Sample size for testing equivalence of two independent means

Equivalence is established if a two-sided 1-alpha confidence interval for the difference of two independent means is contained within the equivalence margin. This is equivalent to performing two one sided t-tests (TOST) at one-sided level alpha/2 to show that the difference is, both, smaller than the upper equivalence bound and greater than the lower equivalence bound.

Mean difference

Equivalence margin +/-