-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Terry,
I attached a small data set to this email. This is what I get (I
restricted the formula to avoid NA's):
> surv = with(small, Surv(time=absence, event=(censored==FALSE)))
> (cox.s = coxph(surv ~ bucket*(today) + strata(activity), data =
> small))
Call:
coxph(formula = surv ~ bucket * (today) + strata(activity), data = small)
coef exp(coef) se(coef) z p
bucket575 0.4526 1.572 0.740 0.612 0.54
todayTRUE -0.0886 0.915 0.676 -0.131 0.90
bucket575:todayTRUE -0.1670 0.846 0.794 -0.210 0.83
Likelihood ratio test=2.32 on 3 df, p=0.509 n= 100, number of
events= 100
> fit = survfit(cox.s, newdata=small[1:50,])
Error in model.frame.default(data = small[1:50, ], formula = ~bucket + :
number of variables != number of variable names
>
also:
> R.version
_
platform x86_64-redhat-linux-gnu
arch x86_64
os linux-gnu
system x86_64, linux-gnu
status
major 2
minor 15.1
year 2012
month 06
day 22
svn rev 59600
language R
version.string R version 2.15.1 (2012-06-22)
nickname Roasted Marshmallows
package ‘survival’ is version 2.36-14
and finally, variable absence is numeric, bucket & activity are
factors and all other variables are logical.
I tested the same formula without 'strata' and I had no problem.
Best and thank you,
ge
On 11/19/2012 09:01 AM, Terry Therneau wrote:
> I can't reproduce the problem.
>
> Tell us what version of R and what version of the survival
> package. Create a reproducable example. I don't know if some
> variables are numeric and some are factors, how/where the "surv"
> object was defined, etc.
>
> Terry Therneau
>
>
>
> On 11/17/2012 05:00 AM, r-help-requ...@r-project.org wrote:
>> This works ok:
>>
>>>> cox = coxph(surv ~ bucket*(today + accor + both) + activity,
>>>> data
>>> = data)
>>>> fit = survfit(cox, newdata=data[1:100,])
>> but using strata leads to problems:
>>
>>>> cox.s = coxph(surv ~ bucket*(today + accor + both) +
>>> strata(activity),
>>>> data = data) fit.s = survfit(cox.s, newdata=data[1:100,])
>> Error in model.frame.default(data = data[1:100, ], formula =
>> ~bucket + : number of variables != number of variable names
>>
>> Note that the following give rise to the same error:
>>
>>>> fit.s = survfit(cox.s, newdata=data)
>> Error in model.frame.default(data = data, formula = ~bucket +
>> today + : number of variables != number of variable names
>>
>> but if I use data implicitly, all is working fine:
>>>> fit.s = survfit(cox.s)
>> Any idea on how I could solve this?
>>
>> Best, and thank you,
>>
>> ge
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