Table 1 Pros and cons of randomized control trials and observational studies

Pros

• Random assignment makes study groups similar and comparable (no confounding at baseline)

• Best fit to establish the efficacy of pharmacologic interventions

• Currently considered as the gold standard for studying the effect of an intervention

• Based on clear and well-established guidelines

• Gives the true effect of an intervention under ideal conditions (internal validity)

• Useful to provide real-world evidence (external validity)

• Relatively fast and inexpensive to conduct when data is already available

• May take advantage of already available data like electronic health records

• Suitable for studies where randomization is not ethical, or not feasible (e.g. rare diseases)

Cons

• Can be costly and take many years to conduct

• Data collected may be biased due to non-compliance and drop-outs (post-randomization bias)

• Possible to overlook biases

• Generalizable only in simple systems, or when the conditions are exactly replicated

• Subject to outside factors that could distort the effect of the intervention (confounding)

• Can be complex to design

• Advanced analytical approaches are often required

• Subject to limitations in the data available