[R] problems with printing and plotting aareg

Terry Therneau therneau at mayo.edu
Fri Oct 5 16:46:22 CEST 2012

It's a bug in summary.aareg which no one found until now.

What's wrong:
If dfbeta=TRUE then there is a second estimate of variance calculated, labeled as 
test.var2. If maxtime is set, then both estimates of variance need to be recalculated by 
the summary routine.  An incorrect if-then-else flow led it to look for test.var2 when it 
wasn't relevant.  My test cases with maxtime also happened to have dfbeta=TRUE.

Short term solution: set dfbeta=TRUE.  A bit more computation time though.
Long term: I'll fix it, and a new version of survival will one day appear.  (With 200+ 
packages that depend on survival, new releases now require a lot of checking.  No 
overnight fixes).

Terry T

On 10/05/2012 05:00 AM, r-help-request at r-project.org wrote:
> Hi all,
> I've ventured into the world of nonparametric survival and I would like to use the "maxtime" option for printing and plotting my aareg fit.
> However, my fit does not have "test.var2" and this stops the print and plot when adding a maxtime.
> My code is as follows:
> Response<-Surv(Time,Event)
> Model<-aareg(Response~Factor1*Factor2)
> Model2<-aareg(Response~Factor1+Factor2)  #Just did this to see if the interaction term had anything to do with it
> Model, print(Model), summary(Model), and plot(Model) seem to work fine, but as soon as I try summary/print/plot(Model, maxtime=400) it tells me that test.var2 is not found and when I look at  summary(Model), there is indeed a NULL under test.var2.
> Anyone know why it doesn't include test.var2? Is this a compatibility problem? I'm using R version 2.13 (I know it's quite old, but updating is a pain when you don't have admin rights to your computer) and just updated the survival package (no warning messages).
> Any input would be much appreciated.
> Cheers,
> Freya

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