[R] Fitting a model with an offset in bigglm

[Richard Jacques]

Hi,

Sorry, I should have said the bigglm() is in the biglm package.

I have tried putting the offset in the model formula as you suggested 
but it doesn't make any difference.  I was comparing the results of 
bigglm() with glm() on a small data set before I applied it to the much 
larger data set, this is when I noticed that bigglm() was ignoring the 
offset.

BW

Richard

Dennis Murphy said the following on 08/02/2011 19:55:
> 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 at sheffield.ac.uk <mailto:R.Jacques at 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
> 
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