TOST Equivalence Test

The hypotheses for an equivalence test are


where and are the lower and upper bounds specified in the TOST option in the PROC TTEST statement, and is the analysis criterion (mean, mean ratio, or mean difference, depending on the analysis). Following the two one-sided tests (TOST) procedure of Schuirmann (1987), the equivalence test is conducted by performing two separate tests:




The overall -value is the larger of the two -values of those tests.

Rejection of in favor of at significance level occurs if and only if the confidence interval for is contained completely within . So, the confidence interval for is displayed in addition to the usual interval.

See Phillips (1990), Diletti, Hauschke, and Steinijans (1991), and Hauschke et al. (1999) for further discussion of equivalence testing for the designs supported in the TTEST procedure.