Sorry for messed up text. Here it goes again:
I am learning to use the gsDesign package.
I have a question about Pocock and OBF boundary. As far as I can understand,
these 2 boundaries require equal spacing between interim analyses (maybe this is
not correct?). But looks like I can still use gsDesign to run an analysis based
on unequal spacing:?> gsDesign(k=2,test.type=2,timing=c(0.75,1),alpha=0.05,sfu='Pocock')
Symmetric two-sided group sequential design with 90 %power and 5 % Type I
Error.Spending computations assume trial stops if a bound is crossed.? ? ? ? ?
Sample? ? ? ? ? Size? Analysis Ratio*? Z? Nominal p? Spend? ? ? ? 1? 0.796 1.82?
? 0.0346 0.0346? ? ? ? 2? 1.061 1.82? ? 0.0346 0.0154? ? Total? ? ? ? ? ? ? ? ?
? ? 0.0500?++alpha spending: Pocock boundary.*Sample size ratio compared to
fixed design with no interim?
Can anyone share some light whether the above analysis is still valid? Or for
unequal spacing, I have to use Lan-Demet?s error spending function
approximations? Thank you,
From: Berend Hasselman <bhh at xs4all.nl>
To: array chip <arrayprofile at yahoo.com>
Cc: R-help Mailing List <r-help at r-project.org>
Sent: Friday, September 22, 2017 11:46 PM
Subject: Re: [R] gsDesign Pocock & OBF boundary
> On 23 Sep 2017, at 01:32, array chip via R-help <r-help at
r-project.org> wrote:
>
> Hi,
>
> I am learning to use your gsDesign package! I have a question about Pocock
and OBF boundary. As far as Iunderstand, these 2 boundaries require equal
spacing between interim analyses(maybe this is not correct?). But I can still
use gsDesign to run an analysisbased on unequal spacing:
gsDesign(k=2,test.type=2,timing=c(0.75,1),alpha=0.05,sfu='Pocock')Symmetrictwo-sided
group sequential design with90 %power and 5 % Type I Error.Spendingcomputations
assume trial stops if a bound is crossed.? ? ? ? ? Sample? ? ? ? ? Size?
AnalysisRatio*? Z? Nominal p? Spend? ? ? ? 1? 0.796 1.82? ? 0.0346 0.0346? ? ? ?
2? 1.061 1.82? ? 0.0346 0.0154? ? Total? ? ? ? ? ? ? ? ? ? ? 0.0500? ++alpha
spending:Pocockboundary.*Sample size ratio compared to fixed design with no
interim Can anyone share some light whether the above analysis is stillvalid? Or
for unequal spacing, I have to use Lan-Demet?s error spendingfunction
approximations? Thank you,
> ??? [[alternative HTML version deleted]]
>
Your example code is a complete mess.
Do NOT post in html. This is a plain text mailing list.
Read the Posting Guide (https://www.r-project.org/posting-guide.html).
Berend Hasselman]
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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