R help - Feb 2011 - Fitting a model with an offset in bigglm

Dear all,

I have a large data set and would like to fit a logistic regression 
model using the bigglm function.  I need to include an offset in the 
model but when I do this the bigglm function seems to ignore it.

For example, running the two models below produces the same model and 
the offset is ignored

bigglm(y~x,offset=z,data=Test,family=binomial(link = "logit"))
bigglm(y~x,data=Test,family=binomial(link = "logit"))

Is it possible to fit an offset using bigglm? And if so, what am I doing 
wrong?

Thanks,

Richard

-- 
Dr Richard Jacques
Medical Statistics Group
School of Health and Related Research
University of Sheffield
Regent Court
30 Regent Street
SHEFFIELD
S1 4DA

Hi:

Did you try putting the offset in the model formula, as in

bigglm( y ~ offset(z) + x, ...)      ?

I haven't tried bigglm() personally (BTW, it's in the biglm package,
which
wasn't mentioned), but this syntax works in the standard glm() function, so
perhaps it maps to bigglm() as well... (?)

HTH,
Dennis

On Tue, Feb 8, 2011 at 6:16 AM, Richard Jacques
<R.Jacques@sheffield.ac.uk>wrote:
> Dear all,
>
> I have a large data set and would like to fit a logistic regression model
> using the bigglm function.  I need to include an offset in the model but
> when I do this the bigglm function seems to ignore it.
>
> For example, running the two models below produces the same model and the
> offset is ignored
>
> bigglm(y~x,offset=z,data=Test,family=binomial(link = "logit"))
> bigglm(y~x,data=Test,family=binomial(link = "logit"))
>
> Is it possible to fit an offset using bigglm? And if so, what am I doing
> wrong?
>
> Thanks,
>
> Richard
>
> --
> Dr Richard Jacques
> Medical Statistics Group
> School of Health and Related Research
> University of Sheffield
> Regent Court
> 30 Regent Street
> SHEFFIELD
> S1 4DA
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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