Equivalence and non-inferiority testing in psychotherapy research

With more than 100 non-inferiority or equivalence trials published per year in many areas of research (Piaggio et al., 2012), statistical and methodological issues involved in these trials become increasingly important. A recent article by Rief and Hofmann (2018) suggests, however, that some of these issues are not sufficiently clear. For this reason, central issues will be discussed here and some misunderstandings will be addressed