hongyuan cao wrote:
> Dear R users,
>
> I tried to fit a cox proportional hazard model to get estimation of
> stratified survival probability. my R code is as follows:
>
> cph(Surv(time.sur, status.sur)~ strat(colon[,13])+colon[,18]
> +colon[,20]+colon[,9], surv=TRUE)
> Error in if (!length(fname) || !any(fname == zname)) { :
> missing value where TRUE/FALSE needed
> Here colon[,13] is the one that I want to stratify and the others are all
> coefficients. How can I solve this problem? Thanks a lot!!!!!
>
> Grace
The Design package does not like you to have complex variable names like
that, and in general storing your data in a matrix when you want to
treat columns as separate variables is not the best approach. I would
use something like
S <- with(d, Surv( ) ) # d = data frame
h <- as.data.frame(colon) # assumes colon is a matrix;make sure it had
column names
cph(S ~ strat(v1)+v2+v3+v4, data=h)
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
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