[R] no. at risk in survfit()

array chip arrayprofile at yahoo.com
Fri Feb 4 21:01:33 CET 2005


Hi,

when I generated a survfit() object, I can get number
of patients at risk at various time points by using
summary():

fit<-survfit(Surv(time,status)~class,data=mtdata)
summary(fit)

                    class=1
 time n.risk n.event survival std.err lower 95% CI
upper 95% CI 
  9.9     78       1    0.987  0.0127  0.963     1
 41.5     77       1    0.974  0.0179  0.940     1
 54.0     76       1    0.962  0.0218  0.920     1
 99.1     38       1    0.936  0.0328  0.874     1

                   class=2
  time n.risk n.event survival std.err lower 95% CI
upper 95% CI 
   6.9    102       1    0.990 0.00976 0.971   1.000
   8.0    101       1    0.980 0.01373 0.954   1.000
  14.4    100       1    0.971 0.01673 0.938   1.000
  16.1     99       1    0.961 0.01922 0.924   0.999
  16.6     98       1    0.951 0.02138 0.910   0.994
  18.7     97       1    0.941 0.02330 0.897   0.988
   :
   :
   :

I have many censoring observations in the dataset, and
I would like to know the number of patients at risk
(n.risk in the above output) for certain time points,
for example at 60, 72, etc, which is not available
from the above printout for class=1. Is there anyway I
can get them?

Thanks




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