[R-sig-ME] Help! What are the typical diagnosis that one can do when, facing

[Ben Bolker]

Highland Statistics Ltd <highstat at ...> writes:


> > Help! What are the typical diagnosis that one can do when facing "fail to
> > converge"?
> > Could anybody please shed some lights on us, besides increasing the number
> > of iteration limit?

  [snip]

> 1. Simplify your model
> 2. Center or standardise your covariates
> 3. Increase the number of iterations
> 4. Lower the convergence criteria
> 5. Provide starting values.

  Very nice.

  #6 try an alternative package/optimization platform, if one
is available (in this case, if you are using a complex model
for heteroscedasticity and want to stay within R, probably not ...)
> 
> Most likely you will need to do 1.
> 2 may work....
> 3-5 is for if you are stubborn and don't want to do 1.
> 
> For a more specific answer you will need to provide more details.