February, 2003
© 2000, 2001, 2003 Scott S. Emerson, M.D., Ph.D.
Because a stopping rule changes the sampling distribution,
the use of a stopping rule should change the computation of
those design operating characteristics based on the sampling
density.
Type 1 error (size of test)
·Probability of incorrectly rejecting the null hypothesis
Power (1 - type II error)
·Probability of rejecting the null hypothesis
·Varies with the true value of the measure of treatment
effect