What are the benefits of a randomized control trial?

• A. Can make the strongest causal inference; Can control confounding/extraneous variables
• B. It is inexpensive and quick
• C. It has perfect external validity
• D. It cannot determine causality

Answer: (A)

Randomized controlled trials provide strong causal inference because random assignment tends to balance both known and unknown confounding factors across the intervention and control groups. This balance means that differences in outcomes are more likely due to the intervention itself rather than preexisting differences between participants. The control condition provides a baseline for comparison, and standardized procedures help reduce variation and biases, making the estimated effect more trustworthy. Blinding, when used, further minimizes expectancy effects from participants and researchers.

They aren’t typically inexpensive or quick, as recruitment and follow-up can be time-consuming and costly. External validity isn’t guaranteed either; highly controlled settings and selective samples can limit how well results generalize to broader clinical populations. And the primary strength of randomized trials is their ability to determine causality, not to address every other type of research question.