Thanks.


On Tue, Mar 26, 2013 at 4:45 AM, Simon Wood <s.wood@bath.ac.uk> wrote:

> For 1) see reply just sent to R help...
> "Re: [R] Use pcls in "mgcv" package to achieve constrained cubic spline"
> (I'm assuming you mean to fix the value of the smooth at a particular knot
> location - i.e. to impose a constraint like f(t_0) = b).
>
> For 2) try 'model.matrix', or 'predict.gam' with argument
> 'type="lpmatrix"' (see ?predict.gam)
>
>
> On 23/03/13 01:05, Antonio P. Ramos wrote:
>
>> Hi all,
>>
>> I am using GAM to model time trends in a logistic regression. Yet I would
>> like to extract the the fitted spline from it to add it to another model,
>> that cannot be fitted in GAM or GAMM.
>>
>> Thus I have 2 questions:
>>
>> 1) How can I fit a smoother over time so that I force one knot to be at a
>> particular location while letting the model to find the other knots?
>>
>
>  2) how can I extract the matrix from the fitted GAM so that I can use it
>> in
>> as an impute for a different model.
>>
>> The types of models I am running are to the following form:
>>
>> gam <- gam(mortality.under.2~ maternal_age_c+ I(maternal_age_c^2)+
>> s(birth_year,by=wealth2) +
>>               + wealth2 + sex +
>>               residence+ maternal_educ + birth_order,
>>             ,data=colombia2,family="**binomial")
>>
>> I've read the extensive documentation for the GAM but I am not sure still.
>> Any suggestion is really appreciated.
>>
>> Thanks,
>>
>> Antonio Pedro
>>
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>>
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>>
>>
>
> --
> Simon Wood, Mathematical Science, University of Bath BA2 7AY UK
> +44 (0)1225 386603               http://people.bath.ac.uk/sw283
>

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