February, 2003
© 2000, 2001 Scott S. Emerson, M.D., Ph.D.
Common features
Stopping
rule specified at design parameterizes the boundary for some statistic
(boundary scale)
At the
first interim analysis, parametric form is used to compute the boundary
for actual time on study
At
successive analyses, the boundaries are recomputed accounting for the
exact boundaries used at previously conducted analyses
Maximal sample size
estimates may be updated