[R] gsDesign Pocock & OBF boundary

[array chip]

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,
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> 

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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