there is no reason to believe the assumptions of the independent-measures t test are violated.