A. Cohort study – Explanation
A cohort study would provide more robust evidence than a case-control study.
Study design
The following table highlights the main features of the main types of study:
| Randomized Controlled Trial | Participants are randomly allocated to either an intervention or a control group (e.g., standard treatment or placebo). Practical or ethical problems may limit use. |
| Cohort Study | Observational and prospective. Groups are selected based on their exposure to a particular agent (e.g., medicine, toxin) and followed to see disease outcomes. The usual outcome measure is relative risk. Examples include the Framingham Heart Study. |
| Case-Control Study | Observational and retrospective. Patients with a specific condition (cases) are matched with controls, and data on past exposure to a possible causal agent is collected. The usual outcome measure is odds ratio. This method is inexpensive, produces quick results, and is useful for studying rare conditions, but is prone to confounding. |
| Cross-Sectional Survey | Provides a ‘snapshot’ of a population at a single point in time, often called prevalence studies. This method provides weak evidence of cause and effect. |
