R help - Sep 2004 - Case-Cohort Analysis

Hi All,
I am in the middle of doing an analysis of a Case-Cohort design. I had three
questions about the analysis:

a) Does any one know of some public code for developing the patient risk sets
(indexed by failure time) or is there a better way to organize the data?

b) I was planning to use the Barlow weighting method. Has this or any other
weighting method (Prentice, Self-Prentice) been implemented in R?

c) Is matching a good thing to do or can the variables that would be used for
matching just be adjusted for in the cox regression (is there a reference for
this because I can??t find one)?  If matching is a good thing to do are there
any R packages that contain matching functions?

Thanks for your help.
Peter Tait

On Wed, 8 Sep 2004 petertait at sympatico.ca wrote:
> Hi All, I am in the middle of doing an analysis of a Case-Cohort design. 
> I had three questions about the analysis:
I would suggest Mayo Clinic tech report #62
http://www.mayo.edu/hsr/techrpt.html
62: Computing the Cox Model for Case Cohort Designs
Prentice proposed a case-cohort design as an efficient  subsampling 
mechanism for survival studies. Several other  authors have expanded on 
these ideas to create a family of  related sampling plans, along with 
estimators for the  covariate effects. We describe how to obtain the 
proposed  parameter estimates and their variance estimates using  standard 
software packages, with SAS and S-Plus as  particular examples.

 	-thomas

>
> a) Does any one know of some public code for developing the patient risk
sets (indexed by failure time) or is there a better way to organize the data?
>
> b) I was planning to use the Barlow weighting method. Has this or any other
weighting method (Prentice, Self-Prentice) been implemented in R?
>
> c) Is matching a good thing to do or can the variables that would be used
for matching just be adjusted for in the cox regression (is there a reference
for this because I can?t find one)?  If matching is a good thing to do are there
any R packages that contain matching functions?
>
> Thanks for your help.
> Peter Tait
>
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Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle