Equivalence in periodontal trials: a description for the clinician

There has been a tendency by clinicians in periodontal research to confuse lack of significance in a clinical trial designed for superiority for equivalence between the treatment arms. This paper is intended to define for the clinician what equivalency means in statistical terms. To demonstrate equivalence, the hypotheses and analysis specific to equivalence must be carried out; the information cannot be extracted directly from trials designed with superiority hypotheses and analysis. Further, acceptable mean differences in equivalency trials should be determined based not only on statistical considerations, but also on the clinical relevance of the proposed differences. The relationship between superiority and equivalency design and analysis is discussed and an example using a hypothetical clinical study is given.