3. Different types of study designs

3.2 Analytical Studies

a. Case-control studies:

  • Case-control studies: The study subjects have a condition. The controls do not. Risk factors and past exposures are then examined, and the resulting frequencies between the subjects and the controls are compared. Such studies are retrospective and, as such, have certain biases (e.g. a recall bias). They are well adapted for the study of rare conditions.
  • Cohort studies :Study subjects are selected according to their exposure to certain risk factors, and are followed for a set amount of time to measure the consequences of this exposure.