A case control study is not characterized by-
.<p>in case of a case control study ,we cannot measure incidence,and can only estimate the relative risk.and it doesnot distinguish between causes and associated factors.and it is also not suited to the evaluation of therapy or prophylaxis of disease.selectin of an appropriate control group may be difficult.</p><p>ref;parks textbook,22 nd ed,pg no 71</p>
Cases with the disease are compared to controls without the disease
Assessment of past exposure may be blased
Definition of cases may be difficult
Incidence rates may be computed directly
Epidemiology