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,
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