3. Types of epidemiological studies

3.2 Analytic studies

Figure 7: The principle of cohort study

Figure 7: The principle of cohort study

3.2.1 Observational studies

B. Cohort studies

An observational study is conducted on 2 groups:

  • Group 1: exposed individuals

  • Group 2: non-exposed individuals

The 2 groups of individuals are observed for a certain period of time, after which the proportion of people who developed the illness in each group is calculated.