Hypothesis testing for difference between two proportions.
Does lovastatin (a cholesterol-lowering drug) reduce the risk of heart attack? In a Texas study, researchers gave lovastatin to 2,325 people and an inactive substitute to 2,081 people (average age 58). After 5 years, 57 of lovastatin group had suffered a heart attack, compared with 97 for the inactive pill.
(a) Status the appropriate hypotheses.
(b) Obtain a test statistic and p-value. Interpret the results at _ = .01.
(c) Is normality assured?
(d) Is the difference large sufficient to be important?
(e) What else would medical researchers need to know before prescribing this drug widely?