[R] ref.df in mgcv gam

[Susan Elias]

Thank you, Dr. Wood, that is very helpful.

Best,

Susan


On Wed, Mar 27, 2019 at 12:10 PM Simon Wood <simon.wood using bath.edu> wrote:

> These are a bit of a throwback really, and are not very useful - they
> are reference degrees of freedom used in computing test statistic and
> the p-values, but since the null distributions are non-standard the
> reference DoF is not very interpretable.
>
> best,
>
> Simon
>
> On 27/03/2019 13:58, Susan Elias wrote:
> > Hello Group.
> >
> > Regarding degrees of freedom in GAM models fit by mgcv, I do understand
> the
> > estimated df, but what does "ref.df" in the summary output mean?
> >
> > I didn't see an explanation in Wood (2017) or find it in the function
> > code.  The answer may be on page 222 of
> >
> > Wood SN. On p-values for smooth components of an extended generalized
> > additive model. Biometrika 2013;100(1):221-228
> >
> > or thereafter, but I am not a statistician.  I could use help
> understanding
> > what the reference degrees of freedom are.
> >
> > Thank you,
> >
> > Susan
> >
> >
> >
> >
> --
> Simon Wood, School of Mathematics, University of Bristol, BS8 1TW UK
> https://people.maths.bris.ac.uk/~sw15190/
>
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-- 
Susan Elias
PhD Candidate, School of Earth and Climate Sciences, University of Maine
Research Associate, Vector-borne Disease Lab, Maine Medical Center Research
Institute
207-756-2761

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