I have two alternative Cox models with C-statistics 0.72 and 0.78. My question is if 0.78 is significantly greater than 0.72. I'm using rcorrp.cens. I cannot find the U statistics in the output of the function. This is the output of the help example:
> x1 <- rnorm(400) > x2 <- x1 + rnorm(400) > d.time <- rexp(400) + (x1 - min(x1)) > cens <- runif(400,.5,2) > death <- d.time <= cens > d.time <- pmin(d.time, cens) > rcorrp.cens(x1, x2, Surv(d.time, death)) Dxy S.D. x1 more concordant x2 more concordant n missing uncensored Relevant Pairs -8.902077e-03 2.649712e-01 4.955490e-01 5.044510e-01 4.000000e+02 0.000000e+00 4.000000e+00 1.348000e+03 Uncertain C X1 C X2 Dxy X1 Dxy X2 1.582520e+05 9.955490e-01 9.762611e-01 9.910979e-01 9.525223e-01 Should I manually calculate the U statistics interpreting the fraction "x1 more concordant" and "x2 more concordant" of the "Relevant Pairs" as Uxy and Uyx? many thanks for any help or suggestion Pietro Bulian ______________________________________________ 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.