[R] error message in cox regression cph()

[Frank E Harrell Jr]

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