Thanks David
However, I tried your trick on val.surv with newdata=test['age'] but still
didn't work.
Still gives the same error message:
Error in val.surv(f.1, newdata = test1["age"], u = 10) :
dims [product 1797] do not match the length of object [2496]
In addition: Warning message:
In est.surv + S[, 1] :
longer object length is not a multiple of shorter object length
Salvo
________________________________
From: David Winsemius <dwinsem...@comcast.net>
Cc: "r-help@R-project.org" <r-help@r-project.org>
Sent: Sunday, August 21, 2011 12:55 AM
Subject: Re: [R] val.surv
On Aug 20, 2011, at 3:32 PM, Salvo Mac wrote:
> Dear R-users,
>
> I have two questions regarding validation and calibration of Survival
> regression models.
>
> 1. I am trying to calibrate and validate a cox model using val.surv.
> here is my code:
> f.1<-cph(Surv(time,event)~age, x=T, y=T, data=train)
> test1<-test[,"age"]
> val.surv(f.1, newdata=data.frame(test1), u=10)
>
> but I get an error message:
>
> Error in val.surv(f.1, newdata = data.frame(testi), u = 10) :
> dims [product 1797] do not match the length of object [2496]
> In addition: Warning message:
> In est.surv + S[, 1] :
> longer object length is not a multiple of shorter object length
>
> I ran the example in the r-documentation but couldn't extract dxy from
>result.
>
> What am I doing wrong?
The fundamental thing you are doing wrong for q1 is failing to unambiguously
describe the test object. I would think that if test were a dataframe then
wrapping data.frame around a vector might not get it named correctly as 'age'.
You might try newdata= test['age']. Just a guess.
>
> 2. In validate and calibrate cph functions. If it is frailty fit, does the
>the bootstrap resample clusters or just individuals
The code above appears to be dependent on the rms package. The frailty function
is part of the underlying survival package and I do not see it mentioned in the
index for Harrell's RMS text. You will probably need to wait until Frank comes
across this. He is generally very good about correction my errors and knowledge
gaps.
>
--
David Winsemius, MD
West Hartford, CT
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