A clinical trial with an interim analysis.
We consider a fixed-sample parallel-group clinical trial with an interim analysis that tests H0:mu x = mu y against H1:mu x less than mu y. If we do not reject at the interim analysis, then the probability of making a type I error by rejecting H0 in favour of H2:mu x greater than mu y and the power at the final analysis are not appreciably affected by performing the interim analysis for certain relevant critical regions.
D001699:Biometry; D002986:Clinical Trials as Topic / Q000379:methods*; D006801:Humans