Oral contraceptives and myocardial infarction [new]. A cohort study was conducted to determine the effect oforalcontractive use on heart disease risk in 40- to 44-year old women (fictitious data). This study found 13 new cases among 5000 OC users over 3-years of follow-up. In contrast, among 10,000 non-users, 7 developed a first myocardial infarct. [Data are fictitious but realistic.]

Using the data above,calculate the measurement.