Superiority, Non-inferiority, Equivalence Test, and Innovative Equivalence Test

Abstract

In pharmaceutical and medical studies, randomized controlled trials (RCTs) aim to prove that a new treatment has better or superior efficacy than standard treatment or placebo. In fact, RCTs can also be used to evaluate the efficacy of a new treatment 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. However, the equivalence trials are another efficacy that RCTs would like to know sometimes. The purposes of this article are 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 and also introduce an innovative equivalence test calls 2-df for shift-scale equivalence test.