> On Feb 14, 2018, at 5:26 PM, David Winsemius <dwinsem...@comcast.net> wrote: > >> >> On Feb 13, 2018, at 4:02 PM, array chip via R-help <r-help@r-project.org> >> wrote: >> >> Hi all, >> >> The survdiff() from survival package has an argument "rho" that implements >> Fleming-Harrington weighted long rank test. >> >> But according to several sources including "survminer" package >> (https://cran.r-project.org/web/packages/survminer/vignettes/Specifiying_weights_in_log-rank_comparisons.html), >> Fleming-Harrington weighted log-rank test should have 2 parameters "p" and >> "q" to control the weighting for earlier vs later times in the follow-up. >> >> For example, setting rho=1 in survdiff() uses the Peto-Peto modification of >> Gehan-Wilcox weights, which I can confirm by setting p=1 & 1=0 in comp() >> from survminer package. similarly rho=0 is equivalent to p=0 & q=0 >> >> I am interested in putting more weights on survival difference in later >> follow-up time. According to comp() from survminer package, that would set >> p=0 & q=1 for Fleming-Harrington weights. >> >> My question is how I can do the same by setting certain values for "rho" in >> the regular survival() function? > > I think that survdiff uses a different version than what you have found. The > G-rho family weights are: > > w_j = [Sˆ(tj)]^ρ > > So rather than two parameters on S(t) and (1-S(t)) as in the p,q version, you > only have one parameter applied to S(t). This class handout says that the > G-rho,gamma weighting scheme is not available in survdiff. >
Forgot to paste the link: http://www.ics.uci.edu/~dgillen/STAT255/Handouts/lecture4.pdf > -- > David Winsemius > Alameda, CA, USA > > 'Any technology distinguishable from magic is insufficiently advanced.' > -Gehm's Corollary to Clarke's Third Law David Winsemius Alameda, CA, USA 'Any technology distinguishable from magic is insufficiently advanced.' -Gehm's Corollary to Clarke's Third Law ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
