[R] Penalised spline regression

[David Mcnulty]

Good Afternoon Everyone,

I am looking for advice fitting a linear mixed model where the random components do not seem to fit within the model formulae for lmer. The columns of Z are not stratified and have the notional random formula (z1 | 1) + ... + (zk | 1). 

Context
I am fitting a penalised thin plate spline with knots k1 to kn. The basis functions Zk are |x-ki|^3 and the penalty matrix has elements |ki-kj|^3. Rather than fit basis functions Zk I have transformed the basis to Z = Zk %*% penalty^(-1/2).

Full details are in section 2: Bayesian analysis for penalised spline regression using winBUGS. https://www.jstatsoft.org/article/view/v014i14/v14i14.pdf

I am specifically looking for an alternative to the function spm() in package semipar.

Thank you for any help or advice.

Dave.

David Mcnulty
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