Maurice Tutor
$15/per page/Negotiable
13.136 Xr13-140 Researchers at the University of Ohio sur- veyed 219 students and found that 148 had Facebook accounts. All students were asked for their current grade point average. Do the data allow us to infer that Facebook users have lower GPAs?
13.137 Xr13-141 Clinical depression is linked to several other diseases. Scientists at Johns Hopkins University undertook a study to determine whether heart disease is one of these. A group of 1,190 male medical students was tracked over a 40-year period. Of these, 132 had suffered clinically diagnosed depression. For each student, the scientists recorded whether the student died of a heart attack (code = 2) or did not (code = 1).
a. Can we infer at the 1% significance level that men who are clinically depressed are more likely to die from heart disease?
b. If the answer to part (a) is “yes,” can you inter- pret this to mean that depression causes heart disease? Explain.
Q720:
13.138 Xr13-142 High blood pressure (hypertension) is a leading cause of strokes. Medical researchers are constantly seeking ways to treat patients suffering from this condition. A specialist in hypertension claims that regular aerobic exercise can reduce high blood pressure just as successfully as drugs, with none of the adverse side effects. To test the claim, 50 patients who suffer from high blood pressure were chosen to participate in an experiment. For 60 days, half the sample exercised three times per week for 1 hour and did not take medication; the other half took the standard medication. The percentage reduction in blood pressure was recorded for each individual.
a. Can we conclude at the 1% significance level that exercise is more effective than medication in reducing hypertension?
b. Estimate with 95% confidence the difference in mean percentage reduction in blood pressure between drugs and exercise programs.
c. Check to ensure that the required condition(s) of the techniques used in parts (a) and (b) is sat- isfied.