[R] gsDesign Pocock & OBF boundary

Berend Hasselman bhh at xs4all.nl
Sat Sep 23 08:46:15 CEST 2017

> 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.
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Berend Hasselman]

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