R help - Sep 2011 - Sample Size Calculation using a Drop the Loser/Keep the Winner Design

Hello Everyone,
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I need to perform a sample size calculation using a drop the loser/keep the
winner design. I've been searching for examples of how to do this using R
but haven't found much.
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The most promising possibility thus far is an R?function called DrpLsrNRst. This
appears in the book "Adaptive Design Theory and Implementation Using SAS
and R". I found the function online?but there's a copyright statement
saying it can only be used by those who have purchased the book.
?
I thought about purchasing the book, but a reviewer on Amazon indicated
it's?mostly?a SAS book with a little R code thrown in and an examination of
the TOC suggests this is the case. I'm still primarily a SAS user, but am in
the process of changing that. So I'm shying away from purchasing what I
perceive to be a SAS book unless it's really necessary.
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Does anyone know of any other resources? 
?
Thanks,
?
Paul
?
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