In this paper, we examine the issue of testing for superiority or inferiority following the equivalence conclusion. We contrast this situation with that of testing for superiority after a noninferiority conclusion. We point out the fact that further testing is irrelevant in situations where the equivalence definition renders the inferred true treatment effect difference nonsignificant from the clinical perspective. Consequently, superiority in the presence of an accompanying equivalence definition has a meaning that is different from its traditional interpretation.
MakuchRWSimonR.Sample size requirements for evaluating a conservative therapy. Cancer Treat Report. 1978;62(7):1037–1040.
2.
DunnettCWGentM.An alternative to the use of two-sided tests in clinical trials. Stat Med.1996;15:1729–1738.
3.
MorikawaTYoshidaM.A useful testing strategy in phase III trials: Combined test of superiority and test of equivalence. J Biopharm Stat. 1995;5:297–306.
4.
HauckWWAndersonS.Some issues in the design and analysis of equivalence trials. Drug Inf J.1999;33:109–118.
5.
Committee for Proprietary Medicinal Products.Points to Consider on Biostatistical Issues Arising from Recent CPMP Discussions on Licensing Applications: Superiority, Non-inferiority and Equivalence. Draft. London: Committee on Proprietary Medicinal Products; September 23, 1999.
