concordancefit {survival}  R Documentation 
This is the working routine behind the concordance
function. It
is not meant to be called by users, but is available for other packages
to use. Input arguments, for instance, are assumed to all be the
correct length and type, and missing values are not allowed: the calling
routine is responsible for these things.
concordancefit(y, x, strata, weights, ymin = NULL, ymax = NULL, timewt = c("n", "S", "S/G", "n/G", "n/G2", "I"), cluster, influence =0, ranks = FALSE, reverse = FALSE, timefix = TRUE)
y 
the response. It can be numeric, factor, or a Surv object 
x 
the predictor, a numeric vector 
strata 
optional numeric vector that stratifies the data 
weights 
options vector of case weights 
ymin, ymax 
restrict the comparison to response values in this range 
timewt 
the time weighting to be used 
cluster, influence,ranks, reverse, timefix 
see the help for the

a list containing the results
Terry Therneau