Principles of Superiority, Equivalence and Non-inferiority trials

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Panuwat Pensawangwat


Normally, randomized controlled trials (RCTs) aim to prove that a new drug has better or superior efficacy than standard treatment or placebo. In fact, RCTs can also be used to evaluate the efficacy of a new drug having similar or equivalence efficacy, or not worse or non-inferior efficacy depending on the objectives of the research. Meanwhile, the non-inferiority trials are more frequently found in research. The aim of this article is to provide a basic understanding for readers about the distinctions among the types of research, statistical hypothesis testing, the interpretation of hypothesis testing as well as the differences between statistical significance and clinical significance.


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