May, Roel wrote:> Hi,
>
> I have been trying to get the cph() function of the Design package to work
but get an error message I don't understand:
>
> Error in if (!length(fname) || !any(fname == zname)) { :
> missing value where TRUE/FALSE needed
>
> I have tried the same for a dummy dataset I made, and than it seems to work
fine. However, it doesn't do it for my own data. Does anyone have a clue as
to what this message means, whether I have made a mistake somewhere(although it
seems ok to me?) and especially how to solve this problem. I know I could have
used coxph() instead, but I'd like to predict the outcome on another dataset
and coxph() does not allow for interaction terms...
>
> I hope anyone can help me here. Underneath is the code I used for my data,
if it's of any use...
>
> Thanks, cheers Roel
>
> Roel May
> NINA, Norway
> modeldata <- as.data.frame(modeldata)
>
> survchoice<-Surv(2-modeldata$USED,is.element(modeldata$USED,1))
>
> d <-
datadist(modeldata$ID,modeldata$ASP_NW,modeldata$ALT,modeldata$SLOPE,modeldata$PLACEMENT,modeldata$DTL,modeldata$TRACK,modeldata$PRIVATE,modeldata$BUSH,modeldata$ROCK,modeldata$GRASS,modeldata$WATER,modeldata$RUGGED,modeldata$CABIN,data=modeldata)
>
Don't use $ in input arguments to datadist. Use the whole data frame or
use with( ).
> options(datadist="d")
>
>
options(contrasts=c("contr.treatment","contr.treatment"))
Remove. This is the default.
>
> interactmodel <-
cph(survchoice~(ASP_NW+RUGGED+SLOPE+GRASS:PLACEMENT+PRIVATE+BUSH:ROCK+RUGGED:ROCK+DTL)+strat(ID),data=modeldata,method="breslow",y=TRUE,x=TRUE,surv=TRUE)
Use * for interactions and to make sure your model follows the hierarchy
principle.
Next time please also give the version of Design you are using.
Frank
>
>
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--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University