Dear all,
Has anyone used the calculator for a "Gehan/Simon Two-Stage Design" that is
available on the website, http://biostat.hitchcock.org/BSR/ ?
If so, did you consider it valid? My calculations indicate that it gives
incorrect type I error rates but I have been known to be wrong (too
often).
I also generated a result for which the stopping rules indicated the trial
must stop after stage 1 but yet it produced calculations related to the
second stage. I'm reluctant to use my final results because of these
concerns.
Does anyone know of diferent calculator for a modified Simon method, where
the modification is to allow the trial to stop after the first stage and
conclude that the treatment is efficacious ?
At this stage I haven't been able to get a response from the people who run
the website above.
Thanks in advance,
Patrick
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