similar to: Adaptive survival design

I have been trying to create code to calculate the power for an adaptive design with a survival endpoint according to the method of Schafer and Muller ('Modification of the sample size and the schedule of interim analyses in survival trials based on interim inspections,' Stats in Med, 2001). This design allows for the sample size to be increased (if necessary) based on an interim look at

A few months ago, I posted a query regarding code for a sample size estimate for a one arm survival trial. Below is some code I created to calculate such an estimate - perhaps it may be of some use. #cox.pow computes sample size for a one arm survival trial. med.0 is the null median #survival, med.a is the alternative median survival, a.time is the accrual time, and #f.time is the follow up

Following up to some extent on Friday's discussion regarding the 'validation' of R, could I ask the list group's opinion on possible advantages of R over Splus from a pharma/devices perspective? I wish to exclude the obvious price difference, which doesn’t seem to carry as much weight as I would have thought. Besides, I have noticed many former Splus users gravitating towards R,

I would like to use R for submissions to FDA/CDRH (the medical device company I work for currently uses only SAS). Previous postings to the list regarding R and 21 CFR 11 compliance have been very helpful. However, reluctance to using open source software for statistical analyses and reporting remains high here at my company. Has anyone used R for an official submission to FDA/CDRH? It would

Does anyone know of a function that computes the necessary sample size to reject a null median survival in favor of a given alternative median survival in a one arm trial? Cody Hamilton, Ph.D Institute for Health Care Research and Improvement Baylor Health Care System (214) 265-3618 This e-mail, facsimile, or letter and any files or attachments transmitted with it contains information

I am running R version 2.4.1 on Windows XP. I have a question regarding the datadist() function from the Design library. I have a data.frame (call it my.data) with 4 columns. When I submit the code datadist(data=my.data) I get the following error message: Error in X[[1]] : subscript out of bounds I suspect there may be something wrong with my data.frame (I'm certain there is nothing

Hello, I'm wondering what's the best way to analyse an unbalanced design with a low number of replicates. I'm not a statistician, and I'm looking for some direction for this problem. I've a 2 factor design: Factor batch with 3 levels, and factor dose within each batch with 5 levels. Dose level 1 in batch one is replicated 4 times, level 3 is replicated only 2 times. all

Hi all, The survivals functions can be tested by the Log-rank test and others, for example the Gehan-Breslow. The graham breslow work with the alpha values. But I don't know how is the Gehan-Breslow test with R. Somebody know a type function?.. or other suggestions? Any help will be really appreciated Jos? Bustos Marine Biologist Master Apllied Stat Program University of Concepci?n

Dear Tim Schafer, Take a look at my sample dovecot-ldap.conf hosts = localhost dn = cn=root,dc=ceylonlinux,dc=com dnpass = secret ldap_version = 3 base = dc=ceylonlinux,dc=com deref = never scope = subtree user_attrs = mail,homeDirectory=mailMessageStore,uidNumber=1003,gidNumber=1003 user_filter = (&(objectClass=user)(mail=%u)) pass_attrs = mail=user,userPassword=password pass_filter =

Dear all, I used cph() function from Frank harrell's Design package to create a survival model, then used functions 'Function' and 'sascode' to generate prediction equation based on the saved survival model. But it failed. I included a stratified variable in the model. If I removed the stratification, they were working well. Does that mean that function 'Function'

Does anyone know if for clinical studies the FDA would accept statistical analyses performed with R ? Delphine Fontaine

Dear r-users, Does anyone know how to draw time-dependent survival curves? Example: Event outcome: CHD Time-dependent covariate: NSAID use, which changes over time for each subject I'm interested in survival curves stratified by NSAID use. I'd like to implement Simon & Makuch (1984) method. Is there a R package/function to draw this graph?

Ooops, this didn't go to the list -------- Original Message -------- Subject: Re: [Dovecot] Supporting local and virtual LDAP users, with seperate mail_env Date: Thu, 17 Aug 2006 11:33:51 -0700 From: Tim Schafer <tim_schafer at shipfsp.com> To: Timo Sirainen <tss at iki.fi> References: <44E4A543.3070100 at shipfsp.com> <1155837188.9142.8.camel at hurina>

Great news! Having spent a significant amount of time porting/mantaining some packages on S4/Splus 5.x and R, I'm interested in your experience as you port Hmisc and Design; I'd like to know of your progress in order to help improve available R/Splus portability tools both at the C and the S language code. These tools include the package SLanguage written by John Chambers, and

Hello R users, I am looking for R (or S) code related to group sequential or adaptive designs for clinical trials. (The most prominent examples are the designs of Pocock or O'Brien/Fleming, the alpha-spending function approach, or Fisher's combination test and the inverse normal method.) I am particularly interested in the calculation of the critical boundaries, the handling of spending

Hello, I am using Dr. Harrell's design package to make a nomogram. I was able to make a beautiful one without stratifying, however, I will need to stratify to meet PH assumptions. This is where I go wrong, but I'm not sure where. Non-Stratified Nomogram:

After several nice and informative discussions with Bill Venables, Duncan Temple Lang, Tony Rossini, Martin Maechler, and Robert Gentleman, I am pleased to announce that I am becoming an R user and have begun porting the Hmisc and Design libraries to R. I have been very impressed with the maturity of R and with its logical design, particularly its online documentation setup and the way packages

After several nice and informative discussions with Bill Venables, Duncan Temple Lang, Tony Rossini, Martin Maechler, and Robert Gentleman, I am pleased to announce that I am becoming an R user and have begun porting the Hmisc and Design libraries to R. I have been very impressed with the maturity of R and with its logical design, particularly its online documentation setup and the way packages

R core team - It took far, far longer than I anticipated, but I have finally finished the next release of the survival code. Primary changes 1. The source has been migrated to Rforge. This will now be the primary source. I've used SCCS -> rcs -> cvs and now svn. Further changes will be someone else's problem. I expect that maintaince will now begin to migrate to a larger

Hi, I am trying to calculate net reclassification improvement (NRI) and Inegrated Discrimination Improvement (IDI) for a survival dataset to compare 2 risk models. It seems that the improveProb() in Hmisc package does this only for binary outcome, while rcorrp.cens() does take survival object, but doesn't output NRI or IDI. Can anyone suggest any other packages that can calculate NRI and IDI