This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
All of the following statements regarding case control study are true, except 
Select and explain. 
A. Used to find the relative risk, B. Odds ratio can be calculated, C. Relatively cheap, D. Used for rare diseases
A: Used to find the relative risk
Answer: A: Used to find the relative risk 
Explanation: Using case control study only odds ratio can be calculated. Incidence rates, relative risk and attributable risk can be calculated using coho study. Case control study is inexpensive, easy to carry out, used to investigate rare diseases, used to identify risk factors, allows study of different etiological factors and is associated with minimal ethical problems. Reference: Parks Textbook of Preventive And Social Medicine 20th edition, page 70.