In the pyramid of causal evidence, are non-controlled experimental studies considered higher or lower than observational studies?

• A. Higher
• B. Lower
• C. The same
• D. Not part of the pyramid

Answer: (A)

In the pyramid of causal evidence, designs that involve an intervention—even without a concurrent control group—are positioned above purely observational studies because they introduce deliberate exposure and a clear temporal sequence. This setup provides a more direct test of cause and effect than simply watching and measuring associations, since the investigator controls the timing and presence of the exposure, which helps distinguish the effect of the intervention from other factors. For example, evaluating outcomes before and after implementing a new protocol within the same population shows whether the change coincides with the intervention, offering stronger causal signals than a cross-sectional or cohort study that observes exposures without manipulation. Of course, the absence of a control group limits the strength of causal inference and leaves room for confounding or secular trends, but the experimental element still places non-controlled experiments higher than observational study designs.