33. A clinical trial is run to investigate the effectiveness of an experimental drug in reducing preterm
delivery to a drug considered standard care and to a placebo. Pregnant women are enrolled and
randomly assigned to receive either the experimental drug, the standard drug or a placebo. Women are
followed through delivery and classified as delivering preterm (< 37 weeks) or not. The data are shown
Is there a statistically significant difference in the proportions of women delivering preterm among the
three treatment groups? Run the test at a 5% level of significance.
34. A study is run comparing HDL cholesterol levels between men who exercise regularly and those who
do not. The data are shown below.
Generate a 95% confidence interval for the difference in mean HDL levels between men who exercise
regularly and those who do not.
35. Suppose a hypertension trial is mounted and 18 participants are randomly assigned to one
of the comparison treatments. Each participant takes the assigned medication and his or her
systolic blood pressure is recorded after 6 months on the assigned treatment. The data are as