Hi R-users

 

I am trying to use the GAM function of the mgcv package. But I am having
problem trying to specify the k parameter.

 

Although I managed to run some models by giving to the parameter some
(random) value, and it is explained by Wood (2006) that it does not seem
to "really" affect the final result, I would like to grasp better its
meaning.

 

I understand that is the 'basis dimension'. Is that refer to the order
of the function used as smother (i.e. for a cubic regression spline it
is 3)? Also it shouldn't be bigger than the number of unique covariate
values. But what is the minimum value it can get? I think it has to do
with the penalty (i.e. the integrated square of the second order
derivative of the smoother function) and the penalty order (m).

 

I would very much appreciate any help or examples you might give to fill
in some of my (many) knowledge gaps

 

Thanks 

 

Lorenzo   


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