Reviewers from the Oregon Evidence-Based Practice Center at the Oregon Health and Science University investigated the effectiveness of prescription drugs in assisting people to fall asleep and stay asleep (source:

S. Carson, M.S. McDonagh, et al., “Drug class review:

Newer drugs for insomnia,” Oregon Health and Science University, 2008, http://www.ncbi.nlm.nih.gov). Suppose a study of two drugs, Sonata and Ambien, was conducted and the resulting data are contained in a file titled Shuteye. The samples reflect an experiment in which individuals were randomly given the two brands of pills on separate evenings. Their time spent sleeping was recorded for each of the brands of sleeping pills.

a. Does the experiment seem to have dependent or independent samples? Explain your reasoning.

b. Do the data indicate that there is a statistical difference in the mean time spent sleeping for people using the two drugs? Test using alpha = 0.05.

Conduct a statistical procedure to determine this.

c. Develop and interpret a 95% confidence interval for the difference in mean sleeping time for people using the two drugs.