Dear David,

Thank you for your reply.  I have come across rcorrp.cens before.  However,
I'm not sure it does quite what I want it to.  It seems to compare whether
one predictor is more concordant than another within the same survival
function.  I want to see whether one predictor is more concordant than
another over two survival functions hence I fitted two rcorrcens functions.

E.g. if I have a development data set with a variable for age and a
validation data set for age then I want to know if the concordance is the
same over the development and validation data sets.

Thank you,
Laura

On 5 May 2011 16:09, David Winsemius <dwinsemius@comcast.net> wrote:

>
> On May 5, 2011, at 8:20 AM, Laura Bonnett wrote:
>
>  Dear All,
>>
>> I am trying to calculate a 95% confidence interval for the difference in
>> two
>> c statistics (or equivalently D statistics).  In Stata I gather that this
>> can be done using the lincom command.  Is there anything similar in R?
>>
>
> Have you looked at rcorrp.cens {Hmisc}?
>
> <snipped>
>
>>
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>>
>
>
> Please post in plain text.
>
> --
> David Winsemius, MD
> West Hartford, CT
>
>

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