[R] iteration limit error in gamm and notExp2

Simon Wood s.wood at bath.ac.uk
Fri Apr 24 11:23:41 CEST 2009


Isidora,

What is the actual model structure that you are trying to fit? 

It's not clear to me that modifying the nonExp2 defaults will help convergence 
here, but it may be that some slight modifications of the model itself will 
sort things out, which is why it would be good to know what the model is. One 
issue with `gamm' is that it is built on PQL estimation, so there is no 
guarantee that fitting will converge, although it usually does. 

best,
Simon

On Thursday 23 April 2009 19:40, isidora k wrote:
> hi,
> I am trying to run a mixed effect gam using gamm (mgcv)
> and I get the following error:
> "Error in lme.formula(y ~ X - 1, random = rand, data = strip.offset(mf),  :
> nlminb problem, convergence error code = 1 message = iteration limit
> reached without convergence (9)"
>
> I've read all about  'notExp2' but since I am not an expert I didn't
> understand that much. I was wondering if anyone has an example of the use
> of notExp2, or another suggestion on solving this problem.
>
> many thanks
> Isidora
>
>
>
> 	[[alternative HTML version deleted]]
>
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-- 
> Simon Wood, Mathematical Sciences, University of Bath, Bath, BA2 7AY UK
> +44 1225 386603  www.maths.bath.ac.uk/~sw283




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