search for: seqtrial

...o Everyone,   I’m a SAS user who has recently become interested in sequential clinical trials designs. I’ve discovered that the SAS based approaches for these designs are either too costly or are “experimental.” So now I’m looking for alternative software. Two programs that seem promising are SPLUS Seqtrial and R.   I recently obtained a 30 day trial for the SPLUS Seqtrial add-on and have worked my way through most of the examples in the manual. I’ve also gotten access to R, installed a package called gsDesign, and worked through most of the examples in its documentation.   Although I don’t yet have...

...ing my way through Whitehead's book to understand his procedures for the distribution of the total number of patients included (which is a random variable) and the final analysis (after study termination). 4) It has been suggested that I contact Scott Emerson, author of an S package called seqTrials. Does someone has an address for him ? I'll start implementing the simple stuff, trying to create a framework flexible enough to allow generalization. I'll probably plea for help at some time in the future ... However, don't hold your breath : I'm doing this in my spare time, o...

...ach, 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 functions and, most of all, power calculations. All I could find were announcements of courses or postings related to the S-Plus SeqTrial module. No code. Can anyone give a hint? Many thanks in advance, Marc -- Jetzt ein- oder umsteigen und USB-Speicheruhr als Pr?mie sichern!

...pective? 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, and I suspect that the reasons are not purely economic. I can think of a few advantages of Splus: 1. SeqTrial (of course that means more $) 2. Tech support 3. The warm fuzzies that management seems to get from proprietary software I can also think of a few advantages of R: 1. Based on my personal experiences, simulations requiring a lot of looping seem to run faster. 2. R interfaces with BUGS, for example...

[my original message to s-news & r-help is attached ] No one possessed or knew of any S/R code for the sequential t-test. Also it doesn't appear in the SAS index. One or two suggested obtaining the S+ seqtrial software which may (or may not) cover this, but this seemed to be a bit of a "hammer to crack a nut". I have written a function based on the treatment in Wetheril and Glazebrook 'Sequential Methods in Statistics', which seems to reproduce the published tables OK (eg, table...