Cohort studies refers to observational studies. These studies
are based on chronological order and successfully describe the
history of any particular condition. These studies have two
designs- Prospective cohort and retrospective cohort. Based on
these designs two groups can be identified in Cohort studies, they
are-
- Internal group design- This group includes the
unexposed members of a particular cohort study. It is reffered as
one of the best groups because comparison is possible between
subjects within this group.
- External group or exposed group- The exposed
group of cohort studies is used when we need a well explained
cohort and there is a requirement to divide it in to exposed group.
The main purpose of this group is to look at the external exposure
of any cohort study which is not possible with the help of internal
comparison group.