February, 2003
© 2000, 2001 Scott S. Emerson, M.D., Ph.D.
Need
methods that allow flexibility in determining number and timing of
analyses
Should
maintain some (but not, in general, all) desired operating
characteristics, e.g.:
·Type I
error
·Type II
error
·Maximal
sample size
·Futility
properties
·Bayesian
properties