What are the limitations of a randomized control trial?

What are the limitations of a randomized control trial?

• A. Artificial—lacking external validity; Expensive/resource heavy
• B. Ethical concerns prevent any manipulation
• C. Always small sample
• D. No control over confounding

Answer: (A)

Randomized controlled trials maximize internal validity by randomly assigning participants to the intervention or comparison, which helps balance confounding factors. But they often lack external validity because the study settings are controlled and participants are selectively chosen, making it hard to generalize to real-world clinical populations. They are also expensive and resource-intensive due to recruitment, follow-up, and stringent procedures. The other statements don’t fit: ethical safeguards do not stop all manipulation, and many RCTs proceed with appropriate ethics oversight; trial sizes vary widely, so they are not inherently small; and randomization is specifically used to control confounding, not to leave it unaddressed.

Randomized controlled trials maximize internal validity by randomly assigning participants to the intervention or comparison, which helps balance confounding factors. But they often lack external validity because the study settings are controlled and participants are selectively chosen, making it hard to generalize to real-world clinical populations. They are also expensive and resource-intensive due to recruitment, follow-up, and stringent procedures. The other statements don’t fit: ethical safeguards do not stop all manipulation, and many RCTs proceed with appropriate ethics oversight; trial sizes vary widely, so they are not inherently small; and randomization is specifically used to control confounding, not to leave it unaddressed.