Evidence-appraisal glossary
Superiority trial
A trial designed to detect whether one treatment is better than a comparator, such as another drug or a placebo. Its goal is to show a difference in favor of the new treatment.
Also called: superiority design.
Most randomized trials are superiority trials: they start from the assumption of no difference and look for evidence that the new treatment beats the comparison on the chosen outcome. A common misreading is to treat a superiority trial that fails to reach significance as proof the treatments are equal; it is not, because failing to find a difference is not the same as showing there is none. Demonstrating similarity requires a non-inferiority or equivalence design with a pre-specified margin.
Read the full Reading the Evidence blog.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.