[R] Why are the number of coefficients varying? [mgcv][gam]

[Andrew Crane-Droesch]

Hi Simon,

Thanks for replying.

On further investigation, I can't reproduce this error on my local 
machine -- it only occurs when sending to a cluster (to run the multiple 
imputations in parallel) that I've got access to.  I send to a friend's 
web server, and I get the same sort of error (but a different set of 
results!) that the cluster gave me.  The seed is set identically across 
the three machines.  gam.check indicates convergence after 16 iterations 
locally, but 21 iterations on both remote machines.  And both remote 
machines give results that penalize the random effects, and the first, 
second and fourth spline terms effectively to zero (res.df ~1e-7).

I then checked versions.  My local machine has mgcv 1.7.22, the cluster 
has 1.7.3, and the server has 1.7.12.  My local machine has R 2.15.1, 
the cluster has 2.12.2, and the server has 2.14.1.  I updated the 
server's R version, and the result was fixed.  Will see if the people 
who manage the cluster can update the cluster.

The tryCatch is there because my imputation models that feed the gams 
are not bug-free.

Thanks anyway for replying.

Best,
Andrew