Thomas, thank you for pointing this out! On another note, do you think coxph() will also take offset(logweight) as part of the formula? Or just use the argument weight=logweight in coxph()?
Thanks! John ________________________________ From: Thomas Lumley <tlum...@uw.edu> Sent: Sun, February 27, 2011 12:14:25 PM Subject: Re: [R] nested case-control study clogit() takes offsets as part of the formula casestatus ~ predictor +strata(matchedset) +offset(logweight) -thomas > Hi, I am wondering if there is a package for doing conditional logistic > regression for nested case-control study as described in "Estimation of >absolute > risk from nested case-control data" by Langholz and Borgan (1997) where > Horvitz-Thompson sampling weight (log of (number in the risk set divided by the > number sampled)) is used with regression. In SAS Proc Phreg, this is >implemented > as an offset (offset=logweight). I checked clogistic() in Epi package and > clogit() in survival package, but couldn't figure out how to incorporate this > weighting with either. > > > Also when considering nested case-control sampling for Cox proportional hazards > model, the above method can estimate absolute risk of developing disease over a > specified time interval. Appreciate if anyone has any suggestion on how to do > this in R. > > Thanks very much! > > John > > > > [[alternative HTML version deleted]] > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > -- Thomas Lumley Professor of Biostatistics University of Auckland [[alternative HTML version deleted]]
______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
