On Fri, 16 Jun 2000 15:03:32 +0200, Bernd Genser
<[EMAIL PROTECTED]> wrote:
> Does anybody know how to calculate the sample size needed to prove
> EQUIVALENCE, not difference of two treatments concerning survival data
> (log-rank test, cox regression).
"Bio-equivalence" might be as close as you will come if you try to
look up keywords. You might find a discussion in Deja News, from a
few months back.
http://www.fda.gov/cder/guidance/1716dft.pdf
- is the Adobe-Acrobat version of a draft document on
"bioequivalence" as it should be used in federal documents such as the
request for approval of a substitute version of a drug.
There are three different ideas discussed. But the simple notion is
that you demonstrate, typically, that all of the 95% Confidence
Interval for drug B is greater than 80% of the point estimate for A
("survival rate"?), and less than 125% of the point estimate for A.
Two one-tailed tests must be performed. The means for A and B must be
pretty close together, and the sampling must be large enough that you
get a pretty narrow CI -- so that all the CI will fall within that
80-125 range.
... "demonstrate practical equivalence" must be more accurate than
saying "prove equivalence."
You will link to an index to a larger list of documents when you
remove the 1716dft.pdf from the URL, above.
--
Rich Ulrich, [EMAIL PROTECTED]
http://www.pitt.edu/~wpilib/index.html
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