The number of knots is really one of the modelling assumptions. Provided you don't make it restrictively small then the results should not be very sensitive to this assumption, since the actual degrees of freedom of each smooth are determined by how heavily the smooth is penalized, rather than simply being the number of knots. The degree of penalization is selected automatically by GCV or AIC/UBRE.
See ?choose.k in the `mgcv' help files for more information on this, as well as information on checking whether the assumed number of knots was large enough. Simon On Tuesday 28 November 2006 22:40, Kathryn Baldwin wrote: > Hi > I was wondering if anyone knew how to work out the number of knots that > should be applied to each variable when using gams in the mgcv library? > Any help or references would be much appreciated. > Thanks > Kathryn Baldwin > > ______________________________________________ > [email protected] 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. -- > Simon Wood, Mathematical Sciences, University of Bath, Bath, BA2 7AY UK > +44 1225 386603 www.maths.bath.ac.uk/~sw283 ______________________________________________ [email protected] 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.
