G�ran Brostr�m <[EMAIL PROTECTED]> writes: > On Tue, Apr 20, 2004 at 10:01:36PM -0700, Deb Montgomery wrote: > > Hi. I am using Windows version of R 1.8.1. Being somewhat new to survival > > analysis, I am trying to compare cph (Design) with coxph (survival) for use > > with a survival data set. > > > > I was wondering why cph and coxph provide me with different confidence > > intervals > > for the hazard ratios for one of the variables. I was wondering if I am > > doing something wrong? Or if the two functions are calculating hazard ratios > > and the 95% confidence intervals differently? > > Yes, for 'Weight.at.age.4' you get differing parameter estimates (0.91 > versus 0.83). Want to know the correct answer? Try 'coxreg' in package > 'eha'! :-) > > More seriously, the difference may well be of numerical character, > different convergence criteria, "unbalanced" data, etc. It is really > impossible to say without knowing what your data are (and without looking > into the code of coxph and cph).
I'd sooner expect that there is a definition issue: The results given for Weight.at.age.4 are almost exactly the square root of those from cph. Perhaps the latter have been raised to the 1.9885th power since that appears to be the range of the variable. > > I have listed part of the code > > and part of the results from the 2 functions. Sorry if this question is a > > repeat, I didn't find it when I searched the archives. > > > > ########################################################### > > # s= Surv(Time1, Time2, censor) > > #f= coxph(s~ Siblings + Weight.at.age.4) > > #summary(f) > > #Call: > > #coxph(formula = s ~ Siblings + Weight.at.age.4) > > # n= 132 > > # exp(coef) exp(-coef) lower .95 upper .95 > > #Siblings 1.52 0.657 0.815 2.84 > > #Weight.at.age.4 0.91 1.099 0.772 1.07 > > ############################################################## > > #s= Surv(Time1, Time2, censor) > > #f= cph(s~ Siblings + Weight.at.age.4,surv=TRUE , x=T, y = T) > > # summary(f) > > # Effects Response : s > > # Factor Low High Diff. Effect S.E. Lower 0.95 Upper 0.95 > > # Siblings 0.000 1.000 1.0000 0.42 0.32 -0.20 1.04 > > # Hazard Ratio 0.000 1.000 1.0000 1.52 NA 0.82 2.84 > > # Weight.at.age.4 8.613 10.602 1.9885 -0.19 0.17 -0.51 0.14 > > # Hazard Ratio 8.613 10.602 1.9885 0.83 NA 0.60 1.15 > > > > > > Sincerely > > > > Deb Montgomery > > > > Department of Fisheries and Wildlife Resources > > University of Idaho > > Moscow, Idaho 83843 > > 208-885-4008 > > [EMAIL PROTECTED] > > > > ______________________________________________ > > [EMAIL PROTECTED] mailing list > > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > -- > G�ran Brostr�m tel: +46 90 786 5223 > Department of Statistics fax: +46 90 786 6614 > Ume� University http://www.stat.umu.se/egna/gb/ > SE-90187 Ume�, Sweden e-mail: [EMAIL PROTECTED] > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
