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? Thank you, John
> On Feb 13, 2018, at 4:02 PM, array chip via R-help <r-help at 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 = [S?(tj)]^? 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. -- David Winsemius Alameda, CA, USA 'Any technology distinguishable from magic is insufficiently advanced.' -Gehm's Corollary to Clarke's Third Law
> On Feb 14, 2018, at 5:26 PM, David Winsemius <dwinsemius at comcast.net> wrote: > >> >> On Feb 13, 2018, at 4:02 PM, array chip via R-help <r-help at 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 = [S?(tj)]^? > > 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 LawDavid Winsemius Alameda, CA, USA 'Any technology distinguishable from magic is insufficiently advanced.' -Gehm's Corollary to Clarke's Third Law