Level 1 is treated as the "baseline". The coefficient for level 2 for example is for the hazard ratio between level 2 and level 1. Same thing for levels 3,4,5 in the output.
HTH, On Sun, 6 Nov 2005, bertrand wrote: > Hello, > i'm a french student of medical oncology and i'm working on breast > cancer. I have a variable with the histologic type of tumor wich is > between 1 and 5. I use as.factor function to make some variable with > level between 1 and 5. When i put it in the cox model i have only the > level between 2 and 5. The level 1 doesn't appear. I think i have to > change the number of level but i don't really know. Please can you help > me? > > > Class > Levels: 1 2 3 4 5 > coxph(formula = Surv(delai.etat, etat) ~ class, data = igr1) > > > coef exp(coef) se(coef) z p > class2 -0.093 0.911 0.245 -0.38 7.0e-01 > class3 -0.749 0.473 0.286 -2.62 8.9e-03 > class4 -0.600 0.549 0.343 -1.75 8.0e-02 > class5 -0.874 0.417 0.197 -4.44 8.9e-06 > > Likelihood ratio test=24.9 on 4 df, p=5.28e-05 n=740 (1 observations > deleted due to missing) > > > > Thanks for your help > > > Bertrand > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > !DSPAM:436dcb0b22713230529779! > ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
