What is the main limitation of observational studies compared to randomized trials?

The primary limitation of observational studies compared to randomized trials is that they cannot determine causation. Observational studies observe and analyze outcomes without any manipulation of variables, meaning that they can identify correlations or associations between factors but do not provide evidence that one factor directly causes another.

In a randomized trial, participants are assigned to different groups, and interventions are applied in a controlled manner, which allows researchers to observe the effects of the intervention directly on the outcomes. This design minimizes the influence of confounding variables and strengthens the ability to establish cause-and-effect relationships.

On the other hand, in observational studies, there may be numerous confounding factors that could influence the results, making it challenging to draw definitive conclusions about causation. Hence, the inability to establish a causal link significantly limits the conclusions that can be drawn from observational studies compared to the more robust findings achievable through randomized trials.