8.2.8) Researchers Jemmott III et al. (Journal of American Medical Association, 1998) reported a study in which a group of inner-city African American adolescents from Philadelphia were randomly divided into three groups as part of an experiment to assess the effectiveness of different HIV prevention programs. One group was given "abstinence HIV intervention," the next group was given "safer-sex HIV intervention," and the third group was given "health promotion intervention," which was to serve as a control. One outcome that was measured was whether subjects who were sexually active during a three-month period reported consistent condom use. The Exercise 8.2.8A table shows the summarized data.

A. Is this an experiment or an observational study? How are you deciding?

b. Identify the observational units.

c. Identify the explanatory and response variables. Also, for each variable, identify whether it is categorical or quantitative.

d. Define the parameters of interest. Assign symbols to these parameters.

e. State the appropriate null and alternative hypotheses.

f. Find the table of expected cell counts; that is, complete the Exercise 8.2.8B table, assuming the null hypothesis is true.

g. Describe how one might use everyday items (e.g., coins, dice, cards, etc.) to conduct a tactile simulation-based test of the hypotheses. Be sure to clearly describe how the p-value will be computed from the simulation.

8.2.13) In a study of the relationship between sleep apnea and hypertension (New England Journal of Medicine, 2000), researchers Peppard et al. categorized the participants by the severity of sleep apnea at the beginning of the study, and four years later recorded whether the participant had hypertension. Here is the table of the summarized data:

Severity of sleep apnea Total Not Somewhat Severe Very Severe Yes 32 142 63 40 277 hypertension? No 155 365 69 27 616 Total 187 507 132 67 893