Analytical studies are further sub-types depending upon the study groups and time. Commonly used analytical studies are as follows:
- Cross-sectional study – Comparison group are not determined earlier because exposure and outcome both measure at the same time.
- Case control study – Comparison groups are selected according to outcome. Study subjects are then interviewed or their records are reviewed to determine any previous exposure tp the causal agent.
- Cohort study – Comparison groups are selected according to previous exposure to a suspected causal agent. Study subjects are then followed to determine their outcome.