This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
In a study 400 smokers and 600 non-smokers were followed up over a period oflO years to find out the incidence of hypertension. The following table summarizes the data at the end of the study: Hypertension YesNoTotalSmokingYes120280400 No30570600 Total1508501000Calculate the risk ratio in this study is: 
Select and explain. 
A. 0.06, B. 0.6, C. 6, D. 60
C: 6
Answer: C: 6 
Explanation: Answer: C. 6. (Ref Park's Textbook of PSM 22nd/Pg.75)# Incidence in exposed (smoker) is = 120/400= 0.3# Incidence in non exposed (non-smoker) = 30/600= 0.05# Risk ratio (Relative Risk) = Incidence in exposed/ Incidence in non exposed = 0.3/0.05 = 6# RR is direct measure of strength of association. RR=1 means no association. RR > 1 means positive association.