search for: cstatisticci

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2011 May 22
1
How to calculate confidence interval of C statistic by rcorr.cens
Hi, I'm trying to calculate 95% confidence interval of C statistic of logistic regression model using rcorr.cens in rms package. I wrote a brief function for this purpose as the followings; CstatisticCI <- function(x) # x is object of rcorr.cens. { se <- x["S.D."]/sqrt(x["n"]) Low95 <- x["C Index"] - 1.96*se Upper95 <- x["C Index"] + 1.96*se cbind(x["C Index"], Low95, Upper95) } Then, > MyModel.lrm.rcorr <-...