[R] C-statistic comparison with partially paired datasets

[Frank E Harrell Jr]

Hanneke Wijnhoven wrote:
> Does anyone know of an R-function or method to compare two C-statistics 
> (Harrells's C - rcorr.cens) obtained from 2 different models in 
> partially paired datasets (i.e. some similar and some different cases), 
> with one continuous independent variable in each separate model? (in a 
> survival analysis context)?
> I have noticed that the rcorrp.cens function can be used for paired data.
>   Thanks for any help,
> 
> Hanneke Wijnhoven
> 

Hanneke,

I'm having trouble seeing how the unpaired observations can contribute 
information in general.  If for example all of the observations were 
unpaired, one C-statistic might be larger because it came from a dataset 
with more extreme observations that were easier to discriminate.

Frank

-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University